• Hi, I have the 1.8 V6 which drives really smoothly until I give it a bit of stick. I can drive it quite hard for a good few miles and it runs so well, but when I get close to home and sit at lights etc the engine starts to splutter and the rev counter jumps around. It is then very juddery on acceleration. Left overnignt it returnes to normal. If I drive around town it never shows up, just after its had a 'good' drive.

    Any ideas before I start poking around (I'm a bit of a novice so don't want to try setting the TPS if its not the cause), and if it is TPS would it not be doing this all the time and from cold?

    Many Thanks for any help…

  • I would say no to TPS as the signal should not be affected by temperature and can be measured under any condition IIRC.

    So what changes after you give it some stick. Something doesn't like getting hot and causes the problems. Maybe a sensor out of range?

    If you drive the car normal for a time will the smoothness return or does it have to cool down overnight (as you say)

  • Quite possibly the coil in the distributor starting to go. Renowned for getting cooked then failing.

  • Mine first mx did the same with the dizzy
    try just replacing cap and rotor arm to start then if still the same you may need one of these ingnition coils

    make sure you get the correct one, there are 2 types for the MX3 on cap arm and coil for the V6

  • YEP! I concur with the above knowledgeable fellows, COIL or HALL trigger unit? :shock: I have had both go on two separate occasions and symptoms are very similar?

    When cold and on fast idle the symptoms are 'camouflaged' due to ECU running on a dedicated warm up ignition curve/profile, as soon as ecu receives a 'normal operating temp' signal from CTS it will use another 'map' and that's where the trouble will begin!!!! mine was like a 'switch' had been flicked, turning the car into a 'kangarooing roadblock'! :( but like yours, could be coaxed around town on light throttle if driven like miss Daisy.

    I would double check TPS set up again ( in How to's ?) first tho? (has it been disturbed recently? or has some one adjusted idle speed without shorting TEN and GND pins in diag box?).

    Coil can be checked for resistance etc but hall trigger/IG unit is V difficult to check for faults :(

    If dissy is at fault take care buying 'working units' :x off 'none' MX3 owners on E bay!!!! I got stung once :oops: never again. try on here first when you locate the offending item? :D

    kev b.

  • Hi guys, thanks for all the help, been a bit busy recently and will be trying some of your ideas soon, didn't want you to think I wasn't grateful for the help….will let you know how it goes.

  • I have changed the ignition coil but have struggled to rebuild the unit. I kept everything in the order it came out but when fitting the metal stepper disc it now touches the plastic housing. I fired it up and had a squealing noise and found it had put a grove into the plastic as it spun around.

    I cannot see any way to raise it enough with the same washers I took out!

    I have had a quick drive and yet to see if the coil has cured my main problem but it does feel smoother. Any tips on the positioning of the parts or any guides?

  • Hi dazse,

    I had exactly the same clearance issues on rebuild !!

    under the coil as you may have seen?? is the spindle bearing supported by a bracket held by two philips screws,

    the bearing is a press fit on the shaft and sits against a shoulder on that shaft preventing the rotating components in the dissy riding up towards the carbon brush/dissy cap, Iirc there is a top-hat spacer and washer under the rotor??? but I think the problem is that the bearing has moved on the shaft and hence the very tight clearance under the rotor has vanished resulting in contact!!!

    You could try:
    A. Firstly mark dissy position at mating flange to head, remove the dissy to gain access to dissy driveshaft end that engages into front exhaust cam,
    gently tap the shaft with a copper or lead faced hammer towards the body of the dissy itself, perhaps take a measurement with a steel rule first to see if there was movement after tapping with hammer??? or rotate the rotor again by hand to see if the interference has been removed?

    B. add another washer or shim under the two rotors between them and the top-hat spacer to raise the rotating components away from the delicate 'Hall triggers',….you may be having 'metal to plastic' contact at mo but if that progresses to 'metal to metal' then things will 'FAIL' !!

    Always best to double check your work tho??... if it was fine before and you've not had something drop on floor and scuttle under workbench???? and now there's a prob, then usually it's pilot error???? :oops:

    Hope this helps a wee and you sort it all out :)

    kev b.

  • Thanks Kev b. thought I was going mad! I will have another look at the weekend. :cheers:

  • All back together now, but unfortunately the original problem is still showing up :(
    Drove for about 10 miles and stopped for a few minutes then revs started jumping around. Erractic to accelerate until approx 3000 revs then smooths out a bit. Held foot on pedal around 1500 revs and the car is juddering.


  • Changed the ht leads for another second hand set, still no joy.

    Found a receipt for a distributor that was fitted a few months before I bought the car, so changing the ignition coil and the hassle of putting it back together was probably not needed :x could have kicked myself.

    Looked at plugs - Denso K16TT so probably OK, got proviso on the exhaust at MOT could it be this?

  • Hi dazse,

    I'd still be looking at dissy mate?
    at fail supect No2!!!! the ignition module! (the thing your rotating vanes were rubbing against)

    Looking at your pics it appears you have the 'strap type' coil to ignition module connection?
    You don't mention what year/spec your MX3 is but Id guess you have a later style dissy as mentioned in all the 'USA' external HEI coil conversions?

    You'd have to check the 'TOT*****' number on your dissy body to make sure that the receipt you found for the dissy replacement, is indeed the correct spec for your cars year/spec ? (think theres about 4 'TOT*****' numbers across the range?) (was it brand new?)

    You have Two options with ignition module,

    Probestore stock them all (approx £75)

    Go down the external coil, HEI mod route? (Enter a search on here with the word 'HEI' and on

    I'd like to do the HEI conversion but I have the 'spade' type coil/ignition module connection and the wiring diagrams by members who have completed the mod appear conflicting for my set up??

    NOT SAYING its THIS for deffo, but I had exactly same symtoms!!!…. swapped whole dissy for a known, good, used unit (off my 2nd scrapped MX3) and without touching anything the car was transformed

    Hope this helps a little?

    kev b.

  • A quick update, through the summer I have replaced the following parts: HT Leads, Distributor cap, rotor, ignition coil, spark plugs but still no joy. I have checked for air intake cracks. Throttle position sensor has been setup.

    Local garage had a quick look for me and can't see anything for sure just suggested some of the above. Did say may be head gasket and I could get a test done on it.

    Might have isolated it to cylinders 4 or 6, in that when it is not revving constsistantly and you pull the lead from these cylinders in turn the engine does not get worse.

    Any last suggestion before I have a head gasket check. Of course money is a bit tight and I would love to change the whole distributor for either a known working one or a second hand one from a good source so I know its 100% but from my parts list above most of the distributor has been done!

    Cheers guys for you help so far…

  • Hi, I'd still be looking at ignition side/electrical components etc as head gasket failure would be apparent on a cold engine? as in your original post, you mention the problem appears after some 'stick' (and hence heat) and is then fine the following day until warms up again?.
    Have you reset ECU and started car with TEN and GND jumped after 'ALL' of your above component swaps? and done a code pull?

    Kev B.

  • I need a working distributor for my MX3 V6, firing order 4,5,3,2,1,6 (clockwise). I have had the car in three garages now the last one being an ex mazda technician and no one can pin point what it is.

    Mazda man says it could be the distributor but I have changed so far the ignition coil, cap, rotor arm, also ht leads spark plugs and crank sensor.

    I am based in Oxford and will to travel a bit to pick one up so please let me know if anyone can help.

    (please see previous page for history of this problem)

  • admin

    Hi dazse,

    So as mentioned at the bottom of the other page, try to pull codes from ecu, this might tell you there's an issue somewhere.

    Secondly, its a long shot but have you checked the vacuum lines? I had an issue with a weird idle some time ago and it was down to a bad hose.


  • The mechanic at the first garage did say he tried the codes but nothing was showing. I'm gonna get the car back later this week and will try it myself to make sure.

    When its back I'll double check for splits in the pipes etc but its now been to three different mechanics and I would have hoped they could have sorted it by now!

  • Is there anyway you can get the car to Banbury ?


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