PontiacBonnevilleClub.com

I decided to start a new thread to keep things clear and current. I have been replacing part after part with marginal improvements in performance, and I think there is one primary problem that we have not been able to see. (To those of you following the last thread, I still have yet to clean the MAF but I have reason to believe there is no possible way that will even come close to being the main problem)

Here are my MAIN symptoms:

1. Engine has virtually no power. It probably has literally 15% of its normal power. At all levels of throttle, it is just very poor. It will drive and accelerate, but it takes forever

2. TERRIBLE mileage. Probably less than 9 mpg.

3. The Car smells like crappy ignition after being driven.

4. There is definitely a small pressure leak down by the gas tank, though I don't think this is that big of a problem.

The car sounds relatively normal in terms of what the engine does, pretty much everything else is normal.


Edit: occasional "o2 sensor heater circuit" error code. Also the old "random/multiple cylinder misfire detected".

Things that have been checked/replaced (I would rather not focus on any of these as a possibility)
Spark Plugs
Spark Plug Wires
Coils
MAF
Fuel Filter

The Fuel Injectors were replaced with other, also used (but supposedly working) Injectors. I seriously doubt these could be the problem though, considering the symptoms. The engine appears to be running with way too much gas in the mix, not too little. At least thats what it sounds like. So even if the injectors do suck, I don't see how it would cause my symptoms.

Who can think of one major thing that could cause the engine to be 85% less powerful without many other obvious symptoms?

Did you check the cat.??? A plugged one can cause lose of power or no power at all.

2002BonnevilleSE wrote:Did you check the cat.??? A plugged one can cause lose of power or no power at all.

The catalytic converter? How do I test that?

It may become very hot.
If the your converter is plugged, it will create a restriction in your exhaust system. The buildup of backpressure will cause a drastic drop in engine performance and fuel economy, and may even cause the engine to stall after it starts if the blockage is severe.
Last car I had this problem on,I just pulled the exhaust apart and cleaned the cat. out with a pipe ....no more problem.

Let the car cool, then crawl under and kick the cat or hit it with a mallet. If it rattles, it's for sure bad. Otherwise you'll have to have a back pressure test done to see if it is the cat or not. It can not rattle and still be bad.

00Beast wrote:Let the car cool, then crawl under and kick the cat or hit it with a mallet. If it rattles, it's for sure bad. Otherwise you'll have to have a back pressure test done to see if it is the cat or not. It can not rattle and still be bad.

Is there a back pressure test I can do at home? Otherwise how much will that cost? And Will it work if my exhaust system sucks?


Also, I ran my OBD sensor... Sometimes I get an error for P0135 which is "O2 sensor heater circuit". I looked online and it seems this means that the whole sensor should probably be replaced...

Here is a graph of my O2 sensor data. You will notice the maximum value is about 1 volt. This is from me starting the car and letting it idle. There is a peak near the end that was me revving the engine. But you will notice is constantly fluctuates from about nothing to 1 volt.


Could this be causing my problem??? Also is should be noted that the car was idling really poorly, and either following or leading (but correlated to either way) this graph in terms of rpms.
The important question here is whether this could possibly be so bad that it would cause an 85% drop in performance.

What was the coolant temp @ idle? The O2 readings aren't used till over 160* ECT.

00Beast wrote:What was the coolant temp @ idle? The O2 readings aren't used till over 160* ECT.

I didn't check for sure but I am 90% sure it was over that, I had just been driving it for a while before that.

Okay I went out and drove it for a little bit and thought I would show you guys some data. I don't really understand all of it but you might. This is all from my OBD scanner. One thing to note is that they don't all follow exactly the same timeline, because the car was running when i told it to start recording some of them. Otherwise, please take a look!

Also one last thing, correct me if I am wrong here.... But my problem cannot possibly be the O2 sensor or MAF, because the car acts exactly the same cold as it does warm, right? Those sensors don't have any effect on how the car runs until it is warm and goes into closed loop is my understanding. Can anyone verify this?

It'll go into closed loop pretty quickly. Usually 2-3 minutes after a true cold start it'll be in closed loop. Coolant temperature has to be above 80*F (if my car is any clue), or 2-3 minutes after it's started on a cold morning from ambient temperature.

If you think it goes into closed loop only once it reaches operating temperature, that's demonstrably false. Alas...

LeSabre in Buffalo wrote:It'll go into closed loop pretty quickly. Usually 2-3 minutes after a true cold start it'll be in closed loop. Coolant temperature has to be above 80*F (if my car is any clue), or 2-3 minutes after it's started on a cold morning from ambient temperature.

If you think it goes into closed loop only once it reaches operating temperature, that's demonstrably false. Alas...

well I do live in minnesota where it is below freezing in the morning, and i can tell you that the car acts exactly the same right off the bat. It could have an engine coolant temperature of 32 degrees and it will still drive like crap. There is never a time when it just drives better. So I can only assume that it is not in a closed loop, and that the problem has to be elsewhere, right?

Don't assume it doesn't enter closed-loop operation. That's something your scanner should pick up. There's no seat-of-the-pants method of telling if a car is running open or closed loop. The computer wants to get to closed loop operation as rapidly as possible so it can protect the catalytic converter and the engine from damage. It "should" set a CEL if closed-loop operation cannot be achieved. And, if the PCM is reporting O2 sensor data, it's running closed loop. My scanner doesn't pick up changes in O2 sensor data until closed loop operation starts.

In your graphs, I'm guessing you started the O2 sensor record right when the car was started. If you look on Bank 1 Sensor 1, you'll see a flatter line indicating the PCM isn't taking that data. Then when the data looks like an earthquake hit at 3 minutes in, that's when it hit closed loop. And started using the data from the oxygen sensor.

And, it's been plenty cold here in the woods and valleys of upstate NY, too. ;-)

Does your exhaust smell like rotten eggs or unburned hydrocarbons after the car's been driven for 10-15 minutes? If it does, it's likely a bad catalytic converter.

If you want, I'll try to get a video of my car going into closed loop on my scanner with coolant temperature displayed.

Pretty sure closed loop doesn't begin till 160*. That's when the knock sensors kick on. I remember having to drive a ranger forever at work one day to get it into closed loop to scan for something.

LeSabre in Buffalo wrote:Don't assume it doesn't enter closed-loop operation. That's something your scanner should pick up. There's no seat-of-the-pants method of telling if a car is running open or closed loop. The computer wants to get to closed loop operation as rapidly as possible so it can protect the catalytic converter and the engine from damage. It "should" set a CEL if closed-loop operation cannot be achieved. And, if the PCM is reporting O2 sensor data, it's running closed loop. My scanner doesn't pick up changes in O2 sensor data until closed loop operation starts.

In your graphs, I'm guessing you started the O2 sensor record right when the car was started. If you look on Bank 1 Sensor 1, you'll see a flatter line indicating the PCM isn't taking that data. Then when the data looks like an earthquake hit at 3 minutes in, that's when it hit closed loop. And started using the data from the oxygen sensor.

And, it's been plenty cold here in the woods and valleys of upstate NY, too. ;-)

Does your exhaust smell like rotten eggs or unburned hydrocarbons after the car's been driven for 10-15 minutes? If it does, it's likely a bad catalytic converter.

If you want, I'll try to get a video of my car going into closed loop on my scanner with coolant temperature displayed.

Ya i think you are right about when it went into closed loop... then again I don't think i had hit the throttle until then either, but they could have easily happened at the same time too. But my whole point in saying all this is that my car acts the same ALL the time, whether it is cold, warm, or anything. I drive it all the time and there is never a time when it has acted any better. (not to say it literally acts exactly the same every single time, just closely enough to rule out anything that is only on SOME of the time from being the sole-contributor (or at least primary contributor) to my massive loss of power).

As to your question about the smell. It definitely does NOT smell like rotten eggs or sulfur at all, but it certainly does smell like unburnt gas. Or gas that didn't burn well in general. It is very strong

Replace the Bank 1 Sensor 1 O2 sensor. It's providing bum data if the heater is broken. They need the heaters to heat the element to some crazy high temperature to read properly. If it's not reaching that temperature, it's considered broken.

After reading your other thread quickly, have you changed plugs? Or, what about your fuel pressure regulator? Find that, pull the hose off, smell for gas. ANY gas smell means it's bad.

So I have found out something interesting... I had recently tested all my coils and found out that one was not working properly. So I did the logical thing and replaced it with a new one. But I never remembered to test the new one at all, until today. It still isn't working. The others still work fine, this one isn't producing any spark. The problem is, it is obviously NOT the coil itself that is bad, and I do not really know how to troubleshoot it to find out what IS bad. How should I go about that?

LeSabre in Buffalo wrote:Replace the Bank 1 Sensor 1 O2 sensor. It's providing bum data if the heater is broken. They need the heaters to heat the element to some crazy high temperature to read properly. If it's not reaching that temperature, it's considered broken.

After reading your other thread quickly, have you changed plugs? Or, what about your fuel pressure regulator? Find that, pull the hose off, smell for gas. ANY gas smell means it's bad.

And ya I will probably replace the O2 sensor eventually, though I don't think it is a priority now, especially since that error code only shows up once in a very long while. And yes, I have replaced all the plugs. And I have not checked the fuel pressure regulator, though I just tested my fuel pressure today and it looks like it sits at about 60, which to my knowledge is okay.

Ignition control module (ICM). Get a junkyard part, it's a rip at the parts stores.

Just replace the dang O2. I gained 2 mpg average after replacing mine. I agree with the ICM. There is nothing else that would not allow that coil to fire.

Hah ya I will definitely replace the O2 sensor as soon as I can. Hopefully I will be able to just replace this ICM without too much trouble...

And Beast, I see your location is collegeville.. Are you a Johnny?? I have a lot of friends that go to SJU