[atheworld0]

So I got a ek and it's a stock ex with a stock y8 in the car. Car is throwing a cell of idle air control valve circuit. Change iacv with a known working one and same problem. When the car is cold, no problems, works as it should. After it warms up, it likes to idle smoothly at 1500rpm. Big problem is at very light throttle, it acts like a fuel cut then a j erk back on the throttle and over and over again, like it has to accelerate or decelerate, no smooth cruise. It doesn't do this when cold, or even after warm if it has not been to an idle for any time, but if I sit at a long light for a few minutes, that is when the problem starts. Any help would be greatly appreciated.

 

[RonJ]

Post the OBD2 CEL code. Then reset the ECU to see if the code returns.

 

[atheworld0]

P0511, and reset it 2 X. One before and 1 after I changed it. Still no fix.

 

[RonJ]

P0511, and reset it 2 X. One before and 1 after I changed it. Still no fix.

This^ is not a Honda code for a stock Y8. Do you mean P0505?

 

[atheworld0]

Sure. It was a week ago when I ran it. I remember the idac malfunction description.

 

[RonJ]

Sure. It was a week ago when I ran it. I remember the idac malfunction description.

There are 2 different IACV-related CEL codes. Knowing which one helps to pinpoint the troubleshooting. Pull the code again, so nobody is guessing.

 

[nuckles]

I hate that problem I've heard the damn ecus can go into "limp mode" on obd2 not sure if this is true though but yeah check the code and post again, I would check map and tps voltage readings just to be on the safe side too

 

[atheworld0]

Well been talking to Matt and he had me check for vacuum leaks again. Sprayed some ether at the manifold and it's leaking right at the gasket. Gonna swap that out tomorrow and see what we get.

 

[nuckles]

Well been talking to Matt and he had me check for vacuum leaks again. Sprayed some ether at the manifold and it's leaking right at the gasket. Gonna swap that out tomorrow and see what we get.

Probably the problem if that's the case hey man at least it's not the IACV sons of betchs are expensive!

 

[HiProfile]

98% of IACV/idle problems are big vacuum leaks. The jerky light throttle could be from the TPS being off, but a vac leak can also contribute. You'll have to test it's voltages at zero and 100% throttle. It should be 0.47v or very close at zero throttle, and 4.5v at WOT. WOT voltage isn't as important as zero throttle voltage.