rpm fluctuating at steady throttle? e67 saab 9-7x

[gumby5ohh]

Hey.

I've recently gotten a mail order tune done along with a couple revisions on my 6.0/4l80e swapped 2007 saab 9-7x. I'm having an issue that I'm hoping someone here can help with. If I'm driving in any gear not heavy on the throttle and hold a steady pedal I can see and feel a slight surge in engine rpms. it's no more than 100 to 200rpms but its extremely annoying it is tuned in sd

2007 saab 9-7x
gen 4 6.0
823 heads
wiseco domed pistons 11.3 c/r
ly6 intake
4 inch intake tube with ls7 maf
btr stage 2 ls3 cam
longtubes
ported factory throttle body
4l80e with pcmofnc harness
circle d 3200 stall

22-11-23 20-03-06.hpl

10.3.22.hpt

[blindsquirrel]

Could very well be something in the tune, but I had a similar steady part-throttle flutter that was caused by the throttle body. The middle gear in the TB had some slop on its axle, boring/sleeving that gear back to zero clearance fixed the flutter. I did that just because it was my own truck and I was curious and had the tools to do it (and also hate throwing things away), but a new TB is only around $100.

Take the TB off, pop off the side cover, see if there's slack in that big middle gear (wiggle it clockwise/counterclockwise).

[gumby5ohh]

Pulled the throttle body and found what I'd say is alot of slop in the gear

[gumby5ohh]

Could very well be something in the tune, but I had a similar steady part-throttle flutter that was caused by the throttle body. The middle gear in the TB had some slop on its axle, boring/sleeving that gear back to zero clearance fixed the flutter. I did that just because it was my own truck and I was curious and had the tools to do it (and also hate throwing things away), but a new TB is only around $100.

Take the TB off, pop off the side cover, see if there's slack in that big middle gear (wiggle it clockwise/counterclockwise).

I found quite a bit of play in the center gear. I got a really good deal on a 09 tbss oem throttle body and I may grab it. Would anything in my tune need to be changed to run it reliably?

[blindsquirrel]

2009 is a different part number. You need '08-down.

[gumby5ohh]

2009 is a different part number. You need '08-down.

I put a brand new Hitachi throttle body on the truck and it's still having the rpm flutters when trying keep a steady rpm. Would you have any ideas on where to start looking tune wise?

[blindsquirrel]

4 inch intake tube with ls7 maf

Any kind of air straightener in there? The MAF sure is noisy, moving around when none of the other PIDs are changing at all.

[blindsquirrel]

Oh, it's in SD...

Don't log any MAF channels when it's supposed to be failed!

Does it still happen when not connected/not logging? Does it do it in MAF-only?

[gumby5ohh]

Oh, it's in SD...

Don't log any MAF channels when it's supposed to be failed!

Does it still happen when not connected/not logging? Does it do it in MAF-only?

It still happens when not logging sir. It has not been ran in maf only due to the tuner tuning it in sd. I will take the maf off of future datalogs.

[blindsquirrel]

10.3.22 - cat & post O2.hpt
screenshot.01-12-2022 21.29.45.png

I haven't seen the cat/post O2 tests give this type of symptom, but they need to be off anyway. I assume you're on one of the newer editor versions that no longer have that tab.

[verlon]

It's a trans related problem. I see surging only when TCC is applied.
Why TCC Slip == Engine RPM? Where is ISS?

tcc.png

Looks like you have low Steady State Line Pressure condition. May be incorrect Torque Model.

Make a new log with:
ISS
Line pressure

[Alvin]

It very well could be related to the ported throttle body. I see far more issues with them than any bit of benefit. The throat/ramp is designed a certain way to give fine control to the throttle control. People see it as a flow restriction and just hog it out. I've also had plenty of TPS sensor slop issues. Only on aftermarket throttle bodies though.

If not that I'll bet its a O2 swing issue. The proportional and integral terms can be adjusted for long tubes so that there isn't a over swing in fueling.

You can test this by forcing open loop with the scanner and see if this takes care of it.

[village_idiot]

I would switch it to MAF only just as a quick test. Just keep an eye on your AFR as I'm assuming your MAF curve has not been touched. Fuel Trims should correct enough at light cruise just for a test though.