So.....I can control my throttle on my zx2 with the fan control. That's normal right?
On my way home from yet another terrible day I put the clutch in and my engine started slowly revving up. I assumed it was the throttle cable so stabbed the throttle and it kind of worked but it kept on happening. The car has a weird low idle problem with the a/c compressor coming on so I usually just run it on the highway. For giggles I turned the fan off when it started revving.....it stopped revving. This only happens when the clutch is dropped and no other time. The car doesn't careen out of control and even with the clutch dropped it's a slow buildup of revs. I can also switch the fan off and on and rev it back and forth.
I also noticed that when I turn on the fan the load seems pretty heavy, the lights dim and do so twice. Also turning on the headlights causes the engine to idle about 100 rpm lower.
Here's my thoughts so far:
Vaccum leak causing something weird with the throttle body? Never heard it revving up something slowly but it kinda makes sense with the low idle and why it happens when the a/c compressor comes on with the fan. TorquePro says no vaccum leak though and I can't hear or find one.
Cruise control getting effected by current running to the blower motor. Off the wall but hey, what the hell
Something computer controlled that tells the engine to rev up a bit under load, and it's doing it badly.
The universe wants to push me a bunch. This seems most likely but I'm not sure what part to replace to fix it.
Thoughts?
With a/c on I expect it would raise the RPMs to overcome the extra load, but with the fan off there would be no need for that. So I think you may be correct that there's a vacuum leak exasperating what's otherwise a stock operating mode.
Could be a sticky/failing IAC, That would explain why you could not use the A/C at idle (IAC not opening), and after driving with the A/C on, the idle would get high (IAC not closing).
Ford IACs of the era were extremely common to fail, too, to the point that we stocked them in a two technician four bay shop.
Pete. (l33t FS) said:
Could be a sticky/failing IAC, That would explain why you could not use the A/C at idle (IAC not opening), and after driving with the A/C on, the idle would get high (IAC not closing).
Ford IACs of the era were extremely common to fail, too, to the point that we stocked them in a two technician four bay shop.
That's a good point, but in my experience the IAC failing means no idle at all?
They are usually cheap and it's old anyway so it's probably worth it to replace
Unrelated electrical components can cause issues if grounds are bad.
I would check ground straps, negative battery cable, etc. to make sure they are making good contact.
Also check the alternator output to see if that's starting to fail and requiring more revs for the ECU to keep the voltage in a range that it likes.
In reply to No Time :
According to Torque Pro the alternator is pumping out roughly 15 amps. When the idke lowers it dies go lower too but that's expected
15Amps at idle or 15Amps while driving? Isn't that supossed to put out around 95Amps? Maybe low alternator output is affecting power going to different modules?
Might be your CCRM. Mine was bad when I got my zx2, car wanted to stall out anytime AC was on. $15 at JY and all is fine.
In reply to 90BuickCentury :
Two things.
The alternator puts out enough current to keep system voltage at 13-14v up to the point that it cannot anymore. Might be 10a, might be 100a. The engine is good for 130hp, but it does not make 130hp all the time, same deal.
The current is not a direct measurement, it is an inferred value based on calculations and modeling. This car would be too old to measure charging system current directly, and I don't think Ford ever did that anyway.
Pete. (l33t FS) said:
Could be a sticky/failing IAC, That would explain why you could not use the A/C at idle (IAC not opening), and after driving with the A/C on, the idle would get high (IAC not closing).
Ford IACs of the era were extremely common to fail, too, to the point that we stocked them in a two technician four bay shop.
I would place a rather sizable bet on this. I'd pay 1.5:1 odds because it's a pretty sure bet.
Pull the IAC off and I'll bet you see it full of fun gunky things.
Antihero (Forum Supporter) said:
Pete. (l33t FS) said:
Could be a sticky/failing IAC, That would explain why you could not use the A/C at idle (IAC not opening), and after driving with the A/C on, the idle would get high (IAC not closing).
Ford IACs of the era were extremely common to fail, too, to the point that we stocked them in a two technician four bay shop.
That's a good point, but in my experience the IAC failing means no idle at all?
They are usually cheap and it's old anyway so it's probably worth it to replace
Failing IAC means funny idle. It could get stuck closed and you get no idle, or it could stick anywhere else and give you fast idle. As it starts sticking, it can also mean that it is sticky everywhere. It won't be consistent. It might stick partly open one time, stick closed the next.
90BuickCentury said:
15Amps at idle or 15Amps while driving? Isn't that supossed to put out around 95Amps? Maybe low alternator output is affecting power going to different modules?
I'm sorry, I meant 15v is what I meant to say but yes, it's at idle.
TorquePro doesn't have an out put from alternator amperage that I know of, so it's basically just a voltmeter
In reply to Subscriber-unavailabile :
I should probably look into that too, although the closest junkyard is roughly 2 hours away
In reply to Antihero (Forum Supporter) :
Might hit up bent valve, he's in process of chopping up ZX to pieces, sure he'd be willing make a deal on some parts for his challenge efforts
sergio
Reader
5/26/20 3:57 p.m.
Might want to check the TB for gunk too.
Finally got a chance to get to it. TB is clean, IAC looked clean but I gave it a wack and sprayed some brake cleaner inside. At cold idke it seemed to do well.
The IAC is buried on these though, that was kinda annoying
