1.8 Turbo hesitation/stutter under full throttle - Page 4

Mean & Green · 10th July 2020, 17:53

Quote:

Originally Posted by wixyw

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

Thanks for your response.

I’m replacing the turbo, just received my reconditioned unit. I’ll be updating soon with the results.

Synchromesh · 10th July 2020, 18:32

I read your post the other night but you appeared to have already checked the waste gate so I didn't provide you with a response I gave in 2011. However as you do not appear to have resolved your problem I thought I would provide it, it may be of some value:

When I had a ZT 1.8T it would pitch violently when it hit 4000rpm. I traced it to the pivot seizing where the waste gate actuator arm attaches to the waste gate. This stopped the actuator from opening the waste gate and the resulting over boost tripped the ignition cut out to protect the engine. I removed the spring clip and prised off the arm. I cleaned the pin and the hole and reassembled with a special high melting point anti seize spray. I also cycled the waste gate several times every few weeks. To do this I traced the small bore pipe from the waste gate actuator up to the ignition cut out (think it was on the battery box). I pulled the pipe off the cut out and carefully pressurised it with an electric tyre pump. You can just see the arm/waste gate if you look down from above. The arm will move across then you should stop the pump when the arm reaches the end of its travel. If you over pressurise you may rupture the diaphragm in the actuator. It only took about 15-20 psi to reach full travel.

Mean & Green · 15th July 2020, 15:27

Update.

I checked the wastegate actuator operation and to me it looked to be operating. I took the car to my local garage for a second opinion, they confirmed the wastegate actuator appeared to be working. They suspected a possible internal fault with the turbo and recommended I had it sent off to to be tested.

Given how much of an inconvenience this would be I decided to get a reconditioned complete turbo. The cost of a reconditioned turbo actually was more cost effective than having mine removed and sent off for testing.

So to eliminate any possible issues that may be being caused with the turbo or actuator, the turbo assembly has been replaced. Now the really annoying part, the problem still persists. Only now it seems to happen slightly later in the rev range.

I’m at a point where I’m giving up.

It’s been on Marinabrians T4 where overboost was conformed. Suspect was dodgy MAP sensor wiring, this is now replaced. No change. Plugs renewed and gapped to 0.6mm, no change. Boost solenoid replaced with a new one, no change. Boost solenoid bypassed, no change. Now complete turbo replaced, no change.

There’s nothing left to change. I’ve had three separate opinions on the issue and have been told it’s not the coils so no need to replace them. I’m beginning to wonder if it’s worth doing them anyway just to add something else to the list of eliminations. Along with a new MAP sensor perhaps, but this is just clutching at straws now and I’m throwing money at a cheap old car for no gain.

I love these cars I really do, but I’m getting pretty NAUGHTY WORD-NAUGHTY WORD-NAUGHTY WORD-NAUGHTY WORD-NAUGHTY WORD-NAUGHTY WORD- off with it now.

Synchromesh · 15th July 2020, 17:56

Have you pressurised the waste gate actuator and confirmed that the arm between the actuator and the waste gate moves through the normal amount of travel. It is at least 10 years since I did this test so I cannot remember how much it moves but it is visible looking down from above. I used a 12V electric pump to pressurise the actuator and I monitored the pressure I was applying with a gauge. I connected the pipes and the gauge with the pump off then the switched the pump on while watching the arm. It moved across as the pressure increased and as soon as the arm reached the end of the travel I stopped the pump so I did not over pressurise and damage the actuator diaphragm. The arm reached the end of its travel somewhere between 15 and 20psi.

LeRich · 15th July 2020, 18:03

Fair play for your determination to solve the issue. Hopefully you'll come to a solution.

Mean & Green · 15th July 2020, 18:53

Quote:

Originally Posted by Synchromesh

Have you pressurised the waste gate actuator and confirmed that the arm between the actuator and the waste gate moves through the normal amount of travel. It is at least 10 years since I did this test so I cannot remember how much it moves but it is visible looking down from above. I used a 12V electric pump to pressurise the actuator and I monitored the pressure I was applying with a gauge. I connected the pipes and the gauge with the pump off then the switched the pump on while watching the arm. It moved across as the pressure increased and as soon as the arm reached the end of the travel I stopped the pump so I did not over pressurise and damage the actuator diaphragm. The arm reached the end of its travel somewhere between 15 and 20psi.

Yes I pressurised the wastegate actuator with a bike pump. Everything looked ok as far as I could tell. I took it to my local garage for a second opinion whom I trust for them to carry out their own pressure/vacuum checks and to check wastegate operation. They recommended having the turbo itself sent off to be checked as visually it looked ok externally.

I’ve just replaced the whole unit including the wastegate actuator. It can’t be that now at this stage.

The only thing I haven’t replaced is the coil packs which I think I’m going to do anyway to 100% eliminate them.

Mean & Green · 15th July 2020, 18:56

Quote:

Originally Posted by LeRich

Fair play for your determination to solve the issue. Hopefully you'll come to a solution.

I hope so too, there isn’t much left to check or replace. I like the car, I’m a big fan of MGs. I don’t want to give up, neither do I want to just put up with it how it is.

The car drives brilliantly if I never ever put my foot down, not much use when it comes to overtaking manoeuvres though.

Mean & Green · 17th July 2020, 10:07

It’s been suggested to me that the retrofitted alloy inlet manifold can cause vacuum leaks due to the mating surfaces not matching up correctly.

Someone else has experienced the same issues as me and replaced everything with no success only to find that the upper section of the manifold wasn’t sealing correctly. So I have something else to investigate further now.

Coil packs are on order as well, probably won’t make any difference - but at this stage I may as well just swap them anyway I’ve replaced everything else what’s another £38 for a pair of new coils and piece of mind

Not giving up hope yet.

roverbarmy · 17th July 2020, 10:14

There was a service bulletin about coil leads breaking down where they fit onto the plugs. My V6 suffered with this lead problem and as only the front bank has leads (on the V6) I hadn't considered it. A change of leads and the problem was solved. On examination, the connections to the plug tops were badly decomposed and the spark must have been jumping the gap and burning. The carbon in the leads also becomes brittle over time and can give intermittent spark problems under load.

JOHNDQ · 17th July 2020, 12:28

Quote:

Originally Posted by roverbarmy

There was a service bulletin about coil leads breaking down where they fit onto the plugs. My V6 suffered with this lead problem and as only the front bank has leads (on the V6) I hadn't considered it. A change of leads and the problem was solved. On examination, the connections to the plug tops were badly decomposed and the spark must have been jumping the gap and burning. The carbon in the leads also becomes brittle over time and can give intermittent spark problems under load.

You sure that wasn't about a problem with the metal on top of the plug if I recall correctly it was a sulphur build up

15th July 2020, 15:27	#33
Mean & Green Regular poster MG ZR Join Date: Jun 2020 Location: Newcastle Upon Tyne Posts: 93 Thanks: 53 Thanked 30 Times in 19 Posts	Update. I checked the wastegate actuator operation and to me it looked to be operating. I took the car to my local garage for a second opinion, they confirmed the wastegate actuator appeared to be working. They suspected a possible internal fault with the turbo and recommended I had it sent off to to be tested. Given how much of an inconvenience this would be I decided to get a reconditioned complete turbo. The cost of a reconditioned turbo actually was more cost effective than having mine removed and sent off for testing. So to eliminate any possible issues that may be being caused with the turbo or actuator, the turbo assembly has been replaced. Now the really annoying part, the problem still persists. Only now it seems to happen slightly later in the rev range. I’m at a point where I’m giving up. It’s been on Marinabrians T4 where overboost was conformed. Suspect was dodgy MAP sensor wiring, this is now replaced. No change. Plugs renewed and gapped to 0.6mm, no change. Boost solenoid replaced with a new one, no change. Boost solenoid bypassed, no change. Now complete turbo replaced, no change. There’s nothing left to change. I’ve had three separate opinions on the issue and have been told it’s not the coils so no need to replace them. I’m beginning to wonder if it’s worth doing them anyway just to add something else to the list of eliminations. Along with a new MAP sensor perhaps, but this is just clutching at straws now and I’m throwing money at a cheap old car for no gain. I love these cars I really do, but I’m getting pretty NAUGHTY WORD-NAUGHTY WORD-NAUGHTY WORD-NAUGHTY WORD-NAUGHTY WORD-NAUGHTY WORD- off with it now. Last edited by Mean & Green; 15th July 2020 at 15:33..

15th July 2020, 18:03	#35
LeRich Posted a thing or two Rover 75 Cont SE 1.8T Join Date: Aug 2010 Location: Cheshire Posts: 1,082 Thanks: 215 Thanked 232 Times in 178 Posts	Fair play for your determination to solve the issue. Hopefully you'll come to a solution. __________________ Rover 75 1.8T Contemporary SE Auto Starlight Silver MBB

17th July 2020, 10:14	#39
roverbarmy This is my second home Roverless + 1.7D Sportage Join Date: Aug 2014 Location: East Norfolk Posts: 7,050 Thanks: 729 Thanked 2,021 Times in 1,449 Posts	There was a service bulletin about coil leads breaking down where they fit onto the plugs. My V6 suffered with this lead problem and as only the front bank has leads (on the V6) I hadn't considered it. A change of leads and the problem was solved. On examination, the connections to the plug tops were badly decomposed and the spark must have been jumping the gap and burning. The carbon in the leads also becomes brittle over time and can give intermittent spark problems under load. __________________ Oil in my veins!

10th July 2020, 18:32	#32
Synchromesh Gets stuck in Rover 75 Saloon Join Date: Jan 2010 Location: Preston Posts: 624 Thanks: 50 Thanked 44 Times in 32 Posts	I read your post the other night but you appeared to have already checked the waste gate so I didn't provide you with a response I gave in 2011. However as you do not appear to have resolved your problem I thought I would provide it, it may be of some value: When I had a ZT 1.8T it would pitch violently when it hit 4000rpm. I traced it to the pivot seizing where the waste gate actuator arm attaches to the waste gate. This stopped the actuator from opening the waste gate and the resulting over boost tripped the ignition cut out to protect the engine. I removed the spring clip and prised off the arm. I cleaned the pin and the hole and reassembled with a special high melting point anti seize spray. I also cycled the waste gate several times every few weeks. To do this I traced the small bore pipe from the waste gate actuator up to the ignition cut out (think it was on the battery box). I pulled the pipe off the cut out and carefully pressurised it with an electric tyre pump. You can just see the arm/waste gate if you look down from above. The arm will move across then you should stop the pump when the arm reaches the end of its travel. If you over pressurise you may rupture the diaphragm in the actuator. It only took about 15-20 psi to reach full travel.

15th July 2020, 17:56	#34
Synchromesh Gets stuck in Rover 75 Saloon Join Date: Jan 2010 Location: Preston Posts: 624 Thanks: 50 Thanked 44 Times in 32 Posts	Have you pressurised the waste gate actuator and confirmed that the arm between the actuator and the waste gate moves through the normal amount of travel. It is at least 10 years since I did this test so I cannot remember how much it moves but it is visible looking down from above. I used a 12V electric pump to pressurise the actuator and I monitored the pressure I was applying with a gauge. I connected the pipes and the gauge with the pump off then the switched the pump on while watching the arm. It moved across as the pressure increased and as soon as the arm reached the end of the travel I stopped the pump so I did not over pressurise and damage the actuator diaphragm. The arm reached the end of its travel somewhere between 15 and 20psi.

17th July 2020, 10:07	#38
Mean & Green Regular poster MG ZR Join Date: Jun 2020 Location: Newcastle Upon Tyne Posts: 93 Thanks: 53 Thanked 30 Times in 19 Posts	It’s been suggested to me that the retrofitted alloy inlet manifold can cause vacuum leaks due to the mating surfaces not matching up correctly. Someone else has experienced the same issues as me and replaced everything with no success only to find that the upper section of the manifold wasn’t sealing correctly. So I have something else to investigate further now. Coil packs are on order as well, probably won’t make any difference - but at this stage I may as well just swap them anyway I’ve replaced everything else what’s another £38 for a pair of new coils and piece of mind Not giving up hope yet.