Running rich

[Bambi]

From the backfiring, uneven running at low revs and the smell of petrol I am under the impression that my car is running a bit of the rich side. :(My mate (Caterham owner) says that cleaning the air filter might help. The engine is a VX 2.0 EX with an SBD 196 throttle body and has a foam air filter - how do you clean it? Any suggestions gratefully appreciated before I start saving   for the engine to be remapped.

Also I have been told that I need a towing eye at the front of the car to get me out of the gravel before I attend a track day - is this a Caterham owner winding me up or is it true.

Thanks in advance.

[Derby Allen]

Bambi, answer to number one, try running the car with the filter off and see if it is any different, i doubt it's down to the filter, No2 they do state at track days that an Eyebolt should be fitted but this generally applies to Tin tops, i haven't got one and have done numerous track days, they will either wrap it around your front wishbones or the top of your rollbar, just watch out if you have a screen fitted for clearence

[stu999]

With reference to 'running rich', it is highly likely to be connected to the 'uneven running' and the 'smell of petrol'. If it is on throttle bodies there should not be a discernable smell of fue at all to be honest - or at least, very rarely.

First and foremost, check for leaks. I would start by cchecking for cracks etc at flexible pipe joints. If that shows nothing, you may have to start the car, as injection fuel systems are only normally 'pressurised' with the engine running.

It is remotely possible that the petrol smell is down to the engine not running properly at low revs. Hopefully it might just be a case of the TB's wanting balancing. However, according to what adjustments are made, may mean that the throttle position sensor needs tweaking too.  

Worry about it running rich once you have the above sorted. Chances are you wont have too...

Finally, if memory serves me correctly,there is an FAQ on air filter cleaning

[Bambi]

Thanks. I'll try what you say and let you know.

[Hammy]

As seen posted elsewhere ....Throttle pot loose ?

[Bambi]

Have ordered some itg dust retention spray and am waiting for it to be delivered before I wash the air filter. The car took about an hour to start on both Sat and Sun and my friendly mechanic thinks the temp sensor for the ecu on the block is defunct along with the water temp sensor so I am going to replace these for a start. The smell of petrol might be me flooding the engine whilst trying to start it. Once running it's rough at low revs but seems OK on the open road. Can't see anything loose (now that I've stopped the mudguards falling off) and you never know I might actually make it on time for a run out in the near future.

[perksy]

What ECU are you using  

Mbe    

[Bambi]

Hope this makes sense - MBE 912 series

[perksy]

Hope this makes sense - MBE 912 series

If it'd of been a 956 or 967 there's away of checking the Coolant temp sensor, Air temp sensor etc using Easimap on the Laptop

But with the 912 that's not possible    

You can check the Coolant temp sensor by connecting a Multimeter to it (set to ohms),  placing it in boiling water and watching the resisitance value alter as the water cools

Coolant temp sensor supplies the ECU with info'

Coolant temp sender supplies the temp gauge with info'

[stu999]

Hope this makes sense - MBE 912 series

Yet more bad news - you are stuck with the map you have. The map is 'burnt' onto the chip on the early MBE ECU's (which this is one of)

[Bambi]

I can see some upgraditis coming on in the near future but I'll have to let the boss recover from the initial purchase first. From what I've read I am looking at £600 for a new ECU and loom; then it will need mapping. I'll have to live with it as it is for a while.

[Big R]

before you buy a new ecu .....

• have you changed anything or has the engine always run like that ?  If not, it’s unlikely to be the map.

• it’s unlikely 2 sensors would fail at the same time, but did you check them ?

• did you do the basic checks for air leaks, loose throttle pot etc ?

If it’s one of the above, a new ECU will not cure your problem ….

[stu999]

before you buy a new ecu .....

• have you changed anything or has the engine always run like that ?  If not, it’s unlikely to be the map.

• it’s unlikely 2 sensors would fail at the same time, but did you check them ?

• did you do the basic checks for air leaks, loose throttle pot etc ?

If it’s one of the above, a new ECU will not cure your problem ….

Agreed

From the symptoms that you have described, there is definately at least one thing wrong with the car, and it is almost definately not ECU related

The 912 is a problem *if* there is something wrong with it (but work through the list above first), or you want to upgrade the engine in the future

[Bambi]

Thanks for all your help - I've had the car for five weeks and enjoyed every minute. If you can't drive it you can talk about it. However, it has always been like it is but there again I've not had it long enough to know any better. Have  checked it over for leaks and loose bits and it appears OK. The  coolant temp sensor appears to be defunct but not sure where to get a replacement as it only has a single terminal and my friendly mechanic says there's nothing like it in the book. He also says that the coolant temp sender is giving a signal but the ecu is not receiving it so in fact the mixture is weak and a squirt of easy start is needed to start it when cold. It therefore appears that the wiring is past its best.

[perksy]

The coolant temp sensor appears to be defunct but not sure where to get a replacement as it only has a single terminal and my friendly mechanic says there's nothing like it in the book. He also says that the coolant temp sender is giving a signal but the ecu is not receiving it so in fact the mixture is weak and a squirt of easy start is needed to start it when cold. It therefore appears that the wiring is past its best.

Errr If what your saying is correct, i think your mechanic is getting his wires crossed (excuse the pun     )

The Coolant Temp SENDER which feeds your Temperature gauge only has one terminal on the XE

The Coolant Temperature SENSOR which feeds the ECU is usually coloured Blue and has Two terminals

The Coolant Temp Sender is available from most motor factors and costs about £5

The Sensor will be more Expensive...

As for the Wiring it could well just be dodgy connections, a Continuity check with a Multimeter should help identify the problem

Don't condem the wiring yet...