hey guys,
hope to get some info to resolve this issue.
i just had a local shop swap a D15B vtec engine into my VX civic.

first of all we used the VX motor harness and it was a mess, the engine ran badly..
so we then used an SI engine harness, and now it runs fine and throttles fine. however the ECU harness on the inside of the car is still VX, not SI.. im seing a few wiring differences between the VX harness for the ECU and an SI harness for the ECU.
-so my first question is weather it's ok to leave the VX harness on the inside of the car from the ECU to the bay, and just use the SI harness in the bay?

CURRENT ISSUE: the car surges at idle between 2000 prm and 900 RPM. goes up to 2000 then quickly drops to 900 and repeats it over and over again..
we have checked all vacum lines, no leak. all other coolant lines seems to be ok
what other things can you guys suggest to try?

 

Try the Fast Idle Valve...they have a tendency to work themselves loose...it's underneath your throttle body...actually made on to it....there is a plate that is held on by 2 screws, loosen those, take them out and see if the valve inside is loose...if so tighten it...that will probably fix your problem...Is your CEL on? If not then this is most likely your problem...

 

Thanks for the info, i'll do that

EDIT: THE CEL IS ON. and when i flash the code, it gives me a SOLID code. what does that mean?>??? i knwo my ecu isnt malfunctioning. could it be because im using a VX ecu harness with an SI engine?

 

Hmm.....that sounds like a wiring issue...with the VX wiring harness to the ecu...

 

can anyone confirm that there are some differences in the wiring harness at the ecu?

i know the vx uses a 5 wire o2 sensor, egr, evap solenoid, and to run the vx motor i put in my cx hatch, i just used a 4 wire o2 and a stock p28.

 

its prob your o2 sensor... what ecu are you using and are you using a 4 wire o2?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hatchofchrist &raquo;</TD></TR><TR><TD CLASS="quote">can anyone confirm that there are some differences in the wiring harness at the ecu?

i know the vx uses a 5 wire o2 sensor, egr, evap solenoid, and to run the vx motor i put in my cx hatch, i just used a 4 wire o2 and a stock p28.

</TD></TR></TABLE>

the vx has a few more wires for the added wire on the o2, egr, etc but everything else is wired the same... there is a very easy way to fix the o2 problem when doing a swap and using a 4 wire o2 and running a p28/p72/etc... ive posted it on here MANY times

 

holy crap! you live in xenia, ohio... i had no idea that was a real city... way off topic but has anyone seen the movie gummo??... if you have you know where im comin from with this

 

gummo!! I remember that movie.. it's really really fucked up... but yeah sorry to be off topic... back on topic..... i think that it's the wiring....

 

thanks alot for the info guys...

could this wiring issue be causing the IDLE SURGE though??
i realize it can be causing the CEL coming on and giving me a solid error code, but could it have anything to do with the IDLE SURGE??

 

maybe?... maybe not?... find out what it is and post it up here so we can try to help

 

ok guys, update:
GOT THE IDLE SURGE FIXED
it was due to a defective TPS, so i replaced the throttle body, and it fixed the issue, engine runs very strong and idles perfect.

Now along to my other issue: CEL comes on after 5 to 10 minutes of driving the car.
runnign a D15B Vtec as mentioned above, using an SI harness, but the ecu harness is still the original VX harness.
also, using a P28 ECU.

when i check the engine code, gives me a SOLID code, i take it it's code 0, which from what i know means faulty ECU or wiring. i know the ECu is fine, since ive tried two of them. how would i fix the wiring to correct this issue?

 

im still leaning towards o2 sensor... you are using a 4 wire o2 correct?

 

What throttle body did you switch to? i have the same problem with my car but it doesnt surge as bad as yours.Im running a cx harness and a p28.Did you check the voltage of the tps before buying a new tb?.

 

in response to the O2 sensor, yes i am using a 4 wire O2 sensor off the SI engine.
and about the TPS, no i ddidnt check the voltage, i just took a Trottle body off an SI EG and put it on.
and it fixed the issue

 

ok well i bet your getting no o2 signal... heres the easiest way to fix it since youre using the si engine harness... if you noticed the vx chassis harness has 4 plugs while the si engine harness only has 3... look at the one vx plug that was left over and find the orange wire with a blue stripe... this is the o2 signal on the vx side of the harness... now look at the other plugs and you will see one with a little rubber boot where a wire would be on the vx side and on the si side you will see a white wire directly opposite of the rubber boot... this white wire is the o2 signal wire on the si engine harness side... simply remove the rubber boot, take the orange/blue wire out of the pin in the extra plug, and repin it in place of the rubber boot... now your o2 sensor circuit should be functioning properly

 

MUCH MUCH thanks for the reply man, i'll try it tomorrow. if i have any more questions i'll post it up. thanks again!!