Tech help on G35 trans problem

[beetlebob]

HELP I have a 7/03 G35 that if you push just a little on the gas feed at 40 mph it down shifts 1 to 2 gears lower and if raining will cause the tires to come loose under car. It has no codes in all places I can read. I have a Modus Snap-on scanner with the newest updates on it. All I can read is line pressure at idle stays at .6 volts. It will drop down when put in gear and power brake little but can not find out what reading are correct to see. Can not find any TSBs on a shift problem. Car has 76,000 on it and do not know if trans has ever been serviced. Beside this the car runs great. Thanks for anything anyone can send.

[audtatious]

If you are not sure about trans service I would get it done. 76k is past a transmission flush. Otherwise, I'm not sure. You can go through the FSM to see if it lists other similar issues but without codes it's hard to diagnose.

[beetlebob]

Thanks for the help. Customer has picked up car and I do not know what he is going to do with it. He is a somewhat DIY but make a lot of mistakes so I have to go back and fix thins he does wrong. I feel he has done something to the wiring or the programing of the computer but with out codes or anything to point me in some direction I will just wait and see.

[audtatious]

Yeah, codes help.

If you need access to FSM's: http://www.nicoclub.com/FSM

[beetlebob]

THANK YOU !!!!!!!!!!!!!!!!

[audtatious]

No problem. Pop back in and say hi from time to time.

[tollboothwilley]

is he running any modifications? the SprintBooster modifies the gas pedal input

[beetlebob]

Good question Car is gone. He did have a modified air intake system on it. Will wait and see if he comes back. Was very hard to get any info from customer. They must have done something and was afraid to say so. Get that a lot just ends up costing more when I have to find it. Would be a lot cheaper to just say what you did and then let me fix it.

[audtatious]

Good point. I understand it somewhat if you are taking it to a dealer and hoping for warranty, but not to a non-dealer shop.

[tollboothwilley]

I find that most people are not quick to point out there own mistakes!!

[beetlebob]

Well customer called and said he took to dealer. They told him that his quick shift down and the tires breaking loose from under car when wet is being caused by "get this" he has clogged cats.Waiting to hear back from him to see how car runs when he gets it back. Something is telling me that they are going to reprogram something and are hiding it with this repair. Will let you all know if I am told how it works.

[tollboothwilley]

i have seen cats clogging on these cars and exhibit strange things. But i would make sure they proved to me the cats were actually the problem. Even then, i wouldn't go with OEM cats as replacements either!

[Low N Pro]

Closest thing I have had to that with mine was my car shuddered at 40 mph slightly gassing it. I had to replace the valve body in mine
-06 AT g35 coupe