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Mpi Running Rough No Power Mystery!


Best Answer thelittlecarcompany , 13 January 2017 - 12:24 PM

Well after a lot of struggling it's finally off! It had very nearly destroyed the crank but after careful rebuild the mystery is solved it now runs perfect. Thanks for all your help guys :) Go to the full post


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#1 thelittlecarcompany

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Posted 07 January 2017 - 10:18 PM

Hi guys new on here, I currently have a p reg mpi in my workshop that will not run right at all, has been to 4 garages before me and no one could solve it. So I'm determined!!

First of all I noticed the tappets were incorrectly adjusted, so reset them correct, after a compression test saw that all 4 were low, remembering that all exhaust valves were very tight I decided to whip the head off. Valves were a mess, real mess! in fact everything was!

Reseated valves - took a decade and a day! checked head, pistons slap and rebuilt, after a dropdown test compression very good.

Still wouldn't run right, put it on 3 different code readers we use in the workshop, one being oe rover gear from a closed down dealers and no codes present, checked everything on live data and lamda voltage is high and map Kpa is around 60 which is also high.

Every earth, sensor, wire etc have been checked/replaced and still no resolve.

On over run ( off throttle from hard revving unladen) it has a nasty rattle from timing chain end, removed belt to check it wasn't alternator or pump (which is what i thought initially so ignored it temporarily) and it's still there, I am assuming it is the chain or guide? Would this cause it to run awful if the chain had stretched? I've never had a fault like this before but is it possible it has a poor quality chain that has just stretched beyond normal thinking?

Thanks guys really stuck on this one!

#2 Archived2

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Posted 08 January 2017 - 10:11 AM

If the timing chain sprocket is worn the chain may have jumped a tooth etc. Needs investigation

Edited by minihobbymini, 08 January 2017 - 10:12 AM.


#3 FlyingScot

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Posted 08 January 2017 - 12:42 PM

MEMS can adjust the timing of most of the motor (spark, injectors) but not the cam timing.
Since it shouldn't be making a racket it could have jumped a tooth as per minihobbymini or may sloppy on the timing.
These MPi motors run fairly close to the wind.

Please give more detail about what you mean by not running right at all.....

FS

#4 thelittlecarcompany

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Posted 08 January 2017 - 02:42 PM

Thanks for your replies, I have had to come to the workshop on a Sunday to investigate as the customer really needs her car back. Annoying!

So running,
It fires up without hesitation
it idles lumpy but doesn't cut out
It coughs pops and bangs when revved freely
Get in it and try to pull away and it has no torque at all even at wheel spinning revs
Sometimes it may be better than others but this may be down to road angles temperature etc

It generally drives like an earlier non injection mini that is miles out on the timing.

Thanks I will get into the chain and see what's going on and report back!

#5 thelittlecarcompany

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Posted 08 January 2017 - 04:32 PM

So after stripping it down I have discovered a heavily worn and snapped in two chain tensioner and the chain has about 10ish mm of play in it, would this cause really poor running? As a matter of course I will change the cam sensor as well while I have access and a known good spare here too.

#6 FlyingScot

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Posted 08 January 2017 - 08:26 PM

I think you know the answer...poor timing will cause this.
The MPi fuel injection will try it damndest to keep the motor running, if it were carb it would stall.
Cam sensor would have thrown a fault on the rover (presume testbook) system if fault.
Points very much to a mechanical issue which is being masked by the bomb proof ability of the injection cars to keep running

FS

#7 FlyingScot

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Posted 08 January 2017 - 08:28 PM

My only concern is what other bodies have the previous garages inflicted on it....

For example is the exhaust and cat free passing?

Start with the basics as you have done :thumbsup: mechanical settings and wiring, earths before thinking anything more complex

Good hunting and please update

FS

#8 thelittlecarcompany

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Posted 08 January 2017 - 11:26 PM

Thanks for your reply, I will fit new timing gear tomorrow and let you know what happens, but yes as you mentioned, it had been to 5 other garages before coming to me, the previous have in total charged the poor customer just short of 1100 quid with no avail. They have replaced various sensors, coil, leads, cat all with what look like cheapo parts plus messed around with tons of wiring ( household screw blocks to join wires) I have removed all of this sorted the wiring and earths and effectively reversed time fitting all known good from stock sensors etc (once resolved I will check and keep/bin items after diagnosis)
So hopefully this is the answer! The poor owner uses it as a daily car she is a full time carer so I have thrown most garage ethics out the window in order to fix this mystery for her!

Also to add to diagnosis, as well as the chain stretched and tensioner cracked, the crank chain pulley has for and aft play which will also throw the timing I guess, new pulley and woodruff key will also be fitted tomorrow.

Fingers crossed! Thanks for your help!!
Scott
The Little Car Company

#9 FlyingScot

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Posted 08 January 2017 - 11:47 PM

Good on you Scott, yes mechanical issues first; shocking amount your customer has paid to get to this stage. MPis can be tricky but step by step will get you there

FS

#10 jamesmpi

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Posted 09 January 2017 - 06:48 PM

How did you get on with this?

#11 thelittlecarcompany

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Posted 09 January 2017 - 08:33 PM

OK so that made no difference at all! It is still running exactly the same, the lambda is reading lean on a standalone lambda gauge, what would cause this? It has good fuel pressure so pump etc are all good.

#12 Archived2

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Posted 09 January 2017 - 09:04 PM

Flywheel has a timing ring. It's rare but I have known these to slip. Also heard of the clutch flywheel location centre being fitted wrong

#13 thelittlecarcompany

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Posted 09 January 2017 - 09:51 PM

If it has slipped how would I be able to tell? That would make sense as to why the ignition timing is out as well. I don't think it would have been fitted wrong it hasn't had a clutch since she's owned it and it did run fine before. Thanks

#14 thelittlecarcompany

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Posted 09 January 2017 - 09:52 PM

Is there any chance it could be the ecu and the company that checked it were wrong? Really need to get to the bottom of this tomorrow as it's just getting silly now :(

#15 Shifty

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Posted 09 January 2017 - 10:00 PM

Has it got the locating rings in the inlet manifold? 






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