99 T&C 3.3L V6 dies while driving with no CEL then restarts with no problem

[mjohns77]

After about 1 mile of driving and while underway the car just dies with no sputtering as though there is some electrical signal to stop the engine. I don't think this is a fuel related problem. After dying, I put it in Neutral and it immediately starts and runs fine for the rest of drive (50 miles). There are no check engine lights or any OBD2 codes. Took it to Liberty Bay Auto and they replaced the Crank Position Sensor (CPS) and also the manifold air pressure (MAP) sensor. Their mechanic was sure this would fix the problem but it did not - same symptoms. Looking at Chiltons my next guess will be to replace the other CPS (Cam Position sensor). In Chiltons I see there is a thing called "Automatic Shutdown Relay" but there is very little detail about it. Can anyone provide guidance for troubleshooting this problem? I am not an auto mechanic but am an engineer who works on diagnosing vibration problems on large Navy ships. I understand the troubleshooting process but am stumped by this one. Thanks in advance for any help.

[danielsatur]

When it dies, can you still turn the lights on and honk horn?
How old is your battery?

[mjohns77]

Sorry to mention. Battery is brand new and I've had it tested by several shops to be a-ok. When car dies all other electrial items (radio, lights, heater, ...) work fine.

[danielsatur]

1) Do you think it's a fuel problem?
2) Is there any fuel at the rail when it dies?
3) Next time it dies, throw some starting fluid in the throttle body.
4) Roll the fuel pump fuse and relay to another pos.
5) Check fuel pressure test.
6) Check catalytic converters, a plugged cat can choke an engine out.

[mjohns77]

Thanks for youre responses.

1. I don't think it is a fuel problem. It has happened over several fillups and also the engine never sputters or stalls like it was either starved or had too much fuel, or the timing was off.

2. Yes, I belive, there is fuel at the rail when it dies.

3. When it dies, the car is coasting at about 25 mph. I immediately put it in Neutral and it starts immediately with no hesitation. While still coasting I put it back in Drive and it is as though there never was a problem.

4. The fuel pump fuse was a-ok. I swapped it for another 20A just to see if it makes any difference.

5. I don't have the pressure gage to do fuel pressure test. I may have the mechanic do this though. I can't imagine this is the problem though.

6. Catalytic Convertor clogged. Hmm. Wouldn't that affect the performance (gas milage, acceleration,...). All performance factors are normal.

By the way, this car has 126,000 miles and the only problem was a tranmission solenoid failure at about 100,000. Replaced the entire xmission solenoid pack and everything has been perfect since.

Thanks again for your suggestions. I am really leaning toward some kind of electrical/electronic issue and not a fuel issue, but I could be wrong.

[plymouthsrock]

Originally Posted by mjohns77

Thanks again for your suggestions. I am really leaning toward some kind of electrical/electronic issue and not a fuel issue, but I could be wrong.

Sounds right.


The fact that it happens at a predictable point in the drive cycle makes me think it is engine management related. The PCM keeps the ASD relay energised as long as it gets valid signals from the crank and cam sensors. So the CMP might be a good guess.

[danielsatur]

Does weather ,snow, ice, or rain play a factor?

Try cleaning electrilcal connectors with CRC electrical connector, use dielectric grease and silicone sealent for protection.

Try turning the battery terminals by hand, and make sure all connections are clean and tight from from the battery, starter, and alternator.

[mjohns77]

To Plymouthsrock: Thanks for your confirmation on the electrical problem and the guidance on the ASD relay. Are there any other signals that feed the algorithm that de-energizes the ASD relay other than the MAP, CPS, and CPS? Should I expect a competent mechanic to have a diagnostic tool that would identify bad components in the ASD relay circuit? Shouldn't the failure of a MAP or Cam sensor trigger a CEL. For example in my OBD book, I see P107 and P108 refer to an irregular MAP voltage and a P0340 (no cam signal at PCM). Thanks again.

To Daniel Satur: Does not seem to matter the weather conditions. All my electrical connections on battery, starter, and alternator have recently been cleaned/groomed and are very tight. I am confident that the resistance across these connections are in the micro-ohm range. It is the circuitry (sensors, wiring, ASD relay) in the PCM that I am suspecting to be the problem.

[RIP]

Can't say its gospel but I've read in several trade articles that starting in 97 the cam sensor signal is no longer used after the engine starts, only while starting. I've never tried it but you could try starting the van then disconnecting the cam sensor and see what happens. You'll get a CE light but you can reset it.

If it consistantly dies around a minute after starting it could be related to the engine management system (EMS) shifting from open loop to closed loop mode. The van starts in open loop meaning EMS is using a fixed set of functional parameters to keep the engine running rich while warming up. Once the O2 sensors reach their normal op temps the EMS enters closed loop meaning it uses the variable O2 sensor inputs and others to run the engine. I have a hunch the PCM is the culprit. Unfortunately, it's going to be near impossible to prove it.

I would take a closer look at any accessable wiring looking for chaffing especially around the exhaust (a common problem). You could also inspect the connections at the PDC making sure there is no corrosion etc. Shake any harness in sight with the engine running. Never disconnect/connect the PCM with the battery connected.

[TXracefan1320]

My 97 with a 3.8 had the same problem and it was the PCM. You should be able to find one on ebay pretty cheap.
One thing that happened with mine is after it would stall, I would check for codes (there would be none) but the monitors were "not ready" as if the battery had been disconnected.

[kpa2004]

For what its worth, I had the same issue with my 97 and it was the spark plugs, apparently the person that owned it before me didnt belive in maintenance. I replaced them, never happened again. By the way the plugs were as sharp as a needle from being worn out so bad.