ECU blowing fuses

Robbo43 · 17th December 2021, 07:12

G'day guys,
This is my first post here and seems to be a bit unusual.
I have just replaced the v6 in my supercharged 220s zt.
That is background information.
The car now exhibits this fault: when trying to start the engine the starter turns the engine over quite strongly, the battery has mucho power and there is fuel in the tank but it will not start.
The mechanics who fitted the engine and the local auto mechanic have found that the ECU 15amp fuse blows when trying to start the engine.
Unfortunately this does not happen every time you try to start the engine and hence is an intermittent fault which is difficult to diagnose.
Just wondering if this rings any bells out there as to what could be causing the fuse to blow sometimes.
Thanks all, hope to hear from you.

COLVERT · 17th December 2021, 11:42

Look on the forum for water ingress into the plenum chamber.--The ECU objects to being made to swim.---

bsafly · 17th December 2021, 12:21

Check the Lambda sensor wiring, it’s not unknown for the wiring to chafe on the exhaust heat shields and short out blowing the ecu/lambda heater fuse.
Happened to my ZT-T 190 after fitting an aftermarket cat which had the sensor boss welded in the wrong position causing the wiring to contact the shield on acceleration.
Hope that helps, Paul.

Robbo43 · 5th January 2022, 03:57

Thanks for the heads up on that. I noticed that there was a tube that had disconnected. I have assumed that is was part of the emission control system because once I reconnected it the fuse has not blown oever several engine restarts.
Fingers crossed, problem solved!!

planenut · 5th January 2022, 08:10

Still try to check wiring condition to sensors, Good luck,and welcome to the Club!

17th December 2021, 07:12	#1
Robbo43 Newbie MG ZT 220S Join Date: Jan 2019 Location: Tilba Tilba Posts: 2 Thanks: 0 Thanked 0 Times in 0 Posts	ECU blowing fuses G'day guys, This is my first post here and seems to be a bit unusual. I have just replaced the v6 in my supercharged 220s zt. That is background information. The car now exhibits this fault: when trying to start the engine the starter turns the engine over quite strongly, the battery has mucho power and there is fuel in the tank but it will not start. The mechanics who fitted the engine and the local auto mechanic have found that the ECU 15amp fuse blows when trying to start the engine. Unfortunately this does not happen every time you try to start the engine and hence is an intermittent fault which is difficult to diagnose. Just wondering if this rings any bells out there as to what could be causing the fuse to blow sometimes. Thanks all, hope to hear from you.

5th January 2022, 03:57	#4
Robbo43 Newbie MG ZT 220S Join Date: Jan 2019 Location: Tilba Tilba Posts: 2 Thanks: 0 Thanked 0 Times in 0 Posts	Bsafly Thanks for the heads up on that. I noticed that there was a tube that had disconnected. I have assumed that is was part of the emission control system because once I reconnected it the fuse has not blown oever several engine restarts. Fingers crossed, problem solved!!

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17th December 2021, 11:42	#2
COLVERT This is my second home R75 Saloon. Join Date: Feb 2009 Location: France/or Devon. Posts: 14,003 Thanks: 3,851 Thanked 2,167 Times in 1,816 Posts	Look on the forum for water ingress into the plenum chamber.--The ECU objects to being made to swim.---

17th December 2021, 12:21	#3
bsafly Just going about! Rover 75 CDTi Connie SE Tourer starlight silver and serpents. MG ZT-T 190+ in Raven Black. Join Date: Mar 2016 Location: Great Leighs Posts: 468 Thanks: 626 Thanked 167 Times in 110 Posts	Check the Lambda sensor wiring, it’s not unknown for the wiring to chafe on the exhaust heat shields and short out blowing the ecu/lambda heater fuse. Happened to my ZT-T 190 after fitting an aftermarket cat which had the sensor boss welded in the wrong position causing the wiring to contact the shield on acceleration. Hope that helps, Paul.

5th January 2022, 08:10	#5
planenut Regional Secretary Rover 1.8T Tourer Join Date: May 2007 Location: Heathrow Posts: 6,948 Thanks: 1,551 Thanked 2,036 Times in 1,264 Posts	Still try to check wiring condition to sensors, Good luck,and welcome to the Club!