Kangaroo jack and hesitant bill

[ShoooRn]

Probably common as muck these two but a little back story.

 

I've had a boost issue for a while, would kangaroo and boost surge from Low RPM, then came a flat spot out of nowhere (make boost then drop off) so figured the N75 valve had failed.

 

On driving to work last friday the car bogged down at 70mph and had an almost intermitment backfire. Getting back on the throttle it was hesitant. It then continued fine but if I tried to accelerate past 3000rpm the car would increase in noise but acceleration would drop off.

 

This seems like a boost hose leak (more pressure=expansion in the hose forcing a leak) but there is no noise to say so.

 

I changed the N75 valve Sunday and reset the codes.

 

Codes still standing:

O2 sensor fail (lambda; I am running a decat).

Coolant temp sensor fail - I changed this two years ago and the code came back within a Day so ignored since then.

 

Driving after the N75 has made the power flatter - there is no surge midrang the power is consistent but the car always feels a little restricted like it's lost some boost as opposed to before, the power is just smoother but not as rushed it is strange.

 

My issues still standing:

 

1. The car still wants to cut out and hesitates on startup, especially when reversing. It sounds like it's running a lumpy cam. When I say on startup this is after the SAI has closed (so 2mins idle then go to pull away).
2. The boost feels restricted - no noticeable extra smoke on hard WOT driving.
3. If I shift down mid driving and get back on the throttle it acts as though it is trying to stall.
4. I still have some kangaroo-ing low down balanced only by the occasional rev.
5. Temp gauge is no longer getting to 90 unless idling on a very hot day possible stuck thermostat?

 

 

My plans for this weekend:

1. Service, oil and filter with sparks
2. Change coolant temp sensor
3. Try to clean MAF.

 

Thoughts:

Could the MAF be playing up but not showing up a fault via the OBD? Would that cause the hesistance?

Could a coil be playing up causing hesistance on downshifting?

Could a exhaust manifold blow cause these things?

Could a worn turbo bearing cause hesistance? Is the turbo finally gone (149k)

 

Any help greatly appreciated.

[mac11irl]

Aftermarket or genuine CTS fitted?

If AM thats the coolant temp issue sorted...

 

Boosting issue might be Maf or MAP sensor related. If you unplug the maf and the idle is still rough, then thats goosed. Like the CTS buy a genuine one not AM as vag engines dont like pattern sensors

 

[ShoooRn]

Cheers for response.

I did indeed have a genuine VAG sensor on order from TPS it currently is living at home on my garage floor (in a box) awaiting instalation. On the journey back from TPS I disconnected my MAF and low and behold got all my boost back alongside no surging. I got home and ordered a BOSCH maf from GSF.

 

Picked up the MAF saturday and the car drove ten times better, still a bit of a surge but no hesitance and no kangaroo-ing.

Next weekend I'm boost hose checking, oil pickup pipe replacing etc etc.