TBI guys - engine help, video

[Element]

Thought setting the timing right fixed the problem, but only to a point. At light throttle, around 1500rpm, the truck starts running really rough - almost like it's missing on a cylinder or two. However, I just changed all the plugs (NGKs to Delcos), and the old plugs looked fine. All the plug wires are on snug, and the truck runs fine just cruising down the road at around 2000rpm, and idles fine. However, if I'm just creeping and giving it very light throttle, it does this:

http://www.youtube.com/watch?v=qoPukS_fG2I

About 18 seconds is when you can really hear it.

I'm, again, out of ideas.

 

[slyguy_22]

did you replace any sensors? your idle control sensor on the dist? map sensor? vacuum leaks? what made you decide you had to time it? need some more info on what all you did to this point

 

[Element]

New EGR, TPS, plugs, wires, cap, rotor, and ignition module. I reset the timing because the previous owner didn't properly tighten the bolt on the retaining clamp, and the distributor was loose enough that a mouse farting could make it spin. Turned out to be about 25* BTDC, instead of 0*.

Prior to fixing the timing, if I was cruising at light idle and let off the gas, the truck would just die - no stumbling, gurgling, nothing, just like I pulled the key out of the ignition. After resetting the timing, the truck idles much better and has a lot more power. I put a new set of plugs in a few months prior to fixing the timing, so I thought it could have fouled the plugs out, hence the plug change tonight.

I've tried the starter spray to check for vacuum leaks, and didn't find any. Haven't done anything with the idle control sensor on the distributor, although it idles fine, it's just at about the throttle one would use to drive through a crowded parking lot that it has issues.

New fuel filter, new alternator, new battery, new IAC, and new air filter, too.

 

[slyguy_22]

huh got me. did you/ or have access to a compression tester? how bout did you check each spark plug wire to make sure there was a good spark? Those tbi setups are so touchy it seems.

 

[Element]

Don't have access to a compression tester. What's weird to me is it's only a specific rpm range, and a specific amount of throttle, that causes the problem. Thing is, that rpm range and throttle application is important when driving around down

 

[HarryH3]

Are you sure that the plug wires are connected in the proper firing order? Just having 2 switched will make some strange stuff happen.

 

[Element]

Yeah, I had that happen when I switched caps, and accidentally crossed the wires up. They're all in the correct order now, although I'll double-check in the morning.