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Old 28th June 2020, 17:36   #21
Mean & Green
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Thanks COLVERT.

I will try giving it some lubrication to see if it makes any difference.

I’m also wondering if I could be unlucky enough to have a faulty new solenoid valve.

Is there any risk to causing damage by bypassing the solenoid valve and linking the black and yellow pipes together temporarily to see if this has any effect?
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Old 28th June 2020, 20:32   #22
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Ok I’ve done a test run with the solenoid valve bypassed and the issue still persists, so I’ve ruled out a potentially faulty new valve.

The wastegate actuator could be seen moving under pressure with a bike pump, but maybe it’s not operating smoothly or reaching full travel. I can try to lubricate it and see what happens.

I could replace the pipework with silicone tubing as this seems to be a common thing mentioned on previous threads. However the piping that’s on looks ok and seems ok with a bike pump.

Failing that I’m wondering if I could have a bad MAP sensor. I know I’ve replaced the plug, but what if it’s the actual sensor? I would have assumed marinabrian’s diagnostic check would have flagged that up though? The diagnostic check ruled out the coils so it’s not those. Perhaps marinabrain could confirm if he reads this?

I’ve only had the car 4 weeks and am yet to experience it driving correctly. Other than a slightly blowing exhaust there is nothing else wrong with the car. Hasn’t lost a drop of any fluids in 500 miles.
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Old 28th June 2020, 20:34   #23
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Stress caused by an aging turbocharger or by a motorist increasing boost pressure from the turbocharger can overwhelm the spring that opens the wastegate at a specified pressure. In these case, the wastegate will flutter because the spring cannot keep the gate fully shut. The boost will oscillate and the engine will stumble and surge as the boost varies rapidly (any given throttle input should create steady boost levels). The engine may also respond sluggishly to throttle input since the wastegate is likely bleeding air.


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Old 28th June 2020, 20:43   #24
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Your comment.

Hasn't lost a drop of any fluids in 500 miles.



Mine hasn't lost a drop of any fluids in 13 years.---

Yes, that does include the rad.--


Now, back to your problem.

There have been members who have had a problem similar to yours. It turned out to be the crank sensor starting fail at high revs.
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Old 28th June 2020, 20:44   #25
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Quote:
Originally Posted by COLVERT View Post
Stress caused by an aging turbocharger or by a motorist increasing boost pressure from the turbocharger can overwhelm the spring that opens the wastegate at a specified pressure. In these case, the wastegate will flutter because the spring cannot keep the gate fully shut. The boost will oscillate and the engine will stumble and surge as the boost varies rapidly (any given throttle input should create steady boost levels). The engine may also respond sluggishly to throttle input since the wastegate is likely bleeding air.


Under light throttle the car is responsive. It will even rev all the way through the rev range when on say about 3/4 throttle with no hesitation or stuttering at all.

Under normal conditions just driving around at sedate engine speeds the car has good torque and no hesitation. The car feels what I would consider normal when driven sedately, with god midrange pickup.

It will only stutter and surge under absolute full throttle beyond 4.5K or 5k RPM. It’s very violent in second gear and I back off. It can be driven through the stutter/surge in third and fourth and will continue to rev only very jerkily between 5 & 6k.

I don’t intent to always drive the car at full throttle, but it would be nice to be able to have it there when needed.

Do you think these symptoms tie in with what you are saying regarding the wastegate?

Last edited by Mean & Green; 28th June 2020 at 20:48..
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Old 28th June 2020, 20:47   #26
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Quote:
Originally Posted by COLVERT View Post
Your comment.

Hasn't lost a drop of any fluids in 500 miles.



Mine hasn't lost a drop of any fluids in 13 years.---

Yes, that does include the rad.--


Now, back to your problem.

There have been members who have had a problem similar to yours. It turned out to be the crank sensor starting fail at high revs.
I was only mentioning the fluids due to the car being new to me. Fluid consumption on a used car is generally an unknown for an initial period. I just wanted to clarify I doubt it’s any gasket related issues.

Wouldn’t sensor failures show up on when plugged into a diagnostic machine?
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Old 29th June 2020, 15:58   #27
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Quote:
Originally Posted by Mean & Green View Post
I was only mentioning the fluids due to the car being new to me. Fluid consumption on a used car is generally an unknown for an initial period. I just wanted to clarify I doubt it’s any gasket related issues.

Wouldn’t sensor failures show up on when plugged into a diagnostic machine?
The T-4 specialists on the forum should able to answer your question.--
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Old 29th June 2020, 16:45   #28
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Quote:
Originally Posted by COLVERT View Post
The T-4 specialists on the forum should able to answer your question.--
I was hoping some would chime in, but I’ve been speaking with Mark from Kmaps after having questionable feedback from some people on FB.

The route I’m going down is to carry out a full test of the wastegate actuator and asses from there. I’ve been doing quite a bit of research on it. I’ll either hopefully get mine working or I’ll just have to replace it.

Whatever is needed to fix it will be done. Even if I have to replace the turbo. I’m just limited to weekends to get under it and have a good poke about. The good thing is the car is still perfectly drivable as it is at the minute under gentle throttle.

I wouldn’t normally ask so many questions. Nothing on MGs or Rovers has been a difficult task to deal with in the past, I’ve just never had a car with a turbo so these symptoms and methods of diagnosis are new to me.

It’s just a learning curve. When I cure it I’ll update.

Last edited by Mean & Green; 29th June 2020 at 16:49..
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Old 4th July 2020, 18:13   #29
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Little update, new turbo ordered and also a back box to replace the blowing one.

Once I get it running right, I can turn my attention to the more minor details and get the car to a more ‘detailed’ standard.
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Old 10th July 2020, 15:24   #30
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Had a similar issue on my Rover 1.8 Turbo tourer. Turned out the wastegate valve was seized. Once unseized it was fine, but, as I don't really drive it that hard, it seized again some months later, so now at the suggestion of Jules I give it a really good blast every journey making sure that I go over 4000 RPM, this seems to beng working ! Might be worth checking if you have not done so ?

Phil
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