Miff Posted June 22, 2003 Share Posted June 22, 2003 Having recently taken the cat off (and moved the Lambda sensor to no. 4 primary) i developed a flatter spot at around 3000rpm in my vhpd. Standard rover ECU. When motoring at altitude this became grossly exaggerated with the 3000rpm spot being 'dead' and other spots appearing all over the rev range. This resulted in the thing being undriveable as the only way around it was max throttle - not the best for safe alpine driving! I presume this was air starvation? How do i fix it (without spending too much cash - i.e. a new ecu is unaffordable at present)? Link to comment Share on other sites More sharing options...
Big Brother Posted June 22, 2003 Share Posted June 22, 2003 Put the cat back on and refit the lambda sensor to its original position. Then run it until am Emerald becomes a realistic prospect Guess I'm not being much help am I.... I'll get my coat Steve Se7en-Up! Less is more! Eagles may soar, but weasels don't get sucked into jet engines! Link to comment Share on other sites More sharing options...
Miff Posted June 22, 2003 Author Share Posted June 22, 2003 It's fine at leicester level so i think I'll carry on as is for the mo. Link to comment Share on other sites More sharing options...
Steve-B Posted June 23, 2003 Share Posted June 23, 2003 as i learned on targa liege 2002 at 9500 feet of altitude (and i had been warned by others and didn't listen ) the MEMS ECU is rubbish at much over sea level. in the alps its a killer. our VHPD was neutered in austria and switzerland and italy due to the MEMS. go get yourself an emerald, if you're on a standard/stock VHPD i'll send you a map, or others will. you'll also gain a respectable increase in power in the mid ranges 3-6K from it too ❗ best upgrade done to our car. *thumbup* Steve 210Bhp Sinister Version-VHPD here Link to comment Share on other sites More sharing options...
WD Posted June 23, 2003 Share Posted June 23, 2003 We are intending to go over a few of the Swiss passes in a few weeks. Up to 2700m in a standard 140 BHP Roadsport (EU3). Reading this thread is not good news . Can I expect the performance to be dire and if so, is there anything that can be done to improve it without a huge outlay 🤔 Link to comment Share on other sites More sharing options...
Miraz Posted June 23, 2003 Share Posted June 23, 2003 The standard plenum engines fare much better than those using throttle bodies - you may end up running a little bit rich, but should be fine. At 2700m my car wouldn't even idle... Link to comment Share on other sites More sharing options...
Steve-B Posted June 23, 2003 Share Posted June 23, 2003 140hp Eu3 is the newer MBE controller isn't it? i suppose that someone come along and correct me if i'm wrong. bear in mind we were doing competetition speeds, at below 0 C temperatures in a large amount of the altitude which would have had an effect too... miraz had his emerald, and didn't have the problems i did. i know v7 slr hasn't had them either. Steve 210Bhp Sinister Version-VHPD here Link to comment Share on other sites More sharing options...
Miff Posted June 23, 2003 Author Share Posted June 23, 2003 I was suckered into helping a friend, sorry aquaintance, getting a fine Rover 100 back into working condition and was dismayed to see the ECU on this fine beast looked very similar to mine, I didn't go as far as inspecting closely, the thought made me feel ill, anyway, are there any other options aside from the emerald? I know everyone says it's the dogs and it is probably the way I'll go once i find some cash, i was just interested. Miff. Link to comment Share on other sites More sharing options...
Myles Posted June 23, 2003 Share Posted June 23, 2003 WD - 140BHP is 'Supersport', Roadsport is 115BHP IINM - which is what I've got ☹️ Is there any point in *just* upgrading to an Emerald - or does it only come into its own with the DVA-style cams and vernier etc. Link to comment Share on other sites More sharing options...
andycox Posted June 24, 2003 Share Posted June 24, 2003 Remember that the its not the box but the program within its "chips" that make the difference. I have had no issues with my 1998 1.6ss at altitude with plenium and MEMS but maybe I am lucky. Myles You maybe be able to fine tune your engine by fitting the Emerald i am sure someone will be along in a moment and tell you exactly by how much, but it really comes into its own if you start upgrading the engine etc and then you can adjust the map to suit the modification. Is it SUMMER yet? 😬 Link to comment Share on other sites More sharing options...
Miraz Posted June 24, 2003 Share Posted June 24, 2003 The Emerald won't actually help you much unless it has some way of compensating for the thinner air at altitude. The MEMS/plenum cars (including the EU3) appear to use a combination of throttle position and the pressure/temp in the plenum to determine the appropriate fuel delivery - as the pressure (or lack of it) in the plenum will vary with altitude the ecu stands a fighting chance of doing the right thing. Most cars equipped with throttle bodies only use the throttle position - even though the VHPD mems is equipped with an internal pressure sensor it seems pretty ineffective and is prone to failure. Loss of power at altitude is common with the VHPD engines - Emerald have *just* started equipping some of their ecu's with external pressure sensors to allow them to compensate for altitude changes - without this they are no better than the other solutions. Link to comment Share on other sites More sharing options...
Bob Corb Posted June 24, 2003 Share Posted June 24, 2003 This is probably the prime driver for Caterhams move to MBE management. All R3/4/500 cars have a barometric pressure sensor which cures this problem. If you were to go that way (look out for a second hand MBE 967 ECU, Count has a suitable wiring loom for sale on his website) I could provide you a map as I've now got my "DIY SLR" running on MBE. Bob Link to comment Share on other sites More sharing options...
WD Posted June 24, 2003 Share Posted June 24, 2003 Miraz -thanks for that explanation. Hopefully we will be able to feed back how the standard arrangement performs over the Grimsel/Furka/Susten circuit. Myles - 1.8 X power 140 BHP is now sold as Roadsport. Link to comment Share on other sites More sharing options...
V7 SLR Posted June 24, 2003 Share Posted June 24, 2003 On the Se7ens list Euro2001 tour over the Swiss Alps I had problems with a failed MEMS. Until that point it ran perfectly OK at altitude (apart from the problems I was already experiencing). There is a MAP sensor in the MEMS which has a take-off from the KV6 manifold (which was standard on my 1999 VHPD) which may have helped but this MAP sensor was NOT used as a baro sensor (important). I actually believe the MEMS was simply overfuelling all the time anyway judging by the smell of fuel. Perhaps my engine was less sensitive to this because the altitude did not affect power (long story about only part throttle being available owing to knackered MEMS... but essentially with foot nailed to floor I performed a "hillclimb" of most of the Alps with no loss of power). Half way through the tour I switched to M3DK although not at altitude. This year I have a baro sensor (essentially a MAP sensor which is NOT linked to throttle vacuum) too so I'll play with the settings as we drive over the Alps. If the engine's mapped well to begin with it will suffer at altitude. Worcs L7 club joint AO.//Membership No. 4379//Azure Blue SLR No. 0077//Se7ens List Tours Link to comment Share on other sites More sharing options...
Myles Posted June 24, 2003 Share Posted June 24, 2003 WD - ah 😳 I was thinking in 1600 terms not 1.8 ❗ Link to comment Share on other sites More sharing options...
Steve-B Posted June 24, 2003 Share Posted June 24, 2003 so how much and what do we ask for for these altitude sensors for the M3DK? one presumes it's just wiring the sensor onto a pin of the connector. Steve 210Bhp Sinister Version-VHPD here Link to comment Share on other sites More sharing options...
V7 SLR Posted June 24, 2003 Share Posted June 24, 2003 If you talk to Karl and ask for a barometric (baro) sensor, he'll know what you want. You may need an update to your M3DK software too but Karl will determine what you need. ISTR it was about 25 quid but as it was bundled into my RR session I can't be certain. Be aware that we haven't actually got the calibration numbers yet. Mick Smith and I were going to experiment and come up with something en route. Worcs L7 club joint AO.//Membership No. 4379//Azure Blue SLR No. 0077//Se7ens List Tours Link to comment Share on other sites More sharing options...
charlie_pank Posted June 24, 2003 Share Posted June 24, 2003 Looking at this problem a totally different way - surely it's a bad thing to put the lambda probe on one of your primaries rather than measuring the output from all 4 cylinders? How does the ECU know that it should be measuring 1/4 of the amount of oxygen than it is used to when gathering data from all 4 cylinders? C Charlie'n'Kermit The plan is: Leave for Le Mans on the 7th S5EVN Link to comment Share on other sites More sharing options...
V7 SLR Posted June 24, 2003 Share Posted June 24, 2003 It's not measuring 1/4 the amount. It's measuring a ratio of oxygen relative to whatever gas passes it. The fact that there is only 1/4 the amount of gas passing it is irrelevant to the lambda. It's only after a ratio. Worcs L7 club joint AO.//Membership No. 4379//Azure Blue SLR No. 0077//Se7ens List Tours Link to comment Share on other sites More sharing options...
scooby dooby doo Posted June 24, 2003 Share Posted June 24, 2003 it should still be after the collector though. otherwise if number 4 is a bit rich the ECU will lean off all four. Then 1,2 and 3 will be lean... HOOPY R706KGU Hoopylight R Link to comment Share on other sites More sharing options...
V7 SLR Posted June 24, 2003 Share Posted June 24, 2003 No 4 works perfectly well in a healthy engine. The assumption that each cyl is burning the same is reasonable. You've also to consider those with lambda in the collector means the lambda is outside of the engine bay. Looks terrible. Must be a better way of hiding it. For what it's worth, better to disregard it altogether once you've been mapped. Mine's switched off. Worcs L7 club joint AO.//Membership No. 4379//Azure Blue SLR No. 0077//Se7ens List Tours Link to comment Share on other sites More sharing options...
scooby dooby doo Posted June 24, 2003 Share Posted June 24, 2003 if everything was perfect then you wouldn't need to measure anything... HOOPY R706KGU Hoopylight R Link to comment Share on other sites More sharing options...
kjp Posted June 24, 2003 Share Posted June 24, 2003 If number 4 is a bit rich and it's in the collector it will still lean out all four. errr and surely you don't need a baro sensor if your fueling is based on MAP (MEMS SLR) KenP Link to comment Share on other sites More sharing options...
Steve-B Posted June 24, 2003 Share Posted June 24, 2003 ken at 8,413 ft on stelvio pass you will. then you'll move the lambda to no. 4, put a 4:1 collector, and an emerald. bob's now your uncle , and co-pilot i know from personal experience as miraz and rgrigsby do. it was called Targa-Liege 2003. and the -8- C made it even more amusing, in a blizzard Steve 210Bhp Sinister Version-VHPD here Link to comment Share on other sites More sharing options...
V7 SLR Posted June 25, 2003 Share Posted June 25, 2003 if everything was perfect then you wouldn't need to measure anythingMy lambda isn't measuring anything anyway. The standard lambda is mostly useless in our applications. Not sure that a MAP sensor can be used to measure barometric pressures. Certainly some cars utilise a single pressure sensor by using the MAP sensor to detect ambient (baro) pressures at the point before the engine turns over. By the time you've fired the engine the variation of pressure in the inlet will be so much greater than any barometric pressure changes in the outside world that they will be undetectable to the MAPS sensor. I think. Worcs L7 club joint AO.//Membership No. 4379//Azure Blue SLR No. 0077//Se7ens List Tours Link to comment Share on other sites More sharing options...
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