slight repetitive idle surge

[farmtruckman]

My 95 X has developed a slight repetitive surge, about 200 RPM, every 4 seconds when at idle. Just enough to move the car if your foot isn't firmly on the brake at stop. Does it in neutral or in gear. Doesn't do it when high idle is engaged when cold but when engine drops to normal idle after warm up, it starts. MAF? I was planning on SeaFoaming this weekend, both oil and PVC valve, but open to any suggestions. Have not read codes yet so can't help there. thanks. FTM

 

[aleej]

i second this question... mine does that sometimes too.. i thought i was just crazy tho... some one had suggested maybe the tps? but im not sure...

 

[manaen]

Check/clean these things
1) IAC module
2) MAF sensor
3) vacuum leaks, cracked hoses
4) EGR functionality
5) FPR (make sure it is not leaking)


Has your fuel mileage suffered at all? and do you notice any smoke of any kind?

When was your last tuneup?

 

[farmtruckman]

No smoke or any real drop in mileage. I am preparing to SeaFoam it and change the oil now. I just noticed a sound coming from somewhere on left side of motor, maybe around maf (not sure yet) that corresponds with the surge. Two quick dull clicks right after each surge. Could be coming from MAF but can't imagine anything moving in there. Any thoughts? I will post when done with oil service. Plugs are new by the way and just serviced K&N air cleaner. I will clean MAF again because I know that sometimes oil from the K&N can build up on MAF.

 

[farmtruckman]

Followup

Just finished service. Did SeaFoam through brake booster, replaced pvc valve and oil service. Surge much less pronounced, barely noticable and can't hear click noise now. Drove around a bit to blow it out and idles much smoother. Stil not quite there though. Need to put a few miles on it to test it out more.

 

[manaen]

Are the clicks coming from the AC pump clutch? turn off all your heat/AC and see if the surge is gone. If it is the AC it could still be as simple as the IAC, however the AC systen could need to be serviced.

 

[manaen]

Just finished service. Did SeaFoam through brake booster, replaced pvc valve and oil service. Surge much less pronounced, barely noticable and can't hear click noise now. Drove around a bit to blow it out and idles much smoother. Stil not quite there though. Need to put a few miles on it to test it out more.

did you check the IAC (Idle air control) valve?

 

[manaen]

Oh also make sure your throttle body stop screw is adjusted properly. When the IAC is unplugged it should idle at about 500 rpms; with no accessories running(no ac etc..)

If it is not at 500rpm's adjust the stop screw until it is, and then plug your IAC back in.

After doing this you need to adjust your TPS to .95v for opptimal throttle response.