Engine not idling after gasket repair!

[Tob3z]

Good afternoon Ladies and Gents,

So my precious 944 has been off the road for a few months. Unfortunately the head gasket failed which meant a lengthy repair stripping the engine right down, having the head skimmed and reassembling after putting the new gasket in.

However, upon attempting to get it started again the engine now does not idle. It fires up and can be kept running using the throttle, however quickly cuts out if the throttle is not engaged.

I started attempting to eliminate the issues. Making sure the air hoses were in correctly and even purchasing a new DME relay which I heard could be the issue.

Has this ever occurred to anyone else? Any tips or things to eliminate?

Any help would be great!

Toby
1986 Porsche 944 2.5L

 

[pse_SC]

There will hopefully be someone along on the forum soon to help diagnose this, as I am alas no mechanic, but there could be a multitude of reasons why, unfortunately. In particular, though, are you sure you have the timing spot on? Presume you put it all back the way you found it? (apart from the dud gasket, of course [])... Paul

If not, and you are based near Bedford (perhaps you’re the Toby I know)... you may have to ask Nick []
(please excuse my rambling if you’re not)

 

[Tob3z]

Hi Paul,

Cheers for the response.

Fairly certain I've got everything where it was beforehand. Marked the timing with tipex so hopefully that shouldn't be the issue.

Not the Toby from Bedford but in fact a Toby from Surrey!

 

[peanut]

just throwing some immediate thoughts out there without really engaging brain (haven't had me dinner yet so brain is fading fast )

make sure you have re connected your engine temperature sensor to the loom
Check that the air idle valve hoses are connected correctly and all 4 joints tightened up and you reconnected the electrical connector to the valve.
Check all your vacuum hoses and pipes are reconnected and you haven't got a vacuum leak
Check you throttle sensor is correctly set and clicks just off the stop
Only other thing I can think of at the moment is the FPR holding pressure ? you might remove the vacuum pipe from the FPR whilst its running and make sure there is no fuel leaking from the FPR into the vacuum system

Does your idle improve once the engine has warmed up a bit ?

 

[Dan944t]

Same as peanut has said check all that first.

also check that your spark plug leads are all on tight, distributor cap is on properly top and bottom, check spark plugs are clean if not clean them or replace would be best.

is the airflow meter connected properly in the j boot with the air pipe connected underneath ect go through everything.

If its a turbo make make sure the intercooler pipes are on tight and have no leaks. Mine ones came slightly loose and cut the engine out making me think my belt had snapped even though I just replaced it.

there a multitude of little gremlins most deffinately something silly but you really need to go right through everything precisely to find it.

On my non turbo when changing the engine for another years and years ago I had a problem with the flywheel sensors letting it start but cuttting it put straight away but I assume you wouldn’t have touched these from the bell housing? Mine were adjusted with the correct clearance but since disconnecting they gave up the gost. Not saying this is your problem but as I say and others there could be many factors but most probably something very simple as been said.

Check out all this stuff first and let us know ??

 

[Tob3z]

Well it certainly has been a while! Busy weekends have kept me away from the car but I managed to fit some time in this week. I started going through what you guys recommended and found the issue when I began to strip it down again. Low and behold there was a hose that wasn't reconnected during the first rebuild. I believe it's an air intake and is seated underneath the upper intake manifold.

Once that was in it started straight away and idled fine!

Thanks for all your recommendations, even though it was my own stupidity that was the issue! Now onto the next fix, for some reason my indicators aren't working (although the hazards are) even though I got a new indicator relay. Time to do some more research!

 

[Dan944t]

Glad to hear you found the culprit!??

regarding the indicators , I had this problem in my 86 non turbo 944 many moons ago and same as you hazards worked but indicators intermittentlY. In the end I changed the indicator stalk and that was The culprit.

I believe I checked the signal through the wiring as I had the dash out already for repair so I figured it out with a multimeter and bought a cheap second had stalk from a breaker and worked perfectly after that.

Just a possibility or maybe a bad wire try fiddling with the wiring that connects the stalk or if it comes to it spray somecontact cleaner as a last resort in the connecting harness going into the stalk itself if that makes sense . But if you do disconnect power first and give it time to evaporate dry.


atb
daniel

 

[Waylander]

if its been laid up and its cold, the grease in the colum switches will have gone like putty, and will be holding the spring loaded contact in,

it will need a good lubing with GT85 and some exercise, that should fix your flashers