c money

^^ this issue didn't occur while stock.... Pardon my ignorance as I'm a FI noob.

w8nfsnow

Okay probably the tune but did you run it really hard before you put the tune in or were you just cruising around for lots of miles? With the new tune you obviously went out and bagged it and it fell on its face?

w8nfsnow

Actually this happened to my chum with a Livernois tune....he put the 93 tune in his truck with 40,000miles and it started to stutter.

He put in new plugs gapped to 0.030".....problem solved.

Al Kohalic

This happened to me. I was running the tune for months with no issues and then I decided to regap my spark plugs and ended up cracking one. I went ahead and replaced all of the spark plugs and got the shutter/misfire shortly afterwards. I would get the shutter on the tune at will with more than 30% throttle, but nothing stock. I ended up replacing the spark plugs again which ended up fixing the issue. I still took my truck into the dealership since it is still under warranty just to check it out and they still said I have a failing coil after testing them. This has been about month ago and no shutter since.

c money

My truck has 1,100 miles on it. Went back to stock and is fine. Hopefully Mark can fix the issue

Watt-maker

FWIW, I was happily using 5 Star's 87 tow/perf up until a couple weeks ago. I changed the plugs and set the gap to a tight .032", changed the oil, and rotated the tires. I decided to try the 91 tune. That tune immediately threw a few codes and it really didn't feel right. Tons of lag. I switched back to the 87. Everything felt ok (no more codes, no more lag). Then I tried climbing a slight grade while accelerating. The best way I know to describe it is, it sounded like it was building too much boost and either the BOVs couldn't handle it or the truck knew it and started dumping boost. The truck would pull hard until this started then it would buck then lose speed, catch the next gear and start all over again. Only with this tune. So my guess is that somehow the 5 Star tunes got currupted. The truck runs good stock and on the SCT tunes. I called Mike who emailed me a new tune right away. Still did it. I called him back but I just ran out of time to try another tune he sent me (with reduced boost supposedly). I still haven't had a chance to try it. Just too busy. Right now I'm running the SCT 87 tune which both me and my truck really like so I don't know if it's even worth changing.

grimsweeper

Thanks, I did put new tire size on order form,still almost 5% off. I will call 5star,hopefully they will have record of order details.

LocDown

@watt-maker,
you did switch to an almost 100% mix of 91 octane gas right? As in almost empty and then filling up.

Watt-maker

I always run 91 no matter the tune. Even stock it feels better on 91. Of course, who knows what we are really getting out of the pump. The worst it ever ran was a tank of ethanol free 91 that I got in AZ. I'm sure it was bad gas though. It took a few tanks for it to pass through.

LocDown

I've actually gotten better mpg with 91 octane with the 87 perf-tow tune towing my boat.