Idle issues with AC

joemomma

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Been fighting some idle issues with the car, but only when the AC is on. More specifically, if the AC compressor has cycled on, and I'm low engine speed, it'll tend to die - especially if turning. I figure this is due to extra load on the engine from the PS pump. I've done the procedure for cleaning TB/MAF and base idle reset recently, and that corrected a lot of it except with the AC running. The linked article in the sticky mentions messing with the throttle stop - I thought this was a no-go? There is another idle screw on the SN95 TB isn't there? Under a rubber plug or something?
 

joemomma

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I'll have to check, I'm not sure. It definitely dips when the compressor kicks on, but it catches itself most of the time if I'm not turning. It seems to be the worst when say I have the clutch in and I'm turning in, like to a driveway or on to a side street.
 

joemomma

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I checked idle, right at 750-800 per the factory tac with no AC, and it dips to 5-600 with AC on. When the compressor kicks on, it will catch it if you're not turning or moving. So, with that in mind, I set about redoing the idle. I found an article over on the corral that was '94-95 specific. I'll try to summarize:

-First step was turn the blade stop screw out until it would just barely drag on a 0.010" feeler gauge. I just eyeballed it, no idea where my feeler gauges are since the move. I got it where it wasn't touching and then turned it just slightly so it would just make contact.
- Start with a cold engine
- Unplug IAC, start car
- Adjust air control valve (under the rubber plug on top of the TB) until it will just barely idle...I had to turn mine out 1.5-2 turns. It mentioned giving a throttle blip to make sure it would recover.
- let car idle for 2 minutes, shut off
- Plug IAC back in, and start car

There were a couple more steps about checking how many turns out you were, but I didn't need to adjust that as I fell within recommended turns. Basically, anything more than two full turns and you needed to adjust the blade stop screw. I was at 2.25 so I didn't mess with it. I haven't driven it yet, but it seems to be much better mannered with sitting in the driveway. I turned all the accessories on and it seemed to catch fine.
 

RAU03MACH

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i used to have a dying problem when the fans would kick in and turning the steering wheel
or coming to a stop
i adjusted the top screw under the rubber cap until it quit dying on me
turned counter clockwise to 2 full turns on mine
every car is different
 

joemomma

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I thought the rpms were supposed to go up slightly with the ac on?
They are supposed to. Mine will idle up when it kicks on, but it often dies before it "catches" it, especially if turning or coming to a stop. It drops to 5-600 before it idles up, and usually it will die before it can catch it. I guess I should have clarified that better. It'll idle closer to 1k once it catches it, assuming it doesn't die.

RAU03MACH - that's essentially what I did as well, just turned the air control screw (or whatever you call it) out. I'm at 2.25 turns out, or thereabouts.
 

joemomma

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Drove the car in this morning, it did die on me once. I'll continue to monitor and see how it goes at lunch and after work.
 

miscreant

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I don't know if it will help much, but your IAC valve could also be dirty causing it to not flow as much. You could try cleaning it but I usually just open up the throttle a tad more as you have stated previously.

I wonder if your could ream out the iac valve more to flow more air....food for thought I guess. I know that's common on cheaper LS throttle bodies.
 

joemomma

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I don't know if it will help much, but your IAC valve could also be dirty causing it to not flow as much. You could try cleaning it but I usually just open up the throttle a tad more as you have stated previously.

I wonder if your could ream out the iac valve more to flow more air....food for thought I guess. I know that's common on cheaper LS throttle bodies.
I did clean the IAC in my first round of attempting to sort out idle issues a few months back. I'll probably just open up the air screw a bit more and see if that helps. I'll see how it acts at lunch today and then on the way home.
 

ttocs

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What mods have all been done to the car? I remember the idle going up with the ac on but I never remember it at 1k at idle. I thought it was actually bad for the tune to adjust the throttle stop but I could be making that up. I might be transferring my holley efi stuff over because I know on there if I make any adjustment to the throttle stop I need to do a throttle position sensor calibration afterwards.
 

RAU03MACH

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i can see not doing that to the holly system because it would throw all the potentiometer readings off
but on stock and some aftermarket parts with EEC will still learn the adjustments
 

joemomma

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What mods have all been done to the car? I remember the idle going up with the ac on but I never remember it at 1k at idle. I thought it was actually bad for the tune to adjust the throttle stop but I could be making that up. I might be transferring my holley efi stuff over because I know on there if I make any adjustment to the throttle stop I need to do a throttle position sensor calibration afterwards.
Mostly stock with the exception of shorty headers (unknown brand), Hurst shifter, and gears.

It ran fine at lunch, and it's probably not 1k. More like 800 or so I'd say (I sat idling in the parking lot waiting on a couple of buddies to show up for lunch). The car was warm at this point. It wasn't fully warm this morning when it died, so that may have been part of the problem. I'll continue to monitor.

As far as the throttle step - yes, it's my understanding that you shouldn't dick with it. Idle should be adjusted with the air control valve under the rubber plug on the top of the TB. I'll see how it does on the way home. I may need to open it just another touch.
 

joemomma

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Died on me twice this morning on the way to work. I'll adjust the air screw today after work. I might even turn the throttle stop out a touch.
 

RAU03MACH

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Died on me twice this morning on the way to work. I'll adjust the air screw today after work. I might even turn the throttle stop out a touch.
my throttle body is a bbk , that screw under the rubber cap on mine is almost to the top , i can post the pics if you want to see to get an idea , but i did have to come out quite a bit , i dont know the mods you have
here is a list on mine
30 over stalk block stock crank
x ford race heads Cylinder Head, X2, Aluminum, Assembled, 64cc Chamber, 188cc
ford roller rockers non adjustable cobra type
b303 cam
7/16 spacer between lower and top intake
gt 40 tubular intake
73 m throttle body
shorty headers no cats supper 44
no emissions
kenny bell boost pump
stock injectors , may be changing those out soon
4 bank tune bama soon to be replaced mega squirt
and this was killing my engine before ac come die turn a corner die stop die lift off the gas die
and 1 little screw made all that better
 

joemomma

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I turned the air control screw out 1/2 a turn after work yesterday. It drove/idled fine this morning with the AC running, so hopefully this has done the trick.
 

miscreant

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my throttle body is a bbk , that screw under the rubber cap on mine is almost to the top , i can post the pics if you want to see to get an idea , but i did have to come out quite a bit , i dont know the mods you have
here is a list on mine
30 over stalk block stock crank
x ford race heads Cylinder Head, X2, Aluminum, Assembled, 64cc Chamber, 188cc
ford roller rockers non adjustable cobra type
b303 cam
7/16 spacer between lower and top intake
gt 40 tubular intake
73 m throttle body
shorty headers no cats supper 44
no emissions
kenny bell boost pump
stock injectors , may be changing those out soon
4 bank tune bama soon to be replaced mega squirt
and this was killing my engine before ac come die turn a corner die stop die lift off the gas die
and 1 little screw made all that better
I know a lot of people have had success with the megasquirt but I also highly recommend a look at a Holley Terminator X. I love mine and install is very straight forward. I feel like their software is much easier to use and understand as well. Sounds like a good build though!
 

ttocs

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It seemed to me the people having the best luck with megasquirt were the ones that had previous tuning experience. I know myself I was a little too green to get into it now but holleys support after the purchase helped out tons.
 

RAU03MACH

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been doing the research on the mega squirt , it looks like a good system , im going to try to pick up a couple more ,one for the cobra and mach 1
 

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