I just installed a OBD1 P28 ecu on my OBD2a car, and now the idle is jumping from about 1500 to 2000 rpm constantly.. what could be causing this?

The engine is still stock with all OBD2a sensors..

 

disconnect your evap solenoid
that should solve it
(no you wont get a cel)

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by pdiggitydogg &raquo;</TD></TR><TR><TD CLASS="quote">disconnect your evap solenoid
that should solve it
(no you wont get a cel)</TD></TR></TABLE>

tried that, no luck

 

interesting
I know exactly what youre talking about, though.
I had a p28 on my y8 awhile back, and after pulling the electrical connector it smoothed right out.

ttt for other suggestions

 

it's actually an automatic ecu, i was going to convert it to manual asap but it started right up and now I get the erratic idle..


also it runs fine with my OBD2a ecu, aside from the occasional hesitation/sputter


Modified by jdm_vtec at 1:25 PM 5/24/2007

 

the fact that its auto could be the problem...
It only takes a couple minutes to convert it to manual spec

 

thanks for your help.. i tried unplugging both the evap solenoid and the IACV, reset the ecu and ran it that way.. the idle was extremely low so i plugged both back in and reset the ecu again..

now the idle is fine but the hesitation/sputter is even worse on this ecu

i've tried new plugs, fuel filter, dizzy cap and rotor button.. what else could it be?

 

well the idle will be extremely low, if the iacv is unplugged, so that was normal
obd1 doesnt check for evap

Were you trying to get rid of sputtering by changing the ecu??

 

no, i need obd1 for my swap..

but i would like to get rid of the sputter (loss of acceleration) on the stock engine.. until I can get my swap together and in the car

 

how are the plug wires?