What could cause this? New to me bought at a good price but the truck feels down on power, so much so that my brothers ford 460 is pulling better and quicker off the line. Something is definitely off, looked for vacuum leaks to no avail and I’m wondering where else to look. No cel, only abs light but that’s another issue for another day.

Side note, what could be causing this thing to sounds like a diesel at 2500-3000 rpm’s specifically when I let off the gas until it shifts up? I’m assuming valve train noise but it sounds like it could be coming front the left side of the motor?
Thanks for any help

 

If mine holds first or second gear to long, the valvetrain will rattle to beat the band. If it shifts at the proper points, no rattle..... It was pretty bad when I bought it, had to replace TPS, Governor pressure sensor/solenoid, and output speed sensor. That dramatically reduced the problem, but, it isn't gone. I suspect my aftermarket TPS just isn't quite up to snuff. It hasn't gotten any better, or worse, since the repair, so, I just live with it.

Disconnect your front O2 sensors, and go for a drive. Yes, that WILL set some codes. See if it runs any better. If it does, replace the sensors. NTK or Denso sensors only please. Just like every other sensor on the truck, they just don't play nice with non-oem parts.

 

Thanks for the quick reply and that makes sense, I’ll unplug the two upstream sensors and see how it performs. Since mine seems to be the “California emissions” style it has a sensor going into the front of the cat, would that affect air fuel ratio you think?

Ya that’s what mine does too, kind of sounds like our 6.0 power stroke work truck to me so I’ll see if I can get it to quiet down with those things. It’s just kind of annoying more than anything.

I’ll update as soon as I can

 

The sensors before the cat are upstream, they have a dramatic influence on fueling. If you have sensors after the cats, they just monitor the cats, and have very little, if any, effect on fueling.

 

Right that’s what I was thinking but what do you think this one does? It’s right inside the front of the cat, never seen anything like it.

 

On the way home from work I had the upstream sensors unplugged and midrange rpm’s it was falling flat on its face, when I got home I looked and the 2 upstream and 1 downstream have ntk stamped on them and look fairly new. Looks like someone else has been chasing this issue. But the one in the cat is old so I’m curious what effect that one has.

 

The one in the cat should be one of the 'front' O2 sensors..... where are the rest of 'em?

 

Sorry haven’t been able to get to the truck in a it. That’s what’s weird tho, there is a sensor on each bank after the headers but before the cat, those definitely being upstream sensors B1S1, B2S1. Then the pipes combine into the one cat and there is the one in the front of the cat itself B1S2. After that it’s a single pipe that’s what I’d assume the average downstream sensor B1S3. Then there’s is a mystery one I can’t find for the life in me that my scanner picked up called B2S2 which seems to read like a downstream sensor.

I can’t find any info on this setup because correct me if I’m wrong but the “non California” trucks are dual exhaust and dual car right?

anyways I’m going to test all the sensors to do with fuel air ratio and see if I can find out why it’s got such a crazy fuel trim since all o2 sensors (except the one that’s inside the car) have apparently recently been replaced with NTK sensors.

 

That IS a bizarre setup..... Real curious how that whole setup works..... Might try unplugging the sensors one at a time, see what code gets set... That would tell you which sensor the pcm thinks is which.

 

Truck info may help. The V10's came in different configurations. Is your truck a HD? HD's had duel cats like CA. Four 02's should be correct for non CA/HD. Two out of the manifolds, one pre and one after the cat.