Car dies when coasting in neutral

[MustangGuy23]

So I have been trying to track down what’s been the issue with my car for about 2 weeks, i recently had opg, new clutch, and a new drive shaft installed, that really shouldn’t mess with anything but when I got the car back I turned it on and it was cranking but took like 5 seconds to actually turn on.

I had the shop look at it, they replaced the crank position sensor even though it’s not likely, they then said maybe it’s the fuel pump, which is coming Tuesday, the shop also put some tune file in it that got rid of my catless CEL and they said it ran smooth. This was kind of the weird part, when going home the car shutoff in traffic 3 times when coasting in neutral to a stop, the a/c on would make it worse.

So I ordered a ford performance alternator kit thinking it is the alternator but replacing it only helped a little, it no longer dies when I turn the ac on stopped and at idle. Now I started to think maybe I should get a fuel pump so I bought one and haven’t got it yet.

I’m starting to think it maybe a tune issue but I’m very confused why starting the car takes longer than used to and why it now dies since they put their file in. I’ve also suspected maybe it’s the throttle body going out or a vacuum leak but I’m still very lost.

I will probably go back to the shop to get it figured out, they are a pretty reputable shop but this is just confusing. Any help is greatly appreciated!

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[ray=out]

Did issues start before or after tune?

 

[MustangGuy23]

Did issues start before or after tune?

The car started having issues cranking before they put a tune in, I originally had a lund tune but now they put this tune in it dies with ac on and coasting at idle. This makes me think it might have started with the slow crank and it’s now progressed to dying when coasting.

 

[Fordphanatic]

I would be willing to bet your problem is with your Tune. You need to contact whoever wrote the tune and have them look at it. Thats where I would start at

 

[Schwerin]

What are your full mods? If you were having issues cranking without the tune maybe you should remove the tune and get that sorted first.

 

[DougS550]

So I have been trying to track down what’s been the issue with my car for about 2 weeks, i recently had opg, new clutch, and a new drive shaft installed, that really shouldn’t mess with anything but when I got the car back I turned it on and it was cranking but took like 5 seconds to actually turn on.

I had the shop look at it, they replaced the crank position sensor even though it’s not likely, they then said maybe it’s the fuel pump, which is coming Tuesday, the shop also put some tune file in it that got rid of my catless CEL and they said it ran smooth. This was kind of the weird part, when going home the car shutoff in traffic 3 times when coasting in neutral to a stop, the a/c on would make it worse.

So I ordered a ford performance alternator kit thinking it is the alternator but replacing it only helped a little, it no longer dies when I turn the ac on stopped and at idle. Now I started to think maybe I should get a fuel pump so I bought one and haven’t got it yet.

I’m starting to think it maybe a tune issue but I’m very confused why starting the car takes longer than used to and why it now dies since they put their file in. I’ve also suspected maybe it’s the throttle body going out or a vacuum leak but I’m still very lost.

I will probably go back to the shop to get it figured out, they are a pretty reputable shop but this is just confusing. Any help is greatly appreciated!

Just wondering. Did your problems start before or after the OPG CS upgrade?

 

[MustangGuy23]

Just wondering. Did your problems start before or after the OPG CS upgrade?

It started after the install

 

[MustangGuy23]

What are your full mods? If you were having issues cranking without the tune maybe you should remove the tune and get that sorted first.

I have JLT intake, 2018+ manifold, long tube headers catless, and the opg cs, lpx clutch, and carbon fiber driveshaft

 

[MustangGuy23]

What are your full mods? If you were having issues cranking without the tune maybe you should remove the tune and get that sorted first.

I had a lund tune but once the opg and clutch were put in, the time it took to crank the car took longer, so I had the shop look at it and the guy said the tune was causing it to run rough. Basically he forced a file in it and it removed the CEL for being catless which he said will help it run smoother because the computer is wanting to put more fuel down because there isn’t any cats.

 

[Schwerin]

If it ran just fine with that tune BEFORE the gears and clutch, then the shop did something when working on the car that's causing the issue. Like a vacuum leak, needing a crank relearn, broken or disconnected sensor... something. The tune won't just randomly change unless it's getting a bad reading about something.

 

[Schwerin]

One thing I may recommend would be restoring to Lunds original tune he gave you and give him a call and see what to data log. He may be able to diagnose what's wrong since the shop seemingly can't.

 

[DougS550]

It started after the install

After the OPG CS replacement BUT before you installed your New Tune.? Now in my experience, your issue is associated/created by the reassemble process. Now, out of all of my years i had probably two times (mechanical work on aircraft included) where something unassociated with my work failed. I consider it like the chances of getting struke by lightning. Good luck, for what ever is causing your issue, it's going to take time through process of elimination.

 

[SHOdaddy68]

I had a similar issue with my motor quitting if I put it in neutral and coasted coming off the freeway. There was never any CEL and it always fired right up. I could keep it from quitting if I gave it a little gas while coasting.
What I found was the intake tube where it connected to the throttle body had come loose. It looked fine when I inspected everything but I didn't realize it was loose until I grabbed it and physically checked it. After I put it back on and tightened the clamp, the issue went away.

 

[MustangGuy23]

Ok so I think I solved it, the sound tube was hanging off of the cabin, which presumably was letting in unmetered air, I will say that I did put a new fuel pump in which helped it even more I believe. Only one issue now which is starting the car still struggles, and it sometimes wants to die right after I start it but it usually keeps itself alive. And when the ac is on the idle also struggles so now I’m planning on getting a better tune, still kinda confused on why it’s starting so rough.

 

[GrabberBargeCaptain]

So they "forced a file" in it when the car had a big vacuum leak. Then you fixed the vacuum leak and still have the "forced file" flashed to it? Maybe they changed some parameters based on the vacuum leak and now that the leak is fixed it's all FUBAR and you need to start from step 1. This could also be all exacerbated by you shotgunning a whole bunch of parts into the car without figuring out first what's going on.

Do you have a device that reads the ECU? How do the fuel trims and AFR look when the car is running like crap?

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