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Mpi Poor Idle And Unable To Drive Along At 30 With Out Car Spluttering


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#16 rossikey

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Posted 29 November 2007 - 06:55 PM

i bought my 98 mpi a year ago as soon as i got the car i needed to put new exhaust on so bought a lcb maniflow which i wish i never got but hey .I also put a k&n on the car run fine untill i drove to france on the journey it stalled a couple of times when i stoped at tolls but then started up again straight away ever since then it hase never idled right just fells lumpey put a new air flow sensor on i think if that is the green one that goes in the inlet manifold .The car also will not drive along now a low revs with out splutering any idea and if anyone has tell me which sensor is which thanks.The maniflow minifold is also a problem because it always knocks and have now had to take cat of because the manifold was making it hit the body . Thanks


Hi all.

I took a look at my Mini today (98 Paul Smith) to see if I could determine the cause of the erratic (Kangarooing) running around 1500rpm and also idle increase to 1500rpm when doing stop starts in traffic.

It had been suggested if there was an exhaust leak it could be causing the problem, but after looking at the exhaust system and finding no leaks and trying to work out how a leaking exhaust could give my issue I determined this was not my problem. I’m sure if the engine was effect by a lack of back pressure in the system then anyone fitting a free flow exhaust system would in my view have an issue but then I’m no expert.

I then decided to remove the inlet manifold and strip it down to see what I found.

On doing this I found a number of issues which was mainly corroded jointing areas around sensors possibly giving leakage issues and no o-ring present on the inlet temperature sensor and was also loose. Other than this the only other item was what seemed to be some dead play on the first part of the throttle travel until it started to move the throttle position sensor, but at the time assumed this was correct. As I have stated I’m no expert. Just an extra bit of info the engine is completely standard including the plastic throttle body which looks like a piece of C**p and will be changed for a Burlen one with a new cylinder head next year.

I cleaned all the parts up and put it back together started it up and let it warm up. Before I even took the car on the road I held the throttle around 1500 rpm and noticed the engine was still surging so assumed I still had my issues. I then assume the engine was struggling to determine the point where the engine would switch from being controlled by the idle control valve to normal throttle.

When I had a look I was positive it was to do with the slack play in the throttle position sensor. When I had a closer look and worked the throttle it was evident the return lever for the throttle position sensor located on the left hand side of the throttle body as you look at it was sticking. I got the good old WD out and gave it a spray which allowed the lever to return correctly.

So for the big test had I made any difference!

I took it for a spin and Bobs your uncle it ran significantly better than before. All I need to do know is to remove clean the throttle body assembly to ensure it won’t stick again. Ultimately the best fix will be to change it for a Burlen one.

Hope this helps.

#17 rossikey

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Posted 30 November 2007 - 12:12 PM

i bought my 98 mpi a year ago as soon as i got the car i needed to put new exhaust on so bought a lcb maniflow which i wish i never got but hey .I also put a k&n on the car run fine untill i drove to france on the journey it stalled a couple of times when i stoped at tolls but then started up again straight away ever since then it hase never idled right just fells lumpey put a new air flow sensor on i think if that is the green one that goes in the inlet manifold .The car also will not drive along now a low revs with out splutering any idea and if anyone has tell me which sensor is which thanks.The maniflow minifold is also a problem because it always knocks and have now had to take cat of because the manifold was making it hit the body . Thanks


Hi all.

I took a look at my Mini today (98 Paul Smith) to see if I could determine the cause of the erratic (Kangarooing) running around 1500rpm and also idle increase to 1500rpm when doing stop starts in traffic.

It had been suggested if there was an exhaust leak it could be causing the problem, but after looking at the exhaust system and finding no leaks and trying to work out how a leaking exhaust could give my issue I determined this was not my problem. I’m sure if the engine was effect by a lack of back pressure in the system then anyone fitting a free flow exhaust system would in my view have an issue but then I’m no expert.

I then decided to remove the inlet manifold and strip it down to see what I found.

On doing this I found a number of issues which was mainly corroded jointing areas around sensors possibly giving leakage issues and no o-ring present on the inlet temperature sensor and was also loose. Other than this the only other item was what seemed to be some dead play on the first part of the throttle travel until it started to move the throttle position sensor, but at the time assumed this was correct. As I have stated I’m no expert. Just an extra bit of info the engine is completely standard including the plastic throttle body which looks like a piece of C**p and will be changed for a Burlen one with a new cylinder head next year.

I cleaned all the parts up and put it back together started it up and let it warm up. Before I even took the car on the road I held the throttle around 1500 rpm and noticed the engine was still surging so assumed I still had my issues. I then assume the engine was struggling to determine the point where the engine would switch from being controlled by the idle control valve to normal throttle.

When I had a look I was positive it was to do with the slack play in the throttle position sensor. When I had a closer look and worked the throttle it was evident the return lever for the throttle position sensor located on the left hand side of the throttle body as you look at it was sticking. I got the good old WD out and gave it a spray which allowed the lever to return correctly.

So for the big test had I made any difference!

I took it for a spin and Bobs your uncle it ran significantly better than before. All I need to do know is to remove clean the throttle body assembly to ensure it won’t stick again. Ultimately the best fix will be to change it for a Burlen one.

Hope this helps.


Just an update. I took the throttle body back off today to see what was causing the sticking position sensor. When I striped down the side of the position sensor I found the throttle shaft bush had worked it way out and in turn pushing the shaft seal out also which was most likely allowing air to leak past. I corrected this by knocking it back in with a deep socket and then striped the lever side to find the bush on this had also done the same. I corrected the issue and put it all back together and gave it a road test to find all worked OK.

This means I have an even better reason to change it for a Burlen item.

Rossikey.

#18 swiss al

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Posted 06 December 2007 - 11:07 AM

thanks just back from holiday and just to say can not see the throttle body being the problem as when i changed inlet manifold it came with a new throttle body and problem was still there

#19 Sprocket

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Posted 06 December 2007 - 07:58 PM

Cam sensor issue?

#20 swiss al

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Posted 09 December 2007 - 09:10 PM

i have fitted new cam sensor on sat and have been out for drive today and car seems to be fixed thanks for help now just got the prob of paying off credit cards for all the probs

#21 Sprocket

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Posted 09 December 2007 - 09:21 PM

Glad to hear that :D

#22 nicksuth

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Posted 30 December 2007 - 06:21 PM

I have some similar problems with my 98MPi (had it about 6 weeks so still getting familiar with it)

It does start okay and idles around 750/850rpm (when warm) no problem, however, I do have the kangaroo symptoms at low revs/speeds, i.e. in traffic.
It has a full Maniflow exhaust system (with the knuckle joint) and all appears to be sealed and engine mounts/steadies etc. are all in good order.
On accelerating it runs great up to about 5,000/5,500 at which point it starts to splutter a bit with power dying off and if you try to just feather the throttle the splutter appears as if the mixture is wrong or fuel is being starved? A good boot of the throttle at any point and in any gear brings it back to life but this means I'm constantly accelerating/decelerating on a run (not good for fuel consumption!!).
I pulled the spark plugs today and they are NGK "Ridium" BKR7EIX although I see from a previous reply NGK BPR6ES are recommended? The ones fitted have a very thin centre electrode, are gapped to 0.025" and colour is a light brown (correct if I remember correctly?).
Just searched through the paperwork that came with the car and found an invoice/report for diagnosis of the same fault (obviously never fully cured?) with the following actions taken.........
- Lambda Sensor changed
- Spark Plugs changed
- Fuel Filter changed
- Fuel Pump Relay fitted (see below)
The above appears to have solved the initial problem as there was only 11.2v at pump and hesitation cured when supply to pump taken direct from the battery, thus relay fitted (is this additional to standard?)
- Thermostat changed
- ECU removed and sent for test = OK
- Wiring from ECU to Coil pack changed

This was all carried out in Aug 2007 and car only done 750 miles since then

ANY OTHER IDEAS FROM YOU MINI EXPERTS ???

PS - the diagnostics cost was £850 which I would rather not spend!!!!

#23 swiss al

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Posted 30 December 2007 - 09:29 PM

as i have found out it was the cam sensor that fixed the problems i was having after changing just about everything it cost 65 pounds from my local ex rover dealer kingsburys just be careful because it took them two hours to find the cam sensor on the computer because it was under crank sensor you will find the cam sensor on the back of the engine routhly were the old fuel pump was on older minis good luck

#24 nicksuth

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Posted 02 January 2008 - 04:36 PM

There are both Camshaft Position and Crankshaft Position Sensors fitted to the MPi, was it definately the "CAMSHAFT" sensor you changed?
How easy was it to change?

#25 swiss al

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Posted 03 January 2008 - 08:55 AM

it was the cam sensor for sure and it is realy easy just take the electrical plug off unscrew one bolt that holds the sensor to the engine then pull the sensor out of the engine mine was a bit stuck so had to pull hard do not forget to put the rubber washer on new one when you put the sensor back in




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