PDA

View Full Version : '84 Riviera T-type - Chip #5867DXP


sosuzguy
08-18-2006, 12:44 PM
Hello,

We have been working on the T-type this week. What we have found is that the PCM is reporting correct values from all the sensors. There was two fuel injectors that had slow pressure drips and we changed them out. We tried two different MAFs and it still runs way too lean. The car doesn't have a MAP sensor so what else could it be? It is around 140 to 140 fuel trim and should be between 126 to 130. My mechanic called someone at GM who said there was a chip update for this car Chip #5867DXP and I have the old one #2269DNP. I need to see if I can find the newer chip for testing or to buy. It's already been discontinued at GM. We have kind of been suspicious that the chip might be bad, it is very very slow communicating with any tools that hook up to it. Any ideas? For a brief flashback on the issues with this car read on below.

Thanks, Jayson Pruitt #3412 DFW/North Texas RC

I've always had a slightly rich exhaust, Code 45 that we could never work out. We finally replaced the Bosh 02 with a Denso 02 and cleaned the original MAF with electrical cleaner and it did run about 92% optimally. The day before I left for Flagstaff I washed the engine. I took every precaution. Shower caps, low pressure water. I used my air compressor to dry stuff off and then let it air dry. Well the car hasn't ran right since. When I started it didn't want to stay running. After messing with it I found some water had gotten down into the air filter container and probably in the MAF. Got that all dried out and it seemed to run somewhat better. I even tried another MAF from an 85 hot air GN and a new MAF from http://www.micro-tech-auto.com/maf.html The car did seem to run better initially with the used MAF From the 85 GN but as it kept running it seemed to get a little worse. I drove that car 1k miles one way to Flagstaff AZ. It now also keeps a code 44 lean exhaust and performed like the non turbo 4.1 V6 Buick engine. But the car did not use any oil, did not over heat, didn't smoke and got anywhere from 24 to 28 MPG on the highway. While trying to fix it sooner than later, I had to use a local shops snapon computer in Flagstaff. The BL was 140 INT 150, way too lean. TPS .58 @ 1900 MAF 9 grams @ 1800/1900. o2 191, no knock, EGR not holding vaccum.

Keller
08-21-2006, 02:34 PM
cleaned the original MAF with electrical cleaner
Bad idea.
The day before I left for Flagstaff I washed the engine.
Another bad idea.
I even tried another MAF from an 85 hot air GN and a new MAF from http://www.micro-tech-auto.com/maf.html
One more bad idea.

I'd say you need a new, good MAF. Not aftermarket. A good rebuilt one is probably your only option. Getting water in them doesn't do good things to them.

It sounds like you already have a scan tool to ready the MAF values and such, correct? You may be able to get the car to run a bit better with the MAF unplugged as a test. It will get a code, but may idle and drive better. Avoid boost if possible.

Note that these ECM's don't have very fast communications. and the 84/85 versions don't provide much data at all.

sosuzguy
08-21-2006, 03:22 PM
We tried a reman MAF and everyone of them either didn't fit right or made the car run like crap. Out of the reman ones 1 out of 5 will work correctly so our experience. We do have a scan tool but with the 84 chip it only gives all the values in field service mode, not a lot to go on when your actually driving it. I just got a the latest version of the 84 chip and we'll try. We've checked all the electrical connections, vaccum hoses, sensors.... only thing left is the PCM or Prom. We'll start with the upgraded chip and hope it gives us a better data stream. Thanks.