So i have put my girl back in her summer mode once again, a little early this year. Installed my H&R's, summer wheels, tune, intake and 3 bar. Mine has the V8 LMS tune. I started seeing some KR at lower RPM's at 60 to 70 mph at mid throttle. Then I started to replicate the issue while logging with Forscan and my laptop. AT mid throttle (without downshifting) (once boost got above 4 PSI) I was seeing KR of 4.5? I decided to try some WOT runs, no KR to speak of but I am getting a hesitation (shudder) at the top end to 2nd and 3rd. I checked all the usual suspects, oil in the CAC nope. Plugs, changed them and gapped to 30. Air cleaner check. Fuel was the last on my list as we still have winter gas in the pumps, changed stations and filled up with 94. No change. Called LMS and they said its probably the fuel. SO in goes some 110 Octane fuel. That should fix it? Nope.... So I then tried to load the 91 V8 tune. Same issues. Frustrated I went to the stock tune and the issues go away. I changed the map sensor only and returned it to stock. All other mods stayed on the car. I even swapped out the map sensor to rule that out. No luck. It was running strong at the end of last year with no problems with the tune and all the mods. I did put the winter package on a little early so it was still above freezing when I did.

Any thoughts? Has anyone experienced similar issues? 

I have noticed at any speed if I accelerate w/o enough throttle to get a downshift KR will rise.  As far as the stutter... Makes me think about the transmission speed sensor... I think  there is a TSB on that.

Thanks BiGMaC, I will look into that. Interesting that it only happens with the Tune loaded. That will be difficult to explain to the dealer lol.


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I see the same thing in terms of knock with winter gas but I don't have any hesitation so I'm not sure your symptoms are related?

Quote from: ShoBoat on April 05, 2015, 01:17:08 PM
Thanks BiGMaC, I will look into that. Interesting that it only happens with the Tune loaded. That will be difficult to explain to the dealer lol

Larrylu had a heck of a time getting them to replace his, but it resolved the shift problem... Otherwise gotta look to the tuner about excessive shift pressures ... Often over 200psi will cause problems.

Have you tried to something to eat up the possible water build up in gas tank?

Almost sounds like infant stages of injector issue also.

Rich

It could be the case that the 2 are unrelated. I will speak to my Dealer regarding the TSB. I will also be speaking to LMS on Monday. The KR was non existent last year in warmer weather. Thanks for the responses.


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Quote from: SHOnUup on April 05, 2015, 01:35:11 PM
Have you tried to something to eat up the possible water build up in gas tank?

Almost sounds like infant stages of injector issue also.

Rich

Injector issues, damn I'll look into that one too.


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Quote from: BiGMaC on April 05, 2015, 01:02:09 PM
I have noticed at any speed if I accelerate w/o enough throttle to get a downshift KR will rise.  As far as the stutter... Makes me think about the transmission speed sensor... I think  there is a TSB on that.

Some e-85 will stop that completely and give you -KR instead 

^^ I wish but I can't get my hands on it here


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Shoboat, you could drop a couple bottles of heet in on next fill up his in case its H2O in the tank.

Heet just happens to be 99% meth as well....

Did you check for any loose turbo,cac,wastegate hoses being loose or split due to the cold weather,also clean those map,iat sensors with some maf cleaner.Z

Thanks for all the responses, I did double check the hoses. I am going to be tearing all of the hoses off and clean the tb and sensors tonight. The heet idea also sounds interesting. I am also going to take some pics of the intake valves with my snake cam. Will report back.


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Quote from: ShoBoat on April 05, 2015, 02:07:03 PM
Thanks for all the responses, I did double check the hoses. I am going to be tearing all of the hoses off and clean the tb and sensors tonight. The heet idea also sounds interesting. I am also going to take some pics of the intake valves with my snake cam. Will report back.


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I wondered about the valves as I read over your posts...great idea.

When you logged did you notice any changes in fuel data compared to old logs?

Rich

When issues "go away" with the stock tune, it is usually because the engine/drivetrain is not being asked to perform to as tight a tolerance as with a tune.  So what might be acceptable stock/OEM, becomes unacceptable tuned.