VX HPC Misfire, please help

7 posts / 0 new
Last post
Martin7H
Martin7H's picture
Offline
Last seen: 1 day 16 hours ago
Joined: 17/04/2014
VX HPC Misfire, please help

Hi 

My 7 has developed a misfire (webers), it happened a couple of weeks ago when the engine warmed up, but then cleared. Today I've taken it out; it started alright then after about 4 miles it happened again, I managed to limp home. 
After a few checks it was confirmed no spark on cylinders 2 and 3. Plugs were found to be ok. 
The ECU is the MBE 912 ver 3. 
Should I suspect the coil pack and change it?

Any advice would be greatly appreciated. Thanks in advance.

Martin

 

Golf Juliet Tango
Offline
Last seen: 4 hours 33 min ago
Joined: 17/04/2014

I'd replace it. Is it a wasted spark system?

For some reason the coil pack on my VHPD (in the 21) is a Vauxhall item. Sadly when it failed there was noting available off the shelf.

Stephen

Democratic dissent is not disloyalty, it is a positive civic duty

Martin7H
Martin7H's picture
Offline
Last seen: 1 day 16 hours ago
Joined: 17/04/2014

Latest update

I have replaced the coil pack, but the symptoms returned. I have just changed the spark plugs; it started instantly and sounded ok. I took it for a drive; it all performed well, then after about 4 miles and with the temperature reading normal, it misfired and lost power. I managed to get back. I let it cool down for a short while. It then started ok, all cylinders firing as shown with a strobe. After about 5 minutes there was no spark on bank 2 and 3. As it's a waisted spark if one lead fails I assume it will bring its pair down? I going to change the leads. What is the part number for HT leads? If that doesn't work it's the ecu? 
Dose anyone have any thoughts on this?
Thanks 

 

SM25T
SM25T's picture
Offline
Last seen: 7 hours 44 min ago
Joined: 17/04/2014

How about the temperature sensor that provides info to the ECU ... not the one for the gauge.

Andrew Gilbert
Andrew Gilbert's picture
Offline
Last seen: 3 days 13 hours ago
Joined: 05/06/2015

Is that MBE the original? I have read that these are showing their age, unfortunately replacements of those are just not readily available it seems.

 

Love a HPC

1992 HPC vx2.0 c20xe goodness....

https://www.facebook.com/groups/caterham7c20xevariants

Nick Chan
Nick Chan's picture
Offline
Last seen: 5 hours 58 min ago
Joined: 17/04/2014

"I have replaced the coil pack, but the symptoms returned. I have just changed the spark plugs; it started instantly and sounded ok. I took it for a drive; it all performed well, then after about 4 miles and with the temperature reading normal, it misfired and lost power. I managed to get back. I let it cool down for a short while. It then started ok, all cylinders firing as shown with a strobe. After about 5 minutes there was no spark on bank 2 and 3. As it's a waisted spark if one lead fails I assume it will bring its pair down?"

Hi Martin, I had exactly the same problem with my VX car many years ago (maybe 2003-04).  Very occasional stutter that got worst until it would only run on 2 cylinder and limp badly along.  Left to cool down, the car would run fine again sometimes for a good run but more likely for 5-10 miles and then back to 2 cylinders and enforced cool down.  The final time though I limped it home and even when fully cold, it wouldn't start on 4.

One of the lads was an electronics wizz and checked the ignition system and determined that there is a pair of transistors (I think he said) in the ECU and one was breaking down with age when it got hot which sounded very logical.  These 50p items were obsolete even then and whilst they could be replaced, it just wasn't cost effective as they were in such short supply as to be not worth trying to locate them.

I ended up buying a new MBE ECU with loom costing around £550.  Loaded with a base map for my carburettor car and it was plug and play.  The car ran perfectly after that and as a bonus, the fuel range went up from 150 to 180 miles/tankful which helped spending the money!  As a further comment, I happened to price a similar ECU from MBE last year for a friend having issues with his VX car, and was surprised the price hadn't gone up very much over the last 20-odd years so could be an option for you?

Nick

 

Andrew Gilbert
Andrew Gilbert's picture
Offline
Last seen: 3 days 13 hours ago
Joined: 05/06/2015

buying a new MBE ECU with loom costing around £550.  Loaded with a base map for my carburetor car and it was plug and play

Sounds the way I'm looking to go, mine is OK but its the original ECU.

Love a HPC

1992 HPC vx2.0 c20xe goodness....

https://www.facebook.com/groups/caterham7c20xevariants