LB7 Lope tune strange issue

[LBZoom]

Hey Guys,
Just tuned an LB7 over the weekend and he wanted a lope on one of his settings. When you start the truck it will sit there and lope just fine, however if you rev it, it will not return back to the low rpm lope... it's almost like the truck "knows" it's not idling normal and maintains a slightly higher rpm to avoid the lope.

After I rev it, it begins to idle at 770 rpm's, and if I set the lope to say the 800 rpm column, then it wants to idle at 950rpm's...

Haven't had this happen before just curious if anyone else has and what the fix was?

Thanks!

[Dmaxink]

i would make a map for mm3 and see where it is staying after you rev it, then start looking at the limiters from there... Record data and see before and after rev where things are staying then go from there.

[LBZoom]

Thanks, I don't think it's actually a limiter since it's staying up as opposed to staying down. I've got a short log that I'm going to review and I'm gonna run some tests on another LB7 today as well.

[Dmaxink]

well limiter/multiplier is what i was saying.. thats odd that it steps up rpm as you up TBIQ oh well, let us know what u find

[LBZoom]

Will do, just tried that same tune on another LB7 and it worked perfect... I'll keep digging!

[Dmaxink]

could just be that OS. I know we have a issue sometimes with LMMs not building boost off the line, it was a earlier 8594os that gave us the problem, but with a updated TIS it does build boost...almost like there was some time of timing hard limit or something, no clue but updated os fixed it..12lbs was all shed give us at the line.

[LBZoom]

Okay here's an update.... tried the same tune on dad's LB7 which is a different OS, tune worked flawlessly, did a full flash of that OS into the customers truck and it was still acting up just like before except that it had a slight delay in the ignition now.... so I flashed his original OS back in. Finally got it to work by lowering the max idle RPM down to keep it in the "lope" range when he put it in gear....everything worked great idle held at 700rpm and it loped good in/out of gear.... about 20 minutes later he called and it's quit loping again!!!

I have no idea what's causing this issue, here's a log, I let it idle in park for a few minutes then, when I put it in gear you can see the pulse width and TBIQ "lock in"

[LBZoom]

It appears that the truck may have an issue with a sensor or something, its just idling too high, and when I limited the idle RPM's it worked for a little while and then it still wuit loping shortly after.... I'm at a loss here. Don't know if it's tuning, or something external that I have no control over, like I say the lope works fine on other trucks....

[bballer182]

I wouldn't be surprised if it was an issue with the OS you are running. try scripting all of the tune over to a different OS and see if that fixes it.

Other than that LB7's are like french to me, sorry man.

[LBZoom]

No problem man, thanks for the reply. I did try two OS's, the stock which was 89044 and a slightly older one 86006.... both OS's have worked fine for other trucks but not this one :(