This is a pretty hard problem for me to troubleshoot. I don't have a lot of experience but I can google symptoms and swap out parts / follow directions, but this one has me stumped.

It happened out of the blue, after driving my truck a bit hard without giving it time to warm up (I'm not sure that has anything to do with this).

It idles very rough with very little power - it can rev high but there just isn't power to accelerate. I can get to speed but it takes forever. It dies sometimes when I'm shifting or slowing to turn a corner and I push the clutch in, and has trouble starting sometimes. When I'm pushing it hard, I smell what smells like 2 stroke exhaust (weed eater).

What I've tried, so far:

• No codes on ECU, no CEL - I have a chinese ripoff OBDII reader that can pull codes and reset them when I've had issues in the past, but in this case idling for long periods and driving for short distances doesn't produce new codes. I did notice that the oxygen sensor 2 is showing 0V while I monitor it with my OBDII app (Torque). I don't trust that reading, since I assume a reading like that would trip a code. Am I wrong? Also, do cheap OBDII readers not read all codes?
• Test coil packs - proper resistance between them, and when I pull the spark plug wire off while it's running I see sparks arcing.
• Checked spark plugs - all 8 (& wires) replaced 3 months ago. I pulled a few and they all looked pretty good with proper gaps. A little sooty and 1 had a bit of oil
• Checked voltage to MAF - gets good battery voltage and idling the sensor sends about 1.5V and revving it gets up to 2.25V or so. It was tricky getting the reading because i didn't have good probes and had to grab the throttle cable while holding the probes. When I pull the MAF cables out while it's running, the idle doesn't change much if at all - does that mean it's a bad MAF (as this video claims? youtube.com/watch?v=b4U_CGkS8ag) - I couldn't pull off the MAF to check if it's dirty/clean it because I don't have the security torx head
• Cleaned IAC - I pulled it off and cleaned it with cleaner, but it wasn't particularly dirty. The grommet/pad was brittle and disintegrated, so when I put it back on it's now just metal on metal with no discernible change in idle
• New PCV hose - This was a long shot, but the old one was soft and falling apart, so I put a new one on. No change
• Incompetent vacuum testing - I sprayed around some carb cleaner listening for a change in idle, but I don't know where all the vacuum lines are.
• Fuel Pressure Check - I checked the fuel pressure with a rented gauge, and got 64 PSI while idling, which is within spec according to my Haynes manual
• Seafoam - I put in a healthy amount of seafoam just in case it was something easy like that. No change

Do you see something obvious that I missed? I would like to eliminate vacuum leak better but I'm not experienced with that, nor equipped I think (I don't have a propane torch or a reliable smoke source at the moment).

I would like to take it in to a self-work garage tomorrow but I don't trust that it will get me there. Thanks in advance for some insight.

Brad

 

I just found a vacuum tube that is broken, a gray line that comes from the cabin. I suppose that might have something to do with this.. I'm heading over to get a replacement. I tried pinching off the ends of the broken tube and I expected to hear the truck idle better, but it didn't - perhaps I misunderstand how the vacuum system works.

 

I sold the sumvabitch - I just wish I could have my week back.

 

bumping an OLD post. But, any advice for someone dealing with similar issues?