Stalling when let go of brake pedal. Need help ASAP

[Mysterio]

My car is throwing a code 54, and it won't start or run if the brake pedal is not pushed in. If I push in the brake it will fire right up fine, then the second I let go of the brake pedal it instantly dies.
The battery had died because I hadn't driven it in a few months. So I charged it, started it up and let it run for about 15 minutes, completely fine. No problems. Shut it off, removed charger, closed hood. Got back in to start it and had the problem. So it just came outa no where.


I looked up 54 and it's something about dyst.pickup.something or something like that.

I figured with it stalling when I let go of the brake it would be vacuum related but I traced all the lines and they looked fine, and they were all re-done less than 6 months ago.

Is the code 54 and the stalling when I let go of the brake related? If so wtf is it!


Also I put a new cap, rotor and coil on it back in September of 06 when I bought the car.
New wires on it like 6 months ago.
New plugs about the same time
New HEP about 6-8 months ago as well.

So all those things are relatively new.

[mcsvt]

What are the car specs? Year? Model?

[Mysterio]

Sorry.

1987 Shelby Charger converted to T2.

[GLHSKEN]

Was it a mopar HEP or aftermarket... BIG difference

[Shelbydaytona91]

Maybe the brake booster tee has a leak? Try plugging the line(s) going to it and see if it makes a difference.

[Mysterio]

Was it a mopar HEP or aftermarket... BIG difference

Mopar HEP from TU.


I'll try blocking the brake booster line tomorrow. Would a vacuum leak from the brake booster cause the car to immedietly die like that when I let go of the brake pedal? It just INSTANTLY dies.


ALSO I am getting a code 23 for the charge air sensor. After doing the T2 conversion I didn't have a port to plug the charge air sensor into so it is not connected. But other than making the car run very rich it hasn't caused any problems as of yet. I have plans to tap a spot for it I just haven't yet. I can't imagine that would be related to this problem though since I've had that code thrown for quite some time now and the car has driven fine all this time.

[GLHSKEN]

Even if you don't have the port, Plug the sensor in and mount it in the valley between the intake and head. Let it hang there

[Mysterio]

Even if you don't have the port, Plug the sensor in and mount it in the valley between the intake and head. Let it hang there

I have the sensor sitting between the head and intake where the fuel rail is. Plugged in as well.

[glhturbo1985]

I don't think I can help much. what I can do is tell you something small that happened to my car for future reference. I was missing the cap on the T fitting that comes out of the brake booster on my 85 GLHT that I converted to TII also. It was actually sucking a small amount of air though the missing cap... but oddly enough when the cap was missing, the car was actualy idling about 100 rpm faster than when I actually plugged it up with the correct cap ( after trial and error with a valve stem cap while at a show in Brady Run Park.

[Mysterio]

Ok I went out and reset the computer and the car started up. I did find a vacuum leak at the brake booster that caused the car to run rough. After about 10 minutes of it running kinda rough it stalled and is now throwing code 54 again.

I pulled the codes and now I'm also getting code 22 for coolant temp sensor. Hooray.

[Mysterio]

I went and got a new battery because my battery was completely dead and I figured that might be throwing things electrically out of wack because it was so low on power.

The car started up fine and ran perfect for about 10 minutes after I reset the computer. Then it just randomly died. I started it back up (completely fine) where it ran for about 5 minutes. Went pretty sporattic going from 1500 rpm to 1000 rpm back and forth a couple of times, settled down then 15 seconds later power loss light came on and it died. Code 54 back. Brake pedal required to start it back up.

I'm going to jump the brake switch behind the brake pedal and see if the car will start when that is pressed but the brake pedal isnt' actually pressed. That way I can narrow down if it truely is something electrical, or a combination of electrical and vacuum.

I also fixed the vacuum leak that was on the brake booster line and replaced a few vacuum caps that looked pretty beat.

THis car is starting to piss me off.

[Mysterio]

Also, I don't know if this has any relevance to the situation. But when the brake pedal is NOT pressed and I crank the motor over. The tach shows 0 rpm and doesn't increase. The second I push the pedal in the rpm's increase and then it fires up. I don't know if that has any relevance to the HEP code and shines any light on anything that anyone can help with.

[3nglenn]

Have you checked all your ground wires, especially the one that goes to the fuel rail?

[Mysterio]

I followed a flow chart about no start related to dyst.sinc.pickup and everything was within specs.

I also tried the method of tapping the distributor with a hammer when it was idling and the car didn't stumble or stall at all. Just stayed fine.

I don't even have to reset the computer for the car to run I found out. If I let it sit for about 30 minutes to an hour after getting the code 54 and it stalling and not running without the brake. then come back and try it it will fire right up fine without requiring the brake.

I decided to pull the fuse for the brake lights to see if it was electrically related to the brakes and I was still getting the code after the car ran for about 10 minutes with the fuse pulled and no power going to/from the brake lights.

I am so absolutely clueless as to what is going on and it is pissing me off like no other. PLEASE someone shed some insight onto this. NOBODY has ever had this problem before?

[Mysterio]

Looked like I made a mistake reading teh flow chart and one of the specs wasn't correct. So I went and picke up a new HEP, and cap/rotor just for good measure and the car has been running for the past 30 minutes without a single problem.

Assuming all is fixed thanks for the help to everyone that chimed in!

[mcsvt]

I've been watching this as it seemed like a really odd problem... surprised it was the HEP... I hope it did fix it though

[Mysterio]

I've been watching this as it seemed like a really odd problem... surprised it was the HEP... I hope it did fix it though

Took it out and drove around for about 30 minutes without a problem. I have no idea how the HEP could possibly cause all those random problems. The funny thing also, is that I replaced the HEP with a mopar HEP around 8 months ago (6 of which the car has been sitting because my license was suspended). So the thing went bad after VERY minimal use!

[looneytuner]

did you put dielectric grease on the last one and this one. Could have been just enough corrosion to cause problems.