Flat Spot Then Accelerating.
 

Hi all,
I have noticed a flat spot then accelerating through 3000-4000 rpm.
It does not happen all the time but then it does happen Its not always the same.
Sometimes it goes flat/lack power from about 3200rpm and will pick back up again around 4000 rpm and other times goes flat then straight away picks up with kick.

I've got a vis tester so it's not that.
I have checked fault codes and it's clear.
And it was fully serviced with new spark plugs 7 mths ago

Any ideas?
Thanks.

MAP sensor?

That was quick!
But surely there would be a fault code for this?
Thanks.

Definitely (from my admittedly limited knowledge) sounds like a power VIS motor thing.

You suggest you've tested it, but given that it's intermittent, I'd say the test is not conclusive, as it may be beginning to fail/struggle.
I'd send "Stocktake" a PM and ask his thoughts, myself.

My MAF sensor was poorly but the fault code cleared when the engine was restarted... try driving with the reader attached to see if you can catch it..
It may only say if it has failed and not if it is reading poorly.

UOTE=Anon3;1706780]Definitely (from my admittedly limited knowledge) sounds like a power VIS motor thing.

You suggest you've tested it, but given that it's intermittent, I'd say the test is not conclusive, as it may be beginning to fail/struggle.
I'd send "Stocktake" a PM and ask his thoughts, myself.[/QUOTE]

Thanks, well I have now had 3 different balance vis motors on the car and it's no difference but the power vis is still the one the car came with. Maybe it is the power vis but I must of tester it about 10 times with my tester and worked fine every time.

Thanks, I will try and watch it tomorrow with torque but what what should normal readings be?

3000-4000 revs:eek:

Mine rarely rev above 2000:shrug:,mind you I am a doddery old man,especially with the caravan behind as well:D

no idea but t would look for fluctuations at steady speed on flat road...
then go through a full acceleration range several times on flat road stopping for a few seconds at each 1000 rpm (ie. 1000 - 2000 - 3000 etc.) and compare the readings to see if there is any variance.

you may even be able to do the second bit in the driveway?, that would get the engine hotter to see if it changes under heat...

My balance VIS was working when Stocktake tested it, but he expressed just a little doubt, so I elected to swap it for one of his refurbs and the car was transformed, as I've often mentioned on here.
The point being that I think mine was a little sticky or lazy, but not plain duff.
It makes sense that the Power VIS can go the same way, imo.

Klarzy's suggestion will be the best way to go first, but you have another route if all is ok with the MAP sensor :}