Engine will not stay running

[Bill in Florida]

I will look into the ignition control module. Thanks for the advise dougtoth. It does sound like it maybe the problem. I read about it and it does cuts spark and fuel delivery to
prevent damage from backfiring if reverse rotation is detected.

Unplugging the the MAF sensor connector did not change anything and I should have waited before installing a new one. Thanks for the advise 96SSEi2

[96 SSEi]

np but unfortunately too late to save you $

bill, please check this site and go through the diagnostics BEFORE you start throwing parts at her!!

http://easyautodiagnostics.com/gm/3.8L/ ... sor-test-1

[MKMike]

You've been operating from the assumption that the problem is fuel based--and it may or may not be the problem.
When you checked the fuel pressure, did you check it while the car was running, car running with fuel pressure regulator vacuum hose removed and with the car shut off?
You could also warm up the car to the point where it runs poorly and see what the fuel pressure is then.

Amongst the other common troubles, as Dougtoth and 96SSEi2 mentioned, the ICM is one; Another is the CPS (crankshaft position sensor).
The link 96SSEi2 provided is a very good one.
If the ICM has failed, it's a good idea to also check the coils because a bad coil can take out a new ICM.

One very simple "test" is to look at the RPM gauge when the engine isn't starting.
If the RPMs aren't showing then your crankshaft position sensor has failed.

In addition to sensor troubles, poor contacts and/or corroded grounds will cause the same problems.
From time to time a fuel pump relay fails, resulting in no fuel (located in the rear fuse box).
In some cases, when the relay heats up a bad solder connection inside separates and then the relay stops working.

Make sure the battery cables have good, clean connections.
2 very important grounds are the ground "pack" below the ICM and the Ignition Control Module ground (on the stud beneath the ICM).
The ground "pack" is a small black box with wires coming out of it.
This particular cluster of grounds is for the ECM/PCM (computer aka electronic control module/powertrain control module), and MAF sensor, as well as the transmission internal mode switch and the oil level switch.

Troubleshooting can be tiresome but it does save money in the long run, as some parts can be very expensive.

Don't rely on the module testers that some parts stores have, as they have been known to deem bad modules good.

Quality parts are crucial. It's getter tougher to find them since parts mfgrs, have either outsourced production to China or have to compete with them.
Delphi is one good brand, as are the ACDelco OE parts (not their Advantage or Professional parts lines).

[Bill in Florida]

Thank you 96 SSEi for the link. I will use it.

Thank you MKMike for the good information. I did not warm up the car to the point where it runs poorly and see what the fuel pressure was. I did do the other furl pressure checks that you mention. The battery cables have good connection. You gave me some good ideas where else to look.
I am close to giving up, but I am learning a lot.
I will never be a great mechanic, but I try to save money. I bought most parts from Rockauto and pick standard and what most people pick. I overlooked the economy parts as I am hoping for better quality.

I appreciate all the good help that has been given to me. I also hope this will help other people when they have a problem like mine. Of course their are many different things that can cause a problem. So far I have been changing parts that were probably good and that is expensive. I need to focus on trouble shooting and using the good information given to me. Glad I have more then one vehicle so I can try to fix things myself.
I will report back on my findings.

[MKMike]

It can easily get pretty frustrating.
The plethora of electronics in cars makes it more challenging to diagnose problems.
Regardless of having changed a couple of working parts, it will still be cheaper than having paid someone to diagnose the trouble, in all likelihood.

"Standard" used to be a great brand before they outsourced their manufacturing.

As I was writing a response to another post, it occurred to me that no one has asked whether or not you've thoroughly checked the fuses.
Not only do our cars have 2 fuse boxes; they also have fuses for things you wouldn't think have fuses.

For example, the Underhood fusebox includes:
Fuse 8 Powertrain Control Module
Fuse 15 Direct Ignition System
Fuse 16 Injector Bank 2
Fuse 20 Oxygen Sensor
Fuse 21 Injector Bank 1

A test light is great for checking fuses . This one at Amazon is cheap and works well
http://smile.amazon.com/ATD-5513-Heavy- ... test+light
There can be problems with relays, which can cease functioning when hot, so I'd have a good look at the one for the Fuel Pump and other vital components.
Switch a good relay of the same type for a non-essential with a suspect relay , unless you want to get into testing relays.

[Bill in Florida]

I want to thank everyone for sharing information on what the problem might be with my 2004 Bonneville. It is running great now. The new MAF sensor fixed the problem. I did buy a scan tool as the engine light came back on. My next step is to change the catalytic converter as a service engine light came on now with 404 code. It probably went bad when the engine was running real bad and the exhaust system turned red hot under the car when I first had the problem.
The engine runs good and when I look at the scanner on the oxygen sensors, #2 is acting like #1, shows they are working, but the catalytic converter is not. oxygen sensor #2 should be steady on the graph. I have heard of people cleaning them and running lacquer thinner in the gas tank, but I will probably just replace the catalytic converter.

[MKMike]

With the downstream 02 sensor rapidly changing readings, you could try replacing the sensor before going for the converter.
Replace it with a Delphi or ACDelco sensor, as problems are not uncommon when using other brands.
If you meant code P0420.http://www.obd-codes.com/p0420
The catalyst, when it melts, usually causes a noticeable loss of power.
You can read what diagnostics Eastern Catalytic suggests here http://www.easterncatalytic.com/educati ... 420-codes/

If the code really is P0404, then that's an EGR code, not a catalytic converter code.
This site lists some good info on causes/fixes http://repairpal.com/OBD-II-Code-P0404