ChrisLovin

Hey Rlisters, My name is Chris Lovin, and I have just recently purchased an '86 Alpine White 951. I live in Virginia Beach, Va I'm 25. I also own a currently running but decommissioned 87 (automatic ) black 944 which was just enough of a taste to get me going and wanting more.

Since purchasing I have replaced the broken door handle (broken linkage arm thingy ) reinstalled the rear view mirror and a sub in the back.

My issue/annoyance is during a cold start the car will fire up and idle for a second and then the idle will drop and sometimes stall (not often) if I dont give it gas. When it does this I notice that my air fuel ratio goes almost entirely to the fuel side (really rich if my terminology is correct). Also I notice when giving it more throttle during this it is not as responsive right away. As soon as it's warm enough for the temp needle to be above the bottom line it's fine.

My girlfriends dad who is a tech whom admittedly knows nought of Porsche's, after listening to it run today ( not during one of these cold starts, said the exhaust sounds as if it might have a hole in it at or around the muffler. He also says this could cause it to not have enough back pressure and possibly give me these kinds of problems.

Any help at all is appreciated and all questions about me the car the problems, and anything else are welcome. Thanks for readin my book of a topic post.

ChrisLovin

I forgot to add the previous owner has installed a cone air filter with Linsey racing AFM(i think) to it and a in my opinion fart can exhaust which I've read makes it sound like there's a hole in the muffler anyways.

Does my problem sound like an FPR problem? I have a brand new one installed on my auto and will try it out tomorrow.

Black51

If there is a hole in the exhaust, it depends on where it is. A hole before the turbo would be detrimental for spool up. Any holes after the turbo don't matter. The only amount of backpressure you need is what the turbo needs to spool up. Anything more than that after the turbo is only hurting power. So if there is a hole after the turbo, it doesn't matter.

Check all vacuum lines, idle stabilizer valve (under the intake), and make sure the filter is clean. There may be something up with the LR MAF in the programing. But I wouldn't bother touching that until the simple things are looked at first.

If the car runs fine at temp, then I doubt it's the FPR. If that failed, the fuel pressure would never be good.

Do you have a A/F gauge installed? What numbers are you seeing when it's rich on a cold start?

Paulyy

defently not your FPR.

It's probably the Lindsey software for the maf. if you're going to modify it more id suggest investing in a Wideband o2 sensor to see what your AFRs are.

post pictures of your car

Tedro951

Welcome to the list! Before going through any involved diagnostics, try setting the idle per clarks garage. Don't skip any steps.

carlege

Couple guys that you might want to know around here. John Woods and Curtp they seem to be around your area. (im not volunteering them to help you but they seem to be good guys to have around if your having trouble with your car)

Whats the history on the car? all maintenance up to date? You might have a vacuum leak

ChrisLovin

Wow thanks for the replies,per tedro's advice i will set the idle using clark's steps then i will be checking out the vac lines and ISV i think the air filter is somewhat dirty not sure how dirty though. As far as running fine at temp, i can't say that for sure because i don't have much to compare it to, i will say the idle at temp is fine.

I do have an Innovate Motorsports Wideband (i believe) from the previous owner and on the cold starts it reads like 20.7 and the light on the gauge is all the way over down to the bottom light. i assume this means its rich because its on the fuel side of the Air/Fuel label. i saw it and thought it looked like a digital guitar tuner i have haha.

Josh B

Congrats on the purchase. You should post up some pics of the dash and engine bay and we might be able to help more. Personally if I were you I would work towards putting the car back to stock. If you want to mod it that is fine but I would make sure everything is operating correctly in the stock configuration first.

ChrisLovin

history on the car is it has 180k on the odometer and previous owner claimed it had a rebuilt engine installed 40k ago by his uncle who owned it prior to him and sold to him after becoming ill. didn't sound like much other maintenance has come to the car in those 40k miles, including timing belt waterpump and rollers

carlege

check anything that is rubber. he may have rebuilt it at 40k but unless you have reciepts for all the parts assume they were reused

also lovin the name

Paulyy

20.7 is extremely lean. you want it to idle on 14.7,
You want boost on around 11-12

the number means 20.7 parts oxygen and 1 part fuel

User 52121

Sticking AFM?

If the door is sticking closed on startups, then the DME thinks there is no air coming into the engine, and therefore gives you very little fuel.

I'd pop the AFM out and take a look, make sure the door opens and closes smoothly.

I'd also check to make sure the TPS is adjusted correctly. You should hear it "click" juuuuuust after you crack open the throttle.

Black51

He said he has a Lindsey meter, which would be a MAF. But if it is in fact the stock AFM, then i agree, check the barn door for proper operation.

Since it looks like you're running very lean, the fuel injectors come to mind. It might be a good idea to have them checked out.

Now it does sound like the FPR might be bad. Change it and see what happens. It would be a good idea for now, and later to install a fuel pressure gauge on the rail to be able to monitor the fuel pressure.

Normally the car should be a bit on the rich side (low A/F number) rather than on the lean side. The car should never be running lean, unless you have a custom tune for cruising or something.

ChrisLovin

Lol at my confusion on the wideband readings. Thnx and yes McLovin can take a hit like a champ.

Paulyy

Pictures?