1995 riviera problems please help

I have a 1995 supercharged riviera with 130000 or so. Here is the problem when I start it up it tuns fine for about ten or fifty minutes and then runs horrible and will not stay running if it not over 3000 rpms. I have replaced the mass air o2 cam shaft throttle position sensore and fuel pump with no luck. I am planning for the crank shaft sensor and ecm and new coils this weekend but figured maybe I could get some help here. I love the car but its killing me that I can't get her going. Any suggestions on where the issue may be would be greatly appreciated. Thinking either pcm ecm or crank sensor oh by the way just gave tune up and everytime I start it I. Pull the plugs and they are covered in black soot any suggestions thanks

Check the wires, that plug into bottom of coils.You will see a nut, on the end,loosen it take it off inspect, if that's all good. Might be that bottom half of the modular. J.Y part $50.00.

U mean the ecm I have had it checked three times but I'm still thinking that could be it. But the wires all looked good and bolted down tight and it runs real good for those first 10 minutes then just falls on its face. Sorry didn't understand the j.y .part what do u mean there

J.Y. means Junk Yard.

The computer under the coils is the PCM not the ECU, the ECU is a big pot-metal box up behind the glovebox in the passenger compartment. The Riv has 5 computers - ECM (just explained that one), PCM (under coil pack), BCM (locks and stuff), there is one in the radio, one under the drivers seat, and I forget wehre the 5th one is.

Now, back to your problem.

Why are you replacing so many parts without doing testing, or pulling fault codes from the OBD II link?

Even if the check engine light is not on you really need to pull the stored codes and see what they are. This wil tell you a couple things:

1) old intermittent problems that were not really corrected

2) whether in fact the OBD II system is working (storing codes and checking faults)

3) whether the problem is related to a component that does not set a code.

Second, pardon my stating this very directly but your hait of throwing parts into the car is semi-nuts. For instance, if it starts and runs OK at first, you are unlikely to need coils.

Third, as difficult as it is to get to the rear bank plugs either you have wispy heatproof hands or you have come up with some magic to reach them 'cause pulling all the plugs after every start is, well, a thankless job. How do you get the rears out? Please explain.

Based on what you are saying it sounds like one of the following:

1) you're making this up (probably not).

2) there is a problem when the car's ECU tries to make the transition from open loop to closed loop operation.

3) I am guessing there may be one or more slightly-busted wire in the big harness to the firewall or to the powertrain control module (under the coil pack).

So here is your help (at least, from me)

1) go on line and find a factory service manual, buy it. You should find them aon eBay and they will not be all that pricey. THey are still around new from GM, for like $200, but you can find them on line for less than half that and at that kind of price (under $100) the manual set pays for itself on your first use. . If you are going to work on this car yourself you will need it, or at least an AllData subscription to get ECU code translations, diagnostic procedures, and specifications.

2) Get a scanner of some sort and pull the codes. The inexpensive WalMart scanner will pull the OBD II emissions-related codes. For more you need to download CarCode (www.obd-2.com) or buy a Tech II or Pegasys or some such. I am sure others will chime in and recommend theri favorite scanner.

3) While you are at WalMart or wherever (autozone?) buy a voltmeter. You will need it to check the sires to the PCM and ECU.

In cases like yours what's usually happened is more than one thing has worn out or quit at the same time. It will take a while to get it right.



Albertj

Thanks for the reply. But my car is the obd 1.5 and in this country town nobody has a computer capable of reading the codes. Trust me that was my first thought also. It has been a project car since I bought it and now I am just really ready for it to be done. I am not good with all the electrical system and stuff so it may just be time for a trailer ride to a mechanic shop. Who knows maybe one day she will run. Do u think a faulty crank sensor would cause those kind of condition or am I wasting my time changing it. Its not expensive just not easy to get off.

Slight correction to Alberts post.

The unit under the coils is the ICM or Ignition Control Module,
And the unit under the dash is the PCM or Powertrain Control Module.
There is no ECM on the Buick. (Engine Control Module) Other manufacturers use ECM's.

I wouldn't just blindly be replacing those units unless you can verify they are bad as they are expensive.

Haven't read the whole thread and have to leave for now, but I'm sure someone with a 1995 can help you out.

The 95's are a bit different in some ways, as you know.

Sounds to me like your ICM may be failing? From what you've decribed, it sounds like it's a Closed Loop concern. Runs fine in Open Loop, runs like butt in Closed. There is a circuit that controls that change that is directly related to the ICM and PCM.

Rickw wrote:

Slight correction to Alberts post.

The unit under the coils is the ICM or Ignition Control Module,
And the unit under the dash is the PCM or Powertrain Control Module.
There is no ECM on the Buick. (Engine Control Module) Other manufacturers use ECM's.

I wouldn't just blindly be replacing those units unless you can verify they are bad as they are expensive.

Rick is correct - when the transmissions became computer-controlled, Engine Control Module became Powertrain Control Module.

I also hate to see you throwing parts & money at it. Is the SES light on?
Before spending any more on parts, maybe you can find a 1.5 code-reader on the Net or eBay for a decent price...

I can see the ICM making it run like poo, and perhaps that PITA crank sensor, but the soot you mentioned on the spark plugs makes me think too much fuel - only problem is, you've already attacked everything I can think of that would affect that: 02, TPS, MAF... One last thought, can you get a fuel pressure gauge on it?

(BTW, do '95s have only 1 O2 sensor?)

I would go to the j y, and get the hole thing, coils and all.When they heat up, lots of times, there's the problem...

Rickw wrote:

Slight correction to Alberts post.

The unit under the coils is the ICM or Ignition Control Module,
And the unit under the dash is the PCM or Powertrain Control Module.
There is no ECM on the Buick. (Engine Control Module) Other manufacturers use ECM's.

I wouldn't just blindly be replacing those units unless you can verify they are bad as they are expensive.

Haven't read the whole thread and have to leave for now, but I'm sure someone with a 1995 can help you out.

The 95's are a bit different in some ways, as you know.

Thanks for the correction, Rick.

Consider using an ALDL cable and software with your laptop to read codes. A cable that should work should be on this page but you'll have to bug the cable supplier to get confirmation:

http://tunertools.com/ALDL_Cables.asp

As far as software goes, TTS DataMaster might work . I was thinking of trying it with a friend who has a '95. More here:

http://www.ttspowersystems.com/DataMaster.html

It lets you try it something like 20 times before you have to buy the 'unlock' code.

Also consider this: The "big picture" is that in most 95 cars GM used an OBD I PCM but changed over to the OBD II connector. All you need to scan these cars is a OBDI scanner and an adapter cord to change the connector pinout. "XRAY Cable" is one such. See the links I found on the Camaro forum, copied below, for more:

http://camaroforums.com/forum/showthread.php?t=20735
http://shbox.com/1/xraycable.jpg

Point being that an OBD I scanner wtih OBD II cable, such as the model EZSCAN 5000 or 6000 "AutoXray" would do this. The 6000 is about $300 new from eToolDirect but I see 'em used on eBay for under $100, if you're patient. Be sure the used one comes with ALL the cables and what-not.

Albertj

EDIT: Nevermind....

I would also want to double-check the coolant temp sensor is working correctly. If not it should set a code, but if it's getting a partial reading it may throw the ECU off but not throw a code.

deekster_caddy wrote:

I would also want to double-check the coolant temp sensor is working correctly. If not it should set a code, but if it's getting a partial reading it may throw the ECU off but not throw a code.

Do the '95s have separate sensors for the PCM and the Temp gauge?
If not, a bad sensor would show up on the dashboard...

Eldo wrote:

deekster_caddy wrote:

I would also want to double-check the coolant temp sensor is working correctly. If not it should set a code, but if it's getting a partial reading it may throw the ECU off but not throw a code.

Do the '95s have separate sensors for the PCM and the Temp gauge?
If not, a bad sensor would show up on the dashboard...

I can't recall but I know some of them did. My '96 chevy van did and the dash gauge was working fine even though the ECU sender was not. Took me a while to figure that one out, it's worth a look.