shuddering regal, rough idle


david95
01-17-2011, 07:34 PM
I have a 95 Buick Regal, V6 3.8 Liter. The symptoms are the following: stuttering idle. And lack of response at times when I try to accelerate. Like sometimes Iíll be driving on the highway, and having no problems. Then Iíll be going up a hill at around 55 mph, and then the car will shudder as I try to maintain a speed of 55 mph. So I have to ease off the accelerator and slow down. At first I thought this was a transmission problem, but Iím guessing itís the same problem that causes my choppy idle.
So I had this acceleration problem on the highway when I was going up a hill. And a weak idle. These problems have been going on for several months now. They were annoying, but didnít seem that serious. Then all of a sudden, on a rainy day, the car was really responding poorly to acceleration at all speeds. I was able to drive around, but I couldnít count on the car responding right away when I hit the gas pedal. And the car would shudder at times.
Then, I didnít drive the car for a few days, and then it was dry, no rain, and the car ran better. So Iím thinking humidity makes the problem worse.
I have also noticed over the past few months, that the car runs best when I start it up after a few days of not running it. Then if I drive the car a few miles and let it sit for about 2 hours or so, it would idle weakly when I would start it up again. The carís been doing that for several months now, but it wasnít really affecting the drivability or the response of the car when I hit the gas pedal.
Now itís gotten much worse. So, Iíve already replaced the following items myself to no avail: mass air flow sensor, oxygen sensor, and egr valve. Iím guessing the next thing to fix is the pcv valve. But I also think it might be the fuel pump. My first guess though is the pcv valve.
What else could it be? And is there any easy way to test to see if the fuel pump is going bad? Or should I just take out the pcv valve and see if it looks bad?

maxwedge
01-18-2011, 03:21 PM
Welcome to AF. There is no quick diagnosis for this, from here your description sounds like an engine misfire, how old are the plugs and wires? Any cel? have you scanned it for misfire codes? You are just throwing parts at this with no idea of where you are. Test fuel pressure also.

david95
01-18-2011, 04:53 PM
Welcome to AF. There is no quick diagnosis for this, from here your description sounds like an engine misfire, how old are the plugs and wires? Any cel? have you scanned it for misfire codes? You are just throwing parts at this with no idea of where you are. Test fuel pressure also.

Thanks for the post maxthread. Unfortunately you are right, I am just throwing parts at the car. I'm not getting a check engine light, and I put new spark plugs in 10k miles ago. The wires were checked at that time and were supposedly ok. So I'm thinking it's not the plugs or the wires.
I'll get the fuel pressure tested though, that's a good idea. Is there an easy way to test the fuel pressure, or do I have to take it to a shop to get tested?

richtazz
01-20-2011, 09:21 AM
David,

If you do a lot of work on your own cars, a fuel pressure tester would be a wise investment. You can get a decent one from Actron for around $30-$35 and they are a nice unit. One diagnostic fee at a garage would cost as much or more.

enslow
01-20-2011, 09:36 AM
1) check the coils.
2) either replace the wires or reseat them all and use dielectric grease in all boots (at the coils too).

It's also a wise investement to get yourself a good scantool. I like the AutoXray, but I'm sure there are others that don't cost too much ($3-500 instead of thousands). Beware though, some cheaper scantools don't sample data frequently enough to be very useful.

david95
01-20-2011, 05:47 PM
David,

If you do a lot of work on your own cars, a fuel pressure tester would be a wise investment. You can get a decent one from Actron for around $30-$35 and they are a nice unit. One diagnostic fee at a garage would cost as much or more.

Thanks for the idea richtazz. What do I connect the fuel pressure tester to? Does the car need to be running when I test it? Thanks for your help. This problem has got me seriously confused and frustrated.

david95
01-20-2011, 05:51 PM
1) check the coils.
2) either replace the wires or reseat them all and use dielectric grease in all boots (at the coils too).

It's also a wise investement to get yourself a good scantool. I like the AutoXray, but I'm sure there are others that don't cost too much ($3-500 instead of thousands). Beware though, some cheaper scantools don't sample data frequently enough to be very useful.

Thanks enslow for the reply. I must admit I'm a bit confused, dumb, or slow, but what do you mean by "check the coils". Is that the distributor? And what kind of tool do I need to check the coils? I'm trying to do as much of the work as I can by myself, and I don't mind getting the right tools, but I haven't done any work on spark plugs or wires before, so I probably don't know the proper terminology.

enslow
01-20-2011, 10:02 PM
As far as I know, a 95 Regal doesn't have a distributor. The spark timing is determined by the computer.

If you look at the plugs, you will see wires that go to three "black boxes" bolted to the side of the engine. These are the coils. You can buy a coil tester from KMS tools or similar stores that sell automotive tools. It comes with instructions. Sometimes a coil can be intermittent, though. If you know some one with a 3.8, you could try swapping coils and see if that fixes your problem.

Wires are cheap, so I'd replace them anyway. I usually stay with GM wires, they seem pretty good. Just make sure they follow the same routing as the old ones you remove. I usually do one at a time so I guarrantee the go on the way the came off.

There are other causes for your symptoms, but I consider plugs AND wires to be part of a regular maintainance thing. If you get your hands on a good scantool, you can determine what plug is misfiring. Then you can move coils around and see if the missfire moves to a new cylinder. If so, then it's your coil.

david95
01-21-2011, 06:20 PM
As far as I know, a 95 Regal doesn't have a distributor. The spark timing is determined by the computer.

If you look at the plugs, you will see wires that go to three "black boxes" bolted to the side of the engine. These are the coils. You can buy a coil tester from KMS tools or similar stores that sell automotive tools. It comes with instructions. Sometimes a coil can be intermittent, though. If you know some one with a 3.8, you could try swapping coils and see if that fixes your problem.

Wires are cheap, so I'd replace them anyway. I usually stay with GM wires, they seem pretty good. Just make sure they follow the same routing as the old ones you remove. I usually do one at a time so I guarrantee the go on the way the came off.

There are other causes for your symptoms, but I consider plugs AND wires to be part of a regular maintainance thing. If you get your hands on a good scantool, you can determine what plug is misfiring. Then you can move coils around and see if the missfire moves to a new cylinder. If so, then it's your coil.

enslow, you're correct. The 95 Regal, 3800 V6 doesn't have a distributor. I'll check the coils next to see if they are the problem after I take a look at the PCV valve.

Right now, I'm trying to check the PCV valve. However, my manual is leading me to the wrong spot. It was telling me the PCV valve was under the MAP sensor. But I think the PCV valve is to the left of the engine, and to the right of the alternator. There's a cylindrical thing attached to the engine with "PCV" written in two places on top. That seems to be a pretty obvious indicator that it's the PCV valve.

So assuming that's the PCV valve, but unfortunately I'm still stuck. I'm trying to get the PCV valve off, and I can't figure out how to do it. I'm guessing I have to push down and turn it counter-clockwise, but I can't get any force on it. Is there a special tool you need to remove the PCV valve? What makes it tough is I have some wiring running right on top of the PCV valve, and I have to use one hand to hold the wiring out of the way, which only leaves me one hand to try to rotate the PCV valve.

enslow
01-21-2011, 08:32 PM
Mine was pretty tough to get off at first also. Basically yeah, push and turn. Good luck! Mine is on the front side and easy to get at. :P

richtazz
01-22-2011, 09:04 AM
use a bungee cord to hold the wiring out of the way (ghetto, but it works) then as enslow said, it's just push and turn. The PCV valve is under the MAP on Vin-K 3800's, not on the Vin-L engine in your car, so your repair manual is incorrect.

As far as where to check the fuel pressure, there is a schrader valve with a black cap on it near the fuel pressure regulator, this is where you attach the fuel pressure gauge. Check the pressure with the key on/engine off first (should be 41-44 psi), then start the engine and it should drop 3-7 psi. With the engine still running, pull the vacuum hose off the regulator and the readings should jump back up to near key on/engine off readings.

enslow
01-22-2011, 11:47 AM
...
As far as where to check the fuel pressure, there is a schrader valve with a black cap on it near the fuel pressure regulator, this is where you attach the fuel pressure gauge. Check the pressure with the key on/engine off first (should be 41-44 psi), then start the engine and it should drop 3-7 psi. With the engine still running, pull the vacuum hose off the regulator and the readings should jump back up to near key on/engine off readings.

One further test with the fuel pressure test: Goose the throttle a little while watching the fuel pressure. It should not drop.

david95
01-24-2011, 09:45 PM
Well, I was finally able to get the PCV valve cover off. I used the two prongs of a wrench to push into the grooves of the PCV valve cover, and then I was able to get enough leverage to twist it counter-clockwise. It only cost $3 for the new PCV valve. The clerk at the auto parts shop said they're supposed to replace the PCV valve with every oil change. However, I doubt it's ever been replaced. I'm not sure what imaginary repair shop he's talking about when he says they should change the PCV valve with the oil change.
Anyway, I noticed the old PCV valve was coated in oil, and the ring had slid down halfway on the bottom part of the PCV valve. That may have happened when I removed it. I could shake the old PCV valve and it rattled, so I don't think it had stopped functioning altogether.
I installed the new PCV valve, and then started up the Buick. I hadn't started the car in over a week, so it sounded a bit choppy and unsteady at first. but then the engine smoothed out, and it sounded much better than the last time I started it. There still is an occasional lull or break in the engine idling, like a spark plug is missing. But it is improved.
However, it was a clear, dry, cool day in Austin, about 50 degrees. I'll have to try the Buick again when it's raining, because that's when the engine has responded horribly in the past. I think there's an improvement, but I'll give it another try soon and make sure. There still is something else going on though, and I suppose I'll check the coils, plugs, and wires next. But I'm optimistic that the new PCV valve actually improved the engine situation.
I'll post again soon when I've started it up again.

david95
01-24-2011, 09:55 PM
Hey, richtazz and enslow, thanks for the tips on how to check the fuel pressure. I'll definitely check that too. I'll probably do it this coming weekend. I'm getting run ragged at work this week and I'm guessing next weekend will be my next chance with some free time.
For some reason, I don't think it's a fuel pump problem, but of course I could be wrong. It's the fact that the engine runs differently based on the humidity (i.e., runs good in dry air, runs terribly in the rain) and that it runs best when I haven't started it in over 12 hours vs. runs poorly when I've driven it 2 or 3 hours prior and then start it up again.
I'm not sure what to make of those clues, but that makes me think it's something with the engine, fuel injection, plugs, wires, or anything that would change based on moisture in the engine, in the oil...?? Frankly, I've got a bunch of guesses but haven't found the solution yet. But I definitely feel like I'm getting closer. And thanks so much for your help, richtazz and enslow, sometimes I get stumped and frustrated and it's good to get some feedback on what to try.

david95
01-26-2011, 08:13 PM
I still have the shuddering, non-responsive problem. I started the car this morning, and it sounded fine at first, and so I took it for a drive. Then as I was stopped at a red light, the engine started misfiring and the RPM meter was jumping up and down as I sat waiting at the red light. Then the car stopped responding normally when I pressed on the accelerator. I could still get around, and the car didn't stall on me, but the engine was clearly not functioning normally.
I guess the next thing I'll check is the fuel pressure. I'm starting to think it could be a fuel pressure problem after all. The engine problems today had nothing to do with humidity or rain.
I'll go to the auto parts store on saturday and get a fuel pressure gauge. I'll post back with the results.

enslow
01-26-2011, 11:56 PM
Did you ever reseat your plug wires or get new wires? Did you ever check the coils? I didn't see from your responses that you did any of this yet.

david95
01-27-2011, 08:35 AM
Did you ever reseat your plug wires or get new wires? Did you ever check the coils? I didn't see from your responses that you did any of this yet.

enslow, no I haven't reseated the plug wires, and no I haven't checked the coils yet. I've never installed plug wires before, and I'm a bit intimidated by the process. I tried to take a plug wire off a few years ago and the damn thing wouldn't come off. So I've stayed away from them since then.

How do the plug wires come off the plugs? Do you just pull and twist? Is there any special technique to use? Is it possible to break the plug wires when you're pulling them off? I guess I've never really understood how the plug wires attach to the plugs, especially since I've never removed them before.

enslow
01-27-2011, 09:47 AM
enslow, no I haven't reseated the plug wires, and no I haven't checked the coils yet. I've never installed plug wires before, and I'm a bit intimidated by the process. I tried to take a plug wire off a few years ago and the damn thing wouldn't come off. So I've stayed away from them since then.

How do the plug wires come off the plugs? Do you just pull and twist? Is there any special technique to use? Is it possible to break the plug wires when you're pulling them off? I guess I've never really understood how the plug wires attach to the plugs, especially since I've never removed them before.

I think it's time to do what you should have done first. Plugs and wires.. It's really not that bad. If you're worried about routing, take a couple of digital pictures.

If you don't already have one, get a Haynes manual, or if you are prepared to wait, get a factory service manual off ebay (even better). Plugs wires just pull straight off. If they've been on for awhile (a few years it seems!) the wire boots may be fused to the plugs so you'll just have to twist, rock, and pull harder. Wear a pair of leather gloves while you do this, especially for the plugs at the back, and your knuckles will thank you. On the rear plugs you may find little heat shields around each boot. This does make the the wires harder to remove, but they come off the same way, just pull.

In general, I'd do the following:
1) take pictures for wire routing.
2) use making tape to number the wires.
3) remove the wires from the plugs, one at a time.
4) remove corresponding plug using a socket for plugs. (there's usually one in a simple tool kit).
5) Gap the new plugs according to the gap specified in the manual. Install and tighten to the torque specified in the manual.
6) smear in a little dielectric grease inside the boots of the new wire.
7) install the wire along the same path as the old until you hear or feel a distinct "click" as the contacts make contact. Be sure to reinstall the heat shield around the rear rear boots.

If you've done O2 sensors, and the other sensors, you're capable of doing this yourself. I wouldn't even bother checking the coil yet, just change the plugs and wires and see how it goes. I'd bet it's just been plugs/wires all along.

BTW, everything you replaced already could have been tested before replacing. It's expensive to just throw parts at a car until something gets fixed. About the only things I'd change without testing are plugs, wires, filters, and oil.

Do this, good luck, and let us know!

enslow
01-27-2011, 09:50 AM
... Is it possible to break the plug wires when you're pulling them off?....


Who cares? You should put new ones in anyway! But, they're pretty hard to brake. If it does, it really did need replaceing in the first place!

To be safe, I'd get GM plugs and wires. They won't really break your bank. There are some good aftermarket wires and plugs, but there are some lousy ones too.

david95
01-28-2011, 08:03 PM
Who cares? You should put new ones in anyway! But, they're pretty hard to brake. If it does, it really did need replaceing in the first place!

To be safe, I'd get GM plugs and wires. They won't really break your bank. There are some good aftermarket wires and plugs, but there are some lousy ones too.

Enslow- I'll definitely replace the plugs and wires. However, I just created another problem. I was looking for the fuel pressure regulator and the schrader valve, and I knocked off a line/tube running from some delco part to another part (which has two tubes connected to it, and then a third tube running to the fuel pressure regulator). I don't know what the other part is either. I'm attaching a picture of the delco part. I have no idea what this part is. I didn't hit the tube that hard to make it break, so maybe it's been about to break, or maybe this is what's been causing the problems with my engine. I looked at my manual and I couldn't figure out what this part is. I was thinking maybe it's the idle air control valve, or the camshaft position sensor, but after checking out those parts, I don't think that's what it is. Do you know what this part is? I clearly need to fix that line, but I don't know what it is.

david95
01-29-2011, 10:07 AM
Here's another picture, showing more of the engine. The part where the line/tube is broken is the part with the light blue and red three-wire connector running to it. It's above and to the right of the fuel pressure regulator. There are 2 tubes running from that part, and one of the tubes broke off. I'm trying to put the tube back in there and use electrical wire to keep it attached for now, but clearly I need to replace that tube. I just don't know what part it is, and so I can't order the right part for it. Any idea what that thing is? And the tube that is broken runs to black, plastic thing in the center of the picture. That central thing (not sure what it is) has two smaller tubes running to it, and then a third bigger tube running out of it going to the right (from the picture point of view). I wish my manual actually had pictures or described these parts. But it doesn't. It's a Haynes repair manual. I really need to get the factory service manual.

enslow
01-29-2011, 01:11 PM
Here's another picture, showing more of the engine. The part where the line/tube is broken is the part with the light blue and red three-wire connector running to it. It's above and to the right of the fuel pressure regulator. There are 2 tubes running from that part, and one of the tubes broke off. I'm trying to put the tube back in there and use electrical wire to keep it attached for now, but clearly I need to replace that tube. I just don't know what part it is, and so I can't order the right part for it. Any idea what that thing is? And the tube that is broken runs to black, plastic thing in the center of the picture. That central thing (not sure what it is) has two smaller tubes running to it, and then a third bigger tube running out of it going to the right (from the picture point of view). I wish my manual actually had pictures or described these parts. But it doesn't. It's a Haynes repair manual. I really need to get the factory service manual.

If I get a chance I'll look in my FSM, but I'm sure some one else can find it before me. I'll admit, I'm relatively new to the 3800 as I've owned one for 2 years after having a Grand Marquis for 12 years. I could almost identify every wire, tube, and box on that 4.6L motor. I guess after 10 years I'll get to the same point on the 3800!

david95
01-29-2011, 03:42 PM
If I get a chance I'll look in my FSM, but I'm sure some one else can find it before me. I'll admit, I'm relatively new to the 3800 as I've owned one for 2 years after having a Grand Marquis for 12 years. I could almost identify every wire, tube, and box on that 4.6L motor. I guess after 10 years I'll get to the same point on the 3800!

I think it's the vacuum hose that creates the air pressure needed for the fuel pressure regulator to increase the fuel pressure when the gas pedal is pressed. Which might be the source of my problem. That vacuum hose came off way too easy - I barely bumped it. So maybe it was already loose.

I still don't know the precise name of this part. I'm still searching.

david95
01-30-2011, 12:49 PM
I'm still stumped with what that part is. But even if I had a replacement rubber hose, I wouldn't know how to detach the current broken hose, or how to put the new hose on. How do you remove that rubber hose/line, and how do you reattach it? Do you need a special tool? I like dealing with simple screws or bolts, but when it comes to these rubber hoses, I don't know how to remove or attach them. I mean, I guess I could just cut it off, but that seems like a bad idea, and that only solves the removal part of the repair.

enslow
01-30-2011, 03:55 PM
Is your Regal supercharged?

This site may help you figure out what you broke:
http://www.autozone.com/autozone/repairguides/GM-Lumina-Grand-Prix-Cutlass-Supreme-Regal-1988-1996/VACUUM-DIAGRAMS/VACUUM-DIAGRAMS/_/P-0900c15280067e96

If yours is not supercharged (VIN K at the bottom of the page) then I suspect you broke the EVAP switch.

david95
01-30-2011, 09:36 PM
Is your Regal supercharged?

This site may help you figure out what you broke:
http://www.autozone.com/autozone/repairguides/GM-Lumina-Grand-Prix-Cutlass-Supreme-Regal-1988-1996/VACUUM-DIAGRAMS/VACUUM-DIAGRAMS/_/P-0900c15280067e96

If yours is not supercharged (VIN K at the bottom of the page) then I suspect you broke the EVAP switch.

Enslow - thanks for the link. No, my regal isn't supercharged. Fig. 43 of the link you sent has the correct diagram. I broke the link from the EVAP canister to the "MANIF PRESS" which I'm guessing means Manifold Pressure. Thanks for posting that link. That helps clear up what the part is. Now I need to buy a replacement rubber tube, figure out how to detach the existing tube where it's still connected to the Manifold Pressure part, and then reattach the replacement tube at both ends. Or maybe I actually have to buy a new EVAP canister, maybe I can't replace the broken tube.

Those types of tubes without a visible connector or fastener have always stymied me whenever I've had to work on them. I just don't know the proper way to detach and then reattach those types of tubes. When there's a screw or a nut then it's a piece of cake, but these unorthodox type of fasteners are a pain in the a**.

So I don't even know if I can do this job myself, even though it should be a piece of cake. The EVAP canister is easy to get to, so it should be easy, but I have no clue how to remove the existing tubes other than cutting them off and destroying them in the process.

enslow
01-31-2011, 09:23 AM
I broke the link from the EVAP canister to the "MANIF PRESS" which I'm guessing means Manifold Pressure.

There is no link between manifold pressure and the EVAP canister. It goes manifold pressure -> EVAP Purge Valve -> EVAP vacuum switch -> EVAP canister. The part that's broken in the picture cannot be the canister. It is probably the purge valve.

In fact, looking at it more closely, the part thats broken looks like a soft rubber hose to connect a hard plastic vacuum line to a hard plastic nipple on the purge valve. Most of these vacuum lines will just pull off. What you need to do is find a length of vacuum tubing that is the same inside diameter as the plastic vacuum hose it broke off. Then see if you can just replace that part on the purge valve.

Careful with the vacuum routing. The diagram appears incorrect compared to your engine. It looks like the vacuum "T" from which all the vacuum lines come is on the alternator/accessory side of the engine. The diagram shows the vacuum "T" on the throttle body side of the engine.

Also, if that rubber vacuum hose broke that easily, check all other vacuum lines.

david95
02-01-2011, 08:11 PM
There is no link between manifold pressure and the EVAP canister. It goes manifold pressure -> EVAP Purge Valve -> EVAP vacuum switch -> EVAP canister. The part that's broken in the picture cannot be the canister. It is probably the purge valve.

In fact, looking at it more closely, the part thats broken looks like a soft rubber hose to connect a hard plastic vacuum line to a hard plastic nipple on the purge valve. Most of these vacuum lines will just pull off. What you need to do is find a length of vacuum tubing that is the same inside diameter as the plastic vacuum hose it broke off. Then see if you can just replace that part on the purge valve.

Careful with the vacuum routing. The diagram appears incorrect compared to your engine. It looks like the vacuum "T" from which all the vacuum lines come is on the alternator/accessory side of the engine. The diagram shows the vacuum "T" on the throttle body side of the engine.

Also, if that rubber vacuum hose broke that easily, check all other vacuum lines.
Enslow - Yeah, you're right, it's the canister purge control valve (or it goes by a few other names). Also, it's got a rubber connector that attaches to the control valve, and then a hard plastic tube that fits inside the rubber connector. I need to find the right size rubber connector and plastic tube to replace those. I guess I should just be able to pull the rubber connector off at the broken end, and also should be able to pull off the other end of the tube that connects to the vacuum T. In my car, the vacuum T is on the throttle body side of the engine, it's confusing because the second picture I posted is rotated 90 degrees compared to the first picture I posted.
I'll probably make an attempt to pull the broken tube off in a few days, when the weather warms up. It's supposed to get to 17 degrees tonight in Austin, but it could be worse - like Chicago with 2 feet of snow in 24 hours.

enslow
02-02-2011, 09:13 AM
Ah, a balmy 17 degrees. It's like -3 here. You can tough it out!

Oh wait, you're American.... 17 F ;) We're like 30 F up here.

david95
02-05-2011, 05:11 PM
Ah, a balmy 17 degrees. It's like -3 here. You can tough it out!

Oh wait, you're American.... 17 F ;) We're like 30 F up here.

It's hard to believe it's warmer in Canada than it is in Texas. But actually, we're back up in the 50's today, so we're thawing out a bit.

I attached my fix to the disconnected tube. I don't know if the little rubber hose I used to connect the plastic tube to the canister purge control valve is good enough. Like maybe some of the gas is leaking out, because I didn't push the little rubber hose over the ridge on the plastic tube. The rubber hose wouldn't even fit onto the plastic tube at first, so I had to stretch it out to get it onto the plastic tube. I doubt it would fit over the ridge. And plus, that plastic tube is loose at the other end where it connects up to the vacuum "T", so I didn't want to put too much force on it by trying to really jam the little rubber hose on there. It seemed like the plastic tube could very easily break loose from the vacuum T if I wasn't careful.

After applying my fix, I started the car, it ran great for about 20 seconds, and then the engine was choppy again. I don't know why it sounds good for the first 20 seconds - the idle is smooth and even just as it should be. Then after about 20 seconds, it gets a little choppy, with it sounding like it's misfiring every few seconds.

Do you think it could be the little rubber hose I used to fix the broken connection? I was thinking of disconnecting the electrical connector that runs to the canister purge control valve, just to see if the engine still has a choppy idle with it disconnected. I know that's not a permanent solution, but I was thinking that would let me know if it really does have something to do with the canister purge control valve and the rubber tube to plastic tube connection.

enslow
02-06-2011, 02:40 AM
It's possible you still have a vacuum leak there, or elsewhere in the system. Don't forget that the first few seconds or minutes the car runs at a higher idle, and perhaps open loop for the computer. Because of this, in the first minute or so electronic faults or small vacuum leaks may be masked by the higher idle. One trick some people use is to spray a can of carb cleaner onto the suspected vacuum leak areas. If the idle changes just after you spray a certain area, you have a leak there.

What I used to do with my 92 Grand Marquis was to measure the vacuum with all vacuum lines connected. Then I'd disconnect and plug all vacuum lines at the throttle body and remeasure the vacuum. If the vacuum increased, I'd suspect a vacuum leak somewhere.

david95
02-15-2011, 06:28 PM
Well, I surrendered. I took my car to the repair shop. They said the spark plug wires were not getting the spark to the spark plugs. I had them replace the 6 wires. I could do the front 3, but the back 3 can only be accessed by coming up from underneath the car, or my rotating the engine with a pry bar (as recommended by the manual - no thanks on that one).
The repair shop also said my catalytic converter was clogged. So they replaced that one too.
It cost me $400, but now the engine runs much better, back to how it should be. The repair shop also said I need new ignition coils, because the resistance isn't between 8 and 11.5 kohms. I didn't have them do that - I'm thinking I should be able to do that myself, as the coils are easily accessible. So ends the saga, at least for now. I haven't taken the car out on the highway yet, that should be the true test if the engine is really better. I wasted a lot of time and money trying to fix parts that weren't causing the problem. I'm a dumbass. I should have taken it to a shop from the beginning. My reason for not doing it was I'm new in Austin and I didn't know or trust any repair shops here. But in the course of buying parts on many trips at the local Autozone, I asked one of the clerks there if he knew any good repair shops. And he recommended Youniversal Auto Care. And I went over there on my bike and talked to them first before taking the car over. I felt like they were straightforward and knew what they were doing. So hopefully I found a good repair shop out of this whole mess. Anyway, I appreciate everyone's help, especially enslow. I'll take a crack at replacing the coils myself, you were right - that was one of the problems. Is there any trick to detaching the spark plug wires from the coils - do you just twist and pull?

enslow
02-15-2011, 11:42 PM
I thought you said you put in new plugs 10k ago? Anyway, please describe the work done more accurately so others can help you. One of us would probably have suggested you do those rear plugs first but we thought they were done. Of course, those 3 rear ones on the Regal are nasty to get at. I guess I'm glad I have a Lesabre instead. Lots of room!

david95
02-16-2011, 11:58 AM
I thought you said you put in new plugs 10k ago? Anyway, please describe the work done more accurately so others can help you. One of us would probably have suggested you do those rear plugs first but we thought they were done. Of course, those 3 rear ones on the Regal are nasty to get at. I guess I'm glad I have a Lesabre instead. Lots of room!

Yeah, I had new plugs put in 10k ago, but the wires weren't replaced at that time. I guess I should have had new wires put in with the new plugs. Would have saved me some hassle.

david95
02-16-2011, 12:02 PM
Sorry it it was confusing what I wrote before - but they only replaced the spark plug wires, they didn't replace the spark plugs. And they replaced the catalytic converter. Those two repairs fixed the problem (as far as I can tell right now). The car did drive much better on the way home from the repair shop. I'll take it out for a highway trip this weekend.

enslow
02-16-2011, 06:32 PM
I'm glad it's fixed anyway.

Right now I'd think about why the cats became plugged in the first place. It is possible that it's been missing for a long time and the raw gas overworked the cat and plugged it up. A catalytic converter can last a very long time. My 92 Grand Marquis has 350000km with the original catalytic converter and it still passes emissions testing with flying colours.

It may be worth getting yourself an OBDII scanner if you can afford it and check the fuel trims to make sure it's not running too rich or lean. However, you could probably assume that the cats were plugged up by a previous condition that has since been solved. Good luck and enjoy your Regal!

enslow
02-17-2011, 09:33 AM
Sorry it it was confusing what I wrote before - but they only replaced the spark plug wires, they didn't replace the spark plugs. And they replaced the catalytic converter. Those two repairs fixed the problem (as far as I can tell right now). The car did drive much better on the way home from the repair shop. I'll take it out for a highway trip this weekend.


Actually, I'm sorry! I misread your posts. I thought for a moment that the shop had changed the plugs, and I'd forgotten you never did get around to doing plug wires. Enjoy!

tinkmiester
07-16-2014, 06:37 PM
Save yourself lots of money replace the crank sensor they are a real pain in the butt to adjust air gap on mine is a 92 with 3800 I replace so many things then spent over 700 bucks at a reputable shop I had replaced the sensor before and did not have adjustment right did not think it was bad as I had just replaced not long ago thought I had a new problem after spending so much on parts and at the shop a mechanic friend of mine said replace the crank sensor I said I just did little while ago he said maybe its a bad one ran out of options have more in it than car is worth. Changed sensor could see bad spots on removed sensor because it was out if adjustment it worked fine for a little bit then started the rough idle stutter on take off miss pulling hills new sensor properly adjusted this time finally all back to normal what makes this even worse is that I'm a heavy truck and equipment mechanic that now has a lot less hair than I did before this all started change the crank sensor and happy motoring

Tech II
07-16-2014, 11:11 PM
Tink, check the date of the posting.....

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