rpm problem

[newtodsm97gst]

Ok here's the situation, while the car is in neutral and try to rev it to 2000 rpm and try to keep it in 2000 rpm, the rpm drops down to 900 and up to 2000 rpm then down again, It's like I have a step 2 or anti lag but I don't. What would be causing this? I notice this when I was doing a seafoam on my car.

 

[GSTurbo1]

may be burning deposit out of the car or sensors are picking up the seafoam... idk, wait till you run all the seafoam out then run some high octane through it.

 

[cjridert1]

Ok here's the situation, while the car is in neutral and try to rev it to 2000 rpm and try to keep it in 2000 rpm, the rpm drops down to 900 and up to 2000 rpm then down again, It's like I have a step 2 or anti lag but I don't. What would be causing this? I notice this when I was doing a seafoam on my car.

So it idles fine now, just your RPMs dropped when when you used the seafoam? Because you are introducing all that extra cleaner that isnt air or fuel into the combustion chamber, you cant expect it to run the same.

 

[steve]

Check your Idle Position Switch (closed throttle switch). It's the critical adjustment in setting your TPS.
The correct adjustment causes the switch to open almost right away when you move the throttle and it sounds like yours isn't.

If the ECU thinks the throttle is still closed and sees the engine RPM outside the normal range it turns off the fuel until the RPMs drop back into range. This causes what is called idle surge where the engine revs up and down over and over.

The switch should be opening indicating that you're making the RPMs rise and that the ECU shouldn't control the idle speed anymore.

 

[goldbomb79]

I've had the same type of situation when using seafoam. Usually there's a fair amount of smoke along with it from burning the junknthenseafoam broke loose.

 

[newtodsm97gst]

its my mtx-l o2 sensor failing.. put the stock back and fixed the problem..

 

[steve]

Very interesting. Thanks for following up on your thread.