440 - Idling Issues

[spanner-uk]

Hi,
having trouble with my 95 440 1.8i - it has issues idling (revs jump up & down and it sometimes stops or revs to about 2500rpm)
I had a diagnostic done (revealed nothing), changed the ECU, Idle control valve, MAP sensor (the one that replaces the Air Mass Meter), Changed the spark plugs, HT leads, & had a smoke test to see if there are and split hoses - none found!

My next option (i think) is to change the Lambda Sensor and/or the ignition coil......anyone have any ideas to save me pulling my hair out??

thanks!!

[B20F]

The B18U engine doesn't come with an idle control valve. Do you mean the steppenmotor inside the throttle housing? If not I suspect that one is gone.

[spanner-uk]

that must be the part (bought it online and they called it an idle control valve).

but yes have changed this part and it hasn't solve anything.

any other ideas?

thanks!

[spanner-uk]

also just realised it only plays up when the engine is warm - don't know if this explains anything??

thanks for your help B20F..

[B20F]

Another option is that the hose from the evap cannister is leaking or it's valve. If you stand in front of the engine then it's located left of the radiator with a small hose running to the intake manifold. Remove the hose from the manifold and plug off the connector on the manifold. Hopefully this will cure it.

[grass hopper]

the 2 thin pipes to the map sensor can split,one has a restrictor in it,also the inlet manifold gasket can blow,but this causes a slight misfire at low revs,also any air leaks on the induction side can cause hunting,also any exhaust blow in the front pipe area before the oxy sensor will give an incorrect reading at the sensor.

try removing the fuse for the ECM for an hour also as this will reset the adaptation in the module.

[spanner-uk]

thanks B20F & Grasshopper,
tried changing the rotor arm & dizzy cap yesterday and although is a smoother drive, the problem still persists. Ill try what you've both suggested, thanks again!

[Nifton]

Spanner, try and test the signal coming from the engine coolant temp sensor on the front of your block, check its in range by measuring it from cold, and see what you get on your multi meter in corespondance to the guage on the dash as the engine heats up to mid-dial. If you have a haynes, the numbers you should be getting through the range are there.

I have heard of this symptom before and it was resolved by swapping the ECT.

[Paul240480]

Originally Posted by Nifton

Spanner, try and test the signal coming from the engine coolant temp sensor on the front of your block, check its in range by measuring it from cold, and see what you get on your multi meter in corespondance to the guage on the dash as the engine heats up to mid-dial. If you have a haynes, the numbers you should be getting through the range are there.

I have heard of this symptom before and it was resolved by swapping the ECT.

YES! If the engine is warm on the guage on the dash & the engine temp sensor is 'dead'. The ecu will assume the engine is cold & will send in more fuel, as in 'choke mode'. Result will be - rough running (idle) poor consumption, fouled up (sooty) plugs.

Lambda sensor, think I replied on your 'other post'? But get a Bosch OE one pre-wired - so just 'bolt on & plug'. Cheaper ones that need to be wired into the original wire can be problematic if you don't get the wiring 'spot-on' - not worth the risk imo

[Nifton]

Spanner, If you're still active and you tried what we've suggested and you need an ECT, then message me as I have a spare one off a low miliage 440 that went to the breakers which should be good for a long while yet.