Hmmm electrical problem??

[ericsmith32]

Well many of may know my ongoing duel with my aspire. I believe I got the timing set correctly, it's running pretty good except it revs up and down while in idle. The crazy thing is it doesn't do it all the time. Sometimes I can put it in reverse or turn the lights off and on and it will quit. I used the festiva alternator when I did the motor swap, both are 5-speeds but the aspire has a/c. I thought they would be the same. The plug-in that goes into the alternator isn't tight, but i've had no problems with charging. It's had this problem since i've first started it. The more I advance the timing the less it does it, so any other way of thinking would be the faster the idle speed the less it does it. Do you think it would be the alternator or something with FI??

[qaking]

I just fixed a very similar problem on my '90 Festiva.
It was the ISC/BPA (idle speed control/bypass air valve assembly).

Some of the other things to rule out:
1. Vacuum leaks.
2. Leaking EGR valve.
3. Dirty air filter
4. Low fuel pressure/volume

Good Luck!
:wink:

[ericsmith32]

I hope its not that part.. it's not exactly cheap new and my guess would that used would be the same. The air filter is new, i've double checked about every hose twice, all seem tight. I'll look at the egr valve this weekend. As far as the fuel pressure that might be possible since it set for 6 months with a half a tank. It only does it when it's warmed fully, and to me it does idle way to fast for way to long. Also it didn't do it on the old motor but it had a blow-by problem, so alot of oil got into the intake. Knowing my luck it probably can't be cleaned.

[qaking]

I bought my ISC valve used and it worked for me. I have also read that if the electrical side of the valve checks out, then you may be able to flush out the air side with carb cleaner as they become gummed up. I have not had time to inspect my old one to see why it failed yet!

Here is the ISC description out of the EVTM:
"The Idle speed Control Solenoid controls engine idle speed by regulating the amount of air allowed to bypass the throttle plates. This allows the ECA to make idle speed corrections to prevent engine stalling during cold engine warm-ups and as engine load changes."

Mine was only idling erratically when I did not have the AC turned on. Once the AC was on the idle would return to normal.

The Haynes book has a check for the ISC-BPA solenoid:
Disconnect the electrical connector and measure the resistance between the 2 terminals, it should be 7.7 to 9.3 ohms.

[ericsmith32]

Mine was at 9.9ohms. I cleaned it no to no avail. I guess it gives me a reason to go to pick-a-part, even though I have no money.

[Tim]

I had a similar problem when the accelerator cable got binded.

If there's too sharp a curve in the cable it creates resistance and can do funky stuff.


Regards,

Tim

[qaking]

ericsmith32,

I forgot to ask if you had checked for any engine codes?

[ericsmith32]

Nope no engine codes. I cleaned it the other day and it only seems like it wants to do have a problem during the initial startup. I didn't fully take it apart since one of the screws was a recessed hex (I think). If I can find the hose for my intake cleaner i'm going to slide in between the hose fittings and give er a good sparying while its running.