Intermittent engine performance issues

[rover3l]

About once a week the Q will not start easily, it has to be cranked about 10 times and finally when it fires it runs like a bear with revs all over then the place. Typically they will vary between 1400 and 200. When they drop to 200 it almost stalls and then it kicks back up to over 1000. It will eventually stabilise when the engine gets to normal operating temperature. The strange thing is that this only happens intermittently making it difficult to problem solve.

Before this happened I had a CEL appear and a KS code was discovered and a loss in injector pressure was detected. He did a full fuel rail flush and TB clean, re-set the codes and then the Q ran like a dream for a week or so before the present intermittent symptoms began.

Any thoughts on how to diagnose or any planned maintainence I should do

[DAEDALUS]

Sounds like a MAF issue. In the past I've ridden around with the ECU on the floor, and a wire probe stuck in the back of the connector hooked up to a DVOM so I could monitor voltages. It works but it's a pain. Best to have someone ride with you, keeping their eye on the meter.

[elwesso]

I agree, it sounds maf-ish... Probably not the connector either..

Dont tell anyone, but if your maf is bad ill sell you one of my extras. I kinda wanted to keep one as a spare, but ill help you out...

[maxnix]

Why not the fuel pump or its controller?

[elwesso]

http://www.nicoclub.com/zerothread?id=95244

Has already replaced the fuel pump and as memory serves, it didnt fail so the controller should be OK..

I dont think a bad controller would cause this sort of problem...

[squeefoo]

Why not the fuel pump or its controller?

Q45 Tech seems to agree here when he refers to symptoms, just ran across this somewhere else. Sounds like it's worth adding to the list of possibilities.

http://nicoclub.com/zerothread?id=73822