So the weather is going to be crappy this weekend so I plan on taking a couple hours with my car in the garage...I read a lot about ground issues causing various problems and would like to check them out...and clean them up.

My car has an issue with cold starting...seems to have a starter draw as it thinks about it and then will start...once started it idles rough. I give it gas keeping the rmp above 1500 for 30sec and then it runs fine. I know this is not likely a ground issue but I figure I would clean them up and then move forward on the diagnosis of the cold start issues.

So where are all these problamatic grouns? Does anyone have a complete list or pictures of where they are located?

 

Grounds to the DME on the bell-housing next to the speed and reference sensor gave me problems once.

 

Here is a good write up:

http://members.rennlist.com/tom86951...housing_gr.htm

BTW - Be careful not to drop anything in the inspection hole.

 

good write up! Can they be accessed without removing the intake?

 

Techno Duck also had a great thread with pictures of the ground locations.

Briefly, though, there are those two on the block and bell housing, one behind each headlight on the frame rails, typically one on the cruise control or near a shock tower, a cluster under the dash, and one between the tail lights.

+1 on covering the inspection hole if you do the block and bell housing grounds.

 

perfect! thanks (again) Charlie

 

Steve, we're doing an informal 944 get together on the 30th in Kingston for lunch, then a drive toward Gann if you want to test your work! There's a thread on it in the Canadian forum, if you're interested.

Post #944!

 

I am off that weekend! Definatly would like to meet up!


And used the search to find this

https://rennlist.com/forums/924-931-...-interior.html

Great write up you were talking about by Techno Duck...pictues are great

 

Got to play in the garage for a few hours today.

Decided to start with something easy...like the crest gasket...NOT!
The old one was out of place and shrunk so I picked one up on Ebay what a pain in the A$$ Finally got it on, it is not perfect but better than the old one.

Then went after some grounds...I was able to get to the one on the LF near the headlight housing, battery tray area and rear hatch...Didnt try to get the ones on the bell housing and under the RF headlight...a lot of work so I will wait until I need to pull parts off that area to get to them.

Had plans to go out tonight so tomorow will be the second part. I want to hit the grounds under the dash, lube up the passenger door which is stiff and look into a couple of issues with the idle...Cold start I have to give it gas for a few seconds...then it runs great...The other day I found the the idle when warm around 1200-1500. Car ran fine except for the high idle. Hopfully something simple.

 

does the idle fluctuate on its own at those rpm's? it is most likely the TPS or ISV.

use an ohm meter to check the resistance it gives on clarks-garage.

 

A good place to start is resetting the idle using the directions on Clark's. This involves disabling the ISV and setting the set screw on the throttle body.. very easy to do and a good chance it will fix your problem.

Glad that ground location page came in handy, i will update it tonight with some pictures of the bell housing grounds finally.

 

I would also recommend covering the final clean connections with some Liquid elec. tape. That way you are protecting the connection from corrosion in the future. You can find it at NAPA Auto Parts for about $9.

 

It just has a very rough idle and will likely stall if i dont give it a bit of gas for a few seconds...only on cold starts...Once warm it is fine but last run I noted the idle was very high.

Reading up on testing the ISV now and will try re setting the idle. I also just noticed on the top of my throttle body there is a screw(looks brass) it had a bit of moisture around it and I can move it without any effort. Going to try and figure out what this screw is and why it is so loose.

**Edit** that was my idle speed screw that is loose...So that should fix the high idle when warm!

 

So I finished up with the car for the weekend...Checked the DME temp sensor. From a stone cold engine I got a reading of 3.85K ohms acording to clark's it should be 3.3k at 15c and should be lower as the temperature goes up. For those who have checked this sensor would that reading be what to expect for my cold start low/rough idle?

 

I'm not sure, but it could be that the sensor was colder than 15c. Did you also try it on a hot engine?

Mine measured right in the range, as per Clark's. I do have a new sensor, though, if you turn out to need one. I thought mine was bad, but it wasn't.