Ok, 99 V10 2500 QCSB 4x4 AT. Has 123,000 miles on it. Bought it super cheap, running rough. Fuel gauge didn't work and fuel pressure was low. Replaced fuel pump, fuel pressure is good, gauge still doesn't work (not the main issue). I've replaced Cam sensor, crank sensor, intake gasket, pulled all injectors, cleaned rails and replaced all O-rings. New plugs, wires and coil packs. Pulled and cleaned TB, replaced IAC, TPS. Replaced both cats with a new exhaust (2 1/2 dual into dual cats, y-ed into 3 inch in/ 2 1/2 out flowmaster super 40). New O2 sensors. Truck still runs rough at an idle, slight backfire out of exhaust at idle as well. Truck runs ok at lower RPM's when truck is cool, gets worse as truck warms up. Also bogs out hard under heavy throttle and has very little power... I'm thinking replace injectors but as a full time student that's kind of a big investment, so I'm just making sure I've covered my bases before pulling the trigger! Any ideas?

Thanks!

 

You've got a good start.

I'd be doing a compression check first.

Next, what brand O2 sensor did you go with? NTK or Denso are the only two that work on these trucks.

Secondly, did you reset the PCM when you replaced the O2 sensor? If not, do so.

 

Try replacing coolant temp sensor. Sounds like its not giving the right reading for when your truck is warmed up and dumping fuel. I had a similar symptom when mine disconnected while driving.

 

Agree with the compression check. if that comes out ok, try running it with the front O2 sensor(s?) disconnected..... see if it runs any better.

 

Only has 2 O2 sensors... Both are OEM bosch parts, about 2 weeks old. Runs the exact same without them. Forgot to mention has a subtle miss that is very pronounced when truck shifts to OD from 50-60 MPH. Whole truck shakes and is undrivable, but only in OD. If I lock out OD it doesn't shake, still has no power though. I guess I'll run compression. It's gonna be a few days before I have time.

 

If you're running Bosch and it runs the same without them, you have a problem with your O2 sensors. lol

What spark plugs did you put in? Copper or platinum?

 

Sounds like a miss-fire, is the check engine light on, if not still check and see if the trucks has any stored codes.

 

Thought the V10 all have four O2 sensors?

 

My 96 only has 2 upstream, no downstream.

+1....

Full time student and you have to pay for parts AND fuel for your 10???
I feel your pain.

 

Ok sorry it's been so long. I'm hitting a wall with this truck. Ditched the cats, new NGK O2 sensors (bosch ones had about 12,000 miles on them and the truck thew a DTC about 10 days ago). Took dual exhaust Y-ed into single, flowmaster muffler and out. Truck ran better, but not great for a few days, and now is getting worse. Took it camping last weekend, pulling a 7% grade, gross at 7200#, truck couldn't maintain 50 mph to save its life. Last few days it's taken to stumbling at an idle when in drive and intermittently will die. If I put it in neutral it will idle but as soon as I put it back into drive to take off it sputters and bogs out for a few seconds then catches and takes off like a bat out of hell. I got a freaking ticket the other night because it cleared up as I was making a right turn with it pinned on campus and lit em up....

I have concerns with a transmission, but I don't think it answers all the issues. I'm starting to lean towards replacing injectors... Thoughts?