1990 Suburban (350 TBI) knock problem

[TheApocalyptican]

I've had a pretty consistent problem with my Suburban since I bought it. But it seems to be getting worse. I have a problem with a bogging at lower rpms that is inconsistent. I have finally tracked it down to the timing. The computer is retarding the timing due to knock counts. Knock counts seem kinda high to me in winaldl, but don't know what "normal" is considered to be. According to the datalogs blm's, I have issues at low rpm with running rich. I thought lean is what caused knocks though? I "think" it is actually pinging, and not something else making a similar noise. Problem is, for the most part, whatever is making the noise is very faint, and thus hard to tell what it is.

I have doubts about the EGR valve as when I hooked up a vac source to it, the engine didn't seem to be effected. Thought I checked the map sensor, but am going to test it again. The tps tests as good. Don't know the fuel pressure, but I have a new delco fuel pump, new filter, and rebuilt tbi (including new fpr spring). Almost positive the exhaust isn't restricted at all. Cap, rotor, wires, and oe plugs are all fairly new. O2 sensor is fairly new as well, but only problem might be that it's a bosch.

Tried to give as much info as I could. Ideas?


Mods: I realize you moved this to the "correct" forum, but I posted it purposefully in the 88-98 section due to more people there having TBI's and experience fixing them.