I have an 07 G35 Coupe AT that I have fitted with a wet nitrous kit from Nitrous Outlet. I’m running a 100 shot.

The last few times out at the drag strip while on a 100 shot the car seems to loose power at around 5.5-6k rpms. Its launches strong and bangs through 1st and 2nd gear just fine but once I’m in 3rd and hit the rpm’s I mentioned above, it clearly experiences a significant loss in acceleration, almost like the nitrous stopped spraying (which it hasn’t).


I haven’t had any other issues with the car or the nitrous kit other than this and I can’t seem to track down the issues. All of my electrical connections for the nitrous system are good as well as the grounds. I’m completely lost here. Am I running out of fuel system or is there something in the ECU that is limiting the car while I’m on spray?

 

Watch your AFR and see what it's doing, if it's fuel related you'll definitely see it leaning out.

You should also pull and inspect your plugs, I would close them up to .035. Might just be blowing out spark, if this problem just started but it used to work properly then it's probably in the spark plugs.

 

Sry for the late reply I’ve been super busy with graduation.
I stupidly don’t have an AFR gauge but I do have Nissan DataScan II if there is a way to monitor AFT from there. I do have the OEM wideband sensors (07 coupe).

I was originally thinking spark as well but when it looses acceleration, the car acts as if it hit the fuel cut rev limiter but well before redline (5.5-6k). Could that also be a symptom of blowing out spark?

 

Yeah because you have no idea what the trim is on the stock fuel map. It can be significantly worse if you have old lazy upstream O2 sensors too.

If you have an Android phone check out the app Torque Pro, you can log data from almost every sensor. That would be a good start that should be accurate enough (it's still going to have fairly poor resolution). I would track the O2 sensor data, rpm, and both banks of fuel trim.

First thing though you need to pull and inspect all the plugs. The ground strap should be a nice shade of tan, the threads (including the top thread) should be a dark sooty black. If the tan color is creeping down the threads of the plug it's too lean, if the soot is creeping up the ground strap it's rich. Same thing with the ceramic insulator around the center electrode, if it's a bright white color it's lean, if it's black it's rich, you want a tan/light brown color.

Depending on the nitrous use you will probably be running a 1 step colder plug as well. Again, just read the plug and see what it needs. And definitely tighten up the gap on a 100 shot, I wouldn't go any tighter than .035 since that's quite a bit tighter than the stock .044.

If you're on old plugs that might be the issue though since they increase gap pretty bad as they age. Just make sure you aren't using a standard spark plug gap wheel. I usually tap the ground strap on a wooden surface to close it up, grab it with a pair of pliers and bend it to open it up.

 

Don't be surprised if your front two plugs are quite a bit leaner, and if bank 2 is quite a bit leaner. Factory deficiency that is corrected by using a 5/16 plenum spacer.

 

This is the spark plug from cylinder #3. I can’t rly tell if it’s lean, rich or “just right”. My current gap is 0.043. Is that good or should I tighten them up (also if so by how much)? I’m using one step colder spark plugs that I put in back in August of 2021.

#3 cylinder

#3 cylinder

 

Heat on the plug looks good, I would tighten them up to .035 - .038 though.

 

1. Do you have a bottle heater? My brother was having trouble with his Dodge Ram at the strip because he didn't have one, later determined on a dyno he was only getting about 80 hp from a 150 hp set-up.

2. Has it been tuned on nitrous?

 

I do have a bottle heater with a digital nitrous gauge. I’m not tuned yet on nitrous. I do need one tho I know that for a fact.

 

Sorry for the late replay. I was on vacation and then got sick right after so I didn’t have time time make it to the track until last night. I did find something interesting however.

Before I went to the track I installed a BLOX plenum spacer (idk why I didn’t do that before hand). I also just cleaned up the wiring. Last night during testing it seems like the spacer FIXED my issue (mind blown). I was able to keep accelerating all the way through the 1/8 mile. It could have been a comb of the wiring I fixed and the spacer but who knows. The car might have just been running lean in the front 2 cylinders causing that issue.

Either way gapping the spark plugs did help actually a bit. Before I did the plenum spacer I did some tests in Mexico and while it didn’t solve my main acceleration issue, the car seemed to shift smoother and didn’t hang as much. Idk if that was because of the spark plugs or just some weird placebo.

Thank you again for your help!!