I'm out of ideas, guys. (Truck runs like crap no matter what I do).

[great white]

Lots of shots in the dark going on here.

Not bad ideas, but not exactly troubleshooting either. Kinda jumping from system to system.

Troubleshooting is a bit more...ummm..,,"methodical".

Its been a while since i've twiddled with a gasser and a tbi but i'll give it a shot if you want:

Step 1. Disconnect battery cables and let it sit 15-20 mins to clear the diagnostic memory.

Step 2. Connect battery, strt up and go for a drive after it's warmed up ro operating temp. Ie: 195f. Let it idle a while and then a short drive to get it the rest of the way there.

Step 3. Get the flashout trouble codes by crossing the diagnostic terminals in the aldl connector: http://www.obd-codes.com/faq/read-gm-2-digit-obd-codes-free.php

Report back with what you find.

Once we have a basic idea of what the ecm is seeing, we'll start eliminating systems.

Any other diagnostic processes you've already done would also help so we don't cover the same ground twice. Ie: compression test results, coolant system pressure test, fuel system pressure test and/or gpm, intake vacuum, etc....

A close up pic of the engine/ engine bay from left/right/front/back wouldn't hurt either. Something obvious may jump out at me in a pic that you cant see because youve become too close to the problem.

No shame in it. It happens to me all the time. Ive been looking right at a problem before, a bud comes over and says "whats that?" Then i'm feeling stupid but it's fixed.....lol.

You can remove the air cleaner to give a better view of the components if its not too cold to do so where you are.

My shot in the dark thought is an engine temp sensor, but that's a wild guess at this time and I wouldn't spend money on one just yet if i were you.

Cheers

 

[jdyates]

Lots of shots in the dark going on here.

Not bad ideas, but not exactly troubleshooting either. Kinda jumping from system to system.

Troubleshooting is a bit more...ummm..,,"methodical".

Its been a while since i've twiddled with a gasser and a tbi but i'll give it a shot if you want:

Step 1. Disconnect battery cables and let it sit 15-20 mins to clear the diagnostic memory.

Step 2. Connect battery, strt up and go for a drive after it's warmed up ro operating temp. Ie: 195f. Let it idle a while and then a short drive to get it the rest of the way there.

Step 3. Get the flashout trouble codes by crossing the diagnostic terminals in the aldl connector: http://www.obd-codes.com/faq/read-gm-2-digit-obd-codes-free.php

Report back with what you find.

Once we have a basic idea of what the ecm is seeing, we'll start eliminating systems.

Any other diagnostic processes you've already done would also help so we don't cover the same ground twice. Ie: compression test results, coolant system pressure test, fuel system pressure test and/or gpm, intake vacuum, etc....

A close up pic of the engine/ engine bay from left/right/front/back wouldn't hurt either. Something obvious may jump out at me in a pic that you cant see because youve become too close to the problem.

No shame in it. It happens to me all the time. Ive been looking right at a problem before, a bud comes over and says "whats that?" Then i'm feeling stupid but it's fixed.....lol.

You can remove the air cleaner to give a better view of the components if its not too cold to do so where you are.

My shot in the dark thought is an engine temp sensor, but that's a wild guess at this time and I wouldn't spend money on one just yet if i were you.

Cheers

So far the only "real" tests I've done are a compression test (175 across the board), and I hooked up a Snap-On scanner to it and there were no codes being thrown, and everything in terms of oil pressure, engine temp, TPS, etc. seemed to be running in spec. I'll snap some pictures in a bit.

 

[jdyates]

Here you go, quite a few pics (and yes, VERY dirty engine bay).

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[ChrisAU]

Does unplugging the CTS in the intake manifold make the truck run even worse than it does already?

 

[jdyates]

Does unplugging the CTS in the intake manifold make the truck run even worse than it does already?

Is that the plug right next to the thermostat?

 

[ChrisAU]

Yep. Does your idle change if you unplug it while idling?

 

[jdyates]

Yep. Does your idle change if you unplug it while idling?

Let me go see.

 

[jdyates]

Okay, I unplugged it while the engine was cold, no change in idle. But once it got warmed up, i unplugged it and the idle went up about 100rpm, SES light came on, then when i plugged it back in, it shuddered and dropped about 300 or 400 rpm and SES light turned off.

 

[TylerZ281500]

you map housing is cracked.

 

[jdyates]

you map housing is cracked.

Yeah, I noticed that too. It's not cracked, it's like an indention, i think i tightened the air cleaner housing too much at one point and it put a dent in it. This MAP is good, though, I pulled it off my brother's suburban which was running beautifully.