Mini running rich and won't rev out
Discussion
Evening all.
I've got a problem with the Rover Mini Cooper MPi engine fitted into my Mini Marcos kit car. I'm just about to put it in for IVA when it started misbehaving.
Everything points to it being a sensor problem but swapping out components from my 99 MPi mini hasn't cured the problem. Googling 'MPi mini won't rev' (or similar) shows lots of people trying to chase a similar fault on Rover cars without really stating a solution.
A fuller write up is here along with suggestions I've received from people with more knowledge in these things than me: http://www.turbominis.co.uk/forums/index.php?p=vt&...
But any suggestions to look at or check are welcome please, as this problem could seriously look to derail this project.
Thanks,
I've got a problem with the Rover Mini Cooper MPi engine fitted into my Mini Marcos kit car. I'm just about to put it in for IVA when it started misbehaving.
Everything points to it being a sensor problem but swapping out components from my 99 MPi mini hasn't cured the problem. Googling 'MPi mini won't rev' (or similar) shows lots of people trying to chase a similar fault on Rover cars without really stating a solution.
A fuller write up is here along with suggestions I've received from people with more knowledge in these things than me: http://www.turbominis.co.uk/forums/index.php?p=vt&...
But any suggestions to look at or check are welcome please, as this problem could seriously look to derail this project.
Thanks,
Suggest you check with the basics:
Have you got the right fuel pressure and is it maintained correctly as the manifold pressure changes?
Is the engine going either lean or rich as it approaches the misfire conditions?
Have you got a strong spark at the plug, and does it remain strong across the rev and load range?
Is the spark at the correct time? I have no idea what your ignition system looks like but I've seen dizzies set up so that HT contacts are outside the angular range of the rotor arm under some conditions, leading to cross firing and misfires and all sorts of weird stuff.
A passive strobe in a plug lead, checking the timing against mechanical TDC (not those lying timing marks on the front pulley) and WB02 ought to tell you what type of problem you're chasing.
Have you got the right fuel pressure and is it maintained correctly as the manifold pressure changes?
Is the engine going either lean or rich as it approaches the misfire conditions?
Have you got a strong spark at the plug, and does it remain strong across the rev and load range?
Is the spark at the correct time? I have no idea what your ignition system looks like but I've seen dizzies set up so that HT contacts are outside the angular range of the rotor arm under some conditions, leading to cross firing and misfires and all sorts of weird stuff.
A passive strobe in a plug lead, checking the timing against mechanical TDC (not those lying timing marks on the front pulley) and WB02 ought to tell you what type of problem you're chasing.
Thanks Green.
I think I've had a break through though - I spoke to Lance at Green & White (Co Durham based mini specialist) today who've helped me out numerous times over the years. After describing the symptoms while he hadn't come across this exact problem he did suggest checking to see if the engine was drawing in air somewhere causing the ecu to try and add fuel. (I said I couldn't see any poor hoses). He said he'd come across quite a few MPi's where the seal between the inlet manifold and the head had been crap, having to have the head and mating face of the inlet manifold skimmed/stoned to try and get them to seal.
To check he suggested opening the throttle just to the point where it was stuttering and spraying the inlet/face joints liberally with carburettor cleaner - if the engine picks up, you're sealing the air leak and that's the problem (poor sealing allowing air to get in). So with fire extinguisher to hand that's what I did and guess what - that's the problem. Happy days.
Some more investigation needed - why has the gasket suddenly given way? Has something happened to the inlet manifold?
And I need to find a reliable way to clamp/seal the head/manifold (I am using the correct metal faced MPi gasket by the way). After all, the cars only done 1.1 mile (perhaps about 90 minutes running in total).
But at last a step forward
(Hope I'm not being too premature).
But thanks for your suggestions. I'll be sure to be back and ask on here for help again.
I think I've had a break through though - I spoke to Lance at Green & White (Co Durham based mini specialist) today who've helped me out numerous times over the years. After describing the symptoms while he hadn't come across this exact problem he did suggest checking to see if the engine was drawing in air somewhere causing the ecu to try and add fuel. (I said I couldn't see any poor hoses). He said he'd come across quite a few MPi's where the seal between the inlet manifold and the head had been crap, having to have the head and mating face of the inlet manifold skimmed/stoned to try and get them to seal.
To check he suggested opening the throttle just to the point where it was stuttering and spraying the inlet/face joints liberally with carburettor cleaner - if the engine picks up, you're sealing the air leak and that's the problem (poor sealing allowing air to get in). So with fire extinguisher to hand that's what I did and guess what - that's the problem. Happy days.
Some more investigation needed - why has the gasket suddenly given way? Has something happened to the inlet manifold?
And I need to find a reliable way to clamp/seal the head/manifold (I am using the correct metal faced MPi gasket by the way). After all, the cars only done 1.1 mile (perhaps about 90 minutes running in total).
But at last a step forward
(Hope I'm not being too premature).But thanks for your suggestions. I'll be sure to be back and ask on here for help again.
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