I just rebuilt my 22re a few weeks ago. It has started to to do something weird when i hit the brakes now. after it warms up if i hold down the brake pedal it will rev and then almost shut off for a second and rev back up for a second, shut down for a second and on and on etc... Its only when i hit the brakes and it is idleing(coasting in neutral while braking or sitting still in any gear with the clutch in). I thought maybe the battery or alternator needed to be replaced but i checked it right when i got home from work today and the battery was charged at 12.7v. Does anyone have any idea what could cause this? thanks

 

how high is the idle, if it's too high hitting the brakes will trip a fuel cut to help slow the truck down.

 

X2

The idel might be too high or the TPS could be going out. Oh and how is the coolant level, low coolant will also cause a surging idle.

 

X2 on the above:
- http://www.4crawler.com/4x4/TLCA_Tru...ech.04.09.html

 

hmm, i dont have a tach so unfortunatly i had to set the idle to what sounded and felt good after the rebuild. i checked the tps a week or 2 ago and that was good. i just checked the coolant level and it was low so hopefully that was the problem. off couse i took my vented radiator cap off to put in a/f and the lever broke off sending the spring and everything else flying, so i guess i will have to wait till tomorrow to get a new cap and test it. thanks for the help.

 

From what it sounds like I think it is a vacume issue. The idle changes with vacume pressure, and tha brake booster also works off vacume pressue. I suspect that there is a vacume leak in the brake booster, or somewhere in the vacume system. How well do your brakes work? Or do you have to push the peddle fairly hard when braking?

 

I suspect a booster leak.

With the truck idling, hold the brakes and listen carefully for a hissing sound. If you hear one, change the booster. If not do the next test.

With the engine OFF, pump the brakes until they are rock hard and HOLD pedal pressure. Crank the engine and see if the pedal falls to normal. If the pedal does not move, change the booster.

If it passes these tests, the booster is fine.

 

Oh, yea, I forgot you just rebuilt the engine. You also need to test the actual vac at the booster. Anything below 16 will be trouble in most cases (really depends on your elevation)

Low vac could indicate a few things: blockage in the exhaust system (plugged catalytic converter, crushed pipe, bad muffler, etc.), or a problem in the engine itself (manifold vacuum leak, bad valve, head gasket, etc.).

 

check the TPS setting

 

it was a bad fuel injector ground