Just swapped an engine in and when started it will idle fine right where I set it and even if i let it warm up for 20+ minutes it will idle perfectly...

BUT...once i tap the gas or anything having to do with throttle it will go ballistic and start jumping from 500-1500 repeadedly and quickly.

TPS is fine i just checked it...
IM/EM/TB gaskets are brand new...

What should i try next? IACV?

Just seems like once i give it some gas it fights to stay alive...or something fights to shut it off.

Vince

 

Is it obd 1? I am assuming since your signature says you have a p28.

What is your o2 sensor situation like?

 

yep p28 obd1...4 wire O2 that loos pretty new.

 

Did you do a DPFI-MPFI swap?

 

it's a d16y8

 

When i hit the brake pedal after starting the car at idle it surges for a second as well...would this hint anything?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by AgentJam &raquo;</TD></TR><TR><TD CLASS="quote">When i hit the brake pedal after starting the car at idle it surges for a second as well...would this hint anything?</TD></TR></TABLE>

I dont think thats a concern. It has to do with vacuum from the motor and the power brakes.

 

vacuum leak ... I had a similar situation

Spray starter fluid whe you first start it up, I bet the idle will change

 

well i thought that could be it to but here's the update...

I searched and someone said to try a 9v battery and flash the IACV to make sure it's okay (found that under load the idle response was kinda delayed). Turns out the 9V burnt it out so for all you guys...dont try to test it that way. I'll hopefully be picking one up tomorrow but guess what happend next.

Well since the IACV is burt out i got a code for it (code 14), and when started the idle is kinda low but when i rev it no oscillations after that!!!

Does the ECU go into a limp mode when throwing a code? Or since i dont get a surging idle without IACV working does that mean it must have been the problem?

Vince

 

up!

 

anyone? When i unplug iacv i have a great idle no problems...just a code.

Vince

 

I'd go ahead and swap in a known working IACV and see if it fixes the problem.

 

OK, now it will idle fine when stared...but after i drive and stop at a light after warm it will surge for up to 30 seconds and then level out. If i very gently let off the gas slowly at a light and kinda bring it back to idle myself it will idle fine.

Almost like it can't recover an idle from the rev drops...I will try different IACV but for now lets assume it works.

Thanks guys!

Vince