944 hard starting

[HardKor944]

ok I have been on the board reading for about 5 months now, great site! I have a 86 944 NA that I got with a blown motor. I replaced the head and timing gear and got it all back together. Good compression 125 on all cly's had the head completly rebuilt with new everything. Now what it is doing is when it sits over night its hard to start, it will start and idle ruff until it warms up, then it runs and starts fine. Now over the winter I replaced the vacuum hoses and adjusted the TPS thinking this would solve it,but nope still doing the same thing and will only start if its WOT.So I cleaned the IAC valve under the manifold and replaced it too. Still nothing. Now while there's snow down I was putting around with it and its almost like its fouling the plugs from to much gas,i pulled the plugs and are soaked in gas .. The only things I haven't changed or tested are the O2 sensor and the AFS in the intake tube. The rotor and ap and wires were replaced by the previous owner. Any ideas would be great.

[AA_Ezra]

I have an early and i had the problem but i forgot exactly how i fixed it.

But i will tell you what i do remember i replaced.

DME Temp Sensor

Coolant Temp Sensor

Oxygen sensor.

I had a spare motor so it was no biggie on the parts for me but..

Maybe Try and clean any connections or components of the Fuel system.. AFM DME Temp Sensor Etc etc.


I'm not 100% sure but if you disconect the oxygen sensor and it run's better/worse it's a sign of it working..

Check out

CLarks-garage.com there is a manual on there that is very usefull

Hopefully someone will chime in with a better knowledge of the later cars

Regards
J

[HardKor944]

so thismorning I took off the air flow meter and tested it , checked out fine,the temp sensor in there workd. So on to the O2sensor.

[AA_Ezra]

2 wire temp sensor with a blue tipped connection right?.

[HardKor944]

nope I tested the one in the air flow meter,i am pretty sure the coolant sensor in the head is working fine cuse the gauge in the dash is working fine. I have been here at work reading and found a few more things why it could be flooding,the fuel presure reg could be bad,so I pulled the injectors today ( cuse I thought one could be leaking) and they all have good spray and they look to be at the right psi but ima have to put a gauge on it. So that will be tomorrows adventure befor work. Once I finnaly get the car running and warmed up it runs great, but I did notice that the car would sometimes die when rolling to a stop! Any other ideas or tricks would be great lol I'm running out of them....a carbed LT1 is sounding god right now!

[HardKor944]

now with unpluggin the O2 sensor do you think it will help stop the flooding? Cuse that's pretty much what's its doing. I ordered a new cap and rotor and wired today and will get another new set of plugs to ruin too while I'm at it. Not to sure if I an get a pressure regulator that easy where I am tho.

[Slam]

Fuel pressure regulator and/or damper? Pull the vac lines off each one and check for fuel. If you find fuel in the vac lines, an internal diaphragm has failed.

[Techno Duck]

I would be inclined to think a leaking injector aswell. Rough idle is possibly that cylinder misfiring until everything burns off the plug.

BTW, there are two temp sensors on the top of the cylunder head. A 2pin blue tipped one (looks like the fuel injector connector) that is for the DME and a 2 prong one with spade connectors for the gauge. When this sensor goes bad it will cause the car to run rich and also ignore the O2 sensor signal completely (DME still thinks its in open loop warm up mode).

[HardKor944]

alright thanks for the info. I pulled the lines off the regulator and I could smell gas ... So I ordered a new regulator. I do see the coolant temp sensor with the spade connectors, but I didn't see the DEM one yet, kinda stuck at work now lol but ill have a look for it tomorrow. I think ill end up ordering a new sensor just cuse . But there must be a way to test it. Looks like ill have to do some searchin.

[Techno Duck]

The DME sensor is right infront of the one with the spade connectors. I havent worked on a n/a in a long time but if i remember right the J-boot is probably right ontop of it. You can test the sensor by checking resistance across the two terminals, Clarks-Garage has good directions on how to do this.

Sensors and Gauges - Information, Troubleshooting, and Testing

Heres a pic of the DME temp sensor, you can see it in the top right corner (blue connector)

[HardKor944]

perfect! Thanks man that's a big help,i did stumble upon the same page on clarks. But awsome pic helps alot. I'm more of a jeep guy but the porsche thing is workin out pretty good.

[HardKor944]

well I took out the temp sensor,all tested fine,i removed the fuel pressure regulator and cap and rotor and plug wires. The cap is gumed up pretty bad. And I smell a little fuel in the vacuum lines. So next weekend I'm replacing everything then trying it again.

[ernie9944]

[QUOTE=Techno Duck;5813752]The DME sensor is right infront of the one with the spade connectors. I havent worked on a n/a in a long time but if i remember right the J-boot _____(is probably right ontop of it). You can test the sensor by checking resistance across the two terminals,

[HardKor944]

I took out both sensors all tesred fine. Pulling out the O2 sensor now to change that.