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94 Trans Sport losing power intermittently


stevenjames
08-18-2005, 02:57 PM
I posted a response to "gordobw", but now I am not sure I am experiencing the same problem or not. I am no mechanic, so I am just hoping someone will have an idea of what else I can ask my local mechanics to check.

My 94 trans sport 3.8 loses power slowly until engine dies (rpm and mph slowly decrease over 30 seconds). This is an intermittent problem, and will sometimes run just fine. When it does finally die, it will start up again after waiting 5-10 minutes. My local mechanic spent a long time checking many aspects, all showed OK (fuel pump pressure, fuel filter, back pressure, cam and crank sensor, Ignition Control Module). They narrowed it down to losing injector pulse and suspect the PCM, but could not test this. Checked injectors and circuit for resistance and short to ground--appear OK, and it does not lose spark or power to injectors.

Previous problem I would have is engine stalling upon slowing through turn in intersection (right or left) or on off-ramp from highway...in these intermittent cases, I would put the car into neutral and it would fire right back up as I coasted. This new problem, the car does not turn back on immediately.

Something my wife has experienced, but I had not, is a simple loss of power every now and then on a cold engine, but it did not die on her on those occasions.

Any ideas?

Mit Snave
09-03-2005, 07:02 AM
I posted a response to "gordobw", but now I am not sure I am experiencing the same problem or not. I am no mechanic, so I am just hoping someone will have an idea of what else I can ask my local mechanics to check.

My 94 trans sport 3.8 loses power slowly until engine dies (rpm and mph slowly decrease over 30 seconds). This is an intermittent problem, and will sometimes run just fine. When it does finally die, it will start up again after waiting 5-10 minutes. My local mechanic spent a long time checking many aspects, all showed OK (fuel pump pressure, fuel filter, back pressure, cam and crank sensor, Ignition Control Module). They narrowed it down to losing injector pulse and suspect the PCM, but could not test this. Checked injectors and circuit for resistance and short to ground--appear OK, and it does not lose spark or power to injectors.

Previous problem I would have is engine stalling upon slowing through turn in intersection (right or left) or on off-ramp from highway...in these intermittent cases, I would put the car into neutral and it would fire right back up as I coasted. This new problem, the car does not turn back on immediately.

Something my wife has experienced, but I had not, is a simple loss of power every now and then on a cold engine, but it did not die on her on those occasions.

Any ideas?

Quote: Seek and you shall find!!!!!!
In regards too your posting: To make a long story short, I had experienced the same issue here recently and upon troubleshooting found that even though the altenator was tested as good by the parts store, when on the car it was not getting a signal to activate. After tracing the wire down, i found that it did not terminate anywhere. I dug into the issue deeper and to make a long story short, found that the regulator located within the altenator was the wrong one. I had a gentlemen who has an altenator business place the coorrect regulator in the altenator, placed it bsack on the car and now all is well. I'm not sure if this was a factory default of whether the previous owner had issues and had the altenator replaced. If your having issues of this nature, charging, ect. I would strongly suggest having the altenator regulator checked to insure it is correct. Can save a lot of headaches. PS. On my 1992, the brown wire is not used and the altenator is suppose to get it's signal from the White/Pink wire that comes from the ignition.

Additionally, to see if your altenator is charging correctly, you can place a meter on the external post of the altenator and a ground of the car and it should read somewhere around 13 to 15 volts if the unit is working correctly. Hope this helps..

Sincerely. Tim

stevenjames
09-06-2005, 10:22 AM
Hm...I will see if I can followup on your ideas. Based on the testing already done, I am expecting this to be a pretty odd problem, and your experience follows that feeling.

Today I could not get the car to start (cranks and either does not turn over, over turns over and immediately dies)...if I can just get it back to my mechanic...

Thanks for your feedback,

Steve

stevenjames
09-27-2005, 02:02 PM
The dealer mechanics checked out my vehicle and found the PCM was indeed the culprit. Separate, but simultaneous, was a bad EGR which explained my intermittent stall that was very different from the more recent loss-of-power-and-then-die-and-then-not-start problem.

Both replaced and working fine now.

pizzaro223
10-03-2005, 09:34 PM
I replaced the Idle control valve, ajusted it as the book said but I got the reverse (high Idle) finally I manually ajusted the pindle and experienced your problem, so I backed the pindle off until it ran perfectly, the book tell you how to check the ICV, later.

toms43
12-07-2005, 03:38 AM
The dealer mechanics checked out my vehicle and found the PCM was indeed the culprit. Separate, but simultaneous, was a bad EGR which explained my intermittent stall that was very different from the more recent loss-of-power-and-then-die-and-then-not-start problem.

Both replaced and working fine now.

Steve,
I read your posting. I have the same problem with my 95 TSport 3.8L. Same happenings, driving, immediate start after stopping , getting worse now and stalling all the time, even my RPM dial goes way up before it dies then all dials fall. I bought a new fuel pump and screen thinking maybe thisis it. But I saw your answer . NOW whats PCM and an EGR?
thanks,
Tom

cdru
12-07-2005, 10:56 AM
NOW whats PCM and an EGR?PCM is powertrain control module...aka computer. EGR is Exhaust Gas Recirculation valve...it's a emissions component that will recycle a little bit of exhaust gases for lower emissions.

toms43
12-19-2005, 03:57 AM
PCM is powertrain control module...aka computer. EGR is Exhaust Gas Recirculation valve...it's a emissions component that will recycle a little bit of exhaust gases for lower emissions.

Do you have a part number on these 2 items. I am in Europe and must have someone from USA bring it to me over Chriatmas
Part # for 1995 3.8L PCM
Part # for EGR

Thanks
Tom

cdru
12-19-2005, 08:03 AM
Do you have a part number on these 2 items. I am in Europe and must have someone from USA bring it to me over Chriatmas
Part # for 1995 3.8L PCM
Part # for EGRNo I don't, but you should be able to call any GM dealership and they can get it for you.

vesamaan
12-19-2005, 11:50 AM
Do you have a part number on these 2 items. I am in Europe and must have someone from USA bring it to me over Chriatmas
Part # for 1995 3.8L PCM
Part # for EGR

Thanks
Tom
Have you checked this site http://www.cars-stripes.com/kataloge/index.htm#kataloge The company is in Europe, and price for refurbished PCM was 229 Euros,
and EGR valve was 219 Euro. Only problem is that whole site is in German :mad:
Hope this helps a bit
Antti

LMP
12-19-2005, 08:50 PM
I have problem with my 95 TSport 3.8L.... driving, immediate start after stopping , getting worse now and stalling all the time, even my RPM dial goes way up before it dies then all dials fall. I bought a new fuel pump and screen thinking maybe thisis it. NOW whats PCM and an EGR?
thanks,
Tom
Tom, PCM is expensive and this failure is rare. EGR valve though is a common problem and that can be tested for 0$ by removing it and blocking all ports on adapter and go for a test drive. THis failure would not stall the engine on the run though, but cause rough idle or not able to idle.
Crank position sensor is also a very frequently reported problem on all 3800 engine vehicles. THis causes difficult engine starts, or starts and then engine stops at next traffic signal or after a short stop nearby... THis is inexpensive but somewhat cumbersome to change.
www.avigex.ca/xport/ckps.jpg
www.avigex.ca/xport/ckpsremoval.jpg
www.avigex.ca/xport/ckpulley.jpg
But ahead of all these considerations, is your CHeck Engine light ON? If that is the case, you should have the codes pulled out.

toms43
12-20-2005, 01:39 AM
Tom, PCM is expensive and this failure is rare. EGR valve though is a common problem and that can be tested for 0$ by removing it and blocking all ports on adapter and go for a test drive. THis failure would not stall the engine on the run though, but cause rough idle or not able to idle.
Crank position sensor is also a very frequently reported problem on all 3800 engine vehicles. THis causes difficult engine starts, or starts and then engine stops at next traffic signal or after a short stop nearby... THis is inexpensive but somewhat cumbersome to change.
www.avigex.ca/xport/ckps.jpg
www.avigex.ca/xport/ckpsremoval.jpg
www.avigex.ca/xport/ckpulley.jpg
But ahead of all these considerations, is your CHeck Engine light ON? If that is the case, you should have the codes pulled out.

No my check engine light is NOt on. Just all the other symptoms like James had. stopping after driving a while and especially after letting off the gas like at an exit on freeway it stops, then I slip it into neutral and start it, then ok for another distance. Although it is getting more frequent now between happenings. I started it up yesterday after sitting in drive for two weeks. After pumping the accelerator a couple of time it starts. I have a new fuel pump ready to install w/screen. I am thinking maybe it could be some of the problem. I'm hoping it is it. Is the fuel pump an "in the tank installation"?
Tom

LMP
12-20-2005, 08:17 AM
Indeed you have to completely remove the fuel tank to get to the fuel pump/sender unit that is mounted on top. However I would change the external in-line filter first and go for a test. I do not like these so called "together" causes like in example above (PCM and also EGR....).....one i$ enough and the other mo$t often i$ overkill.....
One funny thing in the GM manual is they say alcohol in fuel may be detrimental to fuel system components...a well documented fact in small aircraft engines where "occasional" stalling is not an option...
A fuel pressure test could reveal if fuel pump is indeed a culprit.
www.avigex.ca/xport/fuelpressuretest.jpg
Based on repeated questions and assumptions about fuel pump possibly related problems (and most of the time in these forums proving not to be the real problem..and I've seen that in A LOT of car forums..but soimetimes it is..so how do you sort that out), one thing I will install on my van is this: rigging an oil pressure sender (same as the one already on the car) on the fuel rail test point and feed oil pressure and then fuel pressure signals (they happen to be in same range) to a select switch - that is one wire only to select from either sender - so my instrument panel oil pressure gauge would be available to show oil pressure OR fuel pressure, an inexpensive week end job that could prove very useful in troubleshooting (in real time on the fly), or just for the fun of it. I'll post a photo and instructions once done.

toms43
12-30-2005, 05:37 AM
Indeed you have to completely remove the fuel tank to get to the fuel pump/sender unit that is mounted on top. However I would change the external in-line filter first and go for a test. I do not like these so called "together" causes like in example above (PCM and also EGR....).....one i$ enough and the other mo$t often i$ overkill.....
One funny thing in the GM manual is they say alcohol in fuel may be detrimental to fuel system components...a well documented fact in small aircraft engines where "occasional" stalling is not an option...
A fuel pressure test could reveal if fuel pump is indeed a culprit.
www.avigex.ca/xport/fuelpressuretest.jpg
Based on repeated questions and assumptions about fuel pump possibly related problems (and most of the time in these forums proving not to be the real problem..and I've seen that in A LOT of car forums..but soimetimes it is..so how do you sort that out), one thing I will install on my van is this: rigging an oil pressure sender (same as the one already on the car) on the fuel rail test point and feed oil pressure and then fuel pressure signals (they happen to be in same range) to a select switch - that is one wire only to select from either sender - so my instrument panel oil pressure gauge would be available to show oil pressure OR fuel pressure, an inexpensive week end job that could prove very useful in troubleshooting (in real time on the fly), or just for the fun of it. I'll post a photo and instructions once done.

Thank you for your help. I'm on my way to the mechanic with this info
Tom

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