tbss 07 weard 5000 cut off

[franckrem]

I all I have a traillblazer ss with a magnacharger on it and I just put the magnagharger tune file in it...
My truck is working great but I have a small problem with it.the problem is that when I'm at full throttle the truck is pulling real hard until 4500 to 5500rpm and than stop... the fuel injectors just shut down from 15ms pulse to only 2-3ms and the engine stay at that rpm until I let off the throttle. I disabled the TCS completely and it dosent work ether... It seam like an engine protection of some kind I also upped the MAF Flow vs RPM and vs volt of about 50% and it dident do anything. I also tried to remove all the the cutoff of the truck (all!!!) and it still dose that.

It also dose that in neutral...

I have tried every thing I know I dont know what to do whit this...

any one have an idea?

PS: I'm also working with Drew Zimmer from the magnacharger Calibration dep and as of now he did not found the problem...

[swingtan]

Post the tune......

And a log file....

[5.7ute]

X2
It sounds like a rev limiter to me, but without a tune or log file it is really just aguess.

[ScarabEpic22]

Interesting, this is the first time Ive heard of this and I keep my eyes and ears open on the tbssowners site about tuning issues.

To be a broken record here, the ECM and TCM files plus a log would make this much easier to track down. Could be something as simple as a limiter coming into play and cutting fuel.

[doubledip]

might have missed this - is the car auto or manual?

[ChipsByAl]

It should be an LS2 with a 4L70-E
Al

[doubledip]

ok no worries...

have seen many times a very similar problem of a mysterious 4500rpm rev limit and it is when the base tune is an auto but the car is a manual... brings the TM into play.. fresh flash with manual tune and all good

[franckrem]

So I work on the truck today and finally found the problem... First you have to know that the motor was install in a 2003 envoy.

It turn out that the owner ad replace the inlet pipe between the maf and the throttle body with the cheap flexible plastic one of the envoy to make it fit under the hood...The vacuum between the maf and the TB was just enough to make the tube crumble at exactly 5000 rpm every single time and just under boost!!!

I attach a copy of the log file with this post so you can see what kind of reading I was getting from the datalog(you can see the trouble close to the end with the throttle at 100%)

It seamed to me like there was some kind of protection that was closing down the throttle flap but I could see the tps datalog was always 100%

I add quite a headache trying to find this one I can tell you...

Thanks any way for the support and the suggestion, EFILIVE have a great community.

[swingtan]

LOL, that a magnificent log file!

As they say, "Knowledge is power" and the data logging has given all the info needed. Good find!

Simon.

[joecar]

Wow, that caused the MAF sensor to step/stumble... good log...