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K1500 Bogs and Stalls when taken out of Park or Neutral


AiwaSoundSystem
10-16-2010, 09:43 PM
Howdy all, new to the forums here. I have recently been given a '92 K1500 5.7L 4WD. Here's what's going on.

When started up the idle goes to about 200 rpm and then climbs up to 400-600 after about 10 seconds. When shifted from park or neutral and when the steering wheel is turned the engine bogs down and begins running rough. When in gear and throttle is applied it bogs down even more and threatens to stall or stalls all together. It has absolutely no power at all. Now onto what I've done with it over the past two days.

1. I replaced the TPS with a new one - issue remained.

2. I replaced the IAC valve with a new one - issue remained.

3. I replaced the fuel filter - issue remained.

4. I pressure tested the TBI supply line at the fuel filter and it tested within limits 10-13 psi according to the specs on the testing equipment.

5. Tested both injectors by moving the low end connector onto each injector and starting. High end injector was plugged up and not delivering fuel. Replaced high end injector and retested. Both injectors now working.

Here is where is sit. I haven't dealt with many chevy's but would like to get this one up and running. I am 400 miles away from home and have two days to get this going with limited funds remaining. Questions that I have.

1. How do I test the high end injector to see if it working properly on the high side.

2. When testing the fuel pressure the pressure stayed constant (even under throttle) at approximately 12 psi. Should this have increased when given throttle?

3. What other things should I try?

Thanks in advance for any help you guys can muster.

AiwaSoundSystem
10-17-2010, 11:20 AM
Ok so getting started this morning and going to check:

1. Disconnect EGR and see how it runs

2. Check distributor, cap, plugs and wires and check spark strength.

3. If both of those are good I'm going to throw a FPR at it and see what happens.

4. Also, going to possibly throw a O2 sensor at it and see what happens.

After those things I'll be completely stumped. Will report back in a few hours with my findings. Also, I am not getting any CEL so that is making this that much harder.

AiwaSoundSystem
10-17-2010, 03:58 PM
So I disconnected the EGR and plugged the vacuum line. It seemed to run a little better but still lacking in power.

I then reconnected the EGR and manually depressed the diaphram while idling and it seemed to smooth out the idle.

I was told to check this but I don't know if that means it's good or bad. Does anyone know what these troubleshooting steps mean?

jdmccright
10-18-2010, 09:59 AM
If the EGR is affecting the idle, then it may be part of the problem. But I'd first check for any vacuum leaks and leaks between the TBI body and the intake manifold. Spray some carb cleaner around the base and the vacuum lines...if it stumbles or stalls, then where you sprayed is the leak.

After you've fixed the vac leaks, turn back to the EGR and the vacuum-operated sensor. Check for blockages or build-up.

Finally, and this one's a stretch...pull the vacuum lines from the transfer case and check for transmission fluid. If they're full of fluid you have a leaking transfer case switch, which can be had for $15. Cleaning out all the vac lines and front diff actuator is a PITA though.

Good luck!

AiwaSoundSystem
10-20-2010, 03:56 PM
Ok so this is what I've done and where I'm at:

1. Cut exhaust from between the engine and just before the catalytic converter completely off - issue remained.

2. Replaced FPR - issue remained.

3. Checked spark strength:
a. #1 cylinder had weaker spark and swapped with #3 wire. Weakness followed
the wire. Replaced distributor cap, rotor and plug wires. All wires showing a
weaker spark now. Issue still remains - maybe a coil replacement?

4. Removed #1 cylinder plug wire while vehicle was running and it didn't seem to change anything. While testing plug spark could hear compression in cylinder.

5. Haven't swapped EGR, MAP or O2 sensor yet. Will probably try these at next visit.

6. Will follow Jdmccright's troubleshooting on next visit also as I didn't see your post before I had to leave.

Feel free to add any suggestions as it will be a couple of weeks to a month before my return trip to either fix and drive or tow it back home. I will need all the help I can get on this. If all else fails I'll try the ECU.

Throughout troubleshooting this is what it is doing. It starts fine and hangs out around 200 rpm until warmed up then moves to 600-800rpm. Anytime any demand is made to the vehicle via Power steering, or shifting into any gear but Park and Neutral the engine bogs down and will sometimes stall.

If in neutral or park if you use the throttle the engine will climb in rpm. At the lower rpm range you can hear it hesitate and miss some, but once it gets above 2k rpm it smooths out. It's easier to get it going in gear by being easy on the throttle. Giving it more than 1/4 throttle or so while in gear causes it to bog down even worse and stall some of the time.

Thanks again for any insight and help you guys/gals can offer.

AiwaSoundSystem
10-20-2010, 04:00 PM
One other thing. The #1 plug didn't look as if it had been firing like the other plugs did.

tblake
10-20-2010, 07:44 PM
Have you checked compression just to make sure #1 has enough?

I'd probably focus on the EGR if you don't have any vacuum leaks.

Chevy-SS
10-25-2010, 07:50 AM
I have seen these types of problems caused by:

bad coil or
bad cap or
bad wires


Also, I would check to make sure voltage to coil is sufficient. It could be something as simple as a bad ground or corroded electrical connection.

Good luck.

dusty3
10-28-2010, 08:25 AM
Pull all 8 plugs out of the engine. Screw a compression gauge in each cylinder and turn the engine over 4 complete revolutions, record your findings on each cylinder and post back.

Also, there is a tan wire on the passenger side firewall behind a plastic cover, unplug this wire and see if anything changes.

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