So I helped my friend do an engine in his LX. I'm not sure the work he has done is quality, but I am slowly double, and triple checking everything. All vacuum lines look good.

The car throws a P0505 error and the idle pulses, I tried a second used throttle body with no luck. I’ve checked the pins to the iacv and they looked good. I ordered a new iacv which I will place on soon. I am really thinking it is the ECU.

If I clear the codes, the car will idle at 1500 for about 5 minutes. Then the idle starts pulsing, the CEL eventually comes one. Looking at the scanner, the ECU is sending the pulse it looks like. The picture of the iacv command is exactly in sync with the engine pulse.

Could this really be the ECU?

 

Did your friend bleed his system?

 

Coolant was burped before and after the TB was changed. I did this with one of those yellow coolant fillers.

 

Test the TPS and ECT sensor.

Did you bleed like this?

https://honda-tech.com/forums/honda-.../#post39830585

 

I don't think I bleed it 100% like that, the second time.

ECT was changed out with the original after the issue no change. TPS was changed with the throttle body and no difference.

 

Rebleed

If the problem persists, remove the air intake when the idle is hunting and check whether the surging stops when you use your finger to cover the hole leading to the IACV inside the TB.

Was the new TPS calibrated?

If you connect a code reader that reports live data, what readings are seen for the TPS and ECT? Are they stable?

 

Everything looked stable. I'll check again. I'll post back, if I don't get banned by then.

 

Put a new iacv on, tool 3 weeks to get here. I bled the system like stated. Still has idle problem. Here are pictures of all live readings, but I can't tell what is the cause or effect.

 

I only took pictures of values that where abnormal

 

@RonJ any thoughts buddy?