Might need new engine. Whats the diffs?

My 95 PA with the Series II engine took a poop last year and I had the motor rebuilt by a local company in town.

At first it seemed ok but it didnt seem to have the same power as when the original motor was newer. now, it doesnt run very well at all after just 11 months and 15,000 miles.

it lacks vacuum going up hills so the ac vents switch to the windshield. The cruise doesnt hold if you set it going up a hill either.

It also kicks down going up hill from lack of power. And it feels like on the freeway, the pedal needs to be pushed more than normal.

I changed plugs, filters (fuel and air) and no difference.

Did a compression test and the numbers at 4 puffs read around 135 psi (down from 160 from about 7 months ago). If I check the compression max (at like 8 or 9 puffs), it went to about 190 (but after cranking it to check 3 plugs, the max dropped to 160 on all cylinders- even on the ones that originally measured 190).

So i think the motor is not doing so well and Im think of getting a new engine from GM (Part # 89017262).

Does anyone know if the 95 3.8's have the same camshaft as the newer 3.8's (in other words, will it have the same power as the 2004 impalas that I rent when Im on business trips)

Anyone know if the computer needs changing if I decide to dump a new supercharged series III motor in there?

A new Series II 3800 will have 205 horse instead of 195.

I'd actually reccommend the SC Series II as opposed to the Series III The series III makes only 10 more horsepower, with the same torque, and is probably much more expensive than the series II

no warranty on the motor? The new motor will be nice.. Jasper engines makes a decent 3.8 for around 900 bucks rebiult. they have a 3 year 36000 mile warranty.. But a new one would be nice if your car is in great shape..

motor has a 12 month 12,000 mile arranty that expires in November (the 3rd) but I am at 15,000 miles so they will probably say Im outta luck (these kind of places don't like to warranty anything and they will say whatever they can to make the problem your fault and not theirs).

I think I will run it until it is unbearable. a new motor is $2500 on gmpartsdepot which is more than a rebuilt motor (my rebuilt was ~$900) but it is the hassle of pulling and changing.

Anyone know how to prime the oil system with the 3.8 liter?

just a thought, maybe you can try to reset the Valve Lash, sometimes with the rebiulds the rocker arms get loose and don't hold the valves open causing the crappy HP and vacuum... is the motor quiet or does it sound knocky?

hmmm, good point. the motor sounds fine. not knocky at all. I will check it out. I was also thinking that maybe there might be a vacuum leak (I am hoping for something easy).

I should say that I have this tendency to think all automotive problems are the worst possible breakdown (like bad engine, tranny gone south, wheel bearings shot) then when I get into it I find its something stupidly simple (like needs new plugs, ujoint bad etc). So theres a good chance I dont need a new engine.

I'll check the valves and the intake for leaks this weekend. thanks for the hint.

You (parkavechrome) mentioned in another post, that fuel injectors might be suspect after say 150,000. seeing as my car has 192,000, I was thinking that I should check them as well. Is there any way to do this at home or do I need a special setup. I was thinking of pressureizing thethe rail and applying power to each injector to see the spray pattern but Im not sure what power to apply to the injector (+12v??? or something else). any ideas?

I have used a can of injector cleaner that attaches to the pressure fitting on the fuel rail. You disable the fuel pump and run the engine for 10 minutes on the cleaner.

its defiently not +12 volts.. they work on very low signal from the ECM.. if you have 192,000 and there original then there for sure on the way out. if you pull them off and look at them if the tips are burnt or cracked, replace. with 192K they will fail. The only way to test is on a tech machine at the dealer that watches the injectors or weakness or missfire. take them off, crank the motor and watch the spray.. but definetly check the valves. Also you could have bad head gaskets.. presurize the cylinders check for adjacent cylinder pressure.

its defiently not +12 volts.. they work on very low signal from the ECM.. if you have 192,000 and there original then there for sure on the way out. if you pull them off and look at them if the tips are burnt or cracked, replace. with 192K they will fail. The only way to test is on a tech machine at the dealer that watches the injectors or weakness or missfire. take them off, crank the motor and watch the spray.. but definetly check the valves. Also you could have bad head gaskets.. presurize the cylinders check for adjacent cylinder pressure.

And you know for a fact that the injectors aren't pulsed at 12 volts. I beg to differ with you on that.


Also a spray pattern on an injector is a part of a test but that is the last part I would do. A pressure drop test is good to do or a power balance test is even easier. Usually if you have an injector problem you will have a misfire problem. Any car built after 1995 will also give you a check engine light with a stored P0300 misfire code.


There is no time limit or mileage limit on injectors I have seen them fail at 5000 miles up to 250,000 miles. The injectors themselves are reliable/ Its the crud in the gas that kills them.


Bad head gaskets either would leak coolant outside the engine or you would get exhast gases in your radiator. There is a simple test to determine if your headgaskets leak using a chemical that changes color when exposed to exhaust gas.


Instead of wasting your money on throwing parts at the car take it to a good shop pay the one hour diag fee and have them scan the car and see what they find. That 70 dollars is lot cheaper than one injector.

I think the diagnosis idea is a ggod plan. with all of the variables that it could be, I could be under the hood for days. Plus, if the motor is going south, better that I have a professional diagnosis to give to the rebuilders than just my own statement.

I just like doing things myself (however, I have used the professionals to diagnose problems before and then completed the repairs myself)

I biuld Mustangs, work on saabs, and many GMs.. The injectors are not pulsed on 12V...

hmmm, this seems to say that it is a 12v pulsed circuit (at least for the misubishi stealth) through a resistor to limit the current.

http://www.stealth316.com/2-injectortypes.htm

and this,

http://www.megasquirt.info/manual/minj.htm

and this

http://www.cleanairpower.com/files/pdf/SP%20series%20gaseous%20fuel%20injectors.pdf

Of course with this resistor in the circuit, the voltage across the injector will be less than 12v. So, if the PCM has this resistor internal to it, the voltage at the injector will be somewhat less than 12v. If I had a scope, I could measure it.

In any event, I made an appointment to take the car in tomorrow. I'll let you all know what the shop finds out.

the voltage coming to the injectors is well under 12V.. the entire car is a 12V circuit. If you put 12V to the injectors. there toasted, and as far as life expectance, the injectors will go regardless... Its a mechanical item that opens and closes and with that mileage they are prone to fail and known to as well..

its the current that will toast the injectors. a lot of my current research has found that there are high impedance injectors and low impedance injectors. if the inject is low impedance (such as 2.5ohm) then a separate 6 ohm resistor is used to reduce the current to about 1.4 amps max ( 12v/(2.5ohms+6ohms)=1.4amps). this setup drops the voltage at the injector to around 3.5 v (1.4A X 2.5 ohms = 3.5v).

in any event, the injector signal is pulsed so depending on the pulse rate, repetition and duty cycle, the average volateg to the injector is quite small.

I took my car in this morning. I'll let you know what they find. I am now thinking that its not the motor. I seem to have great pickup when I floor it. the car just lacks part throttle ummfph. and the vacuum problem. We'll see what GM has to say about it.

I biuld Mustangs, work on saabs, and many GMs.. The injectors are not pulsed on 12V...

All GM injectors are pulsed at 12 volts look closely at the schematic I am linking to, at the top of the schematic is the fuse for the injectors. If you take a meter to that fuse you can measure it but save your time.

For your info I am a GM master tech working at a Pontiac, GMC and Buick dealership.


LOOK HERE AT THE SCHEMATIC

http://134.39.200.6:9001/servlets/TifToGif?pic=56622

Its a mechanical item that opens and closes and with that mileage they are prone to fail and known to as well..

The whole car is a mechanical item that opens and closes so maybe we should just replace the car and the problem will be fixed.

Anything is prone to fail mileage has no effect on it. I have yet to see an injector fail from too much voltage or current, or too many miles, most fail from the gas, dirt and so on clogging them. Some injector cleaners will eat the injector coil wires on the older cars and this is the only cause I have seen that will make injectors stop working. Some injector cleaners will eat the fuel pump.

So please prove to me injecotrs are not fired at 12 volts.If you want I will take a pic of my meter hooked up to an injector. If you start the engine and measure the voltage at the injector you might see about 6 volts. But you on see 6 volts because the meter isn't fast enough to catch the full voltage. If you use a scopeing meter or a meter with a min/max function you will see 12 volts.

The reason with a basic meter you see 6 volts is the injector isn't on all the time. The injector fires faster then the meter can show the voltage. Going from zero volts to 12 volts the meter averages out the reading and displays that. On a scope you would see a square wave with the top being 12 volts and the bottom being 0 volts.


The injectors recieve a PWM signal on the newer cars. Which is a percentage on on/off time.

Ive seen the same schematic on a number of different websites describing fuel injection. the on/off control in the PCM is switched using transistors. the thing we dont know is what is in the pcm. See, if +12v is at the top of the rail, and goes to the injector, then to some circuit in the pcm, that circuit most likely has some resistor in it to limit the current through the injector. This will, in effect, make the actual voltage across the injector something less than 12v. but i agree that a meter across the injector would not be fact enough to measure the voltage directly and that the meter would most likely only see and average voltage. the best way to measure it is with a scope but I dont think my work would want me taking one out into the parking lot at lunch. By the way, an injector is basically a valve which opens with a solenoid which is a coil. enough current throught the coil will burn it out. that doesnt happen in the regular circuit because the current is limited. Hooking an injector straight to a battery with all that power behind it would definitly toast those smale windings.

You mentioned something about fuel injector cleaners eating injector components. I was interested in trying that fuel injector cleaner that jed rule mentioned. the kind that attaches staright to the fuel rail. Do these types of cleaners (the one i was going to try to get is made by 3m) have this type of problem?

In any event, I got the car looked at by GM on friday and they told me my TPS was bad. I changed it out on saturday and part of my problems are gone. the throttle problem is gone where it feels like a dead spot. and the vents dont blow out the windshield anymore. but I stll have what seems to be a misfire (a kind of rumbling when driving down the road). the service guy said I might have a bad PCM also because when they were testing my car the TPS "lost signal once or twice" and that could be because the 'puter is acting up.

Their is no magic or mystery in a PCM. All a PCM is, is a bunch of switches. 99% of these switches are ground switched which means the PCM controls the ground side of a circuit. Some of the circuits in the PCM use a resistor, this resistor is only used for a feedback. The PCM measures the voltage on the resistor to see if the circuit is working properly.

Since we are still stuck on too much amps going thru the injector coil I will explain some more. If you know what ohms law is you can figure it out no problem. Using ohms law if you have 12 volts with a 6 ohm injector the total current thru the injector is only 2 amps. If the resistance of the injecyor was 2 ohms you would have 6 amps going thru the coil. So I can say 6 amps is nothing to the coil of an injector and it can safely handle the current. Most GM injecotrs are close to 6 ohms.

Those small winding can handle alot more than you think they can. The wires are about the same size as a relay has uet we have relays that handle more than 25 amps of current in them with no problems.

I am not sure of the chemical makeup of the cleaners you are thinking of using but I use something called TOP ENGINE CLEANER sold at GM dealerships. This is mixed with gas and attached to the fuel rail. Whenever doing this type of injector cleaning make sure you isolate the fuel pump from the cleaner, you don't want the cleaners going into the tank. After I perform the cleaning I use a injector cleaner that gets dumped into the tank also made by GM.


When it comes to misfires I use a general rule if the miss is at idle, and goes away under load then its a fuel related miss, under load miss and gone at idle it is ignition breakdown causing the miss.

Either way, put this convo to bed, the fact is the mileage this car has there gunna fail at somepoint regardless end of story. The injectors all fail are known to fail and i am sure as a GM tech your changing injectors all day long.

Either way, put this convo to bed, the fact is the mileage this car has there gunna fail at somepoint regardless end of story. The injectors all fail are known to fail and i am sure as a GM tech your changing injectors all day long.


Yes I agree with your statement that the injectors will fail someday just like the human body will fail someday. Every part on a car will fail some day some parts may take 40 years before they fail but they will. Now what I disagree on is changing parts that work for the sake of just changing them because. I never reccomend changing a part just because it may fail. A new replacement ijnectr may fail in 3K miles so to me that is not a vaild reason to replace parts.

As a GM tech doing this for 12 years now I can say I have only changed a handful of injectors. Most injector problems can be cured with a good cleaning procedure. Of the handful I replaced thye were soo full of gunk that I was unable to clean them where they would hold up. If anyone tells you they change injectors all the time it is only because they are lazy, greedy and a thief.

I never recommend changing a part just because it may fail.

Flatrater I usually agree with you completely but I must question you on this point. When I was younger and less experienced ( and poorer) I drove whatever I had untill the wheels fell off, then tied them on with wire and drove some more. On a trip to Texas when I was in the Army I got stuck at midnight in the middle of no-where, when the water pump went on my 1958 DeSoto. There was nothing within 100 miles except a closed Phillips 66 station. Luckily he left the water hose out at nite and I filled the radiator and a 5 gallon Army gas can. The pump didn't leak too badly below 30 mph so it took 6 hours to cover the 180 miles back to the base while filling the radiator from the can every hour.
Ever since then I change the plugs, filters, belts, fluids etc ahead of the manufacturer's schedule. I change the water pump at 60,000, and rebuild the starter and alternator at the same time. I replace the timing chain and oil pump at 175,000. I watch the tires, brakes and shocks carefully and change them as soon as I detect a weakness.
Now I don't mean that I throw parts at a problem when one develops. If in the course of troubleshooting a problem, my experience makes me suspect some part, I would rather change it if the cost is reasonable and consider it one less part to fail in the future. The security I feel when driving is worth the expense.

I never recommend changing a part just because it may fail.

Flatrater I usually agree with you completely but I must question you on this point. When I was younger and less experienced ( and poorer) I drove whatever I had untill the wheels fell off, then tied them on with wire and drove some more. On a trip to Texas when I was in the Army I got stuck at midnight in the middle of no-where, when the water pump went on my 1958 DeSoto. There was nothing within 100 miles except a closed Phillips 66 station. Luckily he left the water hose out at nite and I filled the radiator and a 5 gallon Army gas can. The pump didn't leak too badly below 30 mph so it took 6 hours to cover the 180 miles back to the base while filling the radiator from the can every hour.
Ever since then I change the plugs, filters, belts, fluids etc ahead of the manufacturer's schedule. I change the water pump at 60,000, and rebuild the starter and alternator at the same time. I replace the timing chain and oil pump at 175,000. I watch the tires, brakes and shocks carefully and change them as soon as I detect a weakness.
Now I don't mean that I throw parts at a problem when one develops. If in the course of troubleshooting a problem, my experience makes me suspect some part, I would rather change it if the cost is reasonable and consider it one less part to fail in the future. The security I feel when driving is worth the expense.

I agree with you to a point. I didn't make myself clear enough I recommend doing all required maintenance per the manufacturer directions. The mileage to do it at depends on your driving habits and the manufacturer lists only a guideline to follow. I never wanted to imply not changing plugs, filters and so on. But I have a problem with changing parts that are good and like you said "WHEN I DETECT A WEAKNESS" is the key to the solution. Many times I have had customers who I recommend a fuel filter to be replaced and they didn't listen to me only to have the car towed in because of it. So yes do the maintenance.

My biggest problem with changing parts is the new parts may fail sooner than the old parts. The new parts may be bad out of the box or fail within a months time. I have seen many parts fail shortly after replacement. Also as a mechanic I have to watch out for my customers best intrests and make the car safe to use. In my line of work I have seen too many thieves and hack fixing cars ripping off people for the sake of making money. I live by one motto "If it works don't fuck with it" because it will break shortly after messing with it.

Jed Rule your maintenance sounds great, I would recommend all car owners to follow your example but my problem was with this statement "there gunna fail at somepoint regardless" and "you have 192,000 and there original then there for sure on the way out." This implies a just change everything attitude because at some point they are gonna fail which is wrong. Injectors have a proven track record and the newer design injectors in use since 1995 have had very little problems.

While we are on the subject this quote also bothers me.

maybe you can try to reset the Valve Lash, sometimes with the rebiulds the rocker arms get loose and don't hold the valves open

Now considering this engine uses hydraulic tappets with no lash adjustment for the valves, how would you reccomend doing this feat of magic.

There has been a ton of misinformation on this topic made by one member and I couldn't allow this to go on, it needed to be fixed.

The thieves and hacks forced me to quit this business after 27 years.
Unfortunately at the dealer I worked for:
The mechanics were in-competent,
The management in-effective,
The owner in-different.

I am driving a limo now --no comebacks.
How many guys reading this site know what a DeSoto is?

The thieves and hacks forced me to quit this business after 27 years.
Unfortunately at the dealer I worked for:
The mechanics were in-competent,
The management in-effective,
The owner in-different.

I am driving a limo now --no comebacks.
How many guys reading this site know what a DeSoto is?
I know the feeling, I am at the same place as you were, but I feel we the top techs of our professional at the dealer level need to change the system. Being outside the system makes it hard to change it. I am here to make changes one person and one action at a time.

I too have had many nights of thinking about leaving this trade and moving on but its not an impossible thing to correct and I am all for trying.

But the thinking isn't getting any lesser. I have been seeing some alarming issues coming up and its scary to watch them unfloding.

Flatrater, Jed, and other techs who read this:

Even though you have to put up with crap, remember why you're doing this, you love cars, and you love working on them. Just because some people don't appreciate you, doesn't mean there aren't people that do. Flatrater has helped me so much over the years, and I'l indebted to him for that.

BTW- Flatrater, check your PM's!