Auto Stalls when put into Drive or Reverse

ram360 · Jul 16, 2008

Trying to figure this out as it has become very annoying. Trans is a 4r70w 94gt. Car idles fine put when I go to put it in D or R the car usually stalls. I usually have to give the car gas an almost drive it like a stick car just to get it moving w/o stalling it out. Tried cleaning the IAC w/ carb clean and the contacts w/ electrical cleaner still no dice...I would buy a new IAC if I knew it would fix the prob but it's a no return item $60 so I don't want to buy it and not fix the prob...Will check the engine vacuum but that's about all I can think of causing this. Does it when its cold or hot

HISSIN50 · Jul 17, 2008

You're smart to check for leaks.

The autos often tend to idle low. Some folks have had luck running out the bleed screw out (any more than ~1.75 turns from seated creates a hanging idle in my experience). If more is needed, using the set screw to raise the idle can work (like on your fox III).

Since the car has a 4R trans, it might have been tuned for the WR gearset. If so, one might want to change the commanded idle. This works very well.

Good luck bud.

ram360 · Jul 17, 2008

HISSIN50 said:
You're smart to check for leaks.

The autos often tend to idle low. Some folks have had luck running the bleed screw out (any more than ~1.75 turns from seated creates a hanging idle in my experience). If more is needed, using the set screw to raise the idle can work (like on your fox III).

Since the car has a 4R trans, it might have been tuned for the WR gearset. If so, one might want to change the commanded idle. This works very well.

Good luck bud.

hey, thanks hissin....yes the trans is a wide ratio. Prob going to sound stupid here but what is a bleed screw? Is that somewhere on the iac itself? These SN cars are new territory for me. thanks

y22kc · Jul 17, 2008

ram360 said:
hey, thanks hissin....yes the trans is a wide ratio. Prob going to sound stupid here but what is a bleed screw? Is that somewhere on the iac itself? These SN cars are new territory for me. thanks

The bleed screw is on the throttle body in front of the IAC. It is located under a rubber cover. Takes an allen wrench for adjustment.

HISSIN50 · Jul 17, 2008

y22kc has ya covered.

Also, picture 2 in this link shows the dust boot (it's just above the sticker on the TB. The cover is kind of a dirty white color and tough to see).

ram360 · Jul 17, 2008

thanks guys will see if I can't get this sorted out.

ram360 · Jul 20, 2008

HISSIN50 said:
y22kc has ya covered.

Also, picture 2 in this link shows the dust boot (it's just above the sticker on the TB. The cover is kind of a dirty white color and tough to see).

I tried backing out the bleeder screw and it still stalls ( I have an aftermarket tb so mine was a slotted screw and not an allen head. Bought a new IAC but haven't installed it since once I break the seal on the bag I can't return it so I def want to make sure it's the problem.

You mentioned change the command idle? what is that? Car idles great around 750 rpm or so throttle response is great too.

HISSIN50 · Jul 20, 2008

The commanded idle is what the EEC wants the car to idle at. Like on your fox, it's 652 RPM (hot, unloaded idle). As you know, some foxes idle much better with more idle. The 5N95's are almost exactly the same spec. To change the commanded idle, you have to get inside the EEC however (chip, Tweecer, etc).

If this car doesnt even have a decent cold idle (it should flash to 1000 RPM or higher upon starting up after sitting overnight), then I'd really be thinking IAC. FWIW, as far as aftermarket IAC's go, Borg Warner's version seems to work very well for most folks. Pep Boys sells them. Other IAC's have been hit or miss.

Good luck bud.

ram360 · Jul 20, 2008

HISSIN50 said:
The commanded idle is what the EEC wants the car to idle at. Like on your fox, it's 652 RPM (hot, unloaded idle). As you know, some foxes idle much better with more idle. The 5N95's are almost exactly the same spec. To change the commanded idle, you have to get inside the EEC however (chip, Tweecer, etc).

If this car doesnt even have a decent cold idle (it should flash to 1000 RPM or higher upon starting up after sitting overnight), then I'd really be thinking IAC. FWIW, as far as aftermarket IAC's go, Borg Warner's version seems to work very well for most folks. Pep Boys sells them. Other IAC's have been hit or miss.

Good luck bud.

the car has an SCT 5 way chip. The guy that dyno tuned the car was not that proficient w/ obd 1 cars. So you think it's more of a dyno tune issue??? Basically when the car is cold in the morning i need to feather the gas for about a min then it idles fine....if I don't it stalls. I cannot get the car to idle w/o the IAC plugged in cold, hot doesn't matter If it's running and I unplug the IAC, it immediately stalls...Not sure if that means the IAC is working and that my tune off or what..

that being said...

I was going to let the car cool again...and close the bleed screw all the way....open the idle screw a good way so it idles at maybe 1500 and start the car cold w/ the IAC unplugged and hopefully it will stay running w/ the idle being that high. Then I was going to back it off as much as I could w/o it stalling on me. Then use the bleed screw to fine tune it? Not really sure if this makes sense or will solve anything but I really have no clue.

HISSIN50 · Jul 20, 2008

The way I used to tweak the AODE idle before Wes chipped me was to leave the bleed screw at 1.5 turns from seated (any more created a slow return to idle). Then I'd just use the stop screw, like you plan to do. All my fine tuning was done with the stop screw. This worked ok for me because the IAC can raise the idle but once you go over the commanded idle (like I did, and you're trying to do), it can shut the IAC off but the idle should not go lower. I probably ran the stop screw in 4 turns from where it was when I bought the car (who knows where it'd been previously adjusted however).

I mark the bleed screw head and the throttle stop screw with a scribe and marker and take notes of all adjustments so I don't lose track of where I am. I keep a running tab of adjustments in the front cover of the repair manual.

For a comparison, when I had my hot unloaded idle at 800 with the idle stop screw, my cold idle flashed to 1500 upon cold start up.

Having a tune/chip and not knowing the specs creates a lot of variables. See if you can get a copy of what was done with the chip. I have the B.E. files that Wes created, for instance.

Can you view Pids (you need a scanner, like an AutoXray 5000)? If so, you can see the duty cycle of the IAC. This helps one to see if it works.

The biggest thing we can see right now is that the cold idle isnt significantly higher than the hot idle. If the ECT is working properly, the cold idle should obviously be higher. Does the idle increase if you turn on the AC or a huge electrical load? It should.

What I'd do: Get it to idle nice and high (750-850 RPM - whatever you want) with the idle stop screw. Now see how the cold idle does. If it idles low, and you dont have load compensation for the AC (etc), then it very well could be that the IAC is bad. If the car idled fine after the chip but before it recently went screwy, then one could assume that the tune didnt hose with the IAC function too badly (because it had a decent idle with the chip in place before).

Good luck.

gcomfx.com · Jul 22, 2008

Have you pulled the codes to make sure everything is on the up and up mechanically?

ram360 · Jul 25, 2008

HISSIN50 said:
The way I used to tweak the AODE idle before Wes chipped me was to leave the bleed screw at 1.5 turns from seated (any more created a slow return to idle). Then I'd just use the stop screw, like you plan to do. All my fine tuning was done with the stop screw. This worked ok for me because the IAC can raise the idle but once you go over the commanded idle (like I did, and you're trying to do), it can shut the IAC off but the idle should not go lower. I probably ran the stop screw in 4 turns from where it was when I bought the car (who knows where it'd been previously adjusted however).

I mark the bleed screw head and the throttle stop screw with a scribe and marker and take notes of all adjustments so I don't lose track of where I am. I keep a running tab of adjustments in the front cover of the repair manual.

For a comparison, when I had my hot unloaded idle at 800 with the idle stop screw, my cold idle flashed to 1500 upon cold start up.

Having a tune/chip and not knowing the specs creates a lot of variables. See if you can get a copy of what was done with the chip. I have the B.E. files that Wes created, for instance.

Can you view Pids (you need a scanner, like an AutoXray 5000)? If so, you can see the duty cycle of the IAC. This helps one to see if it works.

The biggest thing we can see right now is that the cold idle isnt significantly higher than the hot idle. If the ECT is working properly, the cold idle should obviously be higher. Does the idle increase if you turn on the AC or a huge electrical load? It should.

What I'd do: Get it to idle nice and high (750-850 RPM - whatever you want) with the idle stop screw. Now see how the cold idle does. If it idles low, and you dont have load compensation for the AC (etc), then it very well could be that the IAC is bad. If the car idled fine after the chip but before it recently went screwy, then one could assume that the tune didnt hose with the IAC function too badly (because it had a decent idle with the chip in place before).

Good luck.

I got the car to idle w/o the iac plugged in when it's cool. Car has no A/C. Even when I put on an electrical load the rpms do not increase or change at all for that matter. My cold Idle still does not vary from my hot idle. I put on a new Borg warner IAC but still not working. I have a disc w/ my sct tunes on it but cannot view them b/c they are in some sort of weird format. I cannot view pids either. Since my rpms do not vary from cold to hot are you saying it's a bad ECT? Also I did check vacuum seems to be pulling around around 10" hg at idle.

ram360 · Jul 25, 2008

gcomfx.com said:
Have you pulled the codes to make sure everything is on the up and up mechanically?

haven't pulled the codes. Can autozone scan OBD I systems? Is there some way to pull the codes w/ a test light. I used to do it on my fox body but dunno if the 94 has the same capabilities.

HISSIN50 · Jul 25, 2008

You can pull the codes the same way you did on your fox (the test connector is on the passenger side however).

The 10" hg of vac at idle screams vacuum leak, unless you have some big cam in the car.

With the new IAC, you would have to undo your idle reset. Because it idles without an IAC while cold, the EEC might be telling the IAC to shut off because the RPMs are so high. If you have the hot idle at 650-700 RPM, then the IAC should allow easy starting and an idle around 1000-1200 RPM initially, quickly dropping to ~800 after 20 seconds or so.

Right now there are just too many variables (no code info, possible vac leak and the idle set and IAC being up in the air).

ram360 · Sep 13, 2008

HISSIN50 said:
You can pull the codes the same way you did on your fox (the test connector is on the passenger side however).

The 10" hg of vac at idle screams vacuum leak, unless you have some big cam in the car.

With the new IAC, you would have to undo your idle reset. Because it idles without an IAC while cold, the EEC might be telling the IAC to shut off because the RPMs are so high. If you have the hot idle at 650-700 RPM, then the IAC should allow easy starting and an idle around 1000-1200 RPM initially, quickly dropping to ~800 after 20 seconds or so.

Right now there are just too many variables (no code info, possible vac leak and the idle set and IAC being up in the air).

Car has an FTI cam running just over .600" lift. I reset the idle and replaced the torque converter on the car. Car now idles cold w/o giving it gas, shifts in gear w/o stalling too! Adjusting this idle helped a great deal. Problem solved. thanks hissin

drakesdad · Sep 13, 2008

Just another example of why JT is not allowed to leave.....

Road_Runna · Oct 4, 2008

I know that ram360 has probably solved his problem, but couldn't that problem (slow engaging into reverse and drive) also be caused by using a higher stall torque converter?

SVTF150 · Jun 10, 2015

I hope someone can help. I know this is a old post. So what was the out come? the torque converter? I have the same issue I put in a Boss Hog 2200-2800 stall converter and it died when shifting into drive or reverse. PLEASE HELP

toyman · Jun 10, 2015

I don't think it's a converter issue. Pull codes and check for an air leak.

SVTF150 · Jun 11, 2015

Kevin at Karl's East Coast Speed Shop it could be the Torque converter being to tight. Thanks for your reply back. I will start checking for leas. any one else have any comments or ideas

Auto Stalls when put into Drive or Reverse

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