high revver

[jedmate]

Hi folk
has anybody any ideas what is causing this problem i have with my 4.5
On starting up engine hot or cold,it revs to about 2,000 just for acouple of seconds then ,drops down to a steady 900 rpm.
I have cleaned the stepper motor a few times,but the problem is still there
Now for the strange part ,if i let go of the key just as the engine starts to turn it nearly always fires and ,runs at normal tickover speed

thanks in anticipation

[Doc Toad]

jedmate said:

Hi folk
has anybody any ideas what is causing this problem i have with my 4.5
On starting up engine hot or cold,it revs to about 2,000 just for acouple of seconds then ,drops down to a steady 900 rpm.
I have cleaned the stepper motor a few times,but the problem is still there
Now for the strange part ,if i let go of the key just as the engine starts to turn it nearly always fires and ,runs at normal tickover speed

thanks in anticipation

...sounds tricky - don't know why letting go of the key would make a difference, could be a dodgy injector? Possibly the throttle position sensor?

Some folks on here have suffered with bad conections on the wiring loom in the engine bay, (factory installed splices have been blamed, you should be able to find something on the search if its working!)

Best advice is to get hold of the Rovergauge software and lead from Mark (blitzracing) and have a look at what the ECU is seeing. Then get some noids on the injector wiring and enjoy the pretty lights.

This will help you pass the time on these cold winter nights. After you've had your fun, take it to a decent garage and let them sort it...

[taylormj4]

Hi Jed,
My 450 used to do that and now mostly doesn't. I reset the base idle with the air hose to the stepper closed in accordance with the thread that was on here some months ago, which seemed to help.

I recently bought the Rovergauge that is mentioned here, inc a lead from PHer blitzracing. Rovergauge will tell you the idle rpm that the ECU is attempting to achieve so if you see that at 1100rpm and it's doing 2000 odd then you know the ECU isn't asking for it and therefore must be something like stepper or an air leak.

Cheers

[Robert Lees]

Odd my 450 did this last week, for about a minute revs up, then drops nearly to point of stalling, and so on. Left it to settle and all well. However drove off and car felt lumpy, pulled over and number 7 ht lead off ( again!). May have something to do with it?