Revving too high before it will shift...

9CZ71Denali · May 18, 2009

Hello all,

I have an '03 Z that has been well maintained. Recently the engine is revving higher than normal before it shifts, sometimes I have to let off the pedal to get it to shift. Is the tranny going bad or maybe an engine problem? Also quite a bit of pinging and knocking lately. No CE codes when I scanned it. Ran seafoam through it and cleaned the TB about a month ago.

Recently switched wheels from 18"s to 16"s, I havent re-programed the bcm, so my speedo is off too. Could this issue be with the TCU?

Thanks

DarkTahoe00 · May 18, 2009

I'd lean more towards the tranny.but I've heard some people been able to put the vette servo in and it help to stop it. With the seafoam it may have loosen some of the stuff up and that might be why your getting the pinging/knock. I'm sure some of the other guys will chime in and correct me if I'm wrong or with some other insight!

Justin · May 18, 2009

Have you adjusted your intake tube or modified your MAF in any way? Unmetered air would be my first thought with respect to an abruptly new pinging problem.

When the transmission does get around to shifting, how is the shift quality? Does it feel like it's sliding out of gear and then snaps into the next gear or is the shift quality pretty decent?

Grebbler · May 18, 2009

Are you running with the TOW button on?

Rollin Thunder · May 18, 2009

Grebbler said:
Are you running with the TOW button on?

Its sounds like it, But the tow button must be hit every time you start the vehicle.

9CZ71Denali · May 18, 2009

The truck has 81K miles on it, trans fluid/filter changed over the winter. Maybe that is what is killing (killed) it?
When it does finally shift, it is smooth.

I am having a multitude of other issues all of a sudden...

When I accelerate hard (in 4th or 5th), it revs high but doesn't accelerate (as if I were in neutral). When it does respond, there is a rattle from the drivers side or center of the engine compartment.

The engine is louder than normal when accelerating.

Idling rough, the whole vehicle vibrates and shakes.

Tow mode is off, but it drives as if it were on.

My baby is dying! Help!

Thanks in advance... :emotions122:

shsportsfan12 · May 18, 2009

start building a new motor/tranny

munks06denali · May 18, 2009

check tranny fluid level, quality of fluid(brown/smells burnt) As far as rough idle , check your fuel pressure regulator. If I remember correctly its on the drivers side valve cover sticking out of the fuel rail with a little vacuum line running to it. Pull that line off and start the truck, if there is fuel present the nthe bellows in the regulator are bad. I have seen this a few times i friends trucks as well as my old 2K Z71. Hope this helps.

nc6600 · May 18, 2009

9CZ71Denali said:
The truck has 81K miles on it, trans fluid/filter changed over the winter. Maybe that is what is killing (killed) it?
When it does finally shift, it is smooth.

I am having a multitude of other issues all of a sudden...

When I accelerate hard (in 4th or 5th), it revs high but doesn't accelerate (as if I were in neutral). When it does respond, there is a rattle from the drivers side or center of the engine compartment.

The engine is louder than normal when accelerating.

Idling rough, the whole vehicle vibrates and shakes.

Tow mode is off, but it drives as if it were on.

My baby is dying! Help!

Thanks in advance...

My old Tahoe did that turned out to be Intake gaskets, as for the rest i really dont know sounds like your transmission is taking a :poop:

9CZ71Denali · May 18, 2009

munks06denali said:
check tranny fluid level, quality of fluid(brown/smells burnt)

Clean/smells fine...

The thing that is getting me the most is when I accelerate, I don't go anywhere...

Rollin Thunder · May 18, 2009

my tranny did that on the silverado. Replaced it, better but not 100% the first to second shift was crap. Rest were great. Got a BB tune, now its like butter at low speeds, and firm shifts at heavy throttle. Best investment ever for my silverado, and thats on a 4l80e, I would love to see what It could do to a 4l60e Like you guys have.

Grebbler · May 18, 2009

With all these thing happening at once I wonder if the PCM went south.

Wasn't there a condition where a bad/dirty MAP or MAF sensor would cause most of these conditions?

HitandRunDriver · May 18, 2009

Havent heard of that...but honestly try the vette servo, one of the best investments i've had on the truck so far

9CZ71Denali · May 18, 2009

Where is the MAP and how do I clean/replace it? Sorry for the newb question. Thanks for the help guys!

tybardy · May 19, 2009

well, would you say ALL these problems started at the same time or at least within a few weeks of one another... if it was a progresion of problems, do you know which one happened FIRST?

9CZ71Denali · May 19, 2009

The high revving before it shifts was the first problem. Thats been going on for awhile, but it is smooth, so I didn't worry about it. Yesterday, on my way to work, the other symptoms appeared. On my way home I got a P0301 code - Cyl 1 Misfire - after hitting a bump around 70mph. Took it easy on the way home. Today (Monday), I tried romping on it a bit to see if there was an issue, and things just got worse. The rough acceleration, rattling and the rough idling.

I will clean the MAF and my CAI (dirty) tomorrow. I will try the MAP too if someone could give me some guidance. I will look at the service manual in the morning.

Thanks!

tybardy · May 19, 2009

9CZ71Denali said:
The high revving before it shifts was the first problem. Thats been going on for awhile, but it is smooth, so I didn't worry about it. Yesterday, on my way to work, the other symptoms appeared. On my way home I got a P0301 code - Cyl 1 Misfire - after hitting a bump around 70mph. Took it easy on the way home. Today (Monday), I tried romping on it a bit to see if there was an issue, and things just got worse. The rough acceleration, rattling and the rough idling.

I will clean the MAF and my CAI (dirty) tomorrow. I will try the MAP too if someone could give me some guidance. I will look at the service manual in the morning.

Thanks!

Well in cases where your problems seem to be ***********, you can useually track your problem back to the first one, and if your lucky, fixing the first will then fix the rest. But for argument sake, lets say the high reving isnt the culprit, what was the second symtom? was it the P0301 code or did something happen before that?

my next suggestion, IMO, would be to stop driving it if you can because it does sound like you might be working on some real problems

9CZ71Denali · May 19, 2009

It was accelerating rough before the code, and when you'd accelerate, you wouldn't move anywhere, it would just rev up like you were on the gas in neutral.

tybardy · May 19, 2009

all of that sounds like tranny problems.... From what i can tell, and this is all just my assesment based on prior experince, it sounds like your tranny is almost gone. not sure why that would throw the misfire code, someone else may help with that... but my guess is you need a new tranny fast, it seems like it would explain like 90% of the symptoms...

9CZ71Denali · May 19, 2009

I will take it to a mechanic in the morning. Thanks for the help.

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