Matt1977
27 posts
Joined: 05/01/2005 19:21:43
Location: United Kingdom (Excluding channel Islands)
Replacing throttle body on an MPi mini / fitting a stage 3 kit
Hello all, Ive seen that its possible to buy a replacement throttle body for MPi minis. Its made of metal rather than plastic and increases the diameter of the trottle body by 4mm. The advert claims improved torque and acceleration across the whole rev range of ca. 10%. Can anyone explain to me how this is possible, what the effects would be on fuel economy etc? Are there any dangers in doing this? Im also interested in fitting a stage 3 kit to the same car. Does anyone know if this will poison my catalytic converter or cause any other problems?
Posted: Feb 11, 2005 11:52 AM
pickme
672 posts
Joined: 08/09/2004 23:10:14
Location: Chippenham United Kingdom (Excluding channel Islands)
Throttle Body. This replacement (assuming you mean the SU one) is better because: a) its bigger (you can get standard size) so this can improve air flow if you have a suitably modified inlet manifold. This means more fuel/air can get into the cylinders. Strickly speaking, it doesnt ADD power, just removes a bottle neck in the air-in-exhaust-out process which can result in a power increase. b) It opens fully rather than the 75% maximum from the standard. Also improving full throttle air flow. c) its metal, so is less prone to cracking which can cause air leaks and cause the throttle butterfly to jam open. I doubt that the side effects would be that great. The ECU will not let the fuel/air mixture get to the point that it will damage the CAT. Stage 3 Kit. Depends what you mean by a stage 3 kit. This tends to mean different things to different people. If you buy one designed for an MPi Mini, then it should work fine or they wouldnt sell many.
Posted: Feb 11, 2005 03:53 PM
jimbob 1984
6 posts
Joined: 21/09/2004 12:36:32
Location: Figino Switzerland
Body throttle..
Hi I was wondering if the 52mm throttle body that you sell is also for Spi edition minis?! Ive read that this fuel system can produce a power gain up to 10% and that is more reeliable than the original plastic ones.. Thank you!! James
Posted: Aug 10, 2005 05:12 PM
SPi throttle body.
I have a new one for sale if your interested. You could also try Minisport (the only place Ive found online who actually have one) who are selling them for £350 at discount (ouch). Im selling mine for £250.
Posted: Aug 13, 2005 12:10 PM
Jan
37 posts
Joined: 14/10/2004 16:34:54
Location: Oslo Norway
spi inlet and throttle body
Woods and picket has a kit that is giving appx 10 % more according to them. Price is still £350 but I believe this is on exchange only. So you have to take into consideration freight of old kits from Swiss to England. jan
Posted: Aug 22, 2005 09:06 PM
Problem with Burlen 52mm throttle body on my twin point Cooper
Hello all, I recently fitted a 52mm Burlen throttle body to my twin point Mini Cooper and ive had some problems with it namely: 1) The idle speed is high (ca.1300 RPM at idle). 2) The spring on the arm connected to the throttle cable doesnt go back to a hard stop. 3) In traffic when i push down the clutch pedal the engine revs up to about 4,500 RPM and wont go back to normal idle without holding the clutch on the bite-point until the clutch starts smoking! 4) The range of my car has reduced by 30%(probably the high idle) 5) When i change up a gear the revs increase despite me not putting any pressure on the throttle pedal !!! Has anyone had a similar experience or an idea of whats wrong / how to fix it? Every month in MM and MW i see cars with this little blighter fitted and no-one seems to have problems - in fact everyone seems to see an improvement with MpG etc! Have i just got a faulty one or are some of the things listed above a standard improvement over the original part??? Thanks Matt
Posted: Mar 31, 2006 12:18 PM
Andy
20 posts
Joined: 30/11/2004 11:44:55
Location: huddersfield United Kingdom (Excluding channel Islands)
Hi, i have one myself. does the throttle butterfly close fully when your foot is of the peddal? if not the the ecu will not recognise an idle throttle position but you can adjust it with the throttle stop screw on the side, this is what i had to do as mine was miles from closing properly when i got it out the box! hope this helps.
Posted: Apr 01, 2006 12:58 PM
MattBumble
3 posts
Joined: 11/02/2007 22:03:08
52mm Burlen Throttle Body
Hello
I recently fitted a fancy new 52mm throttle body by Burlen.
The problem is, I get a hissing sound when the throttle is in a particular position, just as I slightly accelerate past "maintaining speed at 40mph" kinda position.
Almost like when you turn on a tap and in a certain position its all noisy and wooshy, know what I mean?
Well anyway, this isnt normal is it? If not, how can I find out what the problem is?
Also, what results have other ppl had after fitting one? Ive not really noticed much, apart from a deeper noise and a very slight loss of power at the top end, which Im hoping is just ECU confusion. Although its been fitted for over a week now, surely it would have smoothed out by now?
Cheers guys, I hope you can help
Posted: Feb 11, 2007 10:13 PM
T. Perks
57 posts
Joined: 19/11/2006 09:21:16
Location: Wotton under Edge United Kingdom (Excluding channel Islands)
Sounds very much like you have an ait leak some where, having not fitted one myself, do they have a gasket or an o ring under them check all is lined up right try the old squirt some wd40 around the joints trick and see if its drawn into the engine.
Posted: Feb 12, 2007 11:28 AM
John
1948 posts
Joined: 28/05/2006 16:49:46
Location: cambridge United Kingdom (Excluding channel Islands)
You will get more intake noice/hiss if u have a open intake or a cone type filter compared with original airbox and snorqle. i dont know that you are using tho.
Posted: Feb 12, 2007 01:19 PM
Im using the K&N noise maker at the moment. But i never noticed the hissing with the standard body. Surely the extra few mm shouldnt cause it to hiss??? Im also a bit confused as to why it loses power at the top end now, I cant actually make it redline without thinking "ooooooohhh I have to change up" whereas I know ppl who can take it right up to idiot point, and with the same kind of setup as me.
It seems odd that its silent while maintaining speed (when the valve is only slightly open, and therefore more likely to hiss I would think) but when you begin to accelerate a bit more, it makes the hissing noise.
Posted: Feb 12, 2007 10:45 PM
LewisCr125
136 posts
Joined: 13/04/2006 17:03:39
Location: Old Knebworth United Kingdom (Excluding channel Islands)
The ecu will limit the max fuel injection. This max will be set for perfect running/combustion/emissions blah blah at max revs/air intake with totally standard parts. Now you've fitted high flow air filter and big throttle body it's taking in even more air than before. The ecu will still think it's the standard unit and will not inject more at high revs.
At high revs your engine will be running lean. This is dangerous.
The best bet is to get the fuel ecu remapped. A cheaper option is to fit larger injectors. The ecu can't measure what it injects out. Just the pulse time and length.
Posted: Feb 12, 2007 11:10 PM
Ummmm, not sure thats completely true.
The ECU is not mappable, but self learning (to a certain degree). Kind of like having a built-in portable rolling road. I reset it after fitting the new body so it should be makingmeasurements here and there and changing fuel flow to suit
Posted: Feb 13, 2007 09:26 PM
But there's a point where it won't inject more fuel. programmed from factory. To keep emissions down.
If the throttle body was 60mm or bigger, it wouldn't be able to inject anymore.
They don't exactly self learn. Just measure lambda and adjust fuel accordingly to keep lambda 1. Remember the reason for mini's went to injection was for emissions. The system is going to be based around emissions, not power.
Posted: Feb 13, 2007 11:27 PM
The old MEMS spi used to learn the way you drove and adjusted itself to a certain extent within pre-programed parameters of fuel and ignition map, to the extent that when swapped from one car to another took some time to re set itself tothe new engine and driver, thay do have quite a range and as long as the sensors on the car are all working ok, you can do a fair bit to the engine and it will cope.
Posted: Feb 14, 2007 09:44 AM
Neil
28 posts
Joined: 11/02/2005 07:20:41
Location: Chichester United Kingdom (Excluding channel Islands)
The engine MAP sensor, through the ECU, controls the amount of fuel injected into the engine. Atmospheris pressure - Manifold pressure = Manifold Absolute Pressure (MAP). The ECU will increase the fuelling in response to extra airflow into the engine. The theory is that the 52mm TB will allow more air in at full throttle, the exact amount dependent on head modifications etc. Increasing the TB size past the point where it effectively does not restrict the airflow into the engine will not increase power, and in our experience may cause problems on part throttle operation probably due to decreased air velocity at lower demand situations. True, there will come a point where the ECU will run out of range and the fuelling will not be increased to match the airflow, but unless your engine is very highly modified I would not expect this to be an issue. My SRE engine, (SRE Head, Cam, Maniflow LCB, balanced, etc) to all intents and purposes produces identical figures with both a standard and 52mm TB upto circa 5500rpm, from then on the 52mm body allows around an extra 5bhp max but very importantly is producing around 9BHP more at 6500rpm as it approaches the limiter. Interestingly, the engine produces slightly more power power using a JCW airbox than when running with either K&N Cone filter.
Posted: Feb 22, 2007 09:48 PM
Dutchy
10 posts
Joined: 16/03/2010 22:29:22
Location: Bentleigh East Australia
Not starting & Misfiring through throttle body - SPI
Hi All, finally got to the point where I could crank the engine over for the first time after taking it out of a half cut & putting it in my restored body. Details: 1988 Rover mini with a 1994 1.3 SPI manual. full wiring harness and running gear were installed. the vehicle was running before i removed it from the half cut so i know it should run ok. Things that i have done to the engine are: had the head ported and bigger inlet valves installed. All gaskets changed from the block up. i removed the timing chain and gears after marking them both to ensure it all went back to the same position. The engine cranked and nearly kicked over but just wouldn't go that extra bit to start. Fuel is fine, there is spark. All wiring plugs are connected except the instument cluster plug which i didn't think would make a difference. After checking the rotor i found that it was pointing to cylinder 4 instead of 1 when it was TDC. i changed the leads around and now it back fires through the throttle body and still won't start. It sounded like it would have more chance of starting with the leads the wrong way round but obviously that won't happen. Any ideas or testing that i could do? i have tried everything i know and am stuck. there are heaps of pics on my website incase you want to have a look at what i have done to assist. dutchysmini.com
Posted: Mar 06, 2011 11:33 PM
STOP!!! just worked out that when both 1st & 4th cylinder are at the top that the timing mark will still be at '0' so i will change the leads back to their original position which didn't back fire.
So back to square one. cranks and almosts kisk over but doesn't. i'll go home disconnect the ECU and plug it back in and check the vacumm lines to see if this helps.
Posted: Mar 07, 2011 12:57 AM
Barry Brown
511 posts
Joined: 23/06/2008 12:08:31
Location: New Barn United Kingdom (Excluding channel Islands)
have you done a static timing check? try the old 'indicator bulb and wire' test on it to make sure it is set properly. and i've got to check this one - #1 cyl = water pump end, yes?
(yeh, i know, but it's as embarrassing as calling out the AA when your wife hasn't bothered to fill the tank up last time she borrowed the car.....)
Posted: Mar 07, 2011 09:34 AM
Wooooooo Hooooooo. After adjusting the tappets and setting up the stepper motor and accelerator cable it started first go. unbelievable. the engine sounds strong and smooth. should have it back on the road by the end of the month now to really test it out.
Posted: Mar 08, 2011 11:53 PM