Work I've done within the last year:

New distributor
New dist. cap, rotor, plugs, wires
Removed cat. converter and installed straight pipe

Every time I've done one of these repairs it ran great for a month or so and then it's back to the engine miss on acceleration. It also randomly doesn't turn over when starting. Not sure if it's related. Probably not. I'll probably check ground and wiring before throwing another starter at it.

Any suggestions? Wife wants to get rid of it but it's in really good condition other than this misfire. I'm going to check the codes tomorrow.

 

First off have u used ac delco ignition parts??? This is critical with these motors!!!!!!! I would suggest u do a fuel pressure leak down! And report back with your numbers....as far as the no start or not turning over at times check battery cables for breaks, corrosion , or just plain loose connections....might I also suggest u possibly do a search on the ignition switch here? This is a very well known problem on these trks......all sorts of crazy things can happen when u have a failing ignition switch!!!! I personally wouldn't give up just yet!!! And PLEASE DO NOT just throw another starter at it, hoping to solve on going problem!!!!

 

This is the code and live data I got from the vehicle if it helps.

P0174. System too lean bank 2

Live data

Fuel sys 2. CL
Calc load. 2.7
ECT. 188
Stft b1 -0.7 to -1.5
Ltft b1. 0
Stft b2 0 to -3.1
Ltft b2. -0.7
MAP. 10
Eng rpm. 592-650
Spark adv. 17
IAT. 122
MAF. .685
tPS. 0
Air status off
02S B1 S1 (V). .045 to .935
Stft b1 s1 (%) 0 to -2.3
02S B1 S2 (V) .110 to .685
02S B2 S1(V) .065 to .875
Stft b1 s2 (%) NA
Stft b2 s1 (%) -.7 to -2.3
PTO status. On

 

When the distributor was replaced was the cam retard checked and set to ±2°?

 

Is that MAF reading g/s? It should be reading around 450-500 g/s at idle
Your fuel trims are within acceptable ranges. According to the data both banks are running slightly rich and the computer is shortening the injector time.
Have you done a fuel pressure and leak down test?
Check for an exhaust leak on the passenger side exhaust manifold.

 

No, the research I did before installing it didn't mention anything about that. It ran a lot better for a couple of months after replacing it. Sounds like something I'd have have done.

 

The MAF reading is in lb/min. I'll check for an exhaust leak on passenger side and do a fuel pressure test tomorrow. I replaced the fuel pump a year ago too but knowing the quality of fuel pumps lately that doesn't mean much.

 

I did a fuel pressure test and got 60 psi for a split second and then it dropped to 57 or 58 psi. After shutting off the key it held the pressure. I couldn't find an exhaust leak.

 

I unplugged the MAF and it runs better than it has in a long time. I'll see if it lasts.