Rich Running

[Landcrab1800]

Hi,

when I first start up my car shounds like it is ruinning over rich (chugging)until I have reved it a few times, it can actually stall. If it was a manual choke I would reduce it.
The system is the MEMS ECU thing.(MG Montego 2ltr non turbo)

It also only does about 30 mpg at 70-80 on motorway runs.
The temp gauge does not reach half way, I have blocked of about 1/4 of the radiator and have fitted a 92° thermostat. The coolant sensor was replaced 2,000 miles ago (along with all other consumables).

My thought is that the contacts may be dirty, has anyone come across this before?

Also I was wondering if I could slave a variable resister so I could lie to the chip a tell it it is warmer than the temp sensor says.

Cheers


:banghead:

[G Force]

Originally posted by Landcrab1800
Also I was wondering if I could slave a variable resister so I could lie to the chip a tell it it is warmer than the temp sensor says.

Hi, If you put any resistor across the coolant sensor wires in paralell it will lower the actual resistance read by the ecu, thus fooling it into thinking the coolant is hotter than it actually is.

Cheers Gary ;)

[Landcrab1800]

Cheers for that.
Understand the speak but not the wiring. Any chance of a simple dia?

Cheers

Gordon

[G Force]

Hi again, Roll back the rubber cover on the coolant senor harness at the sensor plug, attatch one leg of the resistor to the pink green wire then attatch the other leg of the resistor to the pink black wire.

Sorry not much of a drawer hope this is clear enough.

Regards gary :)

[Landcrab1800]

Thanks 4 that

Gordon

[E_T_V]

Have you changed the thermostat yet?

I had the same problem when my rover 214 one failed it gobbled juice and was running permemantmy rich because the ECU thought it was still cold (which I guess it sort of was) because of the overcooling because of a dud thermostat.

Change it and see before you start trying to trick the MEMS unit.

[Landcrab1800]

Changed it three times in six months.

First time when I got it (I change all consumables when I buy a car)
Second time for a 88° one
and last week for the 92° one.

Hence the drastic measures.;)

[E_T_V]

Have you also changed the coolant temperature sensor too as these can fail or go out of calibration.