Fuel Pump Relay Click On/off On Overrun????
 

Im not sure when it started, but today I noticed on the overrun, my fuel pump relay clicks on and off. This is the relay under the steering column and I can feel it click if I hold it as Im on the overrun.

It clicks on and off more-so, the harder im on the overrun. Ie. if i just lift off, it does it once or twice as the revs come down. If I engine brake hard it does it much more.

Its strange because if I so much as rest my foot against the accelerator pedal it doesnt do it, and it also doesnt seem to be affecting the way the car runs at all?! Its just really annoying?!?!

Any ideas???

Is your stock AFM still in place?

yes

Then what you are describing is a result of the flapper valve inside the AFM bouncing off the stop when returning to closed throttle. There's a switch inside the AFM that shuts off the relay when the flapper is fully closed. I have a datalog somewhere of this happening back when I ran an EMU before I removed the AFM.


edit: Here's the log, which shows me shifting from boost. The red line is the AFM output, the blue line is a simulation of AFM based on MAP & RPM. Remember that with the AFM, up (higher voltage) is closed.

http://miatajoe.50megs.com/log_snapshot_2.gif

Is there a reason your AFM is still installed?

Any ideas on a solution then? It never used to happen?!

I dont want to remove the afm yet, cos frankly at the moment I dont trust my MS one bit, and im trying to keep the install as simple as possible to limit problem factors