I've got a new problem that I can't seem to put my finger on. Maybe someone here can help with some new ideas of how to tackle this one.

First, I've got an '88 2.8 5-speed and have been running the KFG turbo system for a couple of years. I had it running with a rising rate fuel pressure regulator, 21# injectors and a Mallory hooked up to a map sensor that came with the kit to retard timing. It ran a little rich, but otherwise put out a lot of power. I decided to change it over to run a chip from Dennis LaGrua. I know that there are many people that have had much success running his chips and I can see that he has done his homework. I got a chip from him for the 21# injectors that I'm running. I ditched the Mallory and hooked the map sensor that came with the turbo kit to the stock engine location. I still had a rich condition, we tried a leaner chip and came to the conclusion that I needed to use 19# injectors. He sent me another chip, this time for 19# injectors, I installed some injectors from a Mustang and it runs a lot better with one exception. The car runs absolutely flawlessly up to 3psi of boost. Anything over that and the car does not know what to do. I set my wastegate up to be adjustable and if I run it set to 3psi maximum, the car is perfect at any throttle opening, engine speed or load. Last night, I set it up for 8 psi of boost maximum and anything over 3 psi, the car stumbles and lacks power. I can upshift the car and lug it, floor it and it runs fine until the turbo hits 3 psi of boost, then it runs poorly again. I have replaced the distributor, cap, rotor, plugs, wires, ignition module, tps, reverted back to stock ignition, used the Mallory, checked, adjusted and changed timing, fuel pressures, read the plugs and everything appears normal. I increased the fuel pressure to the point of where it is running in a rich condition and have the same problem so it is not from leaning out. The computer is not setting any codes. I am now suspecting a bad/wrong map sensor and I'm going to hook one up from a 3800 sc tonight. Other than this, I am pretty much stumped as to why this thing would behave this way. Engine passes CA smog, does not burn oil and runs great NA or in original turbo configuration. Any ideas?

Sounds like the MAP sensor to me, sense it just goes crazy at 3psi and above. Are you running a 2bar MAP?

I am running the map sensor that came with the kit, supposedly 2 bar. It is part # 12569241. I looked it up on gmpartsdirect.com and it shows a map sensor with that part number, but no other specifics, so I have no way of referencing whether it is 1 bar, 2 bar or 3 bar. Is there anything besides the map sensor you can think of causing a problem like this?

What you list is the GM part number for a Grand National. I don't know if that is 2bar or 3bar???

Get that thing on a scanner and see what is actually happening. Hell even winALDL, as crude as it is, will show you what your timing advance is. If your advance is dropping way off, chances are its the knock sensor pulling timing. Doesn't their kit use a knock sensor?

If their kit doesn't use a knock sensor, then you will still be able to check the MAP values and see if it is pegging the map sensor voltage..

Edit, I just check GMpartsdirect, they list 12569241 & 16254539 for 2bar MAP sensors... Hmm.

[This message has been edited by Jncomutt (edited 11-10-2005).]

GN/TR maps are two bar.

I just ran it with a known good 2 bar map sensor, no change. It actually feels like the car is misfiring under boost. I will occasionally pick up some interference with the radio, like a "tick" "tick" sound when the car is stumbling. There is no knock sensor on the car. I don't have any software/cabling to monitor the computer and sensors. Any suggestions on free/cheap ways to do this?

Well it sucks, but winaldl is free, and you can make/buy a cord for next to nothing. You can monitor (at a slow rate) some engine functions to get a general idea. Log the parameters and you can see if your O2 is dropping under boost, what your advance is, etc... its not all that great, but its better than nothing.

On second thought, was the chip you got for an 88ecm? The chip would have to be different for the 88ecm than for the typical 85ecm that he usually uses.

[This message has been edited by Jncomutt (edited 11-10-2005).]

He is aware that it is an '88 ecm, so I assume that the chip is correct. If win aldl is lame, I think I'll look around for a scantool. I called the local auto parts places and nobody rents them out. I'm going to check out ebay.

Winaldl isn't any worse than a scanner. It free and worth starting with. The data stream is slow and nothing will change that.

Ok, so how do I go about making a cable? There must be some instructions and downloads posted somewhere, I am going to do a search.

http://winaldl.joby.se/aldlcable.htm

That will link you to how to build a cable. You can also get the software on the same website.

Thanks for the help!!