Tahoe Lack of Power Stumbles on Acceleration when Cold..

[stikky_p]

Ok so i think the dealership is my next stage..

I've started to notice a rough idle in park and in gear. It gets worse with the a/c blowing and has a hesitation when you first step on the throttle lightly. There are no codes being thrown other than PO446 & P0453 (both evap codes)

Things I've done:

-Inspected Air Filter
-Inspected Wires
-Changed Plugs To Factory Replacment ACDELCO
-Changed Fuel Filter
-Cleaned MAF
-Cleaned Throttle Body
-Seafoam Sprayed Vehicle
-Temp Tested And Pressure tested Catalytic Converters

Not sure where to go from here.. I guess i should get it in and get them to diagnose the issue.. Then i know where to go. Unless I'm missing somethign obvious... I think i've done most of the easy ones..

I'm not quite sure where the rougher idle is coming from.. Never had that before..

I did however notice the tranny fluid smelt a little burnt.. looked nice and new but smelt a little odd.. not sure though.. could i have a vacuum leak?

 

[ezdaar]

Take belt off, rotate all pullys, see if they all turn easily...

 

[Kaotik]

any solution yet to this problem

 

[stikky_p]

problem isnt solved... havent found anything yet....... its brutal..

 

[bkboatnsleds]

Intake gaskets?

 

[stikky_p]

Ok so quick update..... I found SOME of the problem.. my hesitation when accelerating from stop and rough idle was almost 100% cured by spark plug wires.. Turns out i got a faulty wire in there somewhere and was having a cyl 6 misfire but no code.. I put the wires in AND IT FIXED THE PROBLEM ALMOST 100%..

Only issue im having is according to the mechanic there was some arc from the wire causing the stumbling.. Could that be due to the spark wire heat sheild? are they nesissary to have on or could they be causing some of my spark arcing issue? Im still having the lack of power and a touch of rough idle but not bad at all.. just thought taking them off might help...

Below is a picture of the spark plug sheild.. its not my setup just a picture for refrence..

 

[SunlitComet]

Heat shields are there for a reason. The arcing is because of weak wire insulation. The shield just provides a closer ground for it to jump to. Make sure you plugs and wires match. Use either delco or msd wires.

 

[ezdaar]

when is last time you replaced fuel filter and run some injector cleaner through?

I like chevron based cleaners, seems to work well when I used it. It got rid of a mild engine vibration in my 2000 Denali.
I ran my Fuel down to under 1/4 tank and poured in 2 bottles, drove for aprox 10 miles then filled up to half tank. By the time I ran it down to under 1/8th tank, my vibration was gone.

Noticed also in your "things I have done" list, you didn't mention PCV, be sure to clean or replace it as well.

 

[stikky_p]

Heat shields are there for a reason. The arcing is because of weak wire insulation. The shield just provides a closer ground for it to jump to. Make sure you plugs and wires match. Use either delco or msd wires.

Tha plug wires are brand new factory wires.. the plugs are changed as well to factory plugs..

I had the stumble and loss of power before i did the plugs, wires, fuel filter and everything else.. The plugs and wires got rid of my rough idle and hesitation at take off but i still have a lack of power.. I bought the pcv valve and injector cleaner.. I dont think the pcv valve will help because the old one rattled and looked in good shape but i'll replace it anyway for the $5..

Do you recomend adding in the fuel injector cleaner at 1/4 tank and running it a bit then filling up? I only purchased 1 bottle (325ml) of injector cleaner.. I'm currently sitting at 1/4 tank..

 

[stikky_p]

I replaced the pcv valve and tried injector cleaner through 2 tanks of gas.. still no fix.. Next step im gonna try is MAF change.. gonna swap it with another one..

I'm getting a dead spot still when i drive and the vehicle is cold.. It will start fine get going but when i try to accelerate it hits the dead spot and doesnt rev or accelerate fast.. its lacking that power.. once the rpms get up past 2000 or so the driving is perfect.. Im totally lost..