Hesitation in 3rd and above

[stacy2704]

It seems like this car never runs right, it accelerates fine in 2nd but in 3rd and above hesitate from 3000 rpm to 4000 rpm, I've changed the diverter, pcv, cam follower and MAP sensor, also borrowed a MAF from a mates working car and nothing gets rid of it, anyone had a similar problem?

[AJP]

You need to get it plugged into VCDS, any fault codes read, and ideally do some live data logging.

Otherwise you'll probably just end up replacing parts with no idea of the cause.

If you have a good VW specialist near you I'd suggest you get it booked in. Or if you fancy tackling things yourself, there might be someone on here that can help with VCDS.

In the meantime though, driving it without any clear idea of the issue might be doing further damage.

[stacy2704]

sorry should have said it was plugged int VCDS at the local Indy today, only fault code is for a evap purge valve which has been replaced.

log was run by a mate but i don't know if its done right or not tbh, nuts and bolts i can do but computers not so much

[AJP]

Someone like @Dan_FR can tell you the specific parameters that need to be logged. You'll need to look at fuelling amongst other things.

When you replaced the cam follower, was the one you took out particularly worn?

[pudding]

Evap valve won't be the problem as it's closed in boost.   What specified / actual parameter was logged there?  Boost?

The most useful things to log are:

Boost - specified and actual
Fuel Rail pressure - specified and actual
Low pressure pump duty % - Shouldn't exceed 55-60% usually.
Throttle position
Lambda regulator
Knock regulator
MAF

You need to find a quiet road and do a full throttle pull to the redline in 4th gear.  May need to do that at 3 in the morning!

The longer you can keep the pedal pinned, the better, as it will show how closely the requested and actuals match and their responsiveness.

From a nuts and bolts perspective, the usual suspects are:  leaking boost pipe O rings, injector(s) going bad, vacuum leaks, high or low pressure fuelling deficiency, worn spark plugs, coil(s) going bad.

And less commonly, a terrible remap can cause problems.  Is the car standard or mapped?

[stacy2704]

its running a stock MAP, and the cam follower was badly worn when i changed it, £20 for a new one is cheap piece of mind

[AJP]

its running a stock MAP, and the cam follower was badly worn when i changed it, £20 for a new one is cheap piece of mind

Did you inspect the cam lobe when you replaced the follower?

A badly worn follower often means damaged cam lobe. A damaged cam lobe can cause bad fuelling and a whole host of expensive issues. The whole idea is changing the follower before any cam damage occurs. A new follower won't fix anything if cam lobe damage is already done.

I hope your cam is in good shape, but be prepared. And get a second opinion. The damage might not be obvious.

Fingers crossed for you.

[pudding]

£20 sounds cheap, normally £30 minimum!

If a cam follower wears through and the cam lobe and pump plunger start bumping and grinding each other, even worn down just a few mm is enough to reduce the pump stroke enough to not meet the pressure requests.

[stacy2704]

This is the old follower


Had a look under the tray and the boost pipe connections are like this. Is it normal to be able to wiggle the boost pipes in their connections?

[AJP]

It's normal to sometimes have 'a bit' of oil around the hoses. If you've got lots, and it doesn't feel a good fit, that might point to a boost leak. If a boost leak is the sole cause of any running problems then you could call it a best case scenario. It's not a major/expensive issue. Just a pain in the arse.

As for the follower, yes, it's worn. But I've seen worse. It's when the pump plunger actually works its way through the follower and onto the cam that the big problems crop up. You might have got there in time.

Check out the hose connections and see how you get on. Hopefully that's all it is, but keep us informed.

[stacy2704]

Changed the hose o rings, made absolutely no difference. I'll have to find a garage that can do logs, or get rid of the damn thing. The last car I hated this much was a rover

[AJP]

Changed the hose o rings, made absolutely no difference. I'll have to find a garage that can do logs, or get rid of the damn thing. The last car I hated this much was a rover

Where are you based?

[r5gtt]

That hose clip needs seating properly

[pudding]

Oil on the pipes = boost pressure forcing it out of the bayonet connections.  That's where some boost is going, but the N75 will just spin the turbo more to compensate, so it's not always noticeable.

[stacy2704]

Changed the hose o rings, made absolutely no difference. I'll have to find a garage that can do logs, or get rid of the damn thing. The last car I hated this much was a rover

Where are you based?

im in bristol