I need help...Again. Engine dies in gear.

I used to think it was a tranny/torque converter problem, but now that I have swapped both and I'm still having trouble, I'm losing my mind! I know the engine is is OT, so mods, I understand if you feel you need to close this thread. The engine is a 350 TBI with a TH350.

Here's what it's doing: after I start it up, I put the transmission into gear and it kills the engine. I rode in the truck that the new converter and transmission came out of, so I know they are good. After the engine has warmed up, it doesn't always die, but it sure sounds like it wants to. Also, I have noticed that I cannot open up the throttle without the engine dieing down and backfiring.

I just reset the timing on the engine and replaced the fuel filter. A friend of mine thinks it might be a weak fuel pump (in the tank). I ordered a fuel pressure gauge from speedway, and it of course didn't come in last night as I expected. I'd like to check the pressure before I swap the pump.

Any other ideas? The video should give you a better idea of what's going on. I press the brake at 0:50 to stop the rear end.

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Thanks guys!

 

Did the engine originally have a computer? My O.T. truck does that when the battery is low. Computer loses memory.

 

Yes, and it still does. That's interesting about the low battery. I've had it disconnected for a while and just hooked it up again. How long do you think the engine should run for the computer to relearn?

 

does it also die when you put it in gear while pressing on the brakes?

 

Yes it does.

 

I would double check ALL grounds and take a good look at the distributor.

And Id check for vacuum leaks too.

 

The engine is grounded with 4 gauge to the frame, and the battery is grounded with two 8 gauge wires, so I'm not worried about those. And the distributor was replaced a few months ago.

 

Vacuum leak?

 

I have looked for possible suspects, but can't find anything.

 

It will be in open loop when cold. I would manually increase the idle. It should be able to idle in gear at 700-750 rpm with the brakes on. Have you set the timing?

 

For my truck, it takes about 5 miles for the computer with a low battery to re-learn. However, when I took it to the dealer for a transmission problem, they had disconnected the battery. It took quite a bit longer for the trans to shift properly. That's why, when you have a new battery installed, the installer attaches a small battery to the cables to preserve the computer memory. I would just leave the engine idling for awhile for the computer to re-learn.

 

Did you check the gasket between the TBI and manifold? Theyve been known to leak there.

If so, Id start looking at the map senor including all wiring to and from, and the coil pick up if you havent yet.

 

bad coil?

Happened to me once, same exact symptoms

 

This makes a lot of sense. When I had a friend helping me out the other day, we messed with it for a long time. By the time we gave up, the engine didn't die anymore, it just sounded weak at idle. I guess the computer had relearned by then. Still, there's got to be something else wrong since the engine doesn't like sudden open throttle.

I haven't pulled off the throttle body and the gasket looks ok, so I'm hoping for the best there. I'll recheck the wiring. The new distributor came with a new pickup coil, so that should all be good.

Pickup coil or ignition coil? Pickup is new, but I figured the truck wouldn't even start if the ignition was going bad.

 

Also check and clean the IAC (idle air control) motor passage and make sure the motor itself is still up to par. I have replaced worn out ones and fixed similar symptoms.

 

I worked on a 92 TBI 350 truck that had ZERO balls, wouldnt do over 30mph. Tried to die when put into gear.

Found that the only thing wrong was substantially retarded ignition timing due to timing chain wear. That old farmer about shit himself when I took him for a ride later and buried the speedo going past his place on the testdrive.

 

Chech the condenser. I had that problem and the wire came out of the condenser with the slightest pull. New condenser VOIALA. Other than that chech the one way valve on the booster.

 

I had an OT truck that did that as well and it ruened out that the battery had a dead cell or a cell that was well on its way out. Once the batter finally took a dump I replaced it with a new battery and problems all went away.

That said it could be the throttle position sensor or the whatever sensor of the mulititude of sensors. have you interigated the computer, what is it telling you is wrong?

 

Thanks, I'll look into that too.

I have my timing set at 0 degrees, think that could still be a problem?

Ok, so I'm an idiot... Condenser? For AC? There's no AC on this truck (compressor is there, but not hooked up), and I'm not sure what else a condenser would be referring too. And also, I don't have a one way valve on the booster, sound like a pretty serious problem? Brakes work great, but could that be a source of a vacuum leak?

Yeah, I've been wondering what sensors are acting up. A carb is starting to look good... I haven't checked to see if there is an engine light from the computer (I know there's a wire, just haven't hooked it up). and I don't know if the OBDI system works or not.



Thanks for the responses, you have given me a lot of things to look in to. If I get it figured out, I'll let you know what I find.

 

Just a shot in the dark here, where is the fuel pump grounded?

I worked on a Ford a few years ago, T-Bird IIRC, the fuel pump and brake lights shared the same poor ground, push the brake pedal and the lights took away the fuel pumps ground.

Like I said, a shot in the dark, good luck.

 

My first thought is vacuum leak

 

There is usually a special procedure to set timing on tbi.
There may be a tan wire with a black stripe near the brake booster to unplug then set timing then plug wire back in. When you do it using the correct procedure you wont be fighting the computer to set it.

 

Just went back and listened to the video. Sounds like the timing is retarded long starting time and no power. Try turning the dist counter clockwise about 1/4 inch and try again.

 

The pump is also ground to the frame. It sounds like it's working strong, but I wont know until I get the gauge on there (darn UPS still hasn't shown up!).

That seems to be the running suggestion here. I'm going to have to look more closely into that.

Yeah, I didn't know about that the first time I set it. My friend help me get it right the other day. Turns out I was 20 degrees advanced!

 

Not sure about 350 tbi but had a mustang with a bad mass airflow sensor did the same thing it wouldn't take throttle and tried to quit just off idle.

 

Did you have this problem when the timing was "about 20 degrees advanced"?
By the way if the engine and trans were sourced from the same doner vehicle, then you have a "lock-up 350". That is a lock-up torque converter and if so then putting on brakes with the converter locked will choke the engine. Check all the wiring to the trans. The unlock-lock wire should be wired through the brake light switch.

 

Hooray! More sensors to look for!

Yes, I had the same problem then too. What's odd is, it hasn't always been like this. It gradually got worse. First time it happened was during a trip around the block with a different tranny. It eventually got to the point where it couldn't go into gear at all like it is now. That was when I did the new tranny and converter. This truck is the biggest mutt. The donor for the engine was a 1990 Chevy and the tranny came out of a 1983 Chevy. I don't believe its a locking converter.

 

My thoughts low fuel pressure pump or fuel pressure regulator the dieing when put in gear could be the idle air valve but that doesn't explain the off idle stumble.

 

Sounds like it is time to check fuel pressure, compression then restricted exhaust. You also can check ground wires in the computer harness at the engine. Let us know what you find.

 

I never knew there was such a thing as a "lock-up 350" trans.