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Car just die at idle

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Good morning, hopefully someone can help me.

My car will die at idle once it's hot. I have to wait like 5-10min before it will restart again. Otherwise it will just crank.

It only started doing that last week. I will come to a stop and the car just die, no splutter. Before that I had 2 HPDE in the past 2 months with no problems.
The strange thing is I have no code at all.

Idle I believe is set at 700rpm.
I've emailed my tuner for suggestions too.
When the car is running, it's running great. No stange noise or behavior.

A friend suggested I could have a bad PCM.
Any other suggestions?
Thanks
 
I have had the same thing happen a couple of times while sitting at a light but it started right back up. Like you said no sputtering or any indication it was going to die. I have over 60k on the car and it has not happened in a while now but it is a daily driver.
 

302 Hi Pro

Boss 302 - Racing Legend to Modern Muscle Car
2,009
441
Southeast
I see you mentioned "My Tuner" so what mods have you done that require a special tune?

I'd hold off on the PCM recommendation until you perform more testing. The interesting thing here is this only happens when hot then then required up to 10 minutes cool down to restart.

Have you performed any fuel system mods? How long does it run before the stall condition begins and once the stall condition begins will it continue to happen every time you let the car idle?

A mod list might help us out here.

Thanks,
302 Hi Pro
 
Tuner (AED) also mentioned checking the intake system.

The mods concerning the engine are :
-Kooks long tube no cats. 2 years in the car
-Deleted PCV. Replaced with Peterson breather can. PCV check valve has been removed too. 3 years in the car
-Deleted EVAP system. 2 years in the car
-Stock air intake. Brand new motorcraft air filter.
-Stock fuel line
-Deleted "sound tube".
-Plugs have been changed last year. Motorcraft too
All the line that have been removed from the intake/manifold has been caped and not showing any cracks.

This morning after the first stall, I drove 5-6 min, stopped at a red light and then idle for a minute and stalled.
My friend towed me back to my shop (15min) and the car started right back.

I'll try to datalog the car and hopefully can catch it on file when it stall.
 
No codes? I'm an old 5.0 pushrod/dist guy so checking for spark was easy but not sure how you could do it with COP but that's what I would check out first. You said it runs fine so that kinda rules out a fuel pressure issue I would think.
 

Grant 302

basic and well known psychic
When we delete the PCV system, there is a small loss of idle air source. Does AED know you have the breather system on?

I'd also try cleaning the TB just in case.
 

302 Hi Pro

Boss 302 - Racing Legend to Modern Muscle Car
2,009
441
Southeast
I would be surprised if this was an intake hose or intake leak related issue. I'm leaning toward the fuel system. This doesn't seem to make sense to me because the stall happens only when hot. Then it restarts when cooled off.

Once the stall condition happens, I would be checking the fuel pump operation, (it's easiest to check). If fuel pump is ok then look into the ignition system to see if you have spark when the stall condition occurs. It reminds me of the old modules and resister bar overheat, no spark conditions we used to see on some cars.

What was the mileage? Sorry if I missed that as I only have iPhone acceess right now

All the best and good luck with your repairs.

2HP
 
Thanks for the answers.

I've about 16500mi on the car. It's mostly a track toy now but I do drive it to work and car show from time to time when it's nice outside.

I've checked CAI and intake, no leak to be seen.

AED knows about my setup but I'm sure it's not the tune because it's been running fine for quite some time with that setup without any problems.
I'll reload the street tune instead the race tune just in case.

I haven't checked the TB yet. Will check that next.

Some of my friends have been saying it could be vapor lock but I have been running the car on the track with way higher temperature than street driving.

The no code display is driving me crazy because most of the possibilities people are telling me should trigger a code
 

302 Hi Pro

Boss 302 - Racing Legend to Modern Muscle Car
2,009
441
Southeast
I guess vapor lock would be fuel that boils in a hot fuel line in the engine compartment?

Leaning away from this due to SB ran this car hard prior to this without vapor lock issues. So it just seems to me if vapor lock is the cause, then something must have changed to allow this condition to happen.

What ever is causing this, I hope the SB finds the cause soon.
302 Hi Pro
 

302 Hi Pro

Boss 302 - Racing Legend to Modern Muscle Car
2,009
441
Southeast
It just seems to me that a vapor lock condition would have shown up earlier with his current setup. Also, IIRC he has run the Boss in hotter weather conditions without issue. Would not a vapor lock condition have other symptoms as well such as a poor running condition just prior to the no idle, no restart condition? I would think so, but first perhaps we should define a "Vapor Lock" condition. I suspect some of us may have some differences in its description. Maybe?

It very may be a fuel supply issue but this can checked when the no start condition is present. Of course having the ability to data log the events leading up to the no idle/no start condition would be most helpful.

With that said, how would a vapor lock condition occur, and how would you check for it? I'm asking in hope that I can learn.

Thanks in advance for your reply,
2HP
 
I don't think it's vapor lock. Most of what I've found on that issue appears mostly in carbureted engine. Very rare on fuel injected engine.
I'm with 302 Hi Pro on this, a fuel issue would make the car sputter before it dies.
Also how can you check vapor lock?
The car doesn't have a fuel pressure sensor.

I went for a few test this weekend.
Saturady I started the car and let it idle for 10min and then took it around the block, did a few WOT to the redline and came back.
The car died after idling for 1 minute. Stupid of me I already stopped datalogging.
I redid the same test drive 3-4 time and the car wouldn't die again.

Today I did the same test and after the first test drive the car also die after 1 minute of idle. I did caught it on the datalog.
I'll email the file to the tuner tomorrow. Hopefully he can find something wrong.
I did that test drive again for 2-3 time and the car wouldn't die a second time.
Then drove it home with plenty of red light and it never dies

If anybody want the datalog file, PM me your email and I will send it to you.
 

Grant 302

basic and well known psychic
When I first saw vapor lock mentioned, I doubted that would be the problem. But several factors could contribute to making that possible. Fuel pump going bad, E10 or bad gas, removal of the insulators, sitting in traffic, oil to air cooler, hot day and certainly other factors I haven't thought of. Or any combination thereof. The need to wait as few as 10-15 minutes for re-start does not rule out vapor lock IMO. I just wouldn't dismiss it as impossible yet.

Might be possible to see the issue in a datalog when the stall happens. Fuel pressure and correct temp readings would be the first things I'd look at.

302 Hi Pro said:
I guess vapor lock would be fuel that boils in a hot fuel line in the engine compartment?
Essentially, but not limited to. Anywhere in the fuel system technically. I didn't see any prior confusion of what constitutes vapor lock.

Leaning away from this due to SB ran this car hard prior to this without vapor lock issues. So it just seems to me if vapor lock is the cause, then something must have changed to allow this condition to happen.

I don't recall ever letting the car idle when on track. ;) So I don't see the comparison there. I usually make use of the cool down lap.



Anyway...considering the removal of the TB bypass air from the PCV delete, the TB does have to 'work more' to control the idle. Some other small change can make it fail to do so. Used to see that all the time on cars with IAC valve, Since the 3Vs, the TB handles that function.
 
I measured the fuel rail at 155F with an IR gun when the car died today.

From what I've read, fuel can boil anywhere from 100F to 400F.

I still have a mix of racegas and 93 in the tank from my last track day. It's about 50/50 mix.
 

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