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Pontiac Forum: Trans Sport quits!
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  #1  
Old December 30th, 2014, 01:51 PM
Trans sporter Trans sporter is offline
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Trans Sport quits!

Hello folks. My 1995 Trans Sport 3.8 is fine when temps are well above freezing but the more the temp falls, the more likely that the engine will quit when asked to make power as in going up hill or heavy acceleration. If the pedal is pressed too far, the engine fumbles, the tachometer jumps around +or- 1000 rpm or so, the transmission disengages, the check engine light (which is on) flashes then goes out, then the engine quits. Restart is not accomplished until the ignition switch has been turned off then back on. Immediately cranking after stalling will not start the engine. The colder the temp, the worse this gets, meaning the engine will give less power before this happens. When temps drop well below freezing, the engine will not run any longer than about 5 seconds. Fuel pressure is between 40 and 45 psi but never drops below 38 psi and a timing light confirms that spark is occurring until the engine stops rotating. Sometimes the tach jumps around even when all is fine. In marginal temps when I can drive the van, it will not do any of this when it is good and thoroughly up to operating temperature. Usually this takes about 30 miles to achieve. A new crankshaft position sensor has been installed and made no difference.
Please see this Youtube video of my problem.
http://youtu.be/QWaTakpqTbI
Thank you for your help!

Codes:
341 intermittent cam position signal
321 No 18x ignition pulses

Historical codes:
341 intermittent cam position signal
321 No 18x ignition pulses
361 EST line not toggling
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  #2  
Old December 30th, 2014, 10:10 PM
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melsg5 melsg5 is online now
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see if these links help you narrow the problem down

http://easyautodiagnostics.com/gm/3....-sensor-test-1
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  #3  
Old December 31st, 2014, 02:06 PM
jeffb jeffb is offline
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Both cam and cranks (18x) signals are processed by ignition module, so as previous poster has indicated, try there. It may be a thermal problem with the unit.
Something else to consider with the age of the vehicle, is the wiring running to sensors. I had an intermittent problem with my MAF that turned out to be a broken wire inside the insulation, about 2 inches from engine connector. I would especially check the wiring to the ignition module, it is a somewhat questionable design in my mind. If you can get it running, gently but firmly twist, push,pull,and manipulate the entire engine wiring harness to see if engine changes. Also check all your coils-even just one failing will cause the engine to stall
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Old January 1st, 2015, 10:30 AM
Trans sporter Trans sporter is offline
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Thanks for the quick reply! Thanks to the link you provided I now understand the 18x code. When I changed the CPS I did notice the reluctors having 3 slots and 18 slots. As you guys saw in the video, the timing light confirms that spark is occurring until the engine stops rotating, at least on that cylinder. Can ignition still be a problem?

Initially, I had suspected a water in fuel problem due to the problem worsening so much below 32 deg. , but I have not found any water in samples and, as you saw in the video, the fuel pressure remains high enough. One other symptom I did not mention is that when below freezing, the fuel pump runs when the ignition is switched on, as it should, but does not stop after a few seconds as it does when it is warmer, but, as I said, the pressure remains. My suspicion, factoring in the flashing service engine light going out when the engine quits and the jumpy tach, is that fuel injection is stopping simultaneously on all 6 injectors for some reason. Could the ECM be losing power during elevated torque and/or rpm ? I had hoped someone here may have encountered this strange set of symptoms before and could save me a lot of work searching for the cause. On my 1994 olds silhouette 3.8 I had found that hardening insulation on wires leading to the doors resulted in broken wires where they flexed during door movement causing my power windows to fail. I wonder if I have a marginal connection somewhere that is temperature sensitive but that could be a wild goose chase. How can I test for this? I do not have a wiring diagram. Can you recommend an oline site for one?

Last night I parked it in a heated garage of about 60 degrees. This morning I started it and it ran perfectly until I stabbed the throttle then it fumbled and quit. I restarted it and pulled it outside into the 21 degree air. No change, at least for the 5 minutes it spent outside while I manipulated the wiring, as you suggested jeffb. I don’t dare drive it anywhere in this weather.

Last edited by Trans sporter; January 1st, 2015 at 11:09 AM. Reason: Additional info.
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Old January 1st, 2015, 07:54 PM
jeffb jeffb is offline
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Wow, you lots going on! Does this constantly running fuel pump issue happen at the same time you have driveability issues" Codes 321 and 341 tend to point to the ignition module or wiring to it issues, but if the fuel pump acts up at same time, only common denomiantor I think is the PCM, or again wiring issues. You don't say where you are from, but as there is snow there, I presume that salt is used on the roads, which is the bane of 20 year old wiring.
Pull the 14 pin connector off the front of the ignition module and check it closely for bent or damaged pins, and any corrosion. Make sure all the pins firmly seat. Repeat for the 30 pin bulkhead connectors, and the 8 pin connector of top of engine.
Another area that has caused ignition problems for me in the past is the loss of the ground terminals located under the ignition module. You will need a mirror to see them, IIRC, there are 3 wires terminating on the stud., but might be wrong. Again, clean, clean, clean.
If that does not work, again squeeze, twist pull the wires, with particular emphasis on the engine side of the 30 pin connector and the 8 pin connector-they are subject to vibration
good luck
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Old January 2nd, 2015, 11:15 AM
Trans sporter Trans sporter is offline
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ICM looks likely

Many thanks for the concerted effort!

Yes the pump runs constantly when it is cold enough to shorten the run time to 5 to 10 seconds (no driveability). Then, simply switching on the ignition will result in its constant operation. Also, since I bought this van, it has always gotten terrible fuel economy. About 16 mpg. Thanks to another guy also helping me with this issue, I can now see that the impaired interaction between the ICM and the PCM can cause this as well.

So far I have removed the ICM and checked all three connectors and the three ground wires on the stud under the ICM mount plate. Since I do live in northern Michigan it was no surprise to see some corrosion on the brackets, plate and stud, but the connections were all clean and shiny. I think the next obvious step is to swap out the ICM with a known to be good one. My Silhouette van definitely has a good one, It ran well and got about 22 to 24 mpg before it spun a bearing during a full throttle 90 mph romp. But, it is outside at my shop (25 miles away). It's about 6 degrees outside so I may not get this done today. Please stand by.
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Old January 3rd, 2015, 06:13 PM
Trans sporter Trans sporter is offline
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Well! Isn’t this something! An ignition unit goes bad but still sparks! Yesterday I transplanted the ICM from my Silhouette to my Trans Sport and, after sitting outside overnight in the cold, the results are: all symptoms have disappeared and the service engine light has gone off. I thought I would at least have to connect a scanner to do that! I wouldn’t have…hell, I didn’t guess that an ignition module that was still sparking would cause all that! The bad ICM that I removed was an aftermarket unit from “Standard”. The unit I pulled from the Silhouette had no markings but works well. This strange batch of symptoms had me thinking something, if not more than one thing, more serious was plaguing me. Thanks for all your help. -Larry-
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Old January 3rd, 2015, 06:53 PM
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glad to hear you got it solved and that was a great way to find the problem.
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