Running too rich

[srdtvr]

My 1993 400 is running rich I've replaced the temperature sensor with no improvement - does anyone know of a local independant workshop who can diagnose it please
Local to Watford Herts.

Cheers
Steve

[blitzracing]

Nope- but check the AFM connections

[jr6yam]

Did you reset the ECU after changing the Temp sensor?

[QBee]

srdtvr said:

My 1993 400 is running rich I've replaced the temperature sensor with no improvement - does anyone know of a local independant workshop who can diagnose it please
Local to Watford Herts.

Cheers
Steve

PM Chimpongas. He s local to you and this is right up his strasse.

[macca]

What's your air filter like? Mine was filthy and clogged up, engine was running rich and sounded lumpy when cold. Cleaned it and now running much better.

[srdtvr]

Thanks for replies
Air fliter is new
I cleaned AFM connections all good as far as I can tell
How do I reset ECU ?
Cheers

[srdtvr]

filter not fliter - whose moved my keys round !

[blitzracing]

Resetting the ECU may clear down a fault condition when the ECU has gone into get you home mode which can run rich. This can be done by simply unplugging the big connector off the side of the ECU found in the passenger footwell for 20 seconds (thats plenty of time). Once its reconnected the ECU has to re-learn its fueling set up to run properly, so you need to run the car until its hot (90'C at least) and let it idle for 2 1/2 minutes. Resetting the ECU wont do any good if there is fault with a sensor or wiring- as the fault will simply make it go back into fall back mode again. Unfortanatley even though the ECU's have a fault light to show its in fall back, its not enabled on the TVR's (most anyway) so you dont know. You really need a diagnostic plugged into the ECU to get the fault code information, or show you what sensor is not reading correctly, as guesswork is never a good plan. Ask if you have anyone locally with an ECUmate or RoverGauge.

On a side point, a misfire will cause the engine to run rich as well and its not ECU related.

Edited by blitzracing on Tuesday 9th April 11:52

[srdtvr]

Many Thanks
Something for the weekend !

Cheers

[srdtvr]

It's been a while but just had MOT and it passed OK but its running really rich
I've been reading old threads on this topic and wondered if this might be my problem ?
When I garage the car I use a battery cut off switch which means the ECU resets, as I understand, so when I restart the car and drive off i haven't gone through the correct procedure i.e start engine let it idle without revving
leave until engine reaches temperature, switch off for 15 minutes (?) and then its ready to go.
Question - if I'm not following this reset procedure would this cause the engine to run rich ?
Can anyone confirm this reset procedure is correct - it came from another thread sometime ago
Thanks
Steve

[Sardonicus]

srdtvr said:

It's been a while but just had MOT and it passed OK but its running really rich
I've been reading old threads on this topic and wondered if this might be my problem ?
When I garage the car I use a battery cut off switch which means the ECU resets, as I understand, so when I restart the car and drive off i haven't gone through the correct procedure i.e start engine let it idle without revving
leave until engine reaches temperature, switch off for 15 minutes (?) and then its ready to go.
Question - if I'm not following this reset procedure would this cause the engine to run rich ?
Can anyone confirm this reset procedure is correct - it came from another thread sometime ago
Thanks
Steve

Hang on a second there is no way your car would of met the cat or bets test if it was rich on the MOT
they all smell fuelie on initial start till the cats do there thing even when warm

[davep]

I hope this helps explain what actually happens with an ECU reset. Disconnecting the ECU's main connector removes an Always On 12Vdc battery voltage for battery backed values held in the ECU's memory (RAM). Operational values held in this area of RAM are continuously adapted and updated by the ECU and are also used to save time during start up when ignition is switched On. The values are:

- Lambda probes: secondaryLambdaR used during lambda calculations; longLambdaTrimR long term trim right probe; secondaryLambdaL; longLambdaTrimL long term trim left probe

- Fuel temperature sensor: hiFuelTemperature

- six faultBits: for any error codes

- Stepper motor: stprMtrSavedValue

- Fuel map: fuelMapNumberBackup number of fuel map according to tune resistor value; fuelMapLoadIdx row index; fuelMapSpeedIdx col index

- Throttle pot: throttlePotMinimum; throttlePotMinCopy; tpsDirectionAndRate throttle pot direction and rate of movement; throttlePot TPS current value

- RAM memory: ramChecksum

- Main voltage value for injectors: mainVoltageAdj

- MAF: mafDirectLo, mafDirectHi

After clearing or resetting the RAM the ECU ‘relearns’ this set of values (except the error codes) so a reset is mainly useful for clearing error codes and bad values once a fault has been resolved. But if there is an underlying fault or problem with any of the associated components that has not been resolved the ECU will simply restore an erroneous value back into RAM again and, in most cases, set one or more error codes.

To check if error codes are present and get some idea as to which component(s) are faulty and possibly causing over fuelling you can use RoverGauge or ECUMate.

It's also worth remembering that repeated disconnection/connection of the ECU's main connector without first isolating the car battery breaks/makes a live DC circuit that is under load, albeit a small load, which may result in transient current spikes to the internal circuits on the same supply.

Edited by davep on Tuesday 19th April 09:27

[srdtvr]

Thanks Davep
I have got a RoverGauge but so far I can't get it to respond to the ECU
I need to try again, I must be doing something wrong
Limited time these days so it takes me awhile to get onto it
Cheers

[blitzracing]

Whats the error message and are the lights flashing on the connector at the USB end when you try to connect?

[PhilH42]

I had this, happened all of a sudden and it was a fudged AFM...The garage managed to shove the plug on the wrong way...not easy to do.

I also had another one go for no apparent reason other than being unplugged a couple of times..just a personal observation but they seem a bit flaky if fiddled with...possibly more so if the battery is not disconnected first.