I need to preface this by saying I do NOT think the issue is related to a burnt TFI or anything in the distributor. The car fires up IMMEDIATELY on the first crank, every time.
The car has recently developed an issue. I have not changed anything with the car prior to this issue developing.
The issue im having is as follows:
From cold, the car will start and idle just fine for approximately 3-5 minutes, and then it will just shut off. It will NOT stumble, search or sputter. It just shuts off. Once it’s got a little heat in the motor, it won’t run for more than 10-20 seconds before it will shut off on its own. But it will fire back up immediately every time.
Fuel pressure is 35ish, 40 without the vacuum line. The car will rev up just fine and doesn’t make any noises that suggest a vacuum leak or anything. No other signs of a problem.
If I keep my foot in the gas, I can keep it running indefinitely.
I’m guessing it’s a sensor or something that once the car goes into closed loop, it triggers and tells the car to shut off. But I can’t figure out what it is.
Right around 2001 or 02 I had a similar issue. Car would start running very poorly until I pulled over, shut it down, then restarted it.
It seemed random and there were no codes, but I finally realized it was water temp related.
Swapped in an ECT and it went away.
Right around 2001 or 02 I had a similar issue. Car would start running very poorly until I pulled over, shut it down, then restarted it.
It seemed random and there were no codes, but I finally realized it was water temp related.
Swapped in an ECT and it went away.
I need to preface this by saying I do NOT think the issue is related to a burnt TFI or anything in the distributor. The car fires up IMMEDIATELY on the first crank, every time.
The car has recently developed an issue. I have not changed anything with the car prior to this issue developing.
The issue im having is as follows:
From cold, the car will start and idle just fine for approximately 3-5 minutes, and then it will just shut off. It will NOT stumble, search or sputter. It just shuts off. Once it’s got a little heat in the motor, it won’t run for more than 10-20 seconds before it will shut off on its own. But it will fire back up immediately every time.
Fuel pressure is 35ish, 40 without the vacuum line. The car will rev up just fine and doesn’t make any noises that suggest a vacuum leak or anything. No other signs of a problem.
If I keep my foot in the gas, I can keep it running indefinitely.
I’m guessing it’s a sensor or something that once the car goes into closed loop, it triggers and tells the car to shut off. But I can’t figure out what it is.
I don’t know if it’s “missing” anything per se, but I’m guessing from the way you worded it that it’s an air intake/idle set issue? So does this point to the IAC?
So what do you think is happening and how do I fix it lol
Come on man I’m just trying to learn. This isn’t a class at university lol I’m just asking for help fixing an issue. My other car is also undriveable because the alternator died and I’m also working on fixing that. So I am in a tough spot and if I can get this fixed it would make my life a lot easier, and the lives of those who depend on me.
Based on the fact that it only exhibits symptoms at idle, I THINK it’s not getting enough air at idle, which leads me to believe it’s the idle air control valve. Based on the similarity in how it cuts out is much like the way it cuts out when the AC is on and I’m coming to a stop, it would make sense that this is the issue. So I’m guessing I need to clean or replace the IAC. Beyond that, based on the fact that it only does this once the car has some temperature in it, my guess would be bad feedback from a sensor once it goes into closed loop.
I am still unsure because it doesn’t idle low, idles perfectly (for a cammed engine) until it just dies. If it was just not getting enough air at idle, I’d expect it to stumble and sputter before dying. Maybe with the cam it doesn’t even have enough vacuum to do that?
It would start and run cold because of the fuel trims in the open loop cycle. Either that, or it’s on the verge of failing completely, and somewhere in the system there’s a part that expands just enough to exacerbate the issue to where it starts stalling.
I plan on starting it up when cold and unplugging the IAC to see if the car dies. If it keeps running and potentially doesn’t stall (despite probably exhibiting some surging) I’ll know it’s the IAC
Im kind of at a dead end. I could test the TPS and the MAF the same way? I don’t know man. I know the basics but I don’t have a clue as far as electrical stuff
I went outside and tried to crank it. It made crunching/clicking sounds almost like a dead battery but not quite, and wouldn’t crank. I adjusted the battery cable terminal and was eventually able to get it to start. (I have video of the noise it made).
I tried disconnecting the IAC. CEL came on, but the car would idle and did the same thing it’s been doing (dying after a few minutes).
I tried disconnecting the MAF. Same exact thing.
I tried disconnecting the TPS. Same exact thing.
I tried disconnecting the other sensor that’s in the cold air intake tube between the MAF and the TB. Same exact thing.
When I first reconnected the unknown sensor and started it with everything in place, it cranked for about 4-5 seconds before it would fire.
Observing the idle closely, it seems to sputter for just one rotation before it dies. It doesn’t struggle at a low idle, it just drops extremely quickly and dies. But prior to that, it idles at a normal RPM.
I also tried a few more times to start it and let it run with everything intact. A couple times it would fire and then IMMEDIATELY die.
My theory is that the IAC is physically stuck or clogged, and needs to be replaced or cleaned.
Honestly, it doesn’t keep running for long so I had to run around and disconnect it. It eventually stalled soon thereafter (maybe a few seconds), but not immediately.
I didn’t notice much of a change in the idle at all, it’s hard to tell with the cam it has. I did also restart it with it disconnected and no difference to how it acted otherwise.
What are you even talking about? Can you show me where I said it doesn’t run cold? Where are you getting this from?
I’m not the one who installed my ****ing HCI. Honestly man what is your deal? This is what happens when people treat newcomers like **** and then wonder why the hobby is dying
From cold, the car will start and idle just fine for approximately 3-5 minutes, and then it will just shut off. It will NOT stumble, search or sputter. It just shuts off. Once it’s got a little heat in the motor, it won’t run for more than 10-20 seconds before it will shut off on its own. But it will fire back up immediately every time.
Dont be mad that you didn’t specify. Why would it be unreasonable to test it in the condition where it actually has the issue?Aren’t base idle resets done with the engine warm?
So I went out just now and started the car up, and immediately disconnected the IAC. The idle dropped to about 500 RPM. The car barely stayed alive but did continue to idle for a bit. I did happen to notice that the fuel pressure, which was at 33-35 PSI before, was now hovering closer to 37 PSI. Not sure if that’s related or not.
My best guess as to what’s happening is that the idle is set too low via the set screw, and the IAC is held or stuck wide open. This allows it to idle just fine while in open loop, but as soon as it goes into closed loop, the IAC has no further to open and the car shuts off.
My other theory is that the IAC is just clogged or stuck in a partially closed position where it can’t open any further, with the same result. This would make more sense since the problem appeared after the car had been driving fine for a while. The IAC could have deteriorated or have had time to get gummed up.
So maybe if I adjust the idle via the set screw with the IAC disconnected, or if I perform a base idle reset and replace the IAC with a fresh one, that might solve it. But I’m really not sure.
Not sure. I haven’t changed anything on the car. I do have a PCV line that goes back into the throttle body. I checked the line, it’s newer hardware and isn’t cracking or anything. The clamps are still secure
Does it have a tune? If so do you know who it is tuned by? If the ecu thinks it's getting hot and has a decipha tune (even his free base tune has it) it may be shutting off due to over heat protection. Overheat protection allows the car to run for about 15 seconds before dying again.
Does it have a tune? If so do you know who it is tuned by? If the ecu thinks it's getting hot and has a decipha tune it may be shutting off due to over heat protection. Overheat protection allows the car to run for about 15 seconds before dying again.
I do not believe it has a tune, and no aftermarket chip or anything. That would make sense, but how would this develop suddenly and how would I fix it? Would the ECT be involved in sending a bad signal that the car is too hot?
Something changed. I suppose you can do your re-set of the idle procedure and see it if sticks. It may help to diagnose the issue, it will also satisfy our curiosity.
I did try disconnecting the battery and letting it drain down and I also verified that the timing is set properly (14 degrees base timing) but I don’t know if it would make a difference as far as the battery disconnect.
I really would like to diagnose the issue but it seems as though I’m at a dead end. I also had my mechanic friend do a once-over and make sure everything looks good visually, and he couldn’t find anything. He’s been a Ford tech for 30 years and he’s done quite a few foxbody builds over the years so I dunno. He didn’t do any in-depth stuff though.
I was thinking you could crank the throttle stop screw a set amount (so you can undo it if doesn't do what you like) to get it to idle without IAC, then plug IAC in (obviously cycle key to re-learn TPS zero position.)
This is a very dumb question, but which is the throttle stop screw and which way do I turn it? I just don’t want to start haphazardly turning screws
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