Engine Performance problem
1992 Chevy S-10 6 cyl Two Wheel Drive Manual
First of all it has the 4.3 ltr V6 with a throttle body. It will idle fine (sometimes) but will not run smoothly after you try to accelerate. It misses and backfires out the exhaust after releasing the gas, and sometimes backfires out the intake while giving it gas. It has new plugs, wires, distributor cap & rotor. The coil and ignition control module both tested good. When the engine is cold it doesn't misfire, but still doesn't have very much power- any ideas?
Dirty fuel injectors (cleaning the injectors often fixes this).
Bad MAP (manifold absolute pressure) sensor
Bad TPS (throttle position) sensor
Bad or dirty MAF (mass airflow) sensor
Low fuel pressure (leaky fuel pressure regulator or weak fuel pump)
Vacuum leaks (intake manifold, vacuum hoses, throttle body, EGR valve)
Bad gasoline (fuel contaminated with water or too much alcohol)
Sometimes, what feels like a hesitation is actually ignition misfire rather than lean misfire. The causes of ignition misfire may include: Dirty or worn spark plugs
Bad plug wires
Weak ignition coil
Wet plug wires
September, 10, 2009 AT 9:40 PM
We bought a new coil, and ignition control module, and cut off the catalytic converter, which seemed to help a lot. After adjusting the timing, w/o putting it in bypass mode, we were able to get it to run perfect! Better than it ever has, but only for about a half hour. Then it stalled and is running about the same, and is very hard to start. Is this a computer problem, since it ran just fine after we adjusted the timing?
September, 10, 2009 AT 9:44 PM
Check the fuel pressure and get back with the readings so we can continue
September, 12, 2009 AT 6:00 PM
Wouldn't the fuel pressure be fine since we had it running exscellent for a about thirty minutes? When the truck is off, just in accessory mode, the pressure goes all the way to 18psi, then slowly drops off to 3 or 4psi.
September, 12, 2009 AT 6:32 PM
Your fuel pressure should be 60-66psi
September, 12, 2009 AT 8:07 PM
That is even when the engine is off?
September, 12, 2009 AT 8:15 PM
Even if its TBI system you should have 9-13psi unless you're leaking at the injectors or fuel pressure regulator.
September, 14, 2009 AT 8:54 AM
So the Fuel pump should maintain 9-13psi even when it is just in accessory mode? It seams that the only problem is the timing, since it ran excellent for about half hour when the timing was adjusted.
September, 14, 2009 AT 1:18 PM
Well, today we got the truck to idle in bypass mode, and and then shut it off like it said. We then reconnected the " set timing connecter" and disconnected the power to the ICM. Alldata said then said to accelerate quickly and then decelerate to teach the computer to run good. It took a couple tries but WE GOT IT TO RUN GOOD. We didn't have to do anything with the fuel pressure, or with the EGR. Thanks for your help! It is much appreciated!