MG ZT 1.8T Harsh Sudden Hesitation Followed by Harsh Jerking When Heavy Accelerating

[Sheraton]

How'do

Your first post sounds like "Fuel Cut" due to Over-Boost - Usually the Control Solenoid at Fault (if All Hoses are Connected Correctly)

there is an easy way to check - if you disconnect the Boost Control Vac Hoses at the Turbo then connect the Compressor side of the Turbo to the Wastegate directly - using the small hose that connects the Boost Control Solenoid to the Air Intake Pipe (use tape to cover the port on the intake)

this allows the turbo to run wastegate pressure and if the issue is gone the Fault is the Boost Control Solenoid - Cheap Easy Fix if it is.

Also If you disconnect the Vac hose from the Boost Solenoid to the Wastegate (leave it connected at the wastegate) it's possible to pressurise this hose with a Bicycle pump and check that the Wastegate is actually functioning (Visible through the Exhaust Manifold)


Paul.

[JamieR07]

Originally Posted by trikey

Here ya go:

https://rimmerbros.com/ItemList--Rov...Coils--m-22325

thanks! i have ordered new coils and leads!

once they come i will change them over and let you guys know!

thank you all for all your help, you guys have been fantastic!

[TourerSteve]

Originally Posted by Sheraton

How'do

Your first post sounds like "Fuel Cut" due to Over-Boost - Usually the Control Solenoid at Fault (if All Hoses are Connected Correctly)

there is an easy way to check - if you disconnect the Boost Control Vac Hoses at the Turbo then connect the Compressor side of the Turbo to the Wastegate directly - using the small hose that connects the Boost Control Solenoid to the Air Intake Pipe (use tape to cover the port on the intake)

this allows the turbo to run wastegate pressure and if the issue is gone the Fault is the Boost Control Solenoid - Cheap Easy Fix if it is.

Also If you disconnect the Vac hose from the Boost Solenoid to the Wastegate (leave it connected at the wastegate) it's possible to pressurise this hose with a Bicycle pump and check that the Wastegate is actually functioning (Visible through the Exhaust Manifold)


Paul.

Thats a more descriptive post to check your turbo control hoses and solenoid
The turbo's are great when running right but are finicky if the turbo not plumbed up right or the solenoid acting up. I sure you will get there with a bit of fettling

[JamieR07]

Originally Posted by Sheraton

How'do

Your first post sounds like "Fuel Cut" due to Over-Boost - Usually the Control Solenoid at Fault (if All Hoses are Connected Correctly)

there is an easy way to check - if you disconnect the Boost Control Vac Hoses at the Turbo then connect the Compressor side of the Turbo to the Wastegate directly - using the small hose that connects the Boost Control Solenoid to the Air Intake Pipe (use tape to cover the port on the intake)

this allows the turbo to run wastegate pressure and if the issue is gone the Fault is the Boost Control Solenoid - Cheap Easy Fix if it is.

Also If you disconnect the Vac hose from the Boost Solenoid to the Wastegate (leave it connected at the wastegate) it's possible to pressurise this hose with a Bicycle pump and check that the Wastegate is actually functioning (Visible through the Exhaust Manifold)


Paul.

Hi there!

Sorry I didn't see this message.

I swapped out the boost control solenoid for another that I had, and the issue was still the same. I was just about to try your fault finding diagnostic when I accidentally broke my purge control valve pipe - leant on it - so I ordered a new one and now it's not faulting!

I am thoroughly confused but it seems to have fixed it


I also replaced the coils as I had ordered them anyway and it still runs a little lumpy from cold, is this a common fault with the K series?

[Yorkshire GOC]

Over the years folk have reported a hunting idle on the 1.8t - however on mine its pretty rock steady.

Try a throttle position sensor reset. Switch ignition on but don't turn to start position. Press throttle to floor and right off again five times. Switch ignition to off position.

See if that helps Some say it does.

[Mean & Green]

I had the same issue with my 1.8T when I bought it. Despite two ‘expert’ opinions telling me it definitely wasn’t an issue with the coils, that’s exactly what it was.

I highly recommend new plugs, HT leads and coils on the 1.8T if is starts to display these symptoms.

As for the rough running when cold, is it loosing any coolant?

[JamieR07]

Originally Posted by Mean & Green

I had the same issue with my 1.8T when I bought it. Despite two ‘expert’ opinions telling me it definitely wasn’t an issue with the coils, that’s exactly what it was.

I highly recommend new plugs, HT leads and coils on the 1.8T if is starts to display these symptoms.

As for the rough running when cold, is it loosing any coolant?

Just done the leads and coils, so that's a good start, also done the plugs when I did the rebuild, but I'll double check them


The coolant level doesn't go down, and I can't see evidence of a drip, so hopefully my rebuild has been successful! Although it can occasionally be a little smokey. The smoke is blue though so definitely oil. But again no level drop with the oil either


I'll try the throttle position sensor reset and check the plugs tonight!

[kaiser]

Cleaning and re-gapping (if possible) of the spark plugs would be my first port of call. These cars are incredibly sensitive to spark plug problems!
If not, then a new set of plugs would be my next move.

[JamieR07]

Hi guys!

So I may have found an issue

Turns out I have a leak 🙄 the head gasket is leaking from the front left side - by the cam belt plastic cover

Hopefully the image has uploaded

Looks like I'll be doing the head gasket again!

[madeupname]

Hi Jamie.
There is an updated head gasket that is thicker and better at avoiding HGF. But I seem to remember someone saying you will need a set of slightly longer bolts to compensate for that or even the new gaskets can blow.
Lots of members have done this job so I'm sure someone will pop on with more info