sorr 0 Posted February 4, 2007 (edited) Would a duff coil and so weak spark cause sooty plugs on an Mi. I would normally say sooty plugs would be over fueling but changing the AFM has made no difference and there is not a strong smell of fuel from the exhaust. Also the coolant temperature sensor and ignition amp are new and injectors have been refurbed. The other sysmtom is what sounds like a miss fire, but not to the same extent as being a cylinder down. Thanks in advance. Stuart. Edited February 4, 2007 by sorr Share this post Link to post Share on other sites
sorr 0 Posted February 4, 2007 Issue now resolved. It was a non-injecting intector. That will teach me to only check 3 out of the 4 plugs. 3 were really sooty so I had assumed the 4th would be, not the case. However this would indicate that my car sounds the same running on 2 cyclinders as it does on 3. I would not have thought it would have run on two, but there we go. Share this post Link to post Share on other sites
sorr 0 Posted February 4, 2007 I spoke too soon, after running fine for about a minute all 4 plugs are now black with soot. Although it must be running rich due to the sooty plugs as I said earlier the exhaust does not smell like there is unburt fuel in the expelled gases. So I am back to square 1, what is causing the plugs to soot up? For info the engine is a rebuilt Mi with a Catcams inlet only, with around 40 minutes of running time. All fuel and ignition componets other than the coil and AFM are new. I would guess the AFM but the plugs that came out the engine before rebuild were normal, so that does not fit unless an AFM can break while sitting on a shelf. Share this post Link to post Share on other sites
taylorspug 7 Posted February 4, 2007 Sounds like you have a similar problem to me. Mine has always run a touch rich (exhaust stinks), and drinks a fair bit of fuel too. Ive tried different everything (bar the ignition amp). Nothing changes at all! In the end ive decided it must be a dodgy AFM, as im not 100% on the other one i tried. So my next move is to get that re-tracked professionally and see if it does anything. It was fine when i 1st got the car running, but has slowly got worse since. Share this post Link to post Share on other sites
B1ack_Mi16 67 Posted February 4, 2007 Water temperature sensor? Share this post Link to post Share on other sites
sorr 0 Posted February 4, 2007 Water temperature sensor? That is new, but I suppose it could be faulty. I think I may need to go down the try another AFM route. Why wil it not just work.... Share this post Link to post Share on other sites
Higgy 0 Posted February 6, 2007 How about oil causing the black plugs? There must be alot about since the engine is re-built. Maybe it just needs burning off? I would get some miles under its belt first, before analyising the engine too much. If your not nailing it then its is not going to go pop even if it is not running 100%. Go up & down the some junctions of the M4 a few times, giving it short 3/4 throttle upto say 4k rpm for say 10 secs then backing off back to say 60mph. Thats what I did for my engine for about 100miles. Nice longish running periods on a open road so everything gets to temperature but will not overheat. Higgy. Share this post Link to post Share on other sites
sorr 0 Posted February 6, 2007 Higgy - Thanks for thr reply. The issue is that the plugs soot up so much that I cannot drive it after a minute or so, so long distance driving is not possible. I did manage to do the cam shaft running and move it about a bit as one of my cleaned injectors was not injecting. It would seem that a non functional intector was enough to lean it off to allow running, and oddly it did not seem to mind running on 3 cyclinders. Any chance you could pop down in yours at some point soon and we could try parts swapping to trace teh fault. I will PM you. Share this post Link to post Share on other sites
j_turnell 137 3 Cars Posted February 6, 2007 Have you had it on a Co machine as afm's are tweeked for each individual engine so putting an unknown afm on a rebuilt engine it will need adjusting.... Share this post Link to post Share on other sites
sorr 0 Posted February 6, 2007 Have you had it on a Co machine as afm's are tweeked for each individual engine so putting an unknown afm on a rebuilt engine it will need adjusting.... But would it be that far out as to soot up the plugs after 30 seconds to a minutes running? To do this I would assume the injectors are giving far more fuel than an out of calibration AFM would, or not? I think it must be a wiring issue as the only time I have seen this before is when a wire AFM connection broke. But I would doubt this as Anthony did the loom and the wires look brand new when you strip back teh rubber cover. So that only really leaves the ECU, why will it not just work! Share this post Link to post Share on other sites
