Inconsistent Idle

[jdhutchin]

Hello all-
I just bought my first DSM, a '94 Eclipse GS (n/t with the 4g63 engine). It has a problem with an inconsistent idle- when idling, the rpm's go up and down from about 600 to 1200. It seems to do it more when the engine is warmed up, and once the engine died while idling. When it's not idling, the car has no problem.

The shop I bought it from said they replaced the MAF, which helped, but did not fix the problem. I've read on this forum that removing the fuel pressure solenoid might help- would that be a good bet?

Thanks, Joshua

 

[brute]

You need a new ISC. You have what's called idle surge. Do some searches on it.

 

[JayRolla]

Yea mine does the same, but more when its cold and when its warm it goes away. Idle surge can be really hard to fix. Do a search like he said and you will find a lot of people with this. Check your throttle cable and make sure its allowing the throttle body plate to close completly. This fix's a lot of idle surge problems. I still havnt tried a new ICS which is my next thing to do.

 

[brute]

I had this exact problem. I went to the junkyard, got an ISC for $10 and it became perfect.

 

[gernoff]

Do a search and you will find info on verifying your ISC. Also check for vacuum leaks.

 

[brute]

http://www.dsm.org/how-tos/tttt/tttt3.html

 

[JayRolla]

I love that write up. Was fun going through it and not fixing my problem. Didnt do the ISC yet narrowed it down to that I hope. One thing I noticed is when it is surging if I take off the BOV recircultion tube off it stops. Is it because of the unmetered air getting in or what?

 

[ixsaves13]

After you check if it's the ISC and do a boost leak test, you may want to check your coolant temp sensor. I had a similar thing happen and found that mine was bad.