I just converted to obd1 in my gs-r about a month ago.
The motor has about 2000 miles on right now. With the p28 chipped ecu I throw no codes , with my stock obdII ecu I throw a cell # 65 ( secondary o2 ) , obviously because I don't need that o2 and run a test pipe with the primary o2 hooked up.

The car revs up fine and runs perfect , the problem is at idle it sits at 1000rpm's and pulsates to 1500. Up and down up and down etc...

any idea's what can be causing this?

1. Im thinking maybe the program ( basic mugen program ) is a running a little rich and the car needs to see a dyno.
2. maybe the obd1 conversion harness from kenji is bad?
3. maybe the chip burn itself might be bad , or the chip itself.

please give me some idea's on what can be causing this , thanks~

 

Did you mess with the TPS sensor at all?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Matador &raquo;</TD></TR><TR><TD CLASS="quote">Did you mess with the TPS sensor at all? </TD></TR></TABLE>

nope, just slapped it on when the swap was being put back together.

if the tps was bad , the p28 would throw cell for that right?

 

help~

 

How tight is the throttle cable. Try putting a bit of slack in it.

 

Also check for vacuum leaks...ecu does a weird fuel cutoff thing like you describe when it sees idle speed go too high.

 

good way to check for vacum leaks , carb cleaner?

 

It may have pissed off your AICV, screw with that if you can. It's a pretty common thing to happen with just a generic program thrown at it, screw with the the idle control also. It takes patience, but you'll get it down. Or you could just gimmie them wheels and I'll fly down and do it for ya


Bump for ya homie

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Reza.. &raquo;</TD></TR><TR><TD CLASS="quote">good way to check for vacum leaks , carb cleaner?</TD></TR></TABLE>

sounds like what my old accord had....vacuum leak. try carb cleaner or wd40. You could also adjust the idle screw to see if that helps.

 

Most the time, if something ECU related (chip or ECU) it will throw a constant CEL.

I think its a mechanical problem like a vacuum leak.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by clean rice &raquo;</TD></TR><TR><TD CLASS="quote">It may have pissed off your AICV, screw with that if you can. It's a
</TD></TR></TABLE>


Thanks clean , how can I adjust that?


<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Br1anPham &raquo;</TD></TR><TR><TD CLASS="quote">Most the time, if something ECU related (chip or ECU) it will throw a constant CEL.

I think its a mechanical problem like a vacuum leak.</TD></TR></TABLE>

really , thats good to know.. I was hoping it wasn't ecu related or chip burn related.

guess it's time to check all the vacum lines, fun times.

 

Reza,

Adjust the idle adjustment screw on your throttle body. That should solve the problem.

The only other thing I can think of is unmetered air (vacuum leak past the MAP sensor).

However, if you put in a different ECU and the problem goes away I would mess with the idle adjustment screw.

Good luck and email me if you need more help.

-kenji

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by kenji &raquo;</TD></TR><TR><TD CLASS="quote">Reza,
The only other thing I can think of is unmetered air (vacuum leak past the MAP sensor).
-kenji</TD></TR></TABLE>

Thanks Kenji, what part is this.. what does it look like?

 

When I say unmetered air I mean air that got in the intake manifold downstream of the MAP sensor.

This can enter via the gap btw the IM and the head, the IAT sensor, at the IACV, at the injector gaskets, or at any other opening on the intake manifold.

-kenji

 

found out it was the IACV , thanks for all your help fellas.