ANGRY Z

2006 LS2 6 speed with 60k miles on it. Car was bone stock when I got it and had zero issues... but them I installed long tubes, cat delete, x-pipe, MAF screen delete, VaraRam intake, 160* t-stat, NGK Iridium IX plugs, new plug wires, all new 02 sensors with extensions and then the codes and problems came. Codes were all 02 sensor related and figured it was because there were no cats. But then the car developed a sort of occasional bad stumble when driving "normal". You can push through the stumble and typically when driving it hard it doesn't do it. It also occasionally will start to idle funny like it is going to die and today it did. Now, assuming the lack of cats and the de-screen of the MAF were the culprits, I took it to my trusted tuner. He tuned it, saw no issues during the dyno tune and the car made a solid 393rwhp/391rwtq. Typically the car runs and drives fine, especially when driving aggressively but it is getting super annoying when it stumbles down to Prius speeds in traffic. Any insight is appreciated. It is about to go get troubleshot at the dealer. I have ordered a new MAF with a screen in it to try this out and see if it eliminates the issue. THanks in advance.

el es tu

The lack of cats isnt doing it.

Id bet it was the maf. Halltech sells a better flowing maf screen if you want to reduce restriction on the intake.
http://www.halltechsystems.com/Hallt...r-p/hc.125.htm



Otherwise you can just convert to the newer card style maf.

Good luck!

ANGRY Z

Interesting... We shall see if the new OEM MAF I have coming fixes it. Then, if so, I shall upgrade to the HallTech screen. Thanks!!

Jers06C6

I have read that it is not a good idea to remove the MAF screen on these cars. Also, did you try to clean the MAF wires or touch them? They are really sensitive.

Alvin@PCMofNC

Your really at the level where you would benefit from a good dyno tune. If you feel like making the trip up here we would be glad to take care of it for you.

ANGRY Z

As mentioned... I already have a good dyno tune.

Yes I used MAF cleaner on the wires, but never touched them.

Kadorja

If all the tuner is using the dyno for is a WOT pull and tune then it's not going to help your issue at all. They really need to drive the car on the street for a few days and tweak the tune accordingly.

ANGRY Z

UPDATE: I went ahead and picked up a reman MAF with a screen in it from PepBoys just to see what it would do. I installed it in their parking lot and after driving for a good 4 hours, on highway, in traffic, taking it easy on it, getting on it here and there, shutting it down, starting back up, etc... It NEVER acted up and ran strong and smooth. Now I typically drive more aggressively than my girlfriend (who the car seems to act up more towards), but today she has it all day and is making a 4 hour trip in it. I will see how it acts for her and report back on that.

el es tu

ANGRY Z

So, the girlfriend reported back that the car ran flawlessly during her 3 hour drive until she was about 5 minutes from her final destination. She got stopped at traffic light after coming off the highway and when she went to take off from the light, after shifting into second at low rpm, it stumbled to accelerate and then surged forward and then was fine after that. I think at this point it is just low rpm shifts after good warm up that this car doesn't like. I see the Halltech honeycomb screen, a FAST 102mm intake manifold, and another tune in this car's future.

ANGRY Z

She drove it again this morning and the girlfriend says she shifted at higher RPMs and drove a bit more aggressively and had only a few slight stumbles that it got through quickly. This was in traffic with lots of stop and go (gear changes). It is still logging lots of 02 sensor codes, even though all the rear codes were turned off in the tune and the sensors are all brand new. Weird.

el es tu

Could be O2 sensors or could be the fact that it was tuned for an unscreened and/or faulty maf sensor

PGSJOE

do you think maybe the 160* tstat is keeping it from reaching optimum operating temps and making it run richer thinking its in warm up mode hence running richer and triggering the O2 codes? just a thought

briancb1

Removing the screen is a bad idea.

The resistors need laminar airflow to give an accurate reading. Even with the new card MAF you'll notice the resistors are places in a small channel that gathers the air evenly.

Glad you figured it out.

tracybarnes

Sounds like classic air and/or exhaust leak. Read the codes again and I'd buy a vacuum gauge at harbor freight. Google how to interpret the gauge readings.

ANGRY Z

UPDATE: New MAF installed, HallTech MAF screen installed. And it still acts up sometimes (as originally described). It went a whole weekend of Autocross and was perfectly fine. Then Monday does the same crap. I know how to work and read my vacuum gauge, but really don't think that is what needs be done. So much has already been replaced and the car truthfully isn't excessively modded from stock and made good power on the dyno. I have an aftermarket warranty, so the car is going in to let GM put it on a Tech2 to see what they come up with. Might as well, since my deductible is only $50. I'll keep you guys posted on this demonic bastard.

tracybarnes

Over-oiled filter intermittently throwing the maf off? Try old intake....

ANGRY Z

Its a dry filter and the MAF is brand new.

tracybarnes

I read they use wd40 to oil those filters. A tech 2 will give you a variety of dtc sub codes that may help point you in the right direction. They are listed at the end on the attached vehicle diagnostics.pdf if you don't have it already.

TLTONEY

Do you have the spacer from Vararam between the throttle body and the intake? If you do, remove it and see if that fixes the issue. Mine would deform and cause a vacuum leak. .02