vt951

When I got my car last year ('86 951 with ~107k miles), the DME and KLR units were bad, so they were replaced by a local Porsche shop with remanufactured ones. The car runs pretty well, but there is a strong exhaust smell, like unburned fuel I guess. I notice it especially at idle, but maybe that's just because when driving the wind blows the smell away. I don't know if this is relevant evidence, but when I did a dyno run last year, there was a major dip in the power curve around 4500 rpm, and the max was only around 155 rwhp.

I'm wondering if maybe there is an aftermarket chip in the DME (such as Autothority) which could cause the car to run rich. I took off the DME cover... does this chip look like the stock one, or could it be an aftermarket chip? The number printed on it is: 1767355235.

If this is an aftermarket chip, is it safe to run with it without other mods? I haven't taken apart the KLR yet. Don't know if the KLR is relevant to this problem.

Thanks for your help!

2bridges

looks like a stock chip to me. My original chips looked same

Is not autothority

Darwantae951

I have the autothority chips in my car, and they say "Autothority" on them, as well as "Stage II" so you definately don't have the autothority chips in there. As for being stock...I couldn't tell ya.

-Darwin

2bridges

I looked at my stock 86 chips. Number is slightly different but of the same form.
KLR - 1267355131
DME- 1267355183

Are exactly the same color/printed black numbers. I would say you have 100% genuine stock chip

Tom M'Guinn

Stock

vt951

Thanks for your help guys. Guess I should take the KLR apart too just to make sure...

special tool

That wouldn't make any difference - don't waste your time.

You need to find out why your boost is low.
Start by pressure checking the intake system.

vt951

How do I pressure check the intake system? You mean put a real boost gauge in the car? The stock boost gauge shows up to around 2 bar when I step on it. Thanks...

special tool

You are going to have to figure out what is wrong.
You should not have 1 bar with stock chips - you should have 11 psi.
2 bar on the stock guage = 1 bar above atmosphere.

Can you take a picture of your injectors and post here (or see if they are green/black) - we will start there.

vt951

Here's a (fuzzy) pic of one of my injectors. Looks green to me. Curious where you're heading with this. Thanks for your help!

Tom M'Guinn

Those appear to be stock injectors. If you are unsure of what was in the car before the dme and KLR were changes, you should take a look at the big banjo bolt in the top intercooler pipe to see if there is a restrictor (carb jet) in there. That is how autothority bumped the boost. If your car had autothority chips before the DME/KLR were swapped out, you may still have the restictor -- which would be a bad thing (too much boost for the amount of fuel offered by the stock chips).

The rich smell at idle may be bad hatch seals. I can run my car pig rich at idle and not smell it from inside the car.

155rwhp is too low even for bone stock -- and very strange if you are boosting higher than stock. Search this forum for tips on pressure testing the system -- or get the smoke tool from speedforce racing. If all ok there, then its time to look at components.