SURGING - Ideas? Checklist?

[Scott W]

My car is surging, mainly under part throttle and low rpms. Please give me some ideas of what to check for.

I have replaced the : Distributor, cap, rotor, wires, plugs, and I have a MSD6al - so I'm pretty sure its not ignition related.

1-tps is .98V, but I haven't check the sweep operation
2-I've heard about 'clocking' the MAF - what is that?
3-best way to check for vacuum leaks?

 

[jrichker]

Clocking the MAF is useful when you have a cold air kit or some other modification to the air box or air inlet before the MAF.

Clocking is turning the MAF housing so that the sensor element is in a different position. It changes the airflow through the MAF to place the sensor pickup in the place where the airflow is the least disturbed.

Best check for vacuum leaks is a vacuum gauge. If you don't get low vacuum readings, don't waste time trying to find non-existant leaks.

 

[tfalk]

You can also try plugging the vacuum line to the EGR valve. That is what
is causing the surging on my 99 - just haven't had time to try to fix it.

 

[Scott W]

I just did a code check, and I came up with a few codes. First I should tell you that i'm having problems with my alternator (unrelated), so some of these codes may be because of low voltage.

3-2 Cannister or EGR valve contol system
8-7 Fuel pump circuit
9-5 Fuel pump circuit
9-6 Fuel pump circuit

I think the fuel pump code may be due to my faulty alternator, so I'm thinking my surging could be the cannister or egr valve.

by the way, tps tested perfect. No vacuum leaks detected.

 

[cmb91LX]

I have had surging idles in the past quite a lot. My best fix so far after all of the abovementioned things has been to pull off the IAC. Shake it and if you dont hear it clicking then it is stuck. Soak it overnight in Throttle body/carb cleaner and the clean the shaft with a small tapered wire brush to remove all of the buildup. This has helped me several times in the past and maybe it will for you. Cheap easy fix and doesnt take much time or effort

 

[Scott W]

Where can I find the iac?

 

[noslow5_0]

its a motor used to control the idle, and it is located right after the throttle body on the intake... cyclinder looking thing... cant miss it!!!

 

[Scott W]

Oh yeah, thanks. does the iac just effect idle, or could it effect my part throttle problems?

Do I need to replace the gasket when I pull off the iac?