Weird RPM Issue on higher rpm

[Rare87GT]

It seems when I get above 4500 rpms in top of 2nd or when it goes into 3rd, where the rpms will go up like 4550 then back down to 4505 then up to 4590 and then up a bit then back down a few rpms throughout the pull. My graph looks like it hits a dead spot and barely goes up but I don't feel anything awkward in the car. Any clues what might be going on to cause this? I have a feeling my converter is not doing so great, but I don't think it explains what's going on. I think I'm losing 2-4 mph in the 1/4 when it does this instead of pulling constantly throughout.

I have some scans to show this, and would like to see what you all thought.

This is on a 3.8L Series II Supercharged and 4t65ehd tranny.

Thanks,
Amir

[mecanicman]

Post the scan and tune.

[Rare87GT]

Here ya go. You can notice in the upper 4000rpm range in 3rd is when it starts to be funky. A few areas on the graph if you go through it closely you can see the rpm do some strange things. Let me know after looking over my tune, etc. I have a LS1 maf, 2.8" pulley, Intercooler and XP cam. It might be the tune, but I dunno. It pulls hard throughout.


Thanks for taking a look.

-Amir

[mecanicman]

As all the settings I looked at seem fine, I am going to say its a combination of your injectors are maxed out and maf calibration. I do not have a stock 2000gtp file to compare, but compared to a 02 or 04 file your maf calibration has been globaly lowered. First get new injectors, then work on the tune.

[mecanicman]

I strongly suggest you getting a wideband, would have a better idea as to what is going on.

[Rare87GT]

I have a wideband in the car. It's an AEM Uego one. It shows I'm at about 11.6-11.9 AFR at WOT. My injectors are maxed? I'm at around 87% duty cycle at absolute highest in 1-2nd gear pull at WOT. Rest of the time I'm under 70% duty cycle. I ran these same injectors and went 12.09 @ 114.9 almost 3 years ago. The maf has been calibrated for my setup by a local tuner. I don't notice any KR. Kind of surprised that they are maxed. I figured at those higher rpms something else was going on.

[mecanicman]

May be something else, but with data you provided thats what I can see. Those injectors are done at 85%. And if you watch the log, you spend a little more time there then you think. You should hook your wideband into hpt.

[Rare87GT]

I understand what you mean...Seems I only see the upper 80% duty cycle only in 1st-2nd. Do you think that's what's causing the weird variation in rpm up high even though the duty cycle is not over 70% in the 2nd-3rd gear area?

[mecanicman]

and start logging maf hz.

[Rare87GT]

I'll log the maf hz tonight. Anything else I should be logging that's not in my table to make sure I am going static on the injectors? I wonder why I don't see any lean spikes if I am. I'm running PRJ rails and a Walbro 255 pump as well.

[mecanicman]

I understand what you mean...Seems I only see the upper 80% duty cycle only in 1st-2nd. Do you think that's what's causing the weird variation in rpm up high even though the duty cycle is not over 70% in the 2nd-3rd gear area?

When you did your run in the log through 3 gears, you shift at lower rpm in 2nd and 3rd. You still hit 80% at 5800 rpm in 2nd. In the other log where you appear to be in 2nd gear and to 6300 rpm you hit high 80% duty cycle. So anytime you run past 6000 you are maxing out the injectors.

You should include maf hz, commanded afr high res, and your wideband. You have NO feed back for fueling visible in the data you have provided, so this is best guess.

[Rare87GT]

I know the logs I have are crap. Wish I had someone around here like you that could explain all this stuff more or less. I am looking on Clubgp for some bigger injectors now. I'm thinking of going with some 65lb ones. Hopefully that fixes any issues up high even before 5,000rpm where it does the rpm shuffle or whatever it's doing lol.

[mecanicman]

Try and put together the scan first. Let me see some more detail. If your fueling is on, you will need new injectors. If it is not, your current ones may be ok. If you have problems setting it up ask or do a search in here. Others have done it, so the info is here or someone will usually provide it.