Revving too high before it will shift...

[tybardy]

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

keep us all posted man, i am interested to see what develops

 

[Rollin Thunder]

keep us all posted man, i am interested to see what develops

I think somthing is wrong with his truck. IDK I could be wrong. lol.

 

[tybardy]

yes but seemingly large problems can develope from very small and easy fixes, like sensors or computer work

 

[9CZ71Denali]

Mechanic is on vacation until tomorrow, but he will look at it bright and early.

Today, on my way down there I the CEL came back on and gave me 2 P0420 codes and later on while accelerating, I lost all power and the CEL flashed with P0300. I am starting to think it's a bad cat or O2 sensor...

 

[tybardy]

it sounds very likely that you are looking at something like a sensor or even a control module issue... for your sake, i hope so! just be easy on her because driving with a sensor gone bad can cause your motor to try and "fix" itself, which will in turn end up doing a lot of damage

 

[9CZ71Denali]

O2 sensors, knock sensors, intake manifold gasket all good. New MAF & fuel filter, throttle body cleaning and seafoam fix nothing... Looks to be the cat, will have them done friday.

How bad would it be to just hammer them out?

 

[tybardy]

Who said it was the cats? as far knocking them out, i havent done that since i had my 82 GMC and that was easy as pie, pull it off and smash the shit out of the interior media with a flat head till its empty.

i dont understand why the cat would be causing all those problems...

 

[Yukonxl]

Mine just started with high rev from 2-3 gear, but it was after I had my trans oil flushed and changed. The mechanic thinks it is a vacuum thing and that the oil change loosened up something. I am taking it in next week, I guess we will see.

 

[9CZ71Denali]

Had both cats and banks replaced, runs like new now!

Thanks again for the help.

 

[tybardy]

good to hear... do you really have a Z71 Denali? i was unaware they made such a thing? you got pics?

 

[bigpapapete]

my tranny did the same thing for a while ,I couldn't figure out the problem until I lost second gear then fourth, sorry hope you have better luck than I did

 

[TallyHo]

Had both cats and banks replaced, runs like new now!

Thanks again for the help.

What do you mean by both banks?
I get that there is bank 1 and 2, but what on bank 1 and 2 did you replace?? Sorry for digging up an old thread. But this sounds exactly like whats happening to me right now.

 

[Pamela]

I've changed sensors, cut cats off and straightpiped, I'm still having issues with that high rev, it says air leak but I think it may be a suffocation, I've checked hoses and sealing, I've sprayed quick start all over to check for a leak and still no luck.

 

[retiredsparky]

If an intake manifold gasket is leaking it can be hard to spray enough around the intake port to find the leak(especially if the leak is on the bottom side of the port). It takes a fair amount of spray intensity to alter the engine idle. A tank of propane with a hose gives better directional flow when doing this kind of troubleshooting.

A note of warning: if there is a loose high voltage ignition connection, this type of testing is dangerous (explosive).

Also, if multiple ports are leaking, this type of testing can be inconclusive.

 

[dreeveal]

I know this is super old, but I thought I would throw in my two cents in case it could help anyone. I had the exact same symptoms on my 2005 Escalade. It turned out to be the MAF. I put in a K&N air filter, the type you oil, and I guess I put too much oil on. It dirtied up the MAF. I pulled it out and cleaned it, symptoms didn't really change much. Finally just bought a new one and the problem disappeared immediately, along with the CEL and several codes indicating everything from bad O2 sensors to exhaust leak. Anyway, I hope that it helps someone with an easy fix.

By the way, I had been running the K&N for at least a year before the engine light came on. Engine light was intermittent for a few months before the tranny symptoms appeared.