Jerky/Hesitation UPDATE. HELP?!?! Stops at 5krpm

[TWR_Jaguar]

This is starting to annoy me now.Since friday, when the car starts to warm I get a very bad hesitation problem. It's not too bad when crusing, but as soon as I put any load on the engine, the car accelerates very lump, like it keeps losing power randomly. It's so bad that it struggles to get up hills.
When it's cold however, the car is fine and pulls like a train. Only when it starts to warm up to I suddenly start losing power. It's not losing boost pressure I think, as the turbo whine is still consitent.
I've changed the CTS, new sparkies and 4 new coil packs on and it hasn't sorted it. Any ideas?

 

[rsmith]

You need to get a scan with vagcom or the likes, it will probably tell you start way.

 

[TWR_Jaguar]

That's my plan. My lecturer has vag com but he's away this week so have till wait till Monday. Was planning on going home for my sisters' birthday but doesn't look like I'll be driving there

 

[MJ]

Air flow meter? lambda probe, cat blocked? lots of possibilities mate

 

[TWR_Jaguar]

Air flow meter? lambda probe, cat blocked? lots of possibilities mate

I had the MAF replaced a month ago, and unplugging it does make a worse difference. However, you mention cat. I did have to drive the car a good week with the MAF unplugged, so don't know if the overfuelling fubared the catalytic converter. Might be a good opportunity to get a decat welded in.

 

[TWR_Jaguar]

UPDATE
Did a bit more investigate with vag com today. It seems I can't get above 5200rpm. It pulls, and as soon as it gets above 5000rpm, it fells like I'm hitting a limiter, except not as violent. However, I has got it's power under 5k now. Really confused
I've got two fault codes come up
1. Throttle Actuator - Under Voltage during basic setting
2. Engine Speed Sensor(G28) - Implausible Signal - Intermittent
I tried aligning the tb but it just comes up with error in the thrtl adp box
Any ideas?

 

[rsmith]

UPDATE
Did a bit more investigate with vag com today. It seems I can't get above 5200rpm. It pulls, and as soon as it gets above 5000rpm, it fells like I'm hitting a limiter, except not as violent. However, I has got it's power under 5k now. Really confused
I've got two fault codes come up
1. Throttle Actuator - Under Voltage during basic setting
2. Engine Speed Sensor(G28) - Implausible Signal - Intermittent
I tried aligning the tb but it just comes up with error in the thrtl adp box
Any ideas?

You need to meet the below criteria before you can complete and TBA.
Also what are the error code, as you can search for them on the Ross-tech Wiki http://wiki.ross-tech.com/index.php/Category:Fault_Codes




No DTC's in the Engine Controller ( clear codes)

Battery voltage at least 11.5 V( usually this does make any difference)

Throttle must be at idling position (keep your foot off the gas pedal)

Coolant temperature must be between 5 and 95C ( this defo needs to be checked)

 

[TWR_Jaguar]

Well, I'm going to have another vag com session tomorrow, and get some decent logs. Will try doing a throttle reset again, checking those things.
Still confused about the hesitation at 5200rpm though.

 

[8bit]

I had lumpy acceleration on a previous car and it turned out to be the cylinder head gasket on its' way out. Check your oil and coolant levels - if either or both are very low then get that checked out.

 

[TWR_Jaguar]

Turned out to be a crank position sensor. Just fitted one this morning and all is well.