Can you guys confirm my findings on my IAC sensor problem - Honda Prelude Forum

Lude004 · 12-06-2002, 12:46 PM

After doing some research, I came to the conclusion that my IAC sensor maybe messed up. I did something wrong with I was installing my FJO sensor to the ECU and things went funny. I had to change my MAP sensor and now I think my IAC sensor is bad too.

Here is why I think the IAC sensor is bad. Sometimes at idle the car would rev up and down around 1500-2000. Sometimes the idle would get stuck at around 2000 rpm until I press the throttle a couple of times before it settles down. And the problem is getting worst.

Also when I am gradually(easy on the pedal) boosting up to 7psi the car would run fine, but when I floor it, the car would get to full boost and would studder some after 30 sec. or so of boost. My fuel map seems fine. Not too lean at those boost range. I didnt have this boost problem before this idle problem started.

Do you think the IAC is the cause? What do you guys think?? I am getting really tired of the problem. I want to change the IAC sensor but want to confirm with you guys first. Any suggestion would be great.

Thanks

Poe

clendaniel · 12-06-2002, 01:36 PM

Quote:

Originally posted by Lude004
After doing some research, I came to the conclusion that my IAC sensor maybe messed up. I did something wrong with I was installing my FJO sensor to the ECU and things went funny. I had to change my MAP sensor and now I think my IAC sensor is bad too.

Here is why I think the IAC sensor is bad. Sometimes at idle the car would rev up and down around 1500-2000. Sometimes the idle would get stuck at around 2000 rpm until I press the throttle a couple of times before it settles down. And the problem is getting worst.

Also when I am gradually(easy on the pedal) boosting up to 7psi the car would run fine, but when I floor it, the car would get to full boost and would studder some after 30 sec. or so of boost. My fuel map seems fine. Not too lean at those boost range. I didnt have this boost problem before this idle problem started.

Do you think the IAC is the cause? What do you guys think?? I am getting really tired of the problem. I want to change the IAC sensor but want to confirm with you guys first. Any suggestion would be great.

What ECU are you running? IIRC the FJO setup doesn't have a simulated narrowband so unless you've got a standalone then that would be causing the issues. If it is a standalone like the AEM it's possible that a temp change has thrown off your idle settings enough for it to go screwy. A nice consistent idle throughout the temp range takes some work.

The IAC valve could be your problem but what's this about the wbo2 install...what went wrong causing you to need a new MAP??

In the unlikely event that it's totally unrelated then pull the iac off the intake and clean it, they tend to get clogged esp on f/i cars...

--Ian

Lude004 · 12-06-2002, 02:09 PM

The FJO was installed to AEM EMS and what happen was I think could have grounded the wrong wires and must have send positive charge to the sensor ground wire to the EMS which could have thrown everything off. I had to send the EMS back to get it fix. Then it could be that the EMS computer board messed up my sensors because it was going wacky on me. AEM said the board was defective and fixed it. Dont know what really happen. All I knew was that I the MAP sensor went bad and I had to replace it. Keep in mind that my car is 2000 and the sensors should not be going out this soon unless something caused it. That is why I think the ECU must have did something to make my Sensors go bad on me.

I think I will clean IAC next before I buy one. Thanks

Poe

Quaalude · 12-06-2002, 04:37 PM

Try datalogging the AIT values and see what you get. A faulty sensor will give you odd readings. Also, it seems that the EMS is hunting for an idle. Try messing with the idle options.

TimeRacer · 12-06-2002, 07:36 PM

If you really think it's the IAC pull the ECU out and use the Helm's manual to see if the valve is working. I just did this the other day, wasn't too fun getting in there. Though I was throwing a CEL light and there was major hesitation around 2000-2500 rpm. But this is with a stock ECU.

clendaniel · 12-07-2002, 11:29 AM

Quote:

Originally posted by Lude004
The FJO was installed to AEM EMS and what happen was I think could have grounded the wrong wires and must have send positive charge to the sensor ground wire to the EMS which could have thrown everything off. I had to send the EMS back to get it fix. Then it could be that the EMS computer board messed up my sensors because it was going wacky on me. AEM said the board was defective and fixed it. Dont know what really happen. All I knew was that I the MAP sensor went bad and I had to replace it. Keep in mind that my car is 2000 and the sensors should not be going out this soon unless something caused it. That is why I think the ECU must have did something to make my Sensors go bad on me.

I think I will clean IAC next before I buy one. Thanks

Poe

Where are you pulling power and ground for the wbo2?? IIRC there are several people over on the aem forum that have had issues with the FJO setups causing readings to go whacky when using power directly from the ecu sensor feeds.

Also did you update the o2 maps for the AEM when you installed the sensor? If you had feedback on with the narrowband voltage settings it would _definitely_ idle funky.

--Ian