Well I have a little issue, iv got a built motor, 8.8:1 compression. I am running 2 step colder ngk copper plugs gapped at .026, single turbo (hx35).

I am getting a misfire (feels like ign cut, but its not) in 2nd gear at around 6k rpm. The boost at that given rpm in 2nd is at around 17psi. If i shift into 3rd, and boost goes to its max at 19-20 psi, I dont get misfires during 3rd. My a/f is at low 11's(11.1-11.3), I am running 50/50 water/meth injection with a 7GPH nozzle. My timing at this boost is 17degree's

Can my misfire be due to the plugs being too cold in range(Maybe 1step colder is enough)? Is it possible that based on the info above, my tune is too conservative and actually hurting me by causing such misfire?

Any info will be greatly appreciated.


Here's one of the plugs thats currently in the car.

 

What engine management are you using?

 

what's your turbo kit?

 

I am pretty sure this is a VQ35 swapped maxima he is talking about. Probably running eManage or Turbo XS EMS with a custom turbo kit.

 

You should have used 1 step cold ngks. When I was running the Utec. I got missfire codes once a week. After I switched over to a haltech. I have not seen that code yet. But my Z is all stock now. stilll running 1 step ngk's. On stock ecu no codes. What it boils down to is the UTEC sucks.

 

I also think its UTEC related though you might want to try a less aggressive tune (lower psi that is) and make sure it's not knock. Does backing off timing 2 degress solve the issue? If it's a UTEC ignition driver issue, you should consistently have issues at high rpm. An HKS DLI-II or Ken Bell Boost-a-Spark have helped others running UTECs. I think the fact that it is gear related does not necessarily let the UTEC off the hook as the rate of change of rpm may also be affecting the ability to produce strong spark as quickly as needed. Also might want to be triple certain that the UTEC is well grounded.

 

 

Thnx for the replies, well I have an Emanage Ultimate, with a custom turbo setup. The issue is at the higher boost, when I lower it, it does not happen. I really doubt its knocking however, because the plugs dont show sign of it, and my knock sensor log does not show knock activity.

 

Get a better ems. At those boost levels. IMO.

 

Well its not an EMS issue, also my options are very limited considering I have a VQ30 ecu.
IMO usually problems with the EU is due to user error and lack of experience with it, I dont see how it would be a problem using it. (not saying its better than a Utec or any other EMS, just saying its not no Apexi SAFC either). I use my EU in relation to my OBD scanner/logger, so for example with timing, I know exactly how much timing I need to take away to output my desired degree's, since I know exactly how the stock ECU's curve/table is.

 

If that is the case I would star buy buying some one step colder plugs and starting there.

 

Good idea., thats the first thing I am going to try out.

 

I would definitely try moving up a heat range, to one-step colder plugs and see if that fixes it.

 

LOL at the people jumping on "UTEC Suck!" right away... At the PSI UTEC does suck though. lol

You may want pull more timing at 17psi. You said before that you were running 21deg @ 15psi and I recommended to pull more timing. I believe you set it to 17deg @15psi, you added 2 more psi and still running 17deg then should be pulling more timing. I think 17deg at 17 psi is just high.

 

So you think I should pull about 2 degree's more?

 

The guys telling you to try the colder plugs may be on to something.

 

Yea, im def going to try that. I know the most commonly used is 1 step colder. I went with 2step since thats what i used to run on a previous VQ (but was nitrous). So i'll get the hotter plug before i try anything else.

 

Unless that timing was set on a dyno then I will always play it extra safe. Did you get a misfire error code? You could be detonating and the ECU is pulling timing.

Edit.
Unless you injector, coilpack, plugs are failing then I dont see why your tune will cause the misfire.

 

You have a rear-mount right? You are hitting 17psi on 2nd gear? I want what you have!!!

 

In my logs I didnt see timing being retarded. What im going to do first, is put 1 step colder plugs, and see if it still does it. For now, I lowerd my shiftpoint to slightly below 6k (stock is 6200RPM), so I dont get in the misfiring range. Either way I wont be doing many WOT runs if any, till I get this solved.

Haha, yea I do have a RMT setup. Its taken me a couple of years to have it running how I do now. That thing back there spools up with the least amount of effort, If i brake boost in 1st gear, id be able to get 20psi in 2nd. Actually by taking out the muffler alone I get the same boost in 2d as i get in 3rd (19--20). (dynomax superturbo muffler is pretty damn restrictive)