dc2100k
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| posted on 21/3/22 at 09:43 AM |
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MBE 9A4B Issues
Hi all,
I joined your forum as I'm led to believe it is where the MBE experts hang out  I've got a new-to-me Lotus Elise S1 that has had a
2.0 Duratec conversion including SBD upgraded cams, Weber throttle bodies and an MBE 9A4B ECU setup. It's a very potent little machine and I
recently had a little bit of work done to it and put it in for an MOT, which it passed. However, after picking the car up there is a persistent
misfire around 2500rpm that wasn't there before and I am looking to try to find a procedure to troubleshoot the ECU. The SBD website isn't
much use and I'm about 90 mins drive from the people that mapped the car so I'd rather do what I can at home first.
The work that the car had done included welding a harness bar onto the existing roll over hoop, so the battery was disconnected from the car for an
extended period. The car turns on fine, you can here the pump prime and it fires up straight away. The car settles to a fairly regular idle at 1000rpm
but does skip up to 1200rpm every couple of seconds then back to 1000rpm. It wasn't doing this before either. You can pull away and drive the
car ok but it hesitates around the 2500-3000rpm mark. Above this it pulls strongly to 5000rpm+, I haven't tried above 5000rpm as I was on cold
B-roads and I didn't want to crash 
I'm going to give a good check over the ignition system including the leads, but in the meantime does anyone know a procedure for resetting the
ECU? Is there anything else that needs to be recalibrated like the TPS or similar?
Thanks in advance.
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SteveRST
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| posted on 21/3/22 at 05:47 PM |
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I'm no expert (far from it!) but I do have some experience of the predecessor of the MBE 9A4 ecu (the MBE 992) in a hayabusa turbo kit car.
However, in order to connect the ECU to a computer you'll need the MBE CAN mapping kit
https://www.sbdmotorsport.co.uk/MBE-MAP-KIT-3-CAN-basic-can-mapping-kit-for-mbe-can-based-ecus.html and possibly another connecting lead
to connect that mapping box to your ecu. It's not cheap!
I had a similar situation to you... where the lower rpm drivability was awful, but it seemed OK under load and at higher rpms. In my case, the TPS had
been slightly knocked which messed up the TPS calibration. However, although I could use a multimeter to read the values from the TPS (at closed and
at full throttle), I had no way of knowing what values the ecu was actually expecting to be seeing i.e. how the TPS values were calibrated and saved
in the ecu. So it was pretty useless trying to adjust the TPS without knowing what values the ecu had been programmed to expect.
So, I bit the bullet and bought the mapping kit from SBD. It proved to be very useful and I've since added a lambda sensor which I've
interfaced with the ecu for closed loop fueling, set up electronic boost control which is controlled by the ecu, set up the cold-start enrichment, and
basically re-mapped the engine myself. So, could be a useful bit of kit if you fancy doing some fault finding yourself.
Edit - SBD do offer remote diagnostics sessions where they can connect to your computer remotely and take a look at ecu related issues. Although, I
guess you'd still need the mapping kit anyway for this option.
Steve
[Edited on 21/3/22 by SteveRST]
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Oddified
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| posted on 21/3/22 at 10:01 PM |
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As mentioned above, you need the 985 CAN-USB interface and connect it to a lap top running Easimap 6 (free download from SBD or Mbe). Then check the
sensors are reading sensible values for coolant temp, air temp etc and the TPS is at site 0.0 at idle/closed throttle and smoothly rises through to
15.0 as you open the throttle. Then with it running, watch for any spurious rpm fluctuations.
If it's been setup with a cam sensor/sequential injection etc (if running on COP's quite likely, if on a coil pack/wasted spark less
likely), then check it's detecting a valid cam sensor signal and syncing
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perksy
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| posted on 21/3/22 at 10:03 PM |
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Been a little while since I've had a fiddle with MBE
Do you have the relevant software on your laptop and the connection lead ?
(It used to be free to download from the SBD website)
This will allow you to check the set-up of the TPS which would be a good start as a multimeter will only take you so far as you really need to see
what setting the ECU is seeing and you'll need to connect to it to see that (the TPS setting will correspond with the programmed map in the
ECU)
Also what type of TPS is fitted, Is it one of the Colvern ones?
I had one of these fail and it gave allsorts of problems until it finally bit the dust 
You could see it had failed as it was jumping all over the shop when viewed on the laptop
Not saying this is your problem though and I'd be giving the ignition system the once over first
Check plugs and leads, start with the simple stuff first and then go from there...
As Ian says above, if you can connect to the ECU you'll be able to see what's going on
Coolant temp sensor and air temp sensors should be within a couple of degrees of each other with the engine cold
[Edited on 21/3/22 by perksy]
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dc2100k
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| posted on 22/3/22 at 11:20 AM |
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Hello all, thanks for the detailed replies. I do have the 985v USB-CAN connector here and a CD-ROM of some description. I will look to get the latest
software set up on my laptop and will plug it in to do some diagnostics. The car has Weber Alpha TBs on it (TPS type TBC) and a standard coil pack so
no wasted spark/COP. The leads are Magnecor but are a good few years old so probably worth an inspection in the dark. I'll pull the plugs as
well and have a look.
Appreciate the help, will report back with an update even if it takes me some time - two small children tend to limit the amount of time one can spend
tinkering in the garage!
[Edited on 22/3/22 by dc2100k]
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