Idle Problems in CRX after trans swap - Page 4 - Fuelly Forums

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Old 04-07-2009, 09:47 AM   #31
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The EACV is the idle control valve. The CRX manual I downloaded does not specify which DPFI or MPFI in the section to set the idle.

I'm not sure about your last question, but my understanding of how the idle is set is that the ECU is trying to determine what the proper voltage to send to the EACV valve to get the idle speed correct.

The pdf manual I have is huge, if you want a jpg of the procedure PM me your email address and I'll send you a screenshot
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Old 04-07-2009, 03:23 PM   #32
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Quote:
Originally Posted by Hal9000 View Post
Would an incorrectly set idle also account for the exceptionally high idle when cold and not dropping to base idle nearly as fast as it should?
Maybe and maybe. Take it one step at a time.
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Old 04-08-2009, 11:49 AM   #33
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Probably, I'll have to recalibrate the TPS as well. I'm guessing that if I have to slow things down, The tps voltage at idle will drop to <.45V.....
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Old 04-08-2009, 07:21 PM   #34
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Quote:
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I'm guessing that if I have to slow things down, The tps voltage at idle will drop to <.45V.....
You should be calibrating the TPS to between 0.5 and 0.45 volts with the throttle completely closed. As in, back the idle set screw off completely and then adjust the TPS.
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Old 04-09-2009, 07:47 AM   #35
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So not 0.45V when the car is at idle or when the butterfly is at the "normal" idle setting? Well I got that wrong, but it turns out that it really doesn't matter much anyway. My idle speed screw was only about one turn from being backed all the way out anyway.

With the ICV disconnected, I can only get the idle down to about 750, and plugging the idle back in causes the same surging to start again immediately.

Also, I think the symptoms may be changing a little bit over time. Yesterday I noticed that when I the car was sitting at the high idle (about 1700 at the time) it was also pulsing a little bit on occasion. It would drop by about 200 then recover. It only did it a few times though, then stopped.

The voltages for my temp sensors were all good when I checked them, but when I disconnected the air temp sensor it didn't cause the idle to change at all. I'm still a little suspicious of it. Can somebody else with a DPFI car maybe disconnect that sensor momentarily and see if it affects their idle drastically?
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Old 04-09-2009, 08:49 AM   #36
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I had a similar high idle problem on my 87 Acura integra (but it was MPFI).

I ended up disconnecting the ICV, but then my "check engine" light came on because the computer didn't see the ICV. So I looked up the resistance specs in a repair manual and bought some resistors of the correct ohms at radioshack and plugged those into the wiring harness to fool the computer thinking the ICV was still in place. It worked OK- but when the AC and lights were on, the engine did idle a little too low.
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Old 04-09-2009, 04:21 PM   #37
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I tried that out of desperation last week. But with the ICV disconnected, the car bucks badly when the gas is applied.
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Old 04-09-2009, 09:01 PM   #38
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Take the cover plate off the top of the throttle body. Start the engine, disconnect the IACV and back off the idle screw completely. Block off the port on the driver's side of the chamber you just uncovered... The port that feeds air to the IACV (use your thumb, it wont hurt you).
If the engine stalls, you've got a bad IACV. If not, you've got a pretty big vacuum leak.
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Old 04-10-2009, 10:44 AM   #39
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It sounds like a combination of a bad or dirty IACV and the TPS not properly calibrated. I had the same bucking issue in my Civic a while ago.

Start off by cleaning everything. After you've cleaned everything, then calibrate the TPS.
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Old 04-10-2009, 01:26 PM   #40
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Bobski,
The IACV appears to draw air directly from the airbox, through a flexible tube to the intake manifold and then to the IACV, not from the throttle body like an MPFI car, but I'll double check that this weekend just to be sure.


I've checked for vacuum leaks with a can of starting fluid (ended up using nearly the whole can... I checked pretty thoroughly) as well.

Optix,
I've cleaned/inspected the IACV twice now, and I recalibrated the TPS again yesterday night. I couldn't tell if it made a difference since the idle wasn't acting up (for once) before I checked/adjusted the TPS. I still can't get the Idle down below 750 using the idle screw and the IACV disconnected though.
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