R300 MBE ECU - Kangaroo

[Casbar]

My engine has a tendency to Kangaroo in 1st and 2nd when on a light throttle. The only way to stop it, is too dump the clutch and put the revs up and try again. After the revs build it goes like a train. The car is a 1800 R160 Roadsport, and I've only had it a couple of days. Is this normal with this spec of engine, and do I just have to learn to drive around the problem, or does it sound like a mapping issue

[knowley]

Does it have the Rxxx throttle bodies? If so, yes its normal and its due to your foot "vibrating" (for want of a better word) on the pedal, some people put a little extra "slack" in the throttle cable.

 

R300 Register

My R300

[Casbar]

What are Rxxx throttle bodies, are they roller barrel or is it a specific type of throttle body - sorry if a little dumb, but new to modern engines, traded in a xflow, which was dead simple.

[knowley]

Yep thats the ones, the Roller Barrel things

 

R300 Register

My R300

[j_thombs]

Yep, Roller Barrels....Rxxx because they are fitted to the R300, R400 and R500 cars

 

My girlfriend has the same problem when she drives my car, you just need to learn to drive round it. I find that being a bit more on/off wih the throttle at lower speeds helps i.e. come off the throttle completely or be a bit more aggressive with it when accelerating rather than tickling it.

 

The worst example is the speed hump in my road, if you hit that with your foot resting on the throttle in 1st you kangaroo all over the place

 

The moral of the story is don't use light throttle, a little bit more is always more fun anyway

 

Jon

 

Ex Beaulieu no31 now Supersport R..

 

My Caterham Pics

[Bob Corb]

I've just fitted roller barrels to my VHPD engine and first time out I noticed this. What is happening is that when the throttle is almost closed (i.e. v light when cruising around the village) the ECU thinks that you've gone to zero throttle and either cuts the fuel off completely (revs greater than ~ 2000rpm) or it tries to make the engine idle at 1000rpm by retarding the spark. This is because the throttle sensor isn't quite where set it should be.

 

I had a fiddle with the throttle sensor on the front of the barrels (its a widget at the front end almost under the nose cone and has a three wire plug on it). I loosened the two screws slightly and twisted the sensor anticlockwise (when viewed from the front of the car) and re tightened the screws. Then went for a drive, the kangarooing had gone but when I stopped at a junction the engine revved at 1500rpm instead of droppping back to idle. This is because it never thinks its at zero....so.... with the engine running I loosened the two screws once more (only v slightly) and moved the sensor very, very gradually (so much so you can barely tell you've moved it) until at some point the revs suddenly drop to a steady 1000rpm. Then re-tightened the screws.

 

Bingo, the throttle sensor is now perfect, the engine will run smoothly right down to idle. I love it. Wicked noise, nice driveability, decent idle and the chaps at the Banbury meet wont start coughing when I drive off (sorry chaps it was a bit rich before 😬 😬).

 

Hope that helps.

 

Bob

 

Edited by - Bob Corb on 9 Aug 2004 21:49:36

 

Edited by - Bob Corb on 9 Aug 2004 21:50:36

[knowley]

Interesting Bob, thanks for the tip *thumbup*

[Adam]

I had a similar story to tell .... get the TPS/throttle setting "correct" and the engine is a lot more smooth. No doubt Bobs methed works, or if you search these forums for "0.45v" you might find the setup process word-for-word from CC.

[Casbar]

So this does seem to be a common problem. But, does this mean that the map Caterham supply is at fault as its a one size fits all Can it be sorted out by getting a different map, as my beast is not subject to emssions and doesn't have a cat, would a tweek to the map (possibly to make it run richer at lower revs) make a difference. Surely if a car is on Rxxx and fuel injected shouldn't it pull easily from low revs. My ECU is an MBE EU2 version, so would that mean I have the older map, the engine was converted in May 2003.

 

Sorry for all the ques, but I'm trying to understand whether it has to be like that or it can be sorted out by getting someone to either, look at the map, or try another ECU (Emerald) and a different map

[Peter Carmichael]

This is either throttle body balance, or a slightly lean mixture condition - it can lean out if the acceleration fuelling is inadequate. The problem is made worse because the roller barrels have the throttle quite a long distance from the valves which gives poorer throttle response and idle - still, it shouldn't be an issue on R300 cams.

 

Check the balance. Check the throttle pot reading at idle.

 

Sahf London;

every 1st Wednesday from 19:30 at The Duck just around the corner from Clapham Junction station

[Casbar]

If the mixture is lean, isn't that a mapping fault, or will the correct setting of the TPS sort this out.

[Bob Corb]

Casbar

 

The map should be fine, there are plenty of Rx00's out there. The "problem" (for want of a better word) is that the MBE ECU does not have the capability to learn the throttle limits (like an OE Rover ECU), it must me told by putting numbers in boxes via a laptop. These numbers have been set at the factory for you and all you need to do is slightly move your throttle pot to make sure its outputting the same values. Caterhams map starts at ~0.43volts which is 0 in the load map and goes to something like 5V which relates to load site 15 (Wide Open Throttle, or WOT).

 

The fact that your car is stuttering suggests that the ECU thinks the throttle is closed when in fact you've got it cracked open for light load...likewise the ECU will always think that the load is less than it should be (i.e. when you've got you foot flat to the floor it may think its at load site 14 rather than the full on 15, not that it makes much difference). As you move higher in load more fuel is injected so its not surprising that it may be a little lean.

 

Setting the throttle pot will make sure that the ECU is correctly matched to your engine and should remove most of these faults.

 

BC

[Casbar]

Thanks for all the sound advice (as always). I'll start by checking the TPS, rather than getting the map checked.