When I compression tested my 944s I had 175 -/+5psi on each cylinder. My engine had higher miles and only used 5-6 cranks on each...fwiw I use 20w-50 as well. Your numbers are consistent so thats a good sign, eh

Why don't you trust a machine shop to deck your head? A porsche head doesn't need any special tricks to machine. Just have them pressure check the head and make sure its flat. If its slightly warped they can deck it for ya..if your interested I can have you have rebuilt head with warranty by thursday..

also dont buy a head gasket set from jagparts on ebay...trust pelican or paragon for that

 

I had the same problem with a car not long back. It would run great, but as soon as the temp came up any, would run so bad I had to keep my foot on the gas. Turns out, it was doing it only when the fans cut on, and would continue even after they went off. Traced it down to the ground for the dme harness. Cleaned it good, and it has never happened again. The ground is right under the heater control valve, where you are probley loosing the small bit of coolant. It leaked small amounts onto the ground point, that it correded terrilby bad.

 

I don't think it is your head gasket. The rings around the top of the cyl bores keeps the coolant from coming into the cyl. If you had a pin hole, and it was going into one of the cyl, your compression # would not be as even as they are.

 

Todd and Mike, thanks for both of your input. I did find that the numbers seemed kind of low compared to what others had been getting in the archives (seemd like 170-ish was the average). I came across a post from Clark Fletcher (who does Clarks-Garage) that said these were the minimum service 'values' ..

944 Turbo - 120#
83-86 944 - 140#
87 - 88 944 - 150#
944S, S2 - 160#

I guess i am getting close to the 'service' value. I do burn about 1 quart of oil every 3k miles, and more depending how much time i spend above 4500 + rpms..which is not often.

Todd, the strange thing about this is that it only happens when i start the car up after it sits for maybe 2-3 + hours. Warm starts its perfect. The car will run rough for only the 10 seconds or so on that cold start and then run perfect the rest of the time. Im going to look into another set of injectors to have sent out and cleaned. The ones on the car now were redone by WitchHunter about 9k miles ago. I am wishing i didnt resell my old ones now.

 

Have you checked the ICV under the intake. Think of it as a choke for fuel injected cars. If operates with input of the engine temp. That is the reason there is a connector on top from the dme.

 

Don't feel bad. I started on the BMW HG today and did a compression check first. 146-155 is spec.
#1: 152
#2: 80
#3: 90
#4: 85
#5: 30
#6: 40

So if it spits coolant at me during the compression test out of the spark plug holes could that indicate my seat belts are too loose?

 

Todd, the ISV is new, was replaced along with the injectors around 9k miles ago. However its possible its gotten gunked up from oil blowing through the intake. Ill have to pull the j-boot off so i can get a look at the throttle body plate and gauge how much oil has been going through the intake.

I really drove the hell out of the car today. 120 miles atleast and it ran fine the entire way...including a 1-2 mile stretch sitting in traffic. It performed great and spent plenty of time at 4500+ rpms on the way up to a get together a few of us had.

 

have you tracked down the problem yet? I'm in the exact same predicament. Have a rough idle at start and have to give it gas to stabilize or it will stall. Only on cold starts. No coolant loss either.

Have replaced everything (plugs, wires, cap, rotor, resealed the throttle, cleaned injectors) you have except the ICV, as your new one hasn't fixed the problem am glad I haven't spent the $$$. One of the fingers on my temp valve was broken so I replaced that thinking it was the cause. Nope.

This AM I opened the brass air valve a couple turns on the throttle housing at cold start and that got rid of the stumble, but once the engine heated up a bit it idled too high. Seems like its being starved for air on cold starts. Now I'm thinking it might be the TPS. Have you replaced yours? or opened the AFS to adjust?

 

It did end up being the headgasket..

https://rennlist.com/forums/showthre...ht=head+gasket

Is your rough idle a misfire or just stumbling at idle?

To adjust the idle, jump the diagnostic plug on the left side of the engine bay with the car warm. This disables the ISV. From here, you need to adjust the idle screw on the throttle body to get the idle within a normal range.

http://www.clarks-garage.com/shop-manual/fuel-08.htm

 

Another thing to check is Fuel Pressure Regulator. Remove the injector plug from one injector. If the idle smoothes out, the FPR is bad. Replace and drive on.

 

Thanks guys! Will try both and see where they lead me.

Its not a misfire, just a stumbling idle. If I bring the RPM's up to 1100 and hold it there for about 30 seconds and take my foot of the gas its good to go - no more stumbling and runs fine.

First thing I replaced when I bought it this past August was the DME Temp sensor, however it was NOT a bosch part. The metric auto parts store didn't have the Bosch one nor did the local porshce dealer so I siad what the hey. Might this piece be non-compatible and the root of all evil?

Now off to search for tips on coolant venting!