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4.3 Liter V-6 Idles rough when in gear, runs fine on highway.
Can you check fuel trims at idle and under load?
If fuel trim is high at low speed and load, look for a vacuum leak.
If fuel trim is high at high speed and loads, look for fuel volumn problem or restriction.
If fuel trim is high at all speeds and loads look for pcm input fault, maybe a maf sensor problem?
If fuel trim is negative low speed and load, look for fuel pressure regulator or injector leak. If fuel trim is negative at all speeds and loads check ect and iac.
If you have the spider fuel system, that system is noted for problems. key on engine off, 60--66 psi fuel pressure.
on Mar 06, 2017
SERIOUS ENGINE MISFIRE, SPARK JUMPING FROM ROTTER INTO THE SCREWS HOLDING THE ROTTER. WHAT DO YOU SUGGEST?
I had a 96 tahoe 5.7 that gave me hell with the Distributor sparking to the wrong terminal. These Vortec engines use computer controlled timing, but still use a rotating distributor to determine which cylinder the coil's spark goes to. Twisting the distributor does not set the timing like it did for older engines, instead it just sets where the rotor is pointing relative to the cap when the computer decides to fire the coil. Aligning the rotor to the cap's electrodes at the instant of spark is called having the cap "indexed" to the rotor.
In my case the distributor was a few degrees off after an intake gasket change. The engine ran fine for a while, but was always sparking off to one side of the electrodes in in the cap due to mis-alignment. After a while, that side of each electrode became corroded, and rather spark around to the far side of the electrode, it was actually a shorter path to the clean side of the next electrode over. This resulted in stumbling and misfires.
I rotated the distributor a few degrees toward the corroded side and changed the cap and rotor. The next cap and rotor went about 10k further before acting up. I rotated towards the corroded side again, and the same cap and rotor have been running ever since.
Scribe a mark on your distributor and intake for reference and twist the distributor a few degrees towards the corroded side of the electrodes in the cap as the cap sits on the distributor. Don't forget if you take the cap off and flip it upside down, then you need to reverse the direction you twist. You want to twist the distributor cap towards the corroded side with the cap sitting in place on the distributor. This will help move the cap's electrodes closer to the center of the spark-range (as the computer jockeys the timing around, where the rotor electrode points at the instant of spark moves).
on Feb 14, 2017
'99 silverado 4x4,new trans,no gears.
I don't see you did anything wrong per your description.
With the engine off, check the level of the transmission oil, replace the dipstick, start the truck and recheck the fluid level, level should drop. This will indicate the front pump is working.
Next, with truck running, put transmission into any gear, then return to park position. Do you hear any ratcheting noise.
Let me know.
on May 13, 2016
Abs oight is on
there is a vehicle speed sensor on the transmission and one on the rearend...have those two replaced and that should solve your problem
on Apr 19, 2016
I have a 2002 silverado
Hi Martin Im AL the owner of Big As Auto Repair.
Martin, the charging system has what you call a fusible link that runs from the positive battery terminal all the way to the alternator. Somewhere along that fusible link it has either corrosion built up are has been damaged and came apart. usually its a large green wire but is different on some vehicles. If you need more help go to my auto-repair-help-website here: http://www.bigasautorepair.com/
on Apr 15, 2016
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