Problem with a 2 Litre zetec running Emerald ECU. with following sensors, crank, airtemp and water temp.
When revs held at 1500 rpm the revs fluctuate between 1000 and 1500 when throttle pedal is held in same position also occuring if held at 2000 rpm.

Have checked the fuel system pressure regulator, pump and filter all appear okay. Ideas please gents

Car is undriveable in low rev range but pulls like a horse above 2k rpm

Mine hunts a little bit if I drop the idle below 1K.
I found fine balancing of the carbs helped a little bit, and I suspect there may be a little air leak at the idle.

[Edited on 16/6/09 by coozer]

This is bordering on dangerous when you attempt to drive off the revs drop off then wallop they rise to about 2500 rpm car will idle at 1000k no problems. when running at higher revs seems sweet as a nut ?????

It may be a bit weak on the low rev bins or the throttle enrichments need adjusting.Is the throttle sensor in good condition as it could be giving a rough signal at small openings.
Paul.

air leak somewhere at the inlet manifold?

engine has been running fine for pat 3 years, mapped by Dave Walker himself, the TPS is a hoda Blackbird item as the carbs are being used as throttle bodies is the tps known to be poor. We have looked at the unit it is a sealed item

if it was an air leak the car would be running erratically even on tickover wouldnt it as said previously if you lock the revs at 1500 the revs drop then rise. The duratin between rise and fall is constant ??

Do you have closed loop lambda on yours? It could be that kicking in. Causes could be anything from a dodgy sensor upwards..

Might be worth a call to the man himself?

I had this on a 2 litre zetec with dta. Turned out to be knacered TPS. They can mask problems quite easily. If it is a jenvey type TPS they can be had at rs components for a lot less money.

Had similar symptoms with my car when I first got it running with the Emerald ECU or rather after about 20 miles. Turned out to be the TPS, ended up refitting the bike one and have had no problems since.