PontiacBonnevilleClub.com

Morning, guys.

TL;DR version, car cranks but doesn't turn over, injectors 3 and 5 pulse about once every second, all others have no pulse. Some pulse once as I crank, or let go.
I have spark and fuel pressure.
CEL comes on, but can't test an OBD 1.5

Car is a 95 Bonneville SSE





I frequent these boards whenever I have a problem with my car and you all usually have the answers I need.

However recently I've had a few issues with my car that I can only find references to, but no actual solutions.

So if anybody could offer some suggestions, please do.

I have a 1995 Pontiac Bonneville SSE with a 3800 non supercharged engine.

My problem is pretty straightforward. I've done some testing so nobody has to suggest it. Not much, but the basics.

My car will not start. It sits there and cranks but won't turn over. Naturally when that happens, it's either not getting spark or fuel.

My fuel pressure is fine. I have spark in all plugs.

What I do know is that only a few injectors are getting power while trying to start the car.
The test I used was simply putting the connectors for a 194 size bulb in the female connectors for the injectors. I know they should pulse when trying to start the car to about 1 blink per second.

Only injectors connected to cylinders 3 and 5 do that. The other ones either don't light up at all, or only when first cranking it, or releasing the key. Only 1 blink in those cases.

See firing order diagram for cylinder reference.


What could be causing them to not get any power? The plastic on the wiring harness itself is kind of brittle to the touch, but the connectors and wires are fine.

Possibly related, the other day my car was just clicking when I tried to start it, but all lights and voltage were fine. My positive terminal was severely corroded. I corrected that problem and the car drove fine for a few days before this started. It stalled out on me while driving only once. I started it back up and it cut out right away. I fought with it doing that for a while, and then it was fine until I parked it again.

I think it's the computer itself, since that's what controls the injector pulses.
But I've heard of people having weak or no injector pulses before and it was the ICM, supposedly. But the ICM doesn't power the injectors, so maybe they're full of it.

I will say that since I bought the car about a month ago, the check engine light turns on when it idles for too long. But when I turn it off and back on, then start driving, it turns off again. It's an OBD 1.5 so I can't check the code, right? Not without buying a special cable (and a computer to check it.)

The check engine light may be unrelated, however when I get the car started and it stalls back out right away, the light comes on and beeps at me a few times.

What do you guys think the problem is? Any other tests you suggest? I have more bulbs, a voltmeter, and for most of the day, a helper.

Not having my car for too long means I lose my job. Also I'm broke as hell, so taking it for a diagnosis is pretty much out of the question.
I really hope you guys can help me out.

Also, just throwing this out there. It may help you to know that when I got this car, it still had the factory spark plugs in it. If that gives you any ideas of just how poorly this car was maintained by the previous owner. So don't eliminate the obvious just yet. That and the valve cover gaskets were basically non-existent. I've never seen so much oil on an engine that still ran. (Not an engine with sensors and stuff. My 1984 Olds Delta 88 had a bit of a leak on it for a while. It has about 2 INCHES of caked on oil and grease. It still runs great.)

I have to check the FSM for the flowchart of things to check
and in which order. I know ICM is pretty soon on the list, and that's what
left my 95 in the driveway for two weeks once. The PCM and crank sensor
are two that also come to mind, but I think they are far down the list.
I will have to get back to you, Mondays are hectic for me.
Do you have access to donor parts to swap and test, from somewhere or a junkyard?

I do recall 95 being an off year for PCMs, seems many members have had problems with them.

There is a small fuse block behind the glove box above the hush new all the way on the passenger side, check to make sure all those fuses are good, I can't recall exactly what they control but I do know there is some vital ones there.

The cam sensor may also play a roll in this, I know it takes care of injector timing.

The Cam sensor is simply a #1 TDC reference... The engine can actually run without it, not the best as it won't run in SFI mode tho..

This does sound a lot like a bad PCM, Make sure the fuses are 100%, as well look at the grounds busses to make sure the PCM is getting the proper grounds..

I wonder if the code stored in the PCM could be a P1361, seems to happen a lot when these PCM's fail

I'm back. The other day I ordered a new PCM from my local Autozone, as it was cheaper than getting a new ICM by about 20 dollars.

That, and Autozone has a very loose return policy that allows me buy a new part and return the old one for my money back.

Anyway, I take the old PCM out and realize that it was the exact same re-manufactured part I got from Autozone. It had been replaced by the previous owner at some point.

I took off the ICM next, and saw that there was about an eighth inch of caked on oil and corrosion in between the ICM and the plate it mounts to.

Cleaned it off and it started right up. Didn't even have to buy a new one.

psiguy wrote:I'm back. The other day I ordered a new PCM from my local Autozone, as it was cheaper than getting a new ICM by about 20 dollars.

That, and Autozone has a very loose return policy that allows me buy a new part and return the old one for my money back.

Anyway, I take the old PCM out and realize that it was the exact same re-manufactured part I got from Autozone. It had been replaced by the previous owner at some point.

I took off the ICM next, and saw that there was about an eighth inch of caked on oil and corrosion in between the ICM and the plate it mounts to.

Cleaned it off and it started right up. Didn't even have to buy a new one.

Nice work! Great way to end the year on a bit of good work. Merry Christmas! - BC

I'm going to bookmark this.....

Great result from a bit of detective work. Congratulations!

psiguy wrote:I'm back. The other day I ordered a new PCM from my local Autozone, as it was cheaper than getting a new ICM by about 20 dollars.

That, and Autozone has a very loose return policy that allows me buy a new part and return the old one for my money back.

Anyway, I take the old PCM out and realize that it was the exact same re-manufactured part I got from Autozone. It had been replaced by the previous owner at some point.

I took off the ICM next, and saw that there was about an eighth inch of caked on oil and corrosion in between the ICM and the plate it mounts to.

Cleaned it off and it started right up. Didn't even have to buy a new one.

Glad you got it cleaned up.. as well check the ground that at the ICM bracket.. Sometimes problem with these cars can turn out simple..lol

psiguy wrote:I'm back. The other day I ordered a new PCM from my local Autozone, as it was cheaper than getting a new ICM by about 20 dollars.

That, and Autozone has a very loose return policy that allows me buy a new part and return the old one for my money back.

Anyway, I take the old PCM out and realize that it was the exact same re-manufactured part I got from Autozone. It had been replaced by the previous owner at some point.

I took off the ICM next, and saw that there was about an eighth inch of caked on oil and corrosion in between the ICM and the plate it mounts to.

Cleaned it off and it started right up. Didn't even have to buy a new one.

Thanks for posting the follow-up.

It's always good to know what resolved the problem.
Nice that it was a simple and free fix!