Locked tune...

[ARC]

I had a custom tune done to my truck while out of town. Now the computer of the truck is locked, its running lean 15.4:1 and some sometimes 17:1. there is a dead spots a 5000rmp and misses a bit till 5400rpm then it wakes up and sets you back in the seat. run slightly rough at idle (950rpm). Its a gmc yukon Denali with a 6.2l vvt comp cam, biggest they make. Ported heads and kooks headers. Comp cams valves springs and lifters and push rods. Any one have any ideas or do i need to get another computer. P.S. when accellerating heavily its is at 12.8:1

[joecar]

I moved your post to the GenIV section...

[GMPX]

Can't you take it back to get the tune revised?

[ARC]

Yes and I will but I am 1200miles away visiting my sick father. Any ways I pIcked up another computer and put the old tune back in. It's a 2l per 100 km harder on fuel but at least I don't have to worry about it running lean. I did make changes to it for the 1 7/8 kooks headers and off road cat less y pipes. What is the safe limit for air fuel ratio? His tune runs at 15.1:1 normally on the highway till I do wot then it hits 12.3:1. I got nervous in the city stuck in traffic it leaned out while sitting there idling to 17:4.

[hog]

I question the accuracy of any wideband O2 sensor at idle. I talked with Ed Wright about this same subject.

You could have run high octane fuel til your retune. I wouldnt worry much unless you were under load.

peace
Hog

[ARC]

15:1 normal on the highway?

[EagleMark]

15.1 AFR, if accurate, would be safe in lean cruise. Can't see how that could be accurate Closed Loop? Even if it were non ethanol...

Set up your wide band properly for Lambda.