V7 SLR Posted August 22, 2001 Share Posted August 22, 2001 During the Se7ens List Euro2001 tour, my MEMS failed. I had noticed V7 ran badly after a particularly hard thrashing on hot days, whether that be on the road or track. It usually took a few days of either cruising (rare) or sitting in the garage before it would run well again. Symptoms started off by the car refusing to rev from 2500rpm to 3200rpm under load, and ending up with only the first 10% of throttle and then nothing for the next 85%, and then the last 5% causing the engine to full throttle (quite unexpectantly). After a lot of swapping over different sensors, which didn't help, we traced the problem to the Manifold Atmospheric Pressure (MAP) sensor built inside the MEMS itself. As the car's over a year old, it's out of the warranty period, so I had our mechanic peel the lid off the MEMS box (it's sealed with silicon sealant) for inspection. Unfortunately the MAP sensor is also sealed, and would be impossible to open without breaking it. In the simplest terms, it is just a diaphram that alters the resistance of a... er... resistor. Like a pot really. The MEMS takes this and adds it to the equation for fueling. Mine wasn't working properly, except at both extremes (feather and full throttle). Any other position of the throttle caused an over fueling situation rather like driving a carbed car with the choke out when warm. I tried an Emerald M3DK that had been mapped for a 1.6 DVA'd engine (see Dave Andrews' web site at: http://hometown.aol.com/DVAndrews/index.htm) and that worked better than the MEMS ever had. Remember, V7 is an SLR. I noted that in the latest Low Flying another SLR's MEMS appeared to fail during the Spanish trip. I wonder if it's a similar failure. I never really liked the MEMS. There are a lot of characteristics that are just not right, like when you take your foot off the throttle there is a slight hesitation before the revs start to die. It's only slight, but it's there. I had an Emerald M3DK brought out to me whilst I was still on tour (thanks Vinnie, DVA and Karl) which had the map from another VHPD engine (thanks Steve) loaded and that works absolutely fantastic. I have so much more mid range throttle response now. I've booked a "finishing" mapping session at Emerald to ensure the map is 100% right for my engine, but indications are that it's close, and is waaaaay better than the MEMS could ever be. Link to comment Share on other sites More sharing options...
Tony Martyr Posted August 22, 2001 Share Posted August 22, 2001 Honestly ! You Guys can't be trusted out. You go for a gentle tour in Europe and suffer from brain-fade. Good thing really you didn't expose yourself to the Le Sept treatment - the AA would have had to bring the bits back in boxes. You have completed blown my chances of selling a fully functional MEMS unit for a Supersport tuned k series that is sitting in my garage looking for a home - one considerate user Link to comment Share on other sites More sharing options...
V7 SLR Posted August 22, 2001 Author Share Posted August 22, 2001 If you've got the rest of the supersport kit, I reckon you'll sell it easily enough. Have you tried appealing to the MGF and Elise owners? I still think the MEMS setup is crap. I suspect it's because they're mapped for emmissions considerations. What ECU have you currently got? I can't remember. Wasn't it a DTA? How much do you want for your supersport kit? Link to comment Share on other sites More sharing options...
Peter Carmichael Posted August 22, 2001 Share Posted August 22, 2001 FWIW, I reckon that using a MAP sensor on throttle bodies with 280 degree cams is an idiotic way of going about things. On a plenum based system with moderate cams it makes a lot more sense. I suspect problems are fewer than with the VHPD. Link to comment Share on other sites More sharing options...
Tony Martyr Posted August 22, 2001 Share Posted August 22, 2001 I have a dta unit. But I do not have the supersport cams to sell wih the rest of the stuff. Anybody can have the MEMS unit for a donation of £25 to Leuk Fund and any of its associated bits - it is a working spare for a K supersport. The two mechanical sensors of the MEMS are the problems - the manifold pressure device and the Idle air valve. I have solved the problems by not having them. of course the unit has been developed as a system to comply with emissions regulations - there are fewer and fewer of us anarchists left. Link to comment Share on other sites More sharing options...
Mick Day Posted August 22, 2001 Share Posted August 22, 2001 I know of one Superlight R which failed to play at the Ring & gave intermittant misfires at Spa. Altitude wise the Ring is much higher than Spa. All was OK though once back in GB. Bearing in mind there was a similar failure on the Spanish trip at high altitude, there is a definite problem. It appears the MEMS as supplied with the SLR cannot fuel properly at lower atmospheric pressures. Mick Link to comment Share on other sites More sharing options...
Peter Carmichael Posted August 23, 2001 Share Posted August 23, 2001 If you have a look at the MBE web site, it reports Caterham approaching them to get an "altitude and slow running" solution for the SLR. This was when the standard SLR ecu changed from MEMS to MBE. Link to comment Share on other sites More sharing options...
V7 SLR Posted August 23, 2001 Author Share Posted August 23, 2001 What's MBE's web site address? Link to comment Share on other sites More sharing options...
oilyhands Posted August 23, 2001 Share Posted August 23, 2001 Nudger.. its www.mbesystems.com Oily Link to comment Share on other sites More sharing options...
V7 SLR Posted August 23, 2001 Author Share Posted August 23, 2001 Ahah..! I thEnk yew. Link to comment Share on other sites More sharing options...
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