right then, I bought an efi mk4 escort cab with a running problem, basically when cold it revs as normal but when warm wont rev above 2500 revs, today I've replaced the map sensor, tps, iscv & charge cooler control thingy i've even tried a new ecu but to no avail, anyone got any ideas????

as an after thought does anyone know how test the co pot?

thanks in advance.Daz.

 

the next episode, lol.

well I've just been a wasted £40 on an efi diagnostic thing, fuel filter & leads. Diagnostic thing said everything is hunky dory, so I disconnected the coolant temperature sensor from underneath the inlet manifold & hey presto revs freely & perfectly now but wont idle below 1200 revs. So the next question is: is this the problem? or have I just bypassed something by disconnecting it? I understand that it is probably revving high due to the connection not being there & I am unable to set the base idle, but I couldn't before. Any ideas anyone?

 

I was just about to say the coolant sensor, if its revving mad when hot it sounds like its permenantly running in cold start mode. The only way really is to test the sensor, which is best done removed from the car.

 

how do i test it?

 

Multimeter set to resistance and a jug of hot water.

 

episode 2,

i've replaced the coolant temerature sensor but as soon as i plug it back in the revving problem re-occurs, plugged in the efi diagnostic thingy to do another round of tests but now it comes up with error 46, thermactor no air in self test, when doing the full throttle test. I'm all out of ideas now.......... bugger.

 

Whats that mean??

 

that's what I'm trying to find out lol, that's the error the diagnostc thing gives me when i do the full throttle test

 

oops my cock up lol, error 46 is: iscv maximum engine speed not reached, does this mean the iscv is shot?

on another point does anyone know the pin numbers on the ecu for the coolant temp sensor, got a feeling it may be shorting out.

 

Im still none the wiser on the fault code but i havent used one myself yet

As for the pin numbers, sounds like a good old spot of trial and error to me Use your multimeter to continuity test the wires.

 

check the voltage acros the 2 wires in the coolant temp sensor

or get a bit wire and earth it to the block then put to earth of the sensor
just incase dodgy earth

on the iscv get some1 to keep the revs up then disconect the multi plug see if it will rev freely

but i think it may be down to a sensor earth my selsf

tommy

 

I'm 99.9% sure there should be no voltage across the pins, it doesn't act as a potential divider, just a resistance value

 

quick update, found out now that uplugging the air charge temp sensor allows the car to rev freely, unplugging the iscv does nothing to help the problem.

 

Do the revs not change or anything when u unplug the ISCV

 

unplugging the iscv causes the revs to drop, so that's fine

 

Ah ok i wasnt too sure what you meant when you said unplugging the iscv does nothing to help the problem.