Started car up one morning to warm it up...sounded fine till it started jumping RPMS or idling from 1 to 2 grand. Then the check engine light came on...i turned it back off and restarted it...came on while i was driving...doesn't make a difference in driving...seems to drive fine...is it the IAC or O2 sensor??? i did take out the stock intake system by the side of the fender for more air flow to the intake...would that cause it to come on? Let me know guys!

 

Sounds like a vacuum leak. Did any of the hoses come loose?

 

What CEL code are you throwing?What year Accord?

 

90 honda accord...stock motor...i'll check all the vaccum lines, but i dont its that. didnt have a chance to check the ecu yet...maybe tps sensor?

 

Although this doesn't explain the RPM Jump, My mom just had a problem with her 98 Accord, when they write to make sure that the fuel cap is turned 3 clicks they really do mean it, in Jersey they pump your gas for you which is REALLY nice when it's freezing in the winter but they tend to not tighten the cap till it clicks, so anyhow that was her CEL problem. Maybe it's part of yours?

 

check the CEL code first..

 

stongly dought its that...i think the 98 accords have a sensor...dought the 90's do, but i'll check into that too...gotta open her up and check the cel tonight...went to autozone for the free testing, but they dont do anything 96 or older...what a bitach eh? oh well

 

replace or bypass the FIV, your current FIV is shot

 

FIV? sorry bout the noobie question...but wats that stand for? Fuel injector Valve or something? Map sensor you say??? hmm could be...but thats alot of bucks to spend...thanks for the input

 

FIV = Fast Idle Valve
MAP Sensor = Manifold Absolute Pressure Sensor

 

I had a similar problem, but it was just after inspection. When they were near the gas tank, they must of hit the sensor with the stick, or whatever. The check engine light was on for a few days, but then I just took it back to the dealer for them to fix it, which they did. One common reason that it turns on is if, when you are getting gas, and you don't turn your car off, the car itself will think there is a malfunction, and report that through the check engine light.

 

hey i work at honda and can give you some help.
1. check coolant level.EVAC runs off of coolant.
2. check idel adj. if it is backed out to much it will rev up and down.
3. tap on EVAC. the valve will start to stick right before it goes out.

i hope this helps you?

 

Coolant temp sensor maybe? But most likely MAP or IAC

 

thanks for the replys guys...yea im starting to thinks its the IAC sensor or MAP...im hoping its not the map sensor though...low coolant level i dont think could trick the ecu to through a code???? could it??? that'll be pretty high tech especially for a 90 accord DX. anywho...im gonna rip her apart and get the ECU code...i'll letchu guys know what it is exactually for bragging rights later thanks again.

 

if the coolant temp sensor is busted then the IAC wont know when to turn off.
The IAC is only on when the car is cold to keep rpms at a certain level. when the car heats up the IAC turns off. If the coolant temp sensor cant tell when the car is hot, then your IAC will stay on resulting in irratic idling. The only way your engine light will come on when relating to the IAC is when it is non-functional; if it stays on all the time the ECU wont think anything's wrong.

 

best thing you can do is to get the number of the code you're throwing

 

good point...i'll keep that in mind...eh you wouldnt happen to have your stock motor would you?

 

dude IM be back.

 

IMed you... oh yeah and it WAS the Coolant temperature sensor...turns out the plug from the harness wasnt connection right. Thanks for all the inputs and help.