Hollymax

I have an EF Fairmont 3.9L (on gas & petrol fitted from new) that regularly runs rough on idle and unable to maintain constant idle speed, with black smoke billowing out of the exhaust on petrol. Doesn't do this all the time though, but seems to do it on longer runs. Otherwise runs & accelarates correctly. Also when slowing down from open road speeds into a town or similar will pull back sharply into a lower gear (4 speed auto). When I remove the TPS from the Throttle Body or loosen the screms and rotate it at idle I get the same effect but not sure if it is the TPS the ICS, the ECU or something else. If I remove the wiring cradles from the TPS & ICS it takes a long time to see any re-action. Would appreciate some help before I start replacing un-necessary parts.

madmelon

EF's Have a 4L (3984cc)

Hollymax

Thanx my Gregory's also says that, but any idea on the problem?

RobsEB11

it could be a number of things, map sensor,coolant sensor, fuel regulatorand also the fuel pump(relief valve faulty=high fuel delivery)
I've been have some problems with something similar, I have an EB11
its been flooding but it started being a problem at idle and got worse.
I'm about to change the fuel pump(which is new) as the diagnostic computer I have (snapon scanner, father owns mechnic shop) gives no problems.
oh almost forgot the power steering sensor also controls idle speed, if its faulty it will cause bad idle
I'll Keep you posted on the fuel pump idea as i'm puting in a new one tommorow.

Hollymax

thanx, I don't think it is the full pump because I get this problem on gas & petrol, although it isn't as noticable on gas (the black smoke), but I'm interested in how you go in case it's some other part. What area is your father's shop. I've taken it to a couple of places but I don't think they know much of what they are doing, and they look at you like I have no idea what I'm talking about. Because it doesn't always do it it's hard to show someone when it's running fine.

Hollymax

I tried a new throttle position switch to see if that helped, but still the same. Spoke to a Gas conversion place who thinks that it might be coming from a faulty earth to the gas switch box near the steering column. Apparently it's a factory type Gas setup, which might explain why it's causing other things to play up. Will let you know what I find out.