'91 olds 98 won't start

The car is a '91 Olds 98 Regency Elite with 3.8 liter v6 with 117000 miles, Auto transmission

After having a radiator split and overheating, it was towed to a radiator repair shop to have radiator replaced. Upon picking up the car from shop the car would not start. All it does is backfire occasionally thru the intake and kick back. the compression reads 145 -155 on all cylinders except #4 which is 110psi. The plugs were gas soaked upon removal and #3 plug had a carbon bridge across the gap. But plugs look fairly new. Cleaned and dried plugs and cranked engine over and let cylinders dry overnight. Removed all fuel injector leads and tried starting engine by spraying starting fluid thru the intake.
The engine exhibited the same response as before backfiring and blowing off some of the vacuum hoses.
I have checked the timing by removing valve cover and feeling out #1 cylinder top dead center and verifying that both valves were closed and marking a timing mark on flywheel that could be observable with a timing light using the engine mounting bracket just above flywheel. The ignition timing seems to be about 10-15 degrees before TDC as marked while cranking. the valves seem to be opening and closing at the proper time meaning that the exhaust valve opens close to bottom dead center and closes while intake valves open close to top dead center on 3rd stroke going down, etc. The spark seems to be possibly a little weak but does jump the gap. I will check the coil pack resistance and see if it reads 10-15 ohms primary and 3k-4.5k ohms on secondary as found on another thread.
I'm doing this for an 80 year old man who hasn't much money would appreciate any help.
Thanks in advance.:banghead:

Welcome to AF. Disconnect the maf see what happens, if you have a scanner check for cranking rpms, if possible get the icm tested maybe at AZ, or Napa.

Thanks for the reply,
Is ICM the ignition coil module?
New developments. Seems as though I got it working now.:smile:
The coil packs checked out OK with resistance checking. Got 1 ohm on primary and 12000 ohms on secondary. all within a 100 ohms or so on all 3 coils. Did find that the signal wire for one of the coils was cut into by the signal terminal of the center coil causing 2 coils to fire simultaneously. Corrected that problem but with no change in results.
I went through and checked all the spark plug wires and recleaned and dried plugs. Found a cracked plug on #2 and an open ignition wire on #4. Changed all the plugs and wires on suggestion of a local mechanic/friend.
The car woould now start, idle rough for a few seconds and quit. Pulled plug on #1 and it was sooted up. Checked fuel pressure regulator and it was running at about 49 psi. Specs say should be 40-47 max. Checked diagpragm on regulator and pulled full vacuum with no leakage. Fuel pressure dropped to about 30 psi Cranked engine and it idled rough at 30 psi fuel press. but it ran.
Obtained scanner and it said no codes OK to drive. Cranked engine, still a very rough idle but continued to run. No new codes genereated. Service engine light still on no check engine light, coolant hot indicator still lit.
Raced engine up and it smoothed out but idled badly and would stall if I letoff too quick. I played with A/C controls and all of a sudden, the indicator lights cleared and the engine smoothed out. I Sprayed out the MAF with carb cleaner wwhile racing engine and things continued to improve.
Now it runs pretty darn good. Still not sure what happened. But I am sure glad I don't own a GM.

This is a follow up.
After letting the car sit overnight, found the problem had returned. It was hard starting and the hot indicator and service engine light returned. Upon starting however, after revving up the engine, the lights would clear and engine would run smooth again. The same problem reoccurs evrytime it is shut off. Kind of like the alternator has to start putting out before it smooths out. While it is idling rough before I rev it up, the indicaor lights kind of flicker.
So my guess is the PCM is still having a problem. Cleaned off the battery cables and checked the pins at the connectors of both power leads for the PCM and I am getting 12 volts. the ground wires do seem to have a high resistance of around 18 ohms however.
If anyone has any other Ideas would appreciate hearing about them.
Thanks

18 ohms is too high, also check the alternator out put. Watch the engine sensor grounds .

I fixed the high resistance ground problem. Bad crimp on engine ground to chassis ground jumper. Still same result. Went on ahead and replaced ecm but used same eprom, (don't know anyone that checks eproms.) Still have same problem.
I did find out in owners manual that the service engine light will remain on until engine runs, I don't know if the Hot light should also stay lit until the engine is running, but they seem to be linked together on the same bulb test circuit.
So as of now the longer the vehicle sits up the harder to start. If I crank it up immediately after shutting down it starts fine, but idle is only slightly erratic.
Is it possible the intake manifold may have cracked if it overheated?
Also checked the alternator and it is fine around 14.7 volts. I pulled the excitation wires off the alternator and the starting results were the same.
I haven't yet tested the ICM. I presume it is working fine since the engine runs good above idle.

Don't discount the icm here, you can get it tested at AZ, but those tests can be inaccurate.

I will get that tested this evening and let you know.

Called autozone. They cannot test the type of ignition module, Napa doesn't test at all here.

had the same problem with my 91/98 i didnt go through all the steps you did because,when i replaced the coil pack a few years back it posed the sam problem, so i took the coil pack and the ignition mudule off and took it to autozone and they did check them both, and the ignition module was bad, so i dont know why they told you they dont check them when they do, maybe that person didnt know how or didnt know which test to use but they have a book with the directions in it on how to and what tester to us.....

I don't know why he told me that, did yours have the type 1 ignition coil pack on it? I wouldn't think it would make any difference but maybe it does.
In the meantime I'm rechecking for vacuum leaks and found a couple. Pulled and cleaned throttle body and IACS, PCV valve and cleaned both. Have not found an EGR valve anywhere on this engine. haynes says it has one and so does alldata.

Maybe I should start a new post as the car will now start but is hard to start when cold.
I had the ICM module checked at autozone. It was as I figured good.
All vacuum lines were checked and fixed all leaks including a vacuum tank seam leak.

It idles rough for a few minutes until it warms up a bit.
If I try to use the A/C the the engine loads up and tries to stall out then picks up. But the A/C compressor keeps cycling on and off probably due to the reduced idle speed. After turning the A/C off the engine continues to seem to try to stall out and recovers and cycles like that until it warms up. Once it warms up the problems go away and it runs smooth.
I wonder if the CALPAK or mempak in the eprom could have gone bad somehow?

Thanks for the help and ideas.

Get a scanner on it and look at the temp sensor readings should be outside air temp when cold and warm up with the engine, also look for lazy o2 activity. Look for raw fuel in the vacuum hose to the fuel pressure reg. also.

No fuel in fuel regulator vacuum hose.
I will check again with scanner but I believe that they were good at last check.

The air and coolant temp sensors were checked with DVM at room temp of 80 degrees. the ohmic values at 80 degrees were close to alldata specs as close as I could determine since they aren't linear, but it fell within a 11 to 18 degree range depending on which chart I used. And they do change resistance properly when heated or cooled.

I applied a resistance box to the CTS leads and preset the values to ohm values equivalent to around ambient when engine was cold.
If it was a CTS problem this should have corrected it. I set it both upward and downwards on the resistance. As I increased the resistance (fuel richer in response to lower engine temp.) the engine would speed up, but the engine hunting would continue until the engine actually warmed up. But indications seem to indicate now that the engine is running too lean.
Even racing the engine above idle around 1200 rpms holding throttle steady the engine continued to hunt(try to stall and come back to set speed) while cold. Almost like the timing was shifting (which I will now check now that I thought of it) or something was opening & closing in the throttle.
Also noticed that the harmonic balancer had about a .010 run out just eyeballing it. I was told that it could affect it. Is that true and wouldn't it hold true even when the engine has warmed up?

.010 runout means nada here unless the outer ring is seperating from the damper portion of the inner hub. common occurence on these engines.. Are you or have you monitored the fp during this event, also have you tried the maf disconnect?

I haven't monitored the fuel pressure while starting or running yet but I will do that. Only a engine off key on test which as mentioned before gives 49 psi at the test port.

As far as the mass air flow sensor, I have pulled the connector and it doesn't seem to affect the starting or running either hot or cold. The service engine light comes on while it is disconnected and when reconnected the engine stalls out and has to be restarted.
As far as the damper is concerned I tried to rock the pulley and it seems not to move relative to the hub which if it was coming loose I should be able to do?

That is a good indication the damper should be ok. The maf disconnected should affect the engine as the pcm goes to a default setting and would not normally perform properly at a higher speed under load., I would check the maf on a scanner to see what the pcm sees for air flow. Still get a fp gage on it under operating conditions first.

OK, I tested the fuel pressure while cranking and running and also checked the scanner sensor reading.
Below is the summary of scanner readings & conditions.

Cold the IAT and CTS were 2 degrees celsius apart. Air was 20 and coolant was 22. The actual measured air temp was 25 centigrade.
Fuel pressure key on engine off = 49 psig, cranking it would drop to 47 psig, Engine running at idle was 40 psig.
After connecting scanner the engine refused to start up, it would occasionally spit out the intake.
I disconnected the crank sensor and it started up, idled rough for a few seconds and smoothed out.
Oxygen sensor reading cold engine idling 443mv. Dropped to 278mv after stopping engine and reconnecting cam sensor and clearing codes warm engine idling. Rich/ lean flag stuck at rich when warmed up.
Scanner shows open loop condition which I think is normal. It seems to run better in closed loop though.
MAF sensor when cold was reading 8 gm/sec in closed loop and dropped to 5 gm/sec when warmed up in open loop. Should be 4.9 (varies) in closed loop operation.
Engine load (LV8) was running 90-100 when cold and dropped to 60 when warmed up.
Block learn seems to run at 149 counts cold or hot. (Alldata says this indicates lean mixture).
Idle air control started out at 70 and in now down to 20 when warmed up.

the fuel integrator was 182 when engine cold and in closed loop and dropped down to 128 open loop and warm.
Spark advance was 14 degrees jumping to 9 degrees briefly at times when warmed up.
Air fuel ratio is 14.76 in closed loop cold, 14.5 in open loop mode warmed up

When the A/c is turned on, while engine is still cool and idling you can hear the intake sound getting louder before the compressor kicks in but the engine doesn't seem to pick up but instead stumbles and the sound lowers before the compressor turns off. this is repetitive like the IAC is trying to compensate for the changing load but the engine fuel isn't coming up proportionally to give it the power therefore stumbling (trying to stall out) causing compressor to turn off. Racing engine does the same thing until warm. file:///C:/WINDOWS/TEMP/moz-screenshot-1.jpgfile:///C:/WINDOWS/TEMP/moz-screenshot.jpg
:runaround:

Is the o2 switching as expected? I'd check engine vacuum also. You the int was 182 cold and closed loop can't be both ,cold is open loop? You say closed loop cold, this doesn't add up. You say you disconnected the crank sensor and it started?

The O2 is no longer switching. Just shows rich on the rich/ lean flag. It used to bounce back & forth before I corrected the vacuum leaks I could find. Still not sure if intake manifold isn't leaking somewhere.
The engine Vacuum was checked this morning when I checked the fuel pressure. Started OK this morning but still hunting & rough idle. Cold and idling, the vacuum was running between 15 & 16 1/2 inches. After it warmed up, the idle speed came up and steadied, it was around 18 inches.

The int was 182 and I guess it was in closed loop because the cam sensor was disconnected at the time with a code 41. And yes the engine started with cam sensor disconnected. It wasn't starting otherwise at the time. I guess closing the loop runs the engine on mempak settings in the prom.

Anyway the scanner, when I started it this morning, showed open loop and stayed open loop. Isn't open loop when the engine sensors are being monitored or is it the other way around.

The O2 is no longer switching. Just shows rich on the rich/ lean flag. It used to bounce back & forth before I corrected the vacuum leaks I could find. Still not sure if intake manifold isn't leaking somewhere.
The engine Vacuum was checked this morning when I checked the fuel pressure. Started OK this morning but still hunting & rough idle. Cold and idling, the vacuum was running between 15 & 16 1/2 inches. After it warmed up, the idle speed came up and steadied, it was around 18 inches.

The int was 182 and I guess it was in open loop because the cam sensor was disconnected at the time with a code 41. And yes the engine started with cam sensor disconnected. It wasn't starting otherwise at the time. I guess closing the loop runs the engine on mempak settings in the prom.

Anyway the scanner, when I started it this morning, showed open loop and stayed open loop. This time all sensors connected.
I found this next paragraph on the forum.
[ To clarify the above, closed loop occurs when all sensors are working and feeding data to the computer. The engine will not enter closed loop operation until the EGO sensor is warmed up - generally between 1-2 minutes of operation. In open loop, the computer discards data from certain sensors and runs a program with pre-determined levels for various conditions - generally this is not optimal and is often referred to as "limp mode". If your SES light is on, you're generally in open loop operation.]as quoted by silicon 212

The SES light never comes on even though it is in open loop. It does come on when key is turned on though and goes out when engine starts.

i do have to say that i had to replace my balancer because the rubber had dry rotted, it was giviing me a rougher idle and alot let power when driving down the road, i thought it was the timing belt, and after i continued to drive like this the rubber finally gave way, the whole time im thinking the timing chain was going out on me, didnt realize it was the balancer that had dry rotten till i got under there and was looking around the timing chain cover and the oil pan

Remember a bad o2 sensor will not allow closed loop operation, same as coolant temp sensor not tell ing the pcm the engine has reached a preset desired temp for closed loop.

I'm thinking that maxwedge has a point about the 02 sensor being out of whack, as it should be showing lean and not rich. The fact that it is showing rich may be causing it to run lean though wouldnt you think or does the 02 sensor have any effect on the fuel air mixture control? But why is it not giving me a code?

Pre obd11 systems may not set a code for this. The pcm assumes the sensor is in range and just tries to correct with the block learn, when it cannot achieve this, then it will set a code.

Since last post, I was going to check out 02 sensor further.
I went to start the car. It now has been sitting for 3 days since I last fooled with it. We are now back to the beginning. It won't start and only backfires. and wants to run backwards a stroke like very early spark timing.
Tried hitting it with starting fluid with same result. Seems the longer it sits the worse it gets starting up.
I pulled the codes using the MIL and had a new code. Code 42 which is ESTcircuit. I used alldata test procedure to check the ignition module since it seems that it is in charge of starting the engine during cranking when cold.(at least that is what I am gleaning from all this info I'm reading. Please let me know anytime I am in error) I got some out of the ballpark resistance readings.
The readings on BC7 (bypass control) should have switched to 6000 ohms to ground, I got infinite resistance instead, when I apply B+ voltage thru a test light to the PCM harness(which has been disconnected from the pcm) to BC6 which is EST control. Harness to Ignition module connector tested good continuity. Pin contacts in connector are good.
I assumed bad ignition module and went on ahead and purchased a new one. After it was installed, the engine fired right up.( Thought I had it made.HA HA) Put the scanner back on code 42 cleared engine still idling rough figuring pcm had to relearn the idle. After engine warmed up it went into closed loop and was running pretty good even though the exhaust O2 was still showing rich the rich lean flag would alternate rich to lean. A road test upon decelleration the O2 would drop down to 4 MV from 230 mv.
Aceeleration would produce some shudder until it would drop into passing gear. ( I will get more into that later).
This morning I went to start it up and back to square one again, I assume the new ignition module went bad.:banghead:

I think by this point. I'd just buy a new car.. but since it's someone else's, I wish you lots of luck figuring it out for him.. sorry I don't have any useful information!

Chris

I'm trying to figure out all causes of ignition module failure besides a beating on it and burning it with a blowtorch. Can a crank sensor cause an ignition module to go belly up or a bad ECM? I am also trying to move the secondary ignition leads away from the main harness which feeds the ICM and alternator, and fuel injectors. the length of wires to 2,4,6 cylinders makes it difficult.

Check for bad engine grounds, check alternator regulated output, check for any bad harness issues to and from the icm and from the crank sensor to the icm, take your time here.

Maxwedge, I am going to direct this at you since you have spent the most time with me on this problem.
I went and pulled the harmonic balancer off and sure enough, it looks like the vanes have been rubbing on the innermost sensor. It looks like the balancer was changed sometime not to long ago and the clearance wasn't set exactly right. So I am going to change it out, but I need to find a pic or detailed description of the vane settings on the balancer to make sure it is set correctly and for getting the distance setting right from the outside edge of crankshaft. I can probably use a caliper and measure the distance from the inside edge of balancer that fits on crankshaft and set the sensor accordingly.
Can you point me in the direction for finding this info?
I appreciate the help so far.

Good work so far, I could walk you thru this, but this link is better than the written word. http://autozone.com/az/cds/en_us/0900823d/80/15/e4/2d/0900823d8015e42d/repairInfoPages.htm

Sorry it took so long to get back. The article was helpful, thanks.
Ended up changing the sensor and harmonic balancer since the one that was installed was made in China and the runout on the reluctor rings was about .040", I tried to recenter the rings but could only get .024" at best and could not keep it from rubbing on one side or the other. The new one was a Pioneer balncer built in Australia. It had slightly thicker rings on it so the clearances were a bit tighter around the sensor and it had a .010 runout on them. The .020 feeler gauge trick wouldn't work because of the clearances involve so I centered the sensor so it would not touch on either side of the rings. Of course the new balancer slots were smaller so I had to grind the puller jaws to get it to fit so I sould remove the balancer and reinstall the shield which was removed to set the clearances. (Definately need to avoid going off road with this vehicle as something could get to this set up like a rock or twig and mess it up.) Anyway so far so good the vehicle still cranks up and behaves pretty much normally.
Still may have that slight shudder around 58 -64 MPH when accelerating. I think we will start a new thread for that one.

2 final things to wrap up this thread.
1 is the harmonic balancer I got from carquest made in Australia under the name pioneer had a powerful little rectangular magnet stuck down beween the reluctor rings. Fortunately I spotted it before installing it otherwise it would have lodged on the crank pickup and probably destroyed it. Don't know if it was intentionally put there or not.
2. The shudder I was having further showed up the next morning on a cold start as a cylinder not firing. #5 had a cracked plug. Changing that out corrected the shudder as well.
Thanks for the help and I hope this helps somebody else .
http://www.automotiveforums.com/vbulletin/images/icons/icon10.gifrunaround:naughty: