Engine Struggling to Accelerate at WoT

[CrashDriver]

Well, I managed to jerry rig a kind of t-junction setup so I could use the fuel pressure gauge; primed with engine off read about 22 psi, and running/driving was about 25 psi.
These numbers may be skewed because I think somewhere one of my makeshift fittings bottlenecked the flow because the truck really struggled to get up to throttle when I stepped on it, but the pressure seems fine (also as a note I connected it directly before the throttle body).

However, after screwing around with a bunch of different stuff on the truck all evening I finally got to taking the cap off - the posts were all cruddy, so I brushed and sanded them as well as the rotor tip.
Fired it up, and the popping was all gone. So today I'm getting a new set and she seems to be ready to rock and roll.
Do I feel somewhat retarded for not checking it sooner? You bet. Do I feel extremely relieved that it's just that and not something worse? Also affirmative.
I'll post an update when I put the new cap on to completely confirm that the problem is solved.

 

[1998_K1500_Sub]

Don't guess.

…

Connect a scan tool, verify EVERY sensor and computer output. Check the fuel trims, especially when the engine is misbehaving.

^^^ This is still good advice. Check everything and, even if everything is proper, you have assurance.

The odd shifting you noted had me wondering about the TPS.

 

[CrashDriver]

well, I took it for a test

^^^ This is still good advice. Check everything and, even if everything is proper, you have assurance.

The odd shifting you noted had me wondering about the TPS.

Unfortunately I don't have an OBD-I scanner and I won't have time to get one before I have to drive the thing on a 20 hour trip to GA this weekend... That's going to be interesting.

So of course the problem isn't as simple as the cap and rotor. The rythmic popping is gone as far as I can tell in the latest test run, but under heavy throttle as it got almost midway through acceleration and the rpms went high, it did pop a little and then had a couple misfires.
The MPG has also decreased. I dunno...

 

[CrashDriver]

Actually when I jumped the scanner plug I just got two new codes - 35 and 42. It's possible 35 is from yesterday when I was screwing with the vacuum and may have had the filter off and stuff but I also have got it before but it always seems to go away. So ICM and IAC valve are possibly suspect?

 

[Schurkey]

Actually when I jumped the scanner plug I just got two new codes - 35

35 = IAC system

GM Code 35 Idle Air Control Valve - FreeAutoMechanic

Trouble Code 35 is not used in the Turbo cars. If this code appears while a computer is connected to the ALDL connector,

www.freeautomechanic.com

and 42.

42 = EST system

GM Code 42 Electronic Spark Timing or Bypass Fault - FreeAutoMechanic

Trouble Code 42 indicates that there may be a malfunction in the Electronic Spark Timing (EST) system. During cranking, the timing is controlled by the

www.freeautomechanic.com

So ICM and IAC valve are possibly suspect?

Possibly. Download the service manual set for your vehicle from the links in the Sticky section of the Engine forum. Connect a scan tool, follow the diagnostic procedure for each code. Find out.

Or clear them, and see what comes back.

 

[Caman96]

Fuel filter

 

[CrashDriver]

Fuel filter

fuel pressure read good at the throttle body

 

[evilunclegrimace]

22 and 25 PSI on the fuel seems abit on the high side.

 

[CrashDriver]

22 and 25 PSI on the fuel seems abit on the high side.

that's what I was kind of thinking, I'm just not sure how I would reduce it... I assumed if the regulator was bad on the throttle body then it wouldn't hold pressure, but I don't know it's internal mechanics

 

[evilunclegrimace]

that's what I was kind of thinking, I'm just not sure how I would reduce it... I assumed if the regulator was bad on the throttle body then it wouldn't hold pressure, but I don't know it's internal mechanics

Make sure that the return line is not pinched/restricted, make sure that there is not a blockage in the TB it self.