Help needed please.
My 3 dr has had a misfire for a while now and its getting me down. It happens at the same place in the rev range (2100rpm) in every gear if i accelerate normally when the car is warm. It dosnt do it when the car is cold. The car gives a sort of cough and the rev counter will jump about wildly. If i put the boot down a bit it will power through and not misfire. On release of the throttle to let the car slow down under its own steam it gets to the said point in the range and the car will surge forward for about a second. Ive changed the crank sensor, plugs, leads but its still the same. Once again it only happens at 2100 rpm.

Any help will be appreciated, im no mechanical genious but i can understand the basics.

 

what's the condition and gap of the phase sensor? what stage is your car and what plugs/gap you running? and I'm sure there's a few more ??? that will be asked tbh!

 

Alvyn thanks.
The car was set up last week by a tuner he sorted out the plugs, i'm not sure about the phase sensor ive got a new 1 in the garage i'll give it a check out.

 

Try a new CPS, sounds like it has a dead spot, totally normal, they wear like anything else.
tabetha

 

new phase sensor now fitted the wires on the old one fell to bits when i removed it ive given it a run round and the car is a lot better it only happened once this time i'll monitor it sorry tabatha not being rude but what do you mean CPS?

 

I meant to say TPS, throttle position sensor, a common cause of this kind of issue.
tabetha

 

not a happy chappy fault is still there at 2100 rpm but only under gentle acceleration

 

who set it up?? could now be a case the co being wrong m8

 

+1 for the TPS they have a habit of wearing at this particular point and once revs are past this point it's fine, most noticeable in traffic.


CPS= Crankshaft Position Sensor

Martin

 

I've got a theory if you will. When i was replacing the phase sensor i noticed play in the dizzy shaft. My theory is that this will be likened to a wheel thats not balanced i.e. it only vibrates the car at a certain speed. Thus the dizzy shaft getting out of shape at the said 2100 rpm and the gap going haywire making the car cough and the ecu light come on. It's just a theory would anyone agree or is it just shite.

 

There should be no play in the dizzy shaft, it sounds very unlikely re the wheel theory TBH, you would notice other issues elsewhere if it was that serious. Did you check the TPS output? They are common for doing this this wear at that position of the throttle and above it are ok which is the exact symptoms you exhibit.

Martin