: Surging when cold

11-03-05, 11:01 AM
Help! I have a '94 SeVille LS (85,000m) and when cold or after a rainfall the engine surges and stalls for a long time (20-25 mins) and then settles out. Runs GREAT the rest of the day. The surges occur at both idle and in drive. The surges also coinside with the clicking sound of a solenoid located under the throttle body and EGR. I don't know what that solenoid is or what it does. The throttle body is clean and the engine is tuned. Any $ saving help would be greatly appriciated. Thanks.

11-03-05, 11:11 AM
ISC motor?

11-03-05, 01:58 PM
What is the ISC motor? Would it cause the surging?

11-03-05, 02:21 PM
ISC = Idle Speed Control motor. Watch the plunger on the ISC motor at the throttle lever on the TB and see if it is extending and retracting, "hunting" for the correct idle.

11-03-05, 02:28 PM
That's it! The ISC is tapping at the lever on the TB. Is the Idle Speed Control Motor bad or is it getting a bad signal from the computer? What are the chances of having a bad ISC motor? I guess the question should be, "Why is the cold and dampness effecting this"?

11-03-05, 07:19 PM
Your PCM is fine, you need to buy a new ISC.

11-03-05, 09:27 PM
Not sure why cold or dampness is affecting it but I agree with Eldyfig. Do a search for the propper adjustment proceedure after installation.

11-04-05, 11:06 AM
Thank you Ranger and Eldyfig.

12-06-05, 11:34 AM
Hey, I want to follow up on this posting. I replaced the ISC motor and the car still ran as miseribly as ever. In fact it ran worse with the cold weather coming in. So I went back to the codes and thought about the problem. My next choice was to replace the MAP sensor. If this failed I was going to take it to the dealer. Fortuneately the MAP sensor was the problem. My Seville now purrs like a kitten. Hope this adds to the information data base.

12-07-05, 12:31 AM
What were the codes? Where was the MAP sensor located on your 94? Did you need to remove the intake?

I just started having a similar problem (I think you jinxed me). My symptoms are very similar to yours. However, the engine isn't stalling, I am not getting any codes, and my manifold absolute pressure is consistent with what it should be. Now, after reading what you wrote, I am thinking, "Yeah, my pressure is right, but maybe my MAP sensor isn't performing correctly."

Darn, I already ordered the ISC too.

12-07-05, 03:39 PM
For my Seville the problem was progressive over a few months. At first it just surged, then the surging got worse and lasted longer and then it started to stall.
OK, here's the codes that my Seville spit out: They all started with the PO prefix - 32,34,52,71,95,99,109. I know that 2 of them refer to the MAP sensor the rest probably have nothing to do with it.
I have a 4.6L Northstar and to get to the MAP sensor I had to remove the big top cover plate and it sits right on top over by the throttle body. I did not measure the Manifold absolute pressure because I don't have any equipment. I just tried to find the most obvious causes. I noticed when I replaced the MAP sensor some of it's protective Gel was oozing out.
Also note that I did adjust the ISC motor as required when I replaced that. I hope some of this helps.
BTW the MAP sensor cost me $106.00

12-08-05, 12:52 AM
You probably should have posted those codes in the beginning. Three of those codes were for the MAP sensor. Recommendations would have been different.

Well, it is good you are all fixed now.