I'm in the market for a new car and found a 1999 honda civic dx with a ls swap from a 98 integra.

While the car is running, it idles extremely weird. Sometimes it will idle fine for a few seconds and then it idles really bad, it kind of sputters and comes very close to stalling but it doesn't actually stall. It doesn't sound anything like an IACV issue. Would it be a vaccum or something wrong with the engine or what?

I should note it is converted to OBD1 (jumper harness to ecu) and is running off a p75 ecu.

UPDATE: After my buddy and i looked over some wires, we started the car and it now throws a check engine light, code 41 and code 20 and my speedometer stopped working, we didn't change anything and the car runs like ****. Any wires we touched we put right back how they were. On my way home from work last night the tachometer died, my radio died and my lights got dim. Sure enough the car dies a little bit after that happens and assume my alternator went out. I think its the wiring, would it be a shitty engine harness install doing all this stuff??? If i were to replace the harness which one would i need?? (car is a 99 civic dx, converted to obd1 (has a jumper harness to the ecu) and i beleive an obd1 engine harness)

Any help is greatly appreciated!

 

i dont think it would affect the idle necessarily as you are describing, but what the owner is referring to is the idle air temp (iat) sensor. on the motor he installed, the sensor is on the intake manifold. on your car, it will be located on the intake pipe. so i would check to make sure it is in fact installed in the pipe. is your cel on for anything by chance?

 

Any cel's?

 

bump

 

There is no CEL. I can't figure out what the hell is going on. It sputters and drops RPM alittle bit when giving it gas to like 3k while idling as well.

The car is converted to OBD1 (jumper harness to ecu) and is running on a p75 ecu, is it the correct ecu?

Anyone have any suggestions???

 

bump

 

Anyone??

 

re-wire the iat sensor from the intake to the manifold their different plugs so cut it and extend it and wire up the correct plug

 

So take it OFF of the intake and put it back on the intake manifold?
There is no sensor on the intake manifold, it has some sort of block off plate.\

and tyrone biggums is the mother ****in ****! lolololol

 

The intake air temp sensor should most likely have no effect on how your car is idling, double check and make sure you have the tps and map sensor in the correct spot and not swapped.

 

Alright ill check them out, thanks.

 

UPDATE: After my buddy and i looked over some wires, we started the car and it now throws a check engine light, code 41 and code 20 and my speedometer stopped working, we didn't change anything and the car runs like ****. Any wires we touched we put right back how they were. On my way home from work last night the tachometer died, my radio died and my lights got dim. Sure enough the car dies a little bit after that happens and assume my alternator went out. I think its the wiring, would it be a shitty harness install doing all this stuff??? If i were to replace the harness which one would i need?? (car is a 99 civic dx, converted to obd1 (has a jumper harness to the ecu) and i beleive an obd1 engine harness)