1.8 Turbo hesitation/stutter under full throttle

[Mean & Green]

Hi chaps,

Been having an issue with my recently acquired ZT-T. I’m aware this seems to be a common issue when researching online, but many threads seem to just go dead without a confirmed solution.

Under full throttle the car pulls very cleanly up to about 4.5k - 5k RPM and then stutters sometimes violently, until it clears itself at around 6k RPM. Sometimes it’s not too bad, but it always does it.

So far I’ve replaced the plugs and gapped them at 0.6mm. Inspected the hoses from the boost solenoid valve and replaced the solenoid valve with a brand new one.

I initially thought the new solenoid valve had improved things, but driving home from work today proved otherwise. I’m new to the turbo K series and as far as I can tell the pipework looks ok.

I’m now wondering should I change the coils and HT leads, or could I be wasting money on that if it’s more likely something else? I’m happy to replace things as I go, but I don’t want to be swapping parts for the sake of it.

I’ve read mentions of sticking wastegate actuators, but can’t seem to find any images to help show me what I’m looking for. Like I said I’m new to the turbo, so bear with me for being stupid.

Appreciate any advice or pointers in the right direction.

I should mention the car had a HG replacement in March before I owned the car, so I’m hoping I can rule out a dodgy inlet manifold gasket, the car also has a metal inlet manifold not the plastic type.

Thanks.

[marinabrian]

Originally Posted by Mean & Green

Hi chaps,

Been having an issue with my recently acquired ZT-T. I’m aware this seems to be a common issue when researching online, but many threads seem to just go dead without a confirmed solution.

Under full throttle the car pulls very cleanly up to about 4.5k - 5k RPM and then stutters sometimes violently, until it clears itself at around 6k RPM. Sometimes it’s not too bad, but it always does it.

So far I’ve replaced the plugs and gapped them at 0.6mm. Inspected the hoses from the boost solenoid valve and replaced the solenoid valve with a brand new one.

I initially thought the new solenoid valve had improved things, but driving home from work today proved otherwise. I’m new to the turbo K series and as far as I can tell the pipework looks ok.

I’m now wondering should I change the coils and HT leads, or could I be wasting money on that if it’s more likely something else? I’m happy to replace things as I go, but I don’t want to be swapping parts for the sake of it.

I’ve read mentions of sticking wastegate actuators, but can’t seem to find any images to help show me what I’m looking for. Like I said I’m new to the turbo, so bear with me for being stupid.

Appreciate any advice or pointers in the right direction.

I should mention the car had a HG replacement in March before I owned the car, so I’m hoping I can rule out a dodgy inlet manifold gasket, the car also has a metal inlet manifold not the plastic type.

Thanks.

You could always pop around to my place, and we can see what it says for itself

I wonder if the VVC manifold was fitted with the correct throttle body for the turbo?

Brian

[Mean & Green]

Originally Posted by marinabrian

You could always pop around to my place, and we can see what it says for itself

I wonder if the VVC manifold was fitted with the correct throttle body for the turbo?

Brian

Thanks, yes that would be great if it’s not too much trouble? We can arrange via PM if you like

[Mean & Green]

Thanks for your help Brian, really appreciated the time you spent today. Was nice to meet such a genuine knowledgeable bloke and who is just around the corner

[COLVERT]

Originally Posted by Mean & Green

Thanks for your help Brain, really appreciated the time you spent today. Was nice to meet such a genuine knowledgeable bloke and who is just around the corner

I do like the way you've spelled Brian.


However your way is true as well.---

[COLVERT]

Mr M&G---Is this you below ???

You're well come to it as your AVATAR if you like.---

[Mean & Green]

Originally Posted by COLVERT

I do like the way you've spelled Brian.


However your way is true as well.---

Oops! Didn’t realise. It’s typing on a touch screen, I always make silly mistakes

Originally Posted by COLVERT

Mr M&G---Is this you below ???

You're well come to it as your AVATAR if you like.---

Bit of a long story. Mean & Green was my old screen name form MG-Rover.org and other MG ZR forums.

My MG ZR was known as Mean & Green on the forums. The car is green and looks well... mean

Still got the ZR after 16 years of ownership from new. I’d post a pic but I can’t get images working for some reason.




EDIT

Got a image to work, for some reason the forum seems quite picky about photo selection. I’ve had to upload a phone pic rather than a decent one from my library. You get the idea anyway!

[JOHNDQ]

Mine decided to randomly do this today on way home knew I should have stuck to K Series with intake throttle bodies

[Mean & Green]

Originally Posted by JOHNDQ

Mine decided to randomly do this today on way home knew I should have stuck to K Series with intake throttle bodies

Managed to find out for certain mine is over boosting, so not an ignition issue.

Plug wiring on my MAP sensor looks badly damaged. Going to swap the plug harness out and take it from there.

[Ravinder]

I remember you from the detailing world forum. Your ZR is lovely. Great you still have it.
What was the issue with the turbo then?