Slight miss but 6 mpg!!? Need help

[Fless]

Looks like it's been running a little rich. Besides the suggestions that @wjburken had, have you checked the fuel pressure, key on - engine off, and with it running?

EDIT: can you graph B1S1 to see how much it's moving? Has the MAF been cleaned lately?

 

[CaptainAmerica1]

How old are the plugs? How bout the wires?

 

[CaptainAmerica1]

Air pressure in the tires? New air filter lately?

 

[Chetty mo]

Looks like it's been running a little rich. Besides the suggestions that @wjburken had, have you checked the fuel pressure, key on - engine off, and with it running?

EDIT: can you graph B1S1 to see how much it's moving? Has the MAF been cleaned lately?

Yes cleaned Maf. Ordered new one. Yes that o2 goes from .1 to .9

 

[Chetty mo]

Yes cleaned Maf. Ordered new one. Yes that o2 goes from .1 to .9

Fuel pressure is at 48 when at idle. 58 when off then turn key to on position

 

[davidavidd]

I imagine you already did it but: new spark plugs, wires and coils?

 

[Chetty mo]

How old are the plugs? How bout the wires?

They were on it when we got it about 4 years ago. Might be time to upgrade.

 

[wjburken]

What caused you to install the new throttle body and throttle position sensor? Anything particular or were you just pulling the trigger on the parts cannon? Not throwing stones, but it’s always good to know what, if anything, drive previous decisions.

 

[Tonyv__]

Read if you dare.

It doesn’t get good until the bottom of page 9. I hope this isn’t your issue but it was for me. Wiped out lifter and camshaft. I tried to diagnose everything before I tore into the engine. I also had a slight miss only at idle and accelerating from idle

SOLVED: Another misfire chasing threads (2008 express van)

Details 2008 Chevy express 3500 cargo van 6.0 58k miles. 8k running hours. No service history So after last weeks fun with the wife’s MB. (I think it’s resolved). my work van started having a rough idle. Code reader says P0307 misfire cylinder 7 confirmed. So I went and changed out the...

www.tahoeyukonforum.com

 

[Chetty mo]

What caused you to install the new throttle body and throttle position sensor? Anything particular or were you just pulling the trigger on the parts cannon? Not throwing stones, but it’s always good to know what, if anything, drive previous decisions.

My scanner is showing in red some values for the throttle position sensor. Position A and B. And absolute throttle position at 5.8% at idle.