1999 Vortec 454 Running rough and drivning me nuts

[montess85]

My 1999 GMC ccsb is running pretty rough. I have already done plugs, wire, cap, and rotor. I have also done the FPR. The previous owner said the injectors were done but im not entirely sure they were. They looked a bit rusty when I had the intake of to do the regulator. He also told me he did the Fuel pump. Again not sure he actually did. I checked the Fuel pressure after I did the rugulator and it was at 51-52 psi with the KOEO. Running it was bouncing all over the place. Spikes to 60 when you give it the gas. Any Ideas?

 

[montess85]

It idles at like 550 and the truck shakes. Misses and stumble when you give it gas

 

[montess85]

No Ideas?

 

[JollyGreen]

Have you pulled the plugs since changing them? What do they look like? Fuel pressure with the key off should be higher than 60 psi. Try clamping the return line and doing the same thing, pressure should be above 75 psi. Getting any codes?

Sent from the Green Mile

 

[montess85]

I got my hands on a scanner. Have 3 codes. P1122,p0122,p0102.

 

[montess85]

Also it has had a new fuel pump and filter in it. But the needle bounces on the gas guage now.

 

[Mangonesailor]

I got my hands on a scanner. Have 3 codes. P1122,p0122,p0102.

These codes come up as TPS and MAF issues. Everything plugged in nice and snug? Missing ground on the T-stat housing?

 

[montess85]

Is that where the ground is? Ill check.

 

[454cid]

Unplug the MAF. The truck will run without it, but could run poorly of getting wrong signals.

 

[montess85]

The truck stalls when I unplug the MAF. Also have a P0135 cide now.