Another breaking up thread and log

[95talongirl]

Well, I have been fighting this issue since getting the car running.... The car will break up pretty bad after 5000rpm. Now before I started some troubleshooting, it would studder randomly as low as 3500 rpm. Sometimes it would break up horribly in all gears, other times just 3rd gear.

Here's what I've done so far:
-New spark plugs - BPR7ES - gapped to .022
-Changed out the Magancore wires in favor of new MSD ones
-Changed out the coil yesterday.
-Verified that there are no boost and/or vac leaks.
-Ran the car off Wastegate pressure for a bit to see if the problem was boost related.... but still did it at 10psi, 19psi, 25psi..ect. So the boost controller is back on it now.

The coil pack seemed to have cleared up most of it... I was getting multiple fairly clean pulls... whereas before I'd get one good one, then a bunch of bad ones. So I logged a 3rd gear pull. I noticed that the TPS seemed to flutter a bit under WOT.... and also noticed that the AirFlowPerRec and Loadfactor oscellate when it's studdering at the higher rpms... so would this mean I'm perhaps looking at a MAF or TPS problem? I've read something about using the MAF clamp function on DSMLink to make the car ignore the MAF signal at the higher RPMS on the GM MAF. Would this be beneficial? Then again, I'd probably need a good MAP sensor to do that.

I know the car is running rich.... but it's really hard to try to tune it when you cannot get a clean pull. :/

The other question I had is what are the provisions DSMLink uses to default into the "fail-safe" maps? At one point we tired to lean it out to see if that would help the studdering, but then it started running richer?! It was showing 9:1; like on the MinOCt tables.

Thanks for any input on this... it's kind-of annoying...

 

[95talongirl]

I just noticed that the TPS isn't seeing 100% anymore, either. hmmm....

 

[gofer]

I can't look at your log until I get home from work however, most of the time the issue is MAFComp tuning being incorrect or not done at all. JeffGST DSMlink MAS/MAF Calibration Page

I'll look at the log tonight, too.

 

[95talongirl]

ok, cool I'll check that out. I have used the MAFcompAdj feature in DSMlink.. but maybe it's not quite right for this MAF.

 

[95talongirl]

Think that was the ticket.... did some adjustments using the math in the link. and it's definatly clearing up. Clean all the way to 6000RPM now! Didn't get to calibrate the MAF at 6000 -up yet.

Also noticed that the TPS is acting really funny now. It would drop form 97% to 71% without me lifting.... and sometimes it was floored and it was only at 71-ish.... SO... going to change the TPS and continue to calibrate the MAF manually.

 

[gofer]

Sweet.

Next time you connect to Link go to your RPM/TPS tab tab in the ECU config (live) and change the TPS offset to -7 and 105%, see if that makes the logged throttle position reflect 0 and 100% respectively.

 

[95talongirl]

Yeah, it used to read 100%...

Then it starred giving me erradic percentages... So going to change it out with a different one and re-set it.