Emissions, Over-fueling and Poor Economy

[AndrewGP]

Ever since I've had my car I've always thought the economy was poor. It's a 1.8K Series on RBTBs with an MBE ECU that was mapped by the previous owner at Northampton Motorsport. It's decatted at the moment and runs beautifully and pulls like a train.

 

Back in January (one year after I bought the car from CC Mids) it had it's first MOT under my care. It failed on emissions initially but was allowed to pass after a quick chat about smoke tests etc However, the poor economy remains and it does smell of fuel at idle sat in traffic and this has nagged at me until now.

 

Fast forward to this morning. Great blat this morning of 100 miles, mixed driving and progressing well, but not exactly thrashing it. I used 3/4 tank which cannot be right so something is definitely not right! I'm suspecting the lambda might be duff but really I'm not sure? As a check I've whipped the plugs out and they look like this:

 

http://thumbsnap.com/s/f6K0EBVS.jpg

 

I guessing that's not good 😬

 

Assuming the map is correct for now, am I thinking along the correct lines about the lambda being duff? I'm going to swap it out this afternoon for a new one that I'm borrowing but anything else I should be looking at?

[charlie_pank]

Yes you're running rich.

 

In my experience, anything other than a proper mapping session or a wired in wideband lambda probe and a self-mapping ecu is just fumbling around in the dark.

 

 

Do you have the ability to plug your pc into the ecu? If you're lucky it might be a duff sensor (eg coolant temp) and you'll see it instantly when reading what the ecu is seeing.

[GPBox]

Hey Andrew, I had the petrol smell thing a month ago too, for me it was just the seal on the fuel level sender totally perished and sloshing fuel out onto the top of the tank (under the boot floor)...easy fixed with a replacement form CC..........G

[AndrewGP]

Charlie, I will go and check the ECU, I've read MBEs are locked by Caterham, but it has been remapped so who knows?

 

Graham, my seal is fine (I checked it last week when I checked the diff oil level) there's definitely something up here, especially looking at the state of my plugs!

[AndrewGP]

I've just checked the ECU, and this is what it looks like. Is the ECU->PC plugs one of these:

 

http://thumbsnap.com/s/ZssWe8FM.jpg

[charlie_pank]

no idea, but I'm sure an r300 owner can tell you

[Mankee]

I don't think MBE ECUs are easily user-adjustable unless you have the right (i.e. possibly expensive) software and cables like pukka mapping companies do. SBD are the main dealers of MBE and their site has some useful information, which may help you. They specifically mention 967s in the below link:

 

http://www.sbdev.co.uk/Engine_Management_Systems/ECU/Easimap_Download.htm

[AndrewGP]

You could be right. A quick download and plugging the serial lead in to the ECU (it's to be found top left of the picture sealed in the bag) reveals 'No ECU found' by Easimap. No idea why.

 

I've also got the old lambda out and it's choked with black deposits much like my spark plugs, however a new lambda does nothing for the over-fueling so as Charlie said that's most likely not the cause. I will probably get a new one though just to be sure.

 

Next stop has to be speaking to Northampton Motorsport who remapped it. But looking at my documentation it was down in 2007 and I've got every MOT certificate since (although only one emissions sheet which showed a pass) so that assumes it has passed emissions testing right up to January this year.

 

We'll see what they say tomorrow, but right now I'm pretty stumped as to what's going on ☹️

[Space Cadet]

May well be engine problem but with the smell of petrol I would second the idea of checking the seals around the fuel tank as I has a similar smell and fall off in economy and all I was doing was leaving a trail of petrol behind me!

[charlie_pank]

Leaking fuel tank won't blacken the plugs!

 

Are there any club members near you who have read an MBE before?

 

I seem to recall that someone on here has done it, perhaps it was 'EFA', he might have been posting as 'Fat Arnie' back then...

[Graham King]

I would go with Charlie's initial thoughts and check the sensors, there are 2 (I think) that could affect this, the water temp sensor in the water rail (you need the ECU sensor not the gauge sensor), from memory this is brown like this one, the other is the air temp sensor in the TB backplate (at least it is on my Jenvey's), this is green like this one. I too believe that the MBE is locked so you won't be able to get into it. You could see if there are any other owners locally that would be prepared to lend you them to test on a run and see if the economy improves.

 

If these don't have any effect then you don't really have any choice but to take it to someone that can open up the ECU to see if that shows anything or to get it remapped (I would suggest the 2 Steve's if you do as they have had very good results with the MBE).

 

Graham.

[charlie_pank]

Anyone know the expected resistances for those two sensors at various temps?

[AndrewGP]

** UPDATE **

 

Ok, the car has been at Neil Garner's today for some testing. Throttle bodies are balanced, ECU is fine, all ECU sensors are fine too. The spark plugs, injectors, injector wiring plugs, coil packs and HT leads were all swapped around and all found to be ok.

 

Issues are: Exhaust primary temps (at ~2.5k rpm) are all around 400F on 1,2 and 3 and only 250F on no 4 (where the lambda is plugged in to). The no 4's plug is fouled too whilst the others are fine suggesting it's running rich in isolation. We then compression tested it and it came out 180, 185, 125, 150.

 

Any ideas as to why the no3 has low compression but runs ok and why one cylinder (no4) is running rich?

 

Edited by - grenpayne on 24 Apr 2012 14:49:57

[AndrewGP]

oops double post 😔

 

Edited by - grenpayne on 24 Apr 2012 14:49:35

[charlie_pank]

You have a physical problem causing the low compression. This could be anything: loose spark-plug, head-gasket (well it is a K-series!), rings, piston, warped head or even cracked liner.

 

Did you confirm that the other 3 cylinders are running at the right AFR? If they are then I guess you've got a duff/different injector on #4

 

Edited by - charlie_pank on 24 Apr 2012 15:35:34

[Paul Deslandes]

If you used a standard serial data cable it won't talk to the ECU. You need the special MBE cable that you can either buy from SBD or make/modify your own, the data for which is on the SBD website here.

 

If you choose to modify a standard cable to match the SBD drawing you can ignore the resistors, just leave them out, and ONLY connect the three wires as shown, cutting off everything else, otherwise you risk damaging either the ECU or your PC or both.

 

Some Caterham software is encrypted and not just PIN protected and you can only do basic checks using Easimap. The best place to get it remapped is Track N' Road. Steve Greenald has the wherewithal and the knowledge to do a first class job. Aftermarket MBE ECUs are 'open' and you can play to your heart's content although you need passwords to get to the higher levels of fiddling.

 

Edited by - Paul Deslandes on 24 Apr 2012 16:13:38

[oilyhands]

IME, stock bottom ends dont like being pushed too far, I have seen far too many with broken pistons (SS engines and any that go above 7200). My guess would be broken lands on pistons 3 and 4.

 

Oily

[AndrewGP]

Charlie, thanks. Injectors were swapped around and are all fine so my initial thoughts are a combination of Head Gasket and piston rings. The car's booked in next week for more work; they're going to do a leak down on all cylinders and then whip the head off to look at valves and rings. I just thought I'd report back to see if the POBC had any more wisdom on the subject.

 

Paul, thanks, my lead didn't work but Neil Garner did have the correct lead and software and the ECU and map are absolutely fine (it has already been remapped from CC's R300 map so no need to do it again!) It's just the weirdness of the symptoms that has got us all confused.

[AndrewGP]

Quoting oilyhands: 

IME, stock bottom ends dont like being pushed too far, I have seen far too many with broken pistons (SS engines and any that go above 7200). My guess would be broken lands on pistons 3 and 4.

 

Oily

 

Oily, surely 170bhp from a CC Supersport R conversion (R300K) engine should not be pushing the bottom end too far?

[Fil M]

hello Grenpayne, My 7(SV) is an 1800k with the CC Supersport R conversion. The very best I ever got from her to date was 32mpg on a long steady drive. Normally with a mixture of spirited and steady use I will get between 24 and 21 mpg. I set my barrells myself. From a full SV tank to three quarters on the guage i am getting about 151 miles. I know this doesnt answer your issues but posted as a comparision for when yours is sorted. Mine has not had the Two Steves rolling road mapping done or Verniers by Oilyhands as yet. The MBE is still on the CC set up. Good Luck

 

Fil

[Paul Deslandes]

Oops, wrong thread!

 

Edited by - Paul Deslandes on 25 Apr 2012 09:50:04

[TonyR]

I would also suggest broken ring lands. They break often on the 140bhp EU3 engines so with a 20% increase in power they are well over the safety limit.

 

Would be better to fit MG Trophy or forged pistons.

 

Tony

 

Edited by - TonyR on 25 Apr 2012 19:03:10

[AndrewGP]

Agreed and that's certainly what I'm preparing for. Forged pistons it is then.

 

The question has to be asked then, why the hell are CC fitting pistons to R300K engines running stock at 160 bhp that are not up to the job?

[Fil M]

Perhaps add, oil sender, water temp sender, brake light switch to the list. I think its so that we have plenty to do when its raining hard and gives the owners who like to get a bit mucky some 'fixin fun'.

 

[Graham King]

GP, I think it is the rev limit not the power rating that Dave (Oily) is questioning. My understanding is that for consistent running above 7200RPM then forged (or trophy) pistons are required. For occasional forays up to the 7600 RPM limit of the supersports then standard are probably ok. So it doesn't matter if it is 140BHP or 190BHP, it is the revs used that are more relevant.

 

Graham.