Here we go - live data - key on, not running



For reference with the temps - if I were to guess it was about 60F in the shop...?

Fired the truck up and actually idled pretty okay for a while and then started struggling. The misfires didn't seem as extreme but it wouldn't stay running on its own. I could keep it idling by just resting the weight of my foot on the pedal.





Killed the motor and checked TPS on live data. Foot off pedal and then pedal to the floor:



Didn't get voltage readings at sensors in hopes the live data would be good enough...? Sort of ran out of time - gotta run back into work and fix something for 2nd shift..

Honestly I was starting to wonder if I had leaky injectors... but we'll see! Haha

I don't know why the heads were reworked - I should've asked but didn't. He said at that time they had also removed the pistons honed the cylinders and put new piston/rings in as well... so I sort of just assumed the truck had been beat on (plow truck) and they were rebuilding the engine.

Honestly I didn't know there was supposed to be ground straps on the backs of the heads! I can say with absolute certainty there is not a ground strap on the back of the passenger side head and pretty sure I couldn't see one on the driver's - additionally did see anywhere, where a ground strap would be coming out from behind there to the firewall...

I pulled spark plugs and looks like I'll be buying new ones! Haha!
Passenger side - in order with cylinder 2 being farthest to the left:

Driver side - cyl 1 to the left


I had just had the engine running and they were all soaked with gas...

 

Wow, near the end there it was pulling a TON of fuel.

How long did it idle to only climb 2 degrees F? You can probably switch to F in the settings somewhere....

You may want to check TPS backprobed with analog meter -- you want to see a smooth sweep as you open the throttle slowly. But I'm not sure TPS is your problem here

 

I didn't run it for too long at that point. Maybe a minute or so?
I kept checking live data but noting was changing other than the IAT and IAC values were rising more or less together

Darn, I'll hopefully get to that tomorrow then... I have to run and get the wifes car in to the dealer for regular scheduled maintenance immediately after work and not sure I'll be waiting around for that to get finished. Haha!

 

What kind of plugs are those? Lookin' at 'em, they look to be some variety of rare-earth spark plug? That may be part of the problem..... Get a set of standard copper plugs, brand of your choice, make sure they are gapped properly, see if it runs any better.

I would like to know why throttle position is at 26% at closed throttle. That seems kinda high to me.

 

i was just looking up spark plugs for our V10s and am not finding this particular number from NGK as the recommended ones. They're coming up "BKR6F GP" - not sure what the difference is...

I'll definitely pick up some copper ones tomorrow!

Could the ground strap to the heads be a factor as well? Is there another good/recommended spot to attach a ground to the heads? Based on what it looked like I'm not sure I can get back there and attach something at this point.

 

Recommended by whom???

These trucks are notorious for not liking the rare-earth plugs... mystery misfires and such.... May not solve your problem, but, eliminates them as a potential contributor.

 

Yeah I looked further in to it and when I put in my vehicle information it then said they weren't it. But they came up on the parts website when I used my trucks year model and engine in the search words.. haha!

Wouldnt it be neat if it was a MAP sensor and spark plugs this whole time? Haha! I mean I'd take it - just feel bad we wasted so much time because I didn't know how to properly test the sensors...

 

We all learned something from that one. I never would have guessed the PCM would send 5 volts back down the signal return wire if they were unplugged.....

 

I kinda wondered that, too. I think I've seen 15-18% on some vehicles but 26 does seem high. I wonder what your V10 says?

But that -26 STFT is troubling. It's trying hard to pull fuel for some reason. Maybe inadequate burn from the fancy plugs, but would it be that simple??

 

I don't have a scanner to read data at the moment....... My laptop died, and the software I had with it wasn't very good to begin with.

I wondered about that too.. .but, an incomplete burn would have more oxygen in the exhaust stream, which would make me think the PCM would ADD fuel...... but, my logic, and the PCM logic, do not always agree. It's worth swappin' 'em out to test though.

Edit: Just out of idle curiosity, do your misfire counters work?