Engine dies when when I hit the brake?? - Toyota 4Runner Forum

zwalker16 · 01-25-2020, 12:14 AM

Just got my engine installed and notice my engine will die when I hit and hold the brake pedal down. The dash lights dim also the headlights. What is going on?

patkelly4370 · 01-25-2020, 01:51 AM

Does it die in neutral too?
I have a Dodge Magnum that would die at stops unless in neutral.
A computer code was not unlocking the torque converter.

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brillo_76 · 01-25-2020, 09:38 AM

Quote:

Originally Posted by zwalker16

Just got my engine installed and notice my engine will die when I hit and hold the brake pedal down. The dash lights dim also the headlights. What is going on?

Does this happen to be an automatic? If so do the test for your Torque converter as that's a very good sign that it's bad.

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zwalker16 · 01-25-2020, 12:16 PM

Quote:

Originally Posted by brillo_76

Does this happen to be an automatic? If so do the test for your Torque converter as that's a very good sign that it's bad.

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What would make a converter go bad? I just installed this engine and really want to make sure it's not a vacuum or electric issue before I rear it apart again.

patkelly4370 · 01-25-2020, 12:58 PM

In my case the dealer had just done a bunch of engine work. The computer code occurred on my way home from picking it up. It didn't have that issue when I brought it in.
Five minutes and they cleared the computer glitch and all has been well since.
Granted, this was on a Dodge. I have no idea if Toyota has the torque converter electronically lock up when in gear. Just tossing out a possibility. That's why I asked if it dies in park and/or neutral, if automatic transmission.

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zwalker16 · 01-25-2020, 01:01 PM

Quote:

Originally Posted by patkelly4370

In my case the dealer had just done a bunch of engine work. The computer code occurred on my way home from picking it up. It didn't have that issue when I brought it in.
Five minutes and they cleared the computer glitch and all has been well since.
Granted, this was on a Dodge. I have no idea if Toyota has the torque converter electronically lock up when in gear. Just tossing out a possibility. That's why I asked if it dies in park and/or neutral, if automatic transmission.

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My issue is when I'm in park so the torque converter isn't the issue. I'm thinking it vacuum

brillo_76 · 01-25-2020, 01:50 PM

Quote:

Originally Posted by zwalker16

My issue is when I'm in park so the torque converter isn't the issue. I'm thinking it vacuum

TC can go bad. However, if you just changed the engine messed with valve covers etc. Quite Possible a bad vacuum leak. As that will still at idle too.

The FSM has a test for the TC if you need to go that route.

Mostly when the TC start going bad it takes alot more rpms to get moving.

I have one with a bad TC its noisy as well.

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brillo_76 · 01-25-2020, 02:01 PM

I missed the line I just installed the engine.

Why TC go bad?

The have bearings in them that can fail. People overheat their transmission fluid that warps the blades. People dont install them properly when changing an engine. The lockout mechanism stays locked thus making a 1:1 ratio fixed. Etc.

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brillo_76 · 01-25-2020, 02:06 PM

Quote:

Originally Posted by brillo_76

I missed the line I just installed the engine.

Why TC go bad?

The have bearings in them that can fail. People overheat their transmission fluid that warps the blades. People dont install them properly when changing an engine / transmission. The lockout mechanism stays locked thus making a 1:1 ratio fixed. Etc.

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Dieselchessy · 01-25-2020, 02:18 PM

Sounds electrical to me. Why else would the dash lights dim.

Guessing you have a brake light wire shorted (would expect it to blow a fuse), or don’t have all the grounds landed properly. Or something else is shorted.

Wouldn’t expect a TC or vacuum leak to cause dash lights to dim unless your battery is crap.

For grounds there is one from the back of the passenger side head to the fire wall.
One from neg terminal to fender, and neg terminal to engine block by driver side motor mount.
Then from the harness at the diagnostic port to the intake manifold drivers side.
Given it cranks to start, I’d expect the engine block one to be landed. Check the other 3.

brillo_76 · 01-25-2020, 09:10 PM

If the idle is low enough. The lights will dim. As they barely charge at idle at it is. If the vehicle has a vaccuum assisted brake booster and the vaccuum leaks are bad enough. I could see the engine stulling out.

How does this engine idle?? As a tall tale sign of a vaccuum leak on the intake is a very rough idle.

If you run around a cold engine with wd40 /brake clear etc. Your engine will speed up when you hit the vaccuum leak.

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Dieselchessy · 01-26-2020, 11:04 PM

That’s easy enough to test. Disconnect the booster vacuum line and plug it.
Then try the brakes again and see what happens.

Id expect a vacuum leak big enough to kill the engine to be whistling.

It seems the usual thing is to forget to connect the vacuum line to the IAC or worse yet swap it with a coolant line.

brillo_76 · 01-27-2020, 09:26 PM

Quote:

Originally Posted by Dieselchessy

That’s easy enough to test. Disconnect the booster vacuum line and plug it.

Then try the brakes again and see what happens.

Id expect a vacuum leak big enough to kill the engine to be whistling.

It seems the usual thing is to forget to connect the vacuum line to the IAC or worse yet swap it with a coolant line.

Not always a whistle though. If its Super smooth idle, I wouldn't suspect a vaccuum leak. Mostly the idles a very rough when a vacuum leak are occurring. As any air entering the intake that's not measured causes issues.

I guess the brake booster could have failed and that sure would cause major vacuum leak but if this was the case. You should hear that leak.

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