I've been running a chipped P28 for a long time, but got a USDM P30 for the future so I can pass emissions. So I put it in today and starts up fine and no CELs, but my idle jumps from 500 to 1700rpms. I didn't have any idle problems with the chipped P28 so I'm just wondering what the problem could be.

 

no cel?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by igo4bmx &raquo;</TD></TR><TR><TD CLASS="quote">no cel?</TD></TR></TABLE>

Nope, I thought I was gonna throw a knock CEL because my OLD JDM P30 threw one, but nope, nothing NO CODE...

 

i've heard of bad ecus.... being the cause of some random things, like the problem you are having. only thing i can think of

good luck

 

I don't think its a bad ECU or at least I hope thats not why...

 

What program is in your chipped ECU? It could have been running in open loop before, so you may need to adjust the air bleed screw on the throttle body.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Jim Truett &raquo;</TD></TR><TR><TD CLASS="quote">What program is in your chipped ECU? It could have been running in open loop before, so you may need to adjust the air bleed screw on the throttle body.</TD></TR></TABLE>

I think its a Skunk2 program 5200vtak! no limiter (I never go pass 8k so I wouldn't know)

Well while driving to school with it today, I threw a knock code but I doubt that has anything to do with it.

 

the "Skunk2 program" typically has about everything disabled that it can.
One of the versions I've seen even ran open loop.
where did you get the program?

it sounds like a IACV problem to me. all though the knock sensor issue needs to be resolved also.

 

Not sure who chipped or where. I just bought it from someone b/c I needed an ECU.

 

That jumping idle is from a disconnected MAP sensor
I've had that happen on my z6 or your map sensor is wired wrong
check your **** out

 

MAP sensor is connected unless its broken...

 

broken map = CEL

 

Its your IACV.. you can disable the IACV with various programs and the stock ecu has a higher Duty cycle for the IACV so thats what your problem is

 

Well I just got back from inspecting everything. I cleaned out my IACV and my knock sensor was hand loose so I tightened it up. I turned it on and the jumping went away, but the motor was cold so I'm gonna go drive it around for a little and see how it goes.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JDMlyfestyle &raquo;</TD></TR><TR><TD CLASS="quote">Its your IACV.. you can disable the IACV with various programs and the stock ecu has a higher Duty cycle for the IACV so thats what your problem is</TD></TR></TABLE>

Yeah I was thinking about trying your bypass loop thingy you said you did, but its getting too cold here . Maybe give it a try tomorrow.

 

Hey its worse here.. yesterday was 73 with tornado warnings everywhere.. today it was 40 and there callin for sunny and 75 on saturday....

WERE ALL GONNA DIE!

 

Well, nothings change. . I started it up and there was no code and no jumping idle I was all happy, then I drive about 15 blocks, come a stop sign. Both jumping idle and CEL come back. Checked code, still 23 (knock sensor).

Another question: How tight is the knock sensor suppose to be?

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JDMlyfestyle &raquo;</TD></TR><TR><TD CLASS="quote">Hey its worse here.. yesterday was 73 with tornado warnings everywhere.. today it was 40 and there callin for sunny and 75 on saturday....

WERE ALL GONNA DIE!</TD></TR></TABLE>

Yeah it was so nice earlier this week, then today bbbuuurrrrrr cold!

 

Knock sensor should be in the block pretty tight.

The knock sensor can throw your car into limp mode and limp mode can cause the irratic idle as well.

 

What size deep socket is it again? I need to buy one

What's limp mode like? Sorry I'm an idiot

 

Limp mode... Engine Runs richer.. higher idle. and i believe it retards the ignition timing slightly all to prevent damage to the engine.. ive seen the erractic idle along with it.

I believe it is either a 17mm or a 19mm socket

 

Well I unthreaded it and tried to put a 21mm (biggest size I had) on it and it was too small

 

Have you tried putting the chipped P28 back in to see if the symptoms transferred? I'd start there and work my way out to the engine bay

 

yeah the ECU won't throw a knock code unless it's looking for it... (engaging VT4K) any vacumn leaks?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Archidictus &raquo;</TD></TR><TR><TD CLASS="quote">Have you tried putting the chipped P28 back in to see if the symptoms transferred? I'd start there and work my way out to the engine bay </TD></TR></TABLE>

Yup, brought it with me just incase something went wrong. Plugged it back in everything was back to normal. I don't know alot about wiring (I didn't do the swap) so you have to bare with me a little.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Leeroy &raquo;</TD></TR><TR><TD CLASS="quote">yeah the ECU won't throw a knock code unless it's looking for it... (engaging VT4K) any vacumn leaks?</TD></TR></TABLE>

What if the knock sensors broken? I'm pretty sure theres no vacuum leaks since when I plug my chipped P28 back in its all fine...

And I don't think its the ECU because this has happened with my old JDM P30 too

 

very well could be a bad knock, although not having a knock sensor or having a bad one will only effect things when the ECU checks for knock at vtec engagement.

So I'm not positive, but pretty sure that won't cause bad idle

 

well is the knock sensor even wired into the ECU? lol