power loss at high speeds

[ken_mag]

Hi folks, I've got an 87 vw bus with an '94 EJ22 conversion. I've got an aftermarket VSS made from magnets and a hall effect sender and suppose to send five pulses/revolution of 5V square waves to the Subie ECU. According to my B10 scan tool/laptop it never reads above 15 mph and will read erractically. This I will diagnose and fix. Would this erratic signal have anything to do with my slight intermittent powerloss at higher cruising speeds of 50+ mph? Does it have an effect on other sensors?

Ken

[Legacy777]

I don't know if the ECU alters things based on road speed. I sort of don't think so, but can't confirm it.

Does the issue occur always at the same speed? Can you describe the issue a little more?

[ken_mag]

It happens mostly above 60 mph - at any speed over that..

Doesn't the computer control the fuel delivery or IAC somehow for deceleration as it senses its slowing down as per the VSS.. and with my erratic VSS signal I would think could cause some issues there.. or maybe I'm barking up the wrong tree??

thanks

Ken.

[Legacy777]

It's possible the erratic VSS signal is causing some issues.

Have you tried resetting the ECU and seeing if the problem changes at all?

That should hint you toward the issue of the VSS and the ECU trying to interpret weird VSS signals.

[ken_mag]

Just an update to this thread, I disconnected the VSS and the powerloss is no longer happening. A little back ground on my aftermarket VSS. its a circular SS vane with 5 magnets magnets spaced out evenly. It is attached to the CV joint so that it rotates with the the joint and the magnets pass by a hall sender which then is suppose to send a 5V square wave to the ECU.. When I test with a volt meter I get voltages all over the place, not a consistant 5V pulse.
I think I'll check to make sure the magnets on the vane have the magnetic poles orientated the same way..

[Imprezive]

pretty sure your vw bus shouldnt go over 60mph anyways for safety reasons

[ken_mag]

Its pretty stable up to 80mph.. its when I hit 100mph its starts to get a bit unnerving.. 4 wheel disk big brake kit is in the works though...

[Imprezive]

haha, yeah I hit 110mph on the freeway last night, the change in handling between cruising at 70mph and 110mph is quite drastic when you hit 110 on a slight downhill the the next turn in the freeway is a somewhat swooping uphill right-hander. It was fun though.