 |
 | Home | Contact Us | FAQ | Search & Site Map | Link to Us |
 | Sign In | Join | Other 45 Sites in Network |
Car Forum / MINI / October 2003Fuel Injection Mini poor fuel economy and stutter on acceleration
Hello, I'm getting very poor fuel economy (21 MPG) on my recently purchased Mini Spi. Its only done 20K miles so I dont expect anything too serious.(P reg) It idles a bit high too, almost like the ECU thinks its still cold - which could account for the poor fuel economy if the temp sensor is broken but the emgine temp on my dash is fine. Are there two engine temp sensors on fuel injected minis ? (Starts well and runs nearly perfectly apart from fault described here) I've had minis in the past and consider myself to know a bit but this is my first fuel injected one. So far I've replaced: 1) Air intake Temp sensor in the air filter housing 2) Distributor cap, Leads, Plugs, Coil 3) Air filter itself. I've alse tested the Lambda sensor on an oscilloscope and it appears fine but its a bit tricky to tell 100% because of the 1sec time base needed. I've not used a Parrallel port Scope yet. I''d like to swap out my Lambda sensor with a known good one but they cost £70. Im convinced its fuel related cos the electrics are fine and under heavy acceleration she coughs and takes time get up to speed. Ive never had a mini do this before. Its like pulling out the choke on a standard carb mini, it kind of chokes. Have taken it to my local Rover Dealer here in Aberdeen(UK)Reg Vardy but they proved utterly useless and said there was nothing wrong with it - thats even after the mechanic road tested it and said he could 'feel' the fault. What now folks ? Its totaly standard 1275 Spi mini equinox. Not going to add all the bells and whistles until the engine is running sweet... Please Please offer any help...Thank you in advance. Jon. > I'm getting very poor fuel economy (21 MPG) on my recently purchased > Mini Spi. Check the diagnostics in the computer. It will log any faults it sees. > It idles a bit high too, almost like the ECU thinks its still cold - Which it would log. > which could account for the poor fuel economy if the temp sensor is > broken Which the computer would log as a fault. > but the emgine temp on my dash is fine. Because that is probably a different sensor. > (Starts well and runs nearly perfectly apart from fault described > here) > I've had minis in the past and consider myself to know a bit but this > is my first fuel injected one. Fuel injected cars are easy because the computer logs faults. > So far I've replaced: > 1) Air intake Temp sensor in the air filter housing > 2) Distributor cap, Leads, Plugs, Coil > 3) Air filter itself. Stop spending money diagnosing by replacement and ask the computer what is wrong. > I've alse tested the Lambda sensor on an oscilloscope and it appears If there is anything wrong with it, the computer will log the fault..... > Im convinced its fuel related cos the electrics are fine and under > heavy acceleration she coughs and takes time get up to speed. Ive > never had a mini do this before. Its like pulling out the choke on a > standard carb mini, it kind of chokes. It's probably running rich. It has probably logged a fault with something like the temperature sensor or the airflow sensor as well as an apparent fault of oxygen sensor always reading rich. Try asking the computer? > Have taken it to my local Rover Dealer here in Aberdeen(UK)Reg Vardy Yay! > but they proved utterly useless and said there was nothing wrong with > it - thats even after the mechanic road tested it and said he could > 'feel' the fault. Oh yeah. A Rover dealer. > What now folks ? Get hold of the diagnostic procedures for the injection system and ASK THE BL**DY COMPUTER! I'm sorry to harp on this, but it really is the first step. > > I'm getting very poor fuel economy (21 MPG) on my recently purchased > > Mini Spi. [quoted text clipped - 60 lines] > > I'm sorry to harp on this, but it really is the first step. Hi Graham, I dont mind you harping on at all if it fixes the problem. The reason it went to Rover WAS to ask the Computer. I asked them to hook it up to their diagnostic equipment which they did and they say nothing is wrong with it! Is there something else I can ask them to check ? There was a fault reported with the throttle potentiometer but that went away after some of the connections were cleaned. Any more ideas Graham ? Thanks again in advance. Jon. > > > I'm getting very poor fuel economy (21 MPG) on my recently purchased > > > Mini Spi. > > Check the diagnostics in the computer. It will log any faults it sees. ... > > Get hold of the diagnostic procedures for the injection system and ASK > > THE BL**DY COMPUTER! > > I'm sorry to harp on this, but it really is the first step. > Hi Graham, > I dont mind you harping on at all if it fixes the problem. Oooh put the pressure on me eh! > The reason it went to Rover WAS to ask the Computer. I asked them to > hook it up to their diagnostic equipment which they did and they say > nothing is wrong with it! Yes, I got the impression you weren't very convinced by them either. OK, this sort of stuff comes up pretty regularly here - has anyone got a copy of or access to the factory manuals for the two injected models of Mini? Can we get a hold of the diagnostic procedures and codes? It shouldn't be necessary to use special diagnostic equipment; typically you just bridge a particular pair of pins on a connector somewhere and then the computer flashes particular sequences on the ECM warning lamp to signal different faults. In my Nissan I can literally do it at the side of the road with a paperclip. Of course without the procedure and the codes you're held to ransom by the Rover dealers, who I gather are frequently not very good. > Is there something else I can ask them to check ? I'd like to see if we can get the documentation first before we start trying to do diagnosis over the internet from the far side of the world based solely on symptoms. > There was a fault reported with the throttle potentiometer but that > went away after some of the connections were cleaned. > Any more ideas Graham ? Many faults in older injected cars turn out to be nothing more than corroded connectors; there's a lot to be said for disconnecting and reconnecting each and every join you can find in the engine management system. hiiya or do what i did and chuck the injection system in the bin, but t was easy for me mine is a 92 , but yours would never pass the emissions test . handy thing with mine is it left me with a redundant lamda sensor in the exhaust system so ive made a reader for it so i can get a constant mixture readout :-) fragged > Hello, > [quoted text clipped - 39 lines] > Please Please offer any help...Thank you in advance. > Jon. <snip> > What now folks ? > Its totaly standard 1275 Spi mini equinox. [quoted text clipped - 3 lines] > Please Please offer any help...Thank you in advance. > Jon. If a sensor comes disconected while the engine is running then the ecu will disregard all the inputs from the sensors and run on a preset 'get you home' setting. AFAIK to reset the ECU you have to disconnect the battery for 24 Hours at least (to deprive ECU of power). This is fine as long as the fault is not still there!! If it was mine I'd change the air filter (youve done it), after that i'd try a coil from a similar car (clean all its connections) then replace the lambda sensor last. If your exhaust has a blow then that will fool the lamda sensor too. Have you made sure all your brakes are not binding? hope any of this helps chris > <snip> > [quoted text clipped - 20 lines] > > chris Hi Chris, No, brakes are not binding. Checked them all myself and they are good, plus its just passed an MOT. I have read about disconnecting the power thing but not done it yet I'll try it tonight though. Anything else ? Jon. > Hi Chris, > [quoted text clipped - 7 lines] > > Jon. I would try a coil from another Spi 1275 and clean all the connections on the LT side of the ignition circuit. Also just as a thought, have you checked for air leaks at the inlet/exhaust manifold? Try also running it with reddex, there is a version which is fine for cat equipped cars. If its just passed an mot then I assume its emmisions are ok? The crank sensor is one of those things which often plays up but wont show up on a rover testing setup. chris. |
Reply to this Message |
 Sign In
 Join
 My Latest Posts My Monitored Threads My Blog My Photo Gallery My Profile My Homepage Start New Thread Enable EMail Alerts Rate this Thread
|
©2008 Advenet LLC Privacy Policy - Terms of Use
This website includes both content owned or controlled by Advenet as well as content owned or controlled by third parties.