Intermittent VBoost cycling at ignition on

[SENTíNEL]

Hi all,

I have an '89 V-MAX and in the last 6 months the VBoost check when turning the ignition on has become intermittent...

There does not seem to be any rhyme or reason; initially it appeared to be linked to ambient temperature i.e. if it was a hot day it went through the self diagnostic open/close, but more recently that's not been the case, indeed as we head into winter in the UK, it may cycle if it's cold and wet, it may not...

Being intermittent it makes it pro magic to troubleshoot, so any and all advice from anyone who has encountered this issue themselves is gratefully received!

Cheers,

PAT


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[VMAXXIMUM]

The most likely cause is a bad vboost controller. If your handy with electronics and a soldering iron they can sometimes be repaired. If not you obviously need a new/used controller. I suggest you look into an ignitech ignition controller. It would replace both the vboost controller and your stock tci unit. It's also fully programmable for many other functions.

 

[Jan Bee]

The most likely cause is a bad vboost controller. If your handy with electronics and a soldering iron they can sometimes be repaired. If not you obviously need a new/used controller. I suggest you look into an ignitech ignition controller. It would replace both the vboost controller and your stock tci unit. It's also fully programmable for many other functions.

I remember them being encased in epoxy-I squeezed one and it worked on and off so i twisted tied a small object to the the backside and it works well now.

 

[caseyjones955]

I resoldered mine but it still matters how the pigtail is routed and wont always cycle when key on cold but it does seem to work warm and when the tach approaches 7k its clearly doing it's job. I'm sure I'll end up with an ignitech next time it gives me a fit.

 

[MaxMidnight]

Before worrying too much about the controller you should first check the integrity of the wiring.
By all means do the V Boost connector wiggle test first and have a look inside for bad joints.
Start by breaking and re-joining all of the relevant connectors. That can often be sufficient to clean any dodgy contacts.
Next step would be to check the continuity of the wiring; can we assume you have a multi-meter and wiring diagram?

If all the above checks out OK then try to beg, steal or borrow another controller to substitute with yours.

A posting on V Max Chat could find a helpful donor or source a replacement if yours is Donald Ducked.

 

[one2dmax]

All good ideas. Most of the time i've been able to peel back the silicon (permanently remove it) and then remelt the solder where the wires enter the board.

I do have a number of good used OEM box's if that doesn't end up resolving the issue.