99 VT clubsport no power/surging

[hsv472]

Hey all
1st time on the forum and need some help.
I have a VTII Clubsport LS1 auto.
I'm having trouble with it surging and a substantial loss in power. When its cold its fine but after around half an hour of driving it starts happening. If you put your foot down to less than half it really struggles to get going and surges. Give it WOT and it goes as it should. It has no codes and engine light never comes on. Been searching the forums but can't seem to find what I'm looking for. I have a obd scanner and the 02's volts are flickering as they should so I'm a bit stumped! Have cleaned throttle body and maf aswell
Any help would be greatly appreciated!

[Micks]

What's your fuel like? Fuel filter been changed? Battery ok?

[hsv472]

Fuel usage is normal, new filter and I guess battery is ok. I can leave it a week without starting and it starts no worries

[Micks]

Wouldn't have picked up shitty fuel perhaps?

[hsv472]

Wish it was that simple. Have been through 2 or 3 tanks since it started happening.

[Micks]

Without it throwing codes etc & short of a loose spark lead etc.. You could try dropping a batt lead off & do a PCM reset! Failing that a full scan of the PCM is required.

[hsv472]

Have reset the PCM. Just doing my head in how it only does it half an hour after drivin

[Micks]

Long shot but it could be mechanical too! I know electrical probs cause approx. 85% but it is a possibility! What about the cats, they could be farked!

[hsv472]

Long shot but it could be mechanical too! I know electrical probs cause approx. 85% but it is a possibility! What about the cats, they could be farked!

Yeah you could be right, might pull one off later and report back

[darcy]

Oxygen sensors maybe?
I know you said that they are swinging, but what do STFTs look like?

If it's been tuned before, then it's very possible that LTFTs have been deactivated, and it's just STFTs leaning you out badly.
This would correspond with also being OK when cold and at WOT, when it is operating in Open Loop and ignoring O2 feedback.

[hsv472]

I just had the scanner back on it looking at the fuel trims. Bank 1 ltft moves up and down a bit but bank 2 is stuck more or less on 3.9. So leaning towards o2's now.

[Micks]

I just had the scanner back on it looking at the fuel trims. Bank 1 ltft moves up and down a bit but bank 2 is stuck more or less on 3.9. So leaning towards o2's now.

There ya go, pretty well solved it yaself!!

[hsv472]

There ya go, pretty well solved it yaself!!

Hope so haha. Might grab a pair through the week and see how it goes. If no good there's always a drum of fuel and a match at the ready lol

[hsv472]

Bit of an update. Changed oxygen sensors and has not helped the problem at all
Have been working away so haven't had much of a chance to muck around with the car. Checked fuel pressure today and it hold 60psi no worries at all.
Just not sure where to go next! Any suggestions???
Its just strange how the car will heat up to operating temp in 10 min of driving but it takes 30 to 40 min of driving for it start running like poo..

[Souljah]

Dicky coil pack or packs?