Well, here we go again!!! I am taking my truck back into the shop MOnday, but wanted to get your guys' opinion......I replaced the chip from my last dyno, and the truck is running high 10's(10.9) to mid 11' A/F. I am happy with that. The problem is that the truck is starting to misfire at the top end. On the dyno, we approached 60 MPH and was fine, start to increase and the truck began to misfire????? I changed the plugs from last week, but forgot to gap them..(I am now using NGK 55IX)...could this be my problem? My fuel is fine for now ....my PSI was about 53 at WOT......any suggestions?

 

I never heard of anyone with those plugs. How about trying some TR6's or BR7EF's. Probably gapped around .032 or something.

 

They are a plug sold up here in Vancouver......I just pulled one and they were gapped at around .053...way off the .032. Would that cause a misfire at the top end?

Michael
01 L

 

Yes, very easily. A gap that large is hard to fire when under boost. Would get worse the harder you loaded it and the higher the rpm.

Jody

 

You might want to try the Autolite AR93 running that much boost and nitrous on top of it. Gap them at .032" for your application.

Here is a link with pics.
Cut back plug thread

 

.053!!!!!

I have been running forced induction since 1996 (see sig) and that IS WAY TO MUCH GAP. The amount of boost, cylinder pressure and intake velocity you are running there is no way for the spark to jump that large of a gap without getting "blown out". Missifiring is probably an understatement, I would imagine the truck would fall flat on its face when the boost started to come on. Drop em down to .032 or even .028 if it still missfires.

Bob

 

10.9 to 11.0 is a bit thick with the fuel dont ya think....I'm no tuner, and by no means an expert, but I think you could safely run that thing around 11.8 to 12.00 and get alot more power....JMO though...And yes, change and re-gap the plugs....

 

EXACTLY. It would start to get into boost then just start to misfire....you could see it on the screen bouncing up and down. Well, at least I got to change the plugs twice in one week. A lot easier second time around.

As far as the A/F goes..... I hope to run mid 11's. I know I can probably easily handle 12.0+, especially with a built lower end, but for the horspower gain to the knowledge I am running somewhat rich is good enough for me. I forgot to mention that the 10.9 was for the nitrous program. That is what I asked of JLP and John gave it to me. As I get more confident in the truck then I may change the tune.

Either way, I am still looking for my first good dyno..maybe Tuesday. Thanks for all your help.


Michael
01 L

 

hey dude

it was nice to see you there,

awesome job with the truck
love the grill can't wait to see your new hood.


you never had the miss fire last time so i would have to say its the plugs,

when you deal with turbo's or supercharge motors the gap is pretty important,

i would take him all out and regap them and go for a burn ;you know your a/f is good.
if its still there replace them with what easterisland or LTNBOLT
recommended. or a quick call to johnny

 

The hood looks great..IMO!!!! Wayne got to see it yesterday.
and yep....as soon as the plugs are changed I am going for a burn the dropping the truck off at Brown Brothers for Monday so Wayne go give it a whirl on the diagnostic machine to make sure it was just the plugs..maybe I can talk him into doing my FTVB!!!!

Talk to you soon.

Michael
01 L

 

another worth while mod


wayne did mine