BodieA

I have a S10 Blazer mud truck I bought from some hill billys with a 5.3 in it. It has a standalone harness and ECM on it already but I don't know the brand or who tuned it.

It starts and idles fine, but you have to warm it up to get it to even move. As it warms up it runs better and better. When its cold, it just sputters and bogs. I have checked fuel pressure, and I believe it was about 50lbs even under load.

I have taken it to Autozone and had the codes checked on their cheapo tool, but nothing came up... I really don't want to just throw parts at it, but I would think its probably an oxygen sensor or vacuum problem.

Any ideas?

TexasGMC08

Needs to be tuned! Find someone with HP tuners or EFI Live that knows what they are doing.

BodieA

So you don't think it has been tuned for stand alone? I thought it wouldn't even run if it wasn't. Once its warmed up its fine, lots of power. I plan to buy HP Tuners anyway for some upcoming projects. I was just told it was already tuned for standalone, so I was leaning towards a different problem.