1992 Bravada idles rough

[mao18]

Hi, I have a Bravada that when it gets to about 150 degrees it idles rough and it almost dies but it catches itself but it only stalled once. It is bringing up that I need to replace the o2 sensor but I have already did that. I have also replaced the ignition control module, IAC valve, pcv valve. I toke it to a shop and they couldn't find anything wrong with it. I was told it could be the MAP sensor. But I have no idea were to move next.

[Gabe25]

First of all we need what size is your motor.

[mao18]

it's got a 4.3 liter. And it is a "W" series. If that matters.

[Gabe25]

Do a fuel pressure test. You should have 60 - 65psi with the key on. Turn the key off and watch to see if the pressure drops for the next few mins. It shouldn't drop below 55psi. Post back your findings.

[mao18]

sorry forgot to mention that we did a fuel pressure test and it was good. I was also told that that there were no vacuum leaks that they could find.

[Gabe25]

OK, if the fuel pressure and the vacuum is all good. When was the last time it had a tune-up. If its been awhile. I'd replace the plug, cap, Wires, and rotor (AC Delco Parts). Let us know what you find.

[mao18]

well I replaced the plug and wires,and cap and rotor and also tried map sensor and throttle body sensor.
Have any other idea?

[Gabe25]

You'll need to do compression test on the cylinders. Record what the pressure reading is for each cylinger and post back your findings. You said tha you did a fuel pressure test and it was all OK. Can you post the reading of the fuel pressure readings as well. I need your pressure readings from when you have the ignition switch on, motor not runing and with the switch off, wait a few mins. and record the pressure dropping.

[mao18]

ok
thanks I'll post what I find as soon as possible.

[Chris Stewart]

What trouble code does it show?

[ericn1300]

Dang, it's getting up to 150 degrees in MI already? I know use guys had no real winter but that's getting bad. Talk about global climate change!

You might just have carbon build up, the 4.3 is notorious for it. How do you drive it? Ever get out on the freeway for a long hot drive or is it just barely getting hot on short trips? Try a good detergent gasoline like Chevron or Texaco with Techlorine in it and take your rig out for a hard, full speed ride. If you don't have those brands around you, you can find Techlorine as a fuel additive at the parts store. I swear by the stuff, my wife's 4.3 was running rough and it cleaned out the carbon and solved the rough idling in less than 2 tanks.

[surfnobc2]

ive heard of that too !!! is there any other easy way

[tempfixit]

surfnobc2 you may want ot check this thread out, it discusses decarbonizing with water.
http://www.automotiveforums.com/vbul...d.php?t=283211