I’ve got a 1994 ford mustang gt it idles fine right around 750-800 but when I drive it I have pretty bad rev hang tried a restrictor plate (small side toward the motor) but it only made it run rougher, any advice on what to do?
yellow94gtPOS
Tried a base idle reset? That puts the throttle plate and throttle air flow back to where it's supposed to be so it's set like factory... Might help.
Dude? Did you ever pull the ECU and inspect it and or send it in to be inspected or repaired?
After all the burning a tune into ECU talk?
That all still has me wondering what moron/ hack mechanic told you he did that.
After all the burning a tune into ECU talk?
That all still has me wondering what moron/ hack mechanic told you he did that.
The idle is not adjustable, it’s electronically controlled. (By the tune)
any attempt to change the idle by mechanical means is partially why you are experiencing “rev hang”
vacuum leaks can also contribute to a hanging idle but it’s most likely because you tried to adjust it.
any attempt to change the idle by mechanical means is partially why you are experiencing “rev hang”
vacuum leaks can also contribute to a hanging idle but it’s most likely because you tried to adjust it.
It might be hanging because it’s idling at 800 rpm. I think stock is closer to 650. If the screw is touching stop on the TB you can lower the idle some “mechanically” by backing the screw off. Set the idle as low as it’ll go and still stay running. If you have an aftermarket cam it might not idle well lower than it is. If the screw is touching the stop that means someone set the idle “mechanically.”
TP sensor needs to be at a certain voltage for the ECU to know that the throttle blade is closed
1. Have you pulled error codes? This should always be your first step.
2. Do the revs drop after a few moments, or do they hang until your car stops (i.e. zero mph)?
The idle speed controller, on the other side of the throttle body from the tps, is usually the culprit.
2. Do the revs drop after a few moments, or do they hang until your car stops (i.e. zero mph)?
The idle speed controller, on the other side of the throttle body from the tps, is usually the culprit.
Everybody and their brother on corral has been trying to help this member for months in multiple threads and posts.
311 and 314 are thermactor codes. Are they still hooked up or are they deleted? If they are hooked up is there vacuum lines still attached to them? You will need to remove the passenger side inner fender liner to inspect them and get a visual on them and see if wiring harness and vacuum tube's are hooked up to and from them.
Try to find a oem ford ccrm. I've never used an autozone unit. If you find a ford one that is in need of repair they can be fixed. The cabin fan blowing only at max speed is probably the fan switch on the hvac controls above stereo. Easy to repair and replace. Remove dash vent trim bezel remove 4 screws on front side and one on backside holding switch in place.
Code 616 does not exist.
Code 616 does not exist.
The CCRM is a box full of relays. Don’t relays either work or they don’t? I don’t think it’s going to be the CCRM.
I don’t think I have followed any other posts relating to this vehicle.
However, since it seems this car was “chipped”, what processor does it have in it - the 94/95 GT or the 94/95 Cobra? Or is this one of those “A9L” converted cars?
Is it running stocker 19lb injectors w/ the stocker MAF? Or is it running aftermarket injectors (what cal) and aftermarket MAF (again what cal)?
The info Dwain gave way above is spot on for the 94-95’s - even though physically the parts look the same as the 87-93 5.0’s - the way they were “tuned” via the stock processor isn’t the same as the prior 87-93’s…. The 94-95 has always been the bastard PCM and playing around with throttle body and TPS isn’t the same as doing it on the 87-93’s…. It won’t produce the same results on the 94/95’s, and I’m pretty sure this has been discussed/proven many times over the years on here.
Seems like the emissions system was tinkered with as well…. Usually in some instances prior owners will pull off emissions components and in doing so they break, crack or do not cap the vac lines… thus creating leaks and other issues downstream that will affect idle and drivability. Definitely trace back any lines and if they are behind black conduit pull the conduit and look for breaks and correct any broken lines.
Does it retain stock ignition or does it have an aftermarket “box” on it - and if so, is it MSD? If yes, yank it and trash it, go back to stock ignition - it’s reliable well up to 500HP as is…
Is the dizzy still stock or aftermarket?
If the PCM was opened and there is corrosion, that’s not good. As mentioned it’s possible the PCM needs to be refurbished or replaced. Can you post any images of what you saw in the opened PCM? Some of the members on here have a keen eye for pointing out bad components on the board.
What does the car do when there is a load on it such as when you turn on the A/C, does idle drop to almost a stall, does it stall (or does this car not have functional A/C)?
Have the spark plug wires been ohm spec’s to see if they are still good? Wires can look great physically but over time the core is what deteriorates. Also what about plugs, have they been pulled and “read”?
Since I have not followed previous posts - maybe some of the above has been gone through already….
One more tip:
It’s easier to stay in a single thread with a concern when it has not been rectified. This way others can track back to see what was recommended or what was already done as far as diagnosis and testing. When multiple threads are started on the same vehicle and the initial problem still exists, it’s hard for some of us to know what others have recommended or what has or has not worked.
However, since it seems this car was “chipped”, what processor does it have in it - the 94/95 GT or the 94/95 Cobra? Or is this one of those “A9L” converted cars?
Is it running stocker 19lb injectors w/ the stocker MAF? Or is it running aftermarket injectors (what cal) and aftermarket MAF (again what cal)?
The info Dwain gave way above is spot on for the 94-95’s - even though physically the parts look the same as the 87-93 5.0’s - the way they were “tuned” via the stock processor isn’t the same as the prior 87-93’s…. The 94-95 has always been the bastard PCM and playing around with throttle body and TPS isn’t the same as doing it on the 87-93’s…. It won’t produce the same results on the 94/95’s, and I’m pretty sure this has been discussed/proven many times over the years on here.
Seems like the emissions system was tinkered with as well…. Usually in some instances prior owners will pull off emissions components and in doing so they break, crack or do not cap the vac lines… thus creating leaks and other issues downstream that will affect idle and drivability. Definitely trace back any lines and if they are behind black conduit pull the conduit and look for breaks and correct any broken lines.
Does it retain stock ignition or does it have an aftermarket “box” on it - and if so, is it MSD? If yes, yank it and trash it, go back to stock ignition - it’s reliable well up to 500HP as is…
Is the dizzy still stock or aftermarket?
If the PCM was opened and there is corrosion, that’s not good. As mentioned it’s possible the PCM needs to be refurbished or replaced. Can you post any images of what you saw in the opened PCM? Some of the members on here have a keen eye for pointing out bad components on the board.
What does the car do when there is a load on it such as when you turn on the A/C, does idle drop to almost a stall, does it stall (or does this car not have functional A/C)?
Have the spark plug wires been ohm spec’s to see if they are still good? Wires can look great physically but over time the core is what deteriorates. Also what about plugs, have they been pulled and “read”?
Since I have not followed previous posts - maybe some of the above has been gone through already….
One more tip:
It’s easier to stay in a single thread with a concern when it has not been rectified. This way others can track back to see what was recommended or what was already done as far as diagnosis and testing. When multiple threads are started on the same vehicle and the initial problem still exists, it’s hard for some of us to know what others have recommended or what has or has not worked.
Are you sure the cam is stock? It seems like not too many people would put a “chip” in it unless they had some modifications that required a “chip.”
616 isn’t a valid code.
don’t use an actual paperclip, use a short piece of wire with spade connectors on each end, then pull your codes again, but use your phone to record it, then decipher the codes by looking at your video.
it’s easy to lose track or get mixed up trying to decode & write it down on the fly
don’t use an actual paperclip, use a short piece of wire with spade connectors on each end, then pull your codes again, but use your phone to record it, then decipher the codes by looking at your video.
it’s easy to lose track or get mixed up trying to decode & write it down on the fly
So it runs ok now but the revs hang? Did you use a timing “gun” when you set the timing to 12*?
Your going to have to get your own timing light if you don't have one. Mark the balancer yourself at 10 degrees. Then set the timing to 10 degrees.
Need to restart with the basics all over again it sounds like.
I dont like any of the aftermarket distributors for these cars. Should find a stock oem ford distributor and put new motorcraft pip in one of those. I could even help on that if you want.
Is there a ridge inside the throttle body caused by the brass throttle body blade operating and wearing over time? Common problem. That would cause a rev hang and If the throttle body is old and original and worn out. Pull the inlet tube off and shine a flash light in throttle body and open and close the blade a few times and see how it operates see if you can move it closed more by hand after it closes on its own. Clean it real good inside there and around the blade top bottom and even backside, use old tooth brush really scrub it clean. Then look for ridges in aluminum with blade closed.
Need to restart with the basics all over again it sounds like.
I dont like any of the aftermarket distributors for these cars. Should find a stock oem ford distributor and put new motorcraft pip in one of those. I could even help on that if you want.
Is there a ridge inside the throttle body caused by the brass throttle body blade operating and wearing over time? Common problem. That would cause a rev hang and If the throttle body is old and original and worn out. Pull the inlet tube off and shine a flash light in throttle body and open and close the blade a few times and see how it operates see if you can move it closed more by hand after it closes on its own. Clean it real good inside there and around the blade top bottom and even backside, use old tooth brush really scrub it clean. Then look for ridges in aluminum with blade closed.
Did you use dielectric grease on the spark plugs and distributor cap terminals when installing new spark plug wires? They are dry inside of plug wires when new and helps to lube each spark plug end and tip with thin layer of dielectric grease and dist cap terminal ends to assist pushing on the new wires. Then you can hear and feel them click on when pressed in all the way. Also lube coil terminal.
What all does it do again? Does it idle smooth but the revs are slow to come down? Or is it running rough?
This 123 code may be the ECU or in the wiring since you have replaced the TPS a few times. So pull the ECU and send it in for repair. That's about all that's left in the parts cannon hasn't been replaced. I sold a few T4MO ECU in the past but don't have any in stock now.
Misfires are a completely different issue than hanging idle, surging idle and stalling.
If it were me, I would try to find the source of the misfire first. Is it a random cylinder(s) or the same one(s)?
I know you have new parts but that doesn’t mean they are good. I would pull the plugs and inspect them. (Wet, oily, damaged)
Then do a compression test on each cylinder to rule out any mechanical issues.
After getting the misfire fixed, it needs a tune. Cams & Throttle bodies require a tune.
If it were me, I would try to find the source of the misfire first. Is it a random cylinder(s) or the same one(s)?
I know you have new parts but that doesn’t mean they are good. I would pull the plugs and inspect them. (Wet, oily, damaged)
Then do a compression test on each cylinder to rule out any mechanical issues.
After getting the misfire fixed, it needs a tune. Cams & Throttle bodies require a tune.
It's a stock cam and stock throttle body I believe. Shouldn't need a tune. Might need a new throttle body with the issues with throttle stop bolt or set screw.
I agree if it’s idling rough and misfiring then there is more going on than a “rev hang.” A “rev hang” would be caused by something like too much air going through the IAC or TB but since it’s misfiring there’s something else going on. Even if he had it idling over 1k rpm it wouldn’t cause a misfire. Would the base timing being set at 12* cause any issues?
Timing at 12 degrees might cause top end detonation on the '94-'95 car's but doesn't have anything to do with what's going on here.
It only misfires at idle but when I drive its perfect except for the occasional rev hang and bucking but it’ll idle perfect when I come to a stop for a good 10seconds then it will start acting up again but when I pull the grey top hat thing by my intake I’m pretty sure it’s called the pip sensor or something it’ll idle perfect
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