MG ZT 180 Behaving Weirder Than A Goth A Cheer Leader Trials

ps42912 · 22nd September 2018, 09:25

So it started with a intermittent hesitation, misfire whilst driving in the mid rev range.

Fault codes and Toaf showing Random multiple Misfire

It moved from the mid rev range to the very low range when you are just pressing the throttle slightly whilst driving.

Fault codes and toaf showing the same random multiple misfire, but also intake air temp to high/short to ground (which I understand is a MAP related fault)

I have checked all the electrical connections removing and refitting each connector. VIZ motors are rebuilt units from Byron and have been in and fine for the last few months. No obvious wiring damage.

Then we went really off the wall in that it would put the revs of the clock and not want to change down at full throttle, even though there were more gears to be had. The ODB revs readout was notably lower than the dash at all times (going more out higher up the range) so assuming ODB was reading the correct revs. This all happening with the hesitation/misfire. If you drive the car normally seems to drive and change fine. Give it some beans and it goes spastic like its having a ECU seizure.

I have swapped the MAP for a spare I had and no joy, I have a brand new MAP arriving today.

Its a long shot but anyone else had this.

The only parts changed recently were the instrument cluster which was working fine when it went in and was coded to the car.

#Iswearthiscardoesntwanttobesaved!

T-Cut · 22nd September 2018, 09:43

Quote:

Originally Posted by ps42912

The only parts changed recently were the instrument cluster and was coded to the car, which was working fine when it went in - - -

That has to be a big clue I'd say.
Can you get an independent T4 analysis?

TC

ps42912 · 22nd September 2018, 12:37

I thought that too, so I popped the old cluster back in and did not improve things same faults, the original cluster just seemed to cause an erratic idle.

Do the cluster have a big control over the cars running?

ps42912 · 22nd September 2018, 12:56

So last night I thought i would disconnect the battery, the old switch it of and on again approach to it issues. I noted the negative terminal was lose.

Today I popped the negative cable back on the battery tight and fitted a better quality new MAP sensor (the last new one was a very cheap one) and she runs like a dream.

It seems the viginised cluster i purchased and coded to the car has a out of calibration rev counter. It actually changes fine its just where may revs would sit just about the start of the red, they now show well past the red line and heading full circle back to the 0RPM!

Think i will have a chat to the guy who did the cluster for me. Unless the rev calibration can be corrected in TOAF?

cb750chris · 22nd September 2018, 13:46

I would guess your new cluster is calibrated as a diesel, but has been fitted to the petrol car. The rev counter on the diesel doesn't go as high, but the needle had the same movent.

Don't know if a correction can be applied without re-virginising the ipk - PhilT4 may be able to advise?

Chris

22nd September 2018, 09:25	#1
ps42912 Newbie MG ZT Join Date: May 2018 Location: CRAWLEY Posts: 5 Thanks: 0 Thanked 0 Times in 0 Posts	MG ZT 180 Behaving Weirder Than A Goth A Cheer Leader Trials So it started with a intermittent hesitation, misfire whilst driving in the mid rev range. Fault codes and Toaf showing Random multiple Misfire It moved from the mid rev range to the very low range when you are just pressing the throttle slightly whilst driving. Fault codes and toaf showing the same random multiple misfire, but also intake air temp to high/short to ground (which I understand is a MAP related fault) I have checked all the electrical connections removing and refitting each connector. VIZ motors are rebuilt units from Byron and have been in and fine for the last few months. No obvious wiring damage. Then we went really off the wall in that it would put the revs of the clock and not want to change down at full throttle, even though there were more gears to be had. The ODB revs readout was notably lower than the dash at all times (going more out higher up the range) so assuming ODB was reading the correct revs. This all happening with the hesitation/misfire. If you drive the car normally seems to drive and change fine. Give it some beans and it goes spastic like its having a ECU seizure. I have swapped the MAP for a spare I had and no joy, I have a brand new MAP arriving today. Its a long shot but anyone else had this. The only parts changed recently were the instrument cluster which was working fine when it went in and was coded to the car. #Iswearthiscardoesntwanttobesaved! Last edited by ps42912; 22nd September 2018 at 09:26.. Reason: typo

22nd September 2018, 12:37	#3
ps42912 Newbie MG ZT Join Date: May 2018 Location: CRAWLEY Posts: 5 Thanks: 0 Thanked 0 Times in 0 Posts	Zr180 I thought that too, so I popped the old cluster back in and did not improve things same faults, the original cluster just seemed to cause an erratic idle. Do the cluster have a big control over the cars running?

22nd September 2018, 12:56	#4
ps42912 Newbie MG ZT Join Date: May 2018 Location: CRAWLEY Posts: 5 Thanks: 0 Thanked 0 Times in 0 Posts	Good News So last night I thought i would disconnect the battery, the old switch it of and on again approach to it issues. I noted the negative terminal was lose. Today I popped the negative cable back on the battery tight and fitted a better quality new MAP sensor (the last new one was a very cheap one) and she runs like a dream. It seems the viginised cluster i purchased and coded to the car has a out of calibration rev counter. It actually changes fine its just where may revs would sit just about the start of the red, they now show well past the red line and heading full circle back to the 0RPM! Think i will have a chat to the guy who did the cluster for me. Unless the rev calibration can be corrected in TOAF?

22nd September 2018, 13:46	#5
cb750chris Trader Rover 75 Tourer Join Date: Apr 2011 Location: Portsmouth Posts: 849 Thanks: 201 Thanked 292 Times in 200 Posts	I would guess your new cluster is calibrated as a diesel, but has been fitted to the petrol car. The rev counter on the diesel doesn't go as high, but the needle had the same movent. Don't know if a correction can be applied without re-virginising the ipk - PhilT4 may be able to advise? Chris __________________ Now offering T4 services in the Fareham area Replacement keys programmed / supplied / cut Diesel 135 upgrade available IPK virginisation and T4 matching available Sorry, due to a big change in home circumstances, I am unable to do any large jobs at present, but can still offer evening time diagnostics.