stalling/no start

In recent weeks my RIv has stalled a couple times while running and has not not restarted.

I am trying to figure out what to check next and would appreciate your input/suggestions.

Here is the background:

It had been 2 years since the last time it stalled without seting a code. That itme it was the crank sensor.

Recent maintenance includes plugs (Delco Iridiums).

What happened was it stalled, I had it towed to the dealer and they could not find anything - so we replaced the crank sensor; it then ran fine. This time we used a Delphi crank sensor (last time we used a Blue Streak).

I am working with local Buick dealer to figure this one out. The mechanic and I both wonder what's wrong. They replaced the ignition module (granted, it was a guess) and they let the car run, I am told, most of the day (I hate that - no good can come of letting the car idle unattended). They supposed this fixed the problem. Then as luck would have it when I went to pick up the car, I stopped on the way out of the dealership lot and it stalled & would not restart. Checked it with a TechII at that time (me and the service manager). All we found was that the injectors were not being told by the PCM to fire for some reason - why we are not real sure. Crank sensor, MAP, o2 sensors signals all looked fine. Basically it should have been running but had no injector pulse. I told the service manager that it'd be nice if the folks at OnStar HQ (car had the cell phone kit for the OnStar option, whcih I had removed) would quit pushing the Trade In Stall Commanded button - I am in no position to buy a car right now.

It has yet to set a code (that I know of).

While it was stalled at the dealership we tried checking for fuel (fuel pump is OK and pressure is in spec according to the Tech II) spark (no problem) and injector pulses (using a NOID). The NOID would not flash on any cylinder.

I do not remember if we disconnected the cam sensor - if the cam sensor is internally shorted it will inhibit starting - that is, it is internally shorted you can then get the car to start and run by disconnecting the cam sensor. Point is I don't remember trying that.

Anyway, I pushed the car into a parking space at the dealer and left. When the service manager went to look at the car again, it started right up. They tried some other things: cleaning the grounds (all the ones in engine compartment are now cleaned up and coated with conductive grease); checking the TPS and engine temp senders; running the Powertrain OBD check; checking for more than 10C temp difference betwen coolant and intake air sensor readings when engine is stone cold. No problems indicated.

It stalled again today btut started right back up.

I suspect PCM or Crank sensor- any of you have any ideas? Help!

Albertj

One of those good issues. If you saw no pluse at the injectors while trying to start there are only a couple things that can cause that. In the FSM's it's detailed out what the items are, I think you are correct on the crank sensor and PCM though.

i had a similar problem that the thieves at the diagnostic center diagnosed as a bad pcm. cost a fortune to replace,had i known how inexpensive a used replacement was i might have saved that money..but i went the route you did. new crank sensor ,that was not it. then pcm, that solved the start prob...

Thanks guys!

Update -I keep a service record in a "journal" in the car. One of the best "dollar store" dollars I've spent - I write all the services, every oil change, etc. in the thing. It makes it MUCH easier to diagnose things, and gives me the ability to get things fixed right if I am on the road (no guessing as to what needs/does not need done).

Anyway, based on the record and the FSM troubleshooting, I went ahead and ordered a PCM used (eBay) from a gent in Ohio that pulls them out of wrecks and reflashes them. They are Select Core Company. They do eBay business as "spareECM" name is Rodney Brenner, selectcore@aol.com, (330) 473-0426. Rodney warrants the replacemetn for a year as long as you do not alter the programming (CASE Learn is not altering). Makes sense to me. Anyway... it just arrived.

My hunch is I have a PCM gone bad or a crank sensor connector issue. Dealer mechanic (Doug) assures me it is not the connector...

Anyway right now I have a stupid problem - problem is I changed laptops; new laptop does not have a 9-pin serial port so I can't use my OBD-II dongle until I get a USB/9-pin adapter (or until the dock arrives). Doh.

As for the car, I will take it back to dealer today or tomorrow. If I had a Tech II or HPTuners software I'd just put the ECM in. I may have the dealer put it in (customer request) and then run the CASE learn.

Alternatively - I am having a local independent mechanic (Marty) replace the front wheel bearings and the SC coupler (well actually we're taking the SC apart and replacing bearings as well if needed. Most likely don't need bearings). If "nothing happens" at the dealer I may have the independent also install and CASE teach the replacement PCM.

Thanks very much for your comments - any other input (including echoes) welcome, this is really throwing me for a loop.

It's funny... I had a Volvo 740 that I had to replace the ECU on as well - it just started doing stupid stuff. What is it with these electronics that gets them failing? Sunspots? Thirst?

Albertj

PS - I don't know what your weather is like but around here we are having crisp, postcard-clear days, kind of on the cool side. Notice the weather where you are and try to enjoy it, rain or shine.

I went through similar diagnostics trying to troubleshoot my no-start a few weeks ago. The FSM guide takes you through testing only a few items before recommending to replace the PCM, so in your shoes I'd say it's cam sensor, and if that doesn't fix it, PCM.

The dealership should be following these troubleshooting tables for no-start and arrive at the same conclusion.

Sounds exactly like the stalling problem my Park Ave had last summer.
It was the fuel pressure regulator.
I know you say pressure was checked, but that's all it was on my car.

Sweepspear wrote:

Sounds exactly like the stalling problem my Park Ave had last summer.
It was the fuel pressure regulator.
I know you say pressure was checked, but that's all it was on my car.

Thanks Dale, but... unless the FPR is supposed to provide feedback to enable the injectors to fire, and is not, this is not it.

Just the same I will check it. I know when I am stumped and this is one of those times.

By the way...

You should have seen/heard the mechanic groan when I suggested we test for fuel by using a key to push the pintle in the schraeder valve on the fuel rail. I just looked at him and shrugged and said I had not had my shower yet today and since the car's not moving this was as good a time as any.

Albertj

I replaced the cam sensor today, and talked with mechanic (Doug).

Most likely will replace the PCM - I have the replacement. The LED indicators on backprobes into the FI harness are still in place.

It stalled twice today but restarted up again while rolling (I was at high highway speed on an interstate) so I could not check the indicators.

I gotta take a second look at the FPR.

Albertj

Took a second look at the FPR. On our cars (well, on the '98 Riv) it's modulated by vacuum and gives no feedback to engine controls. You can actually disassemble and clean the sucker.

I'm thinking I'm installing a PCM soon... real sooooooon...

Albertj