Gapping pulley belt teeth to Crank Sensor

Technical Area Engine, Transmission, Exhaust etc
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  1. My model of MX-5 is: __2002 1.8 S-VT
  2. I’m based near: __Watford
  3. I’m looking for technical help or recommendations on: __ how to gap pulley belt teeth to crankshaft sensor !

Having sorted rust & suspension Madge cut out with a brief warning from the engine light and RAC diagnosed crankshaft position centre both loose and not giving signal.

Thought it looks an easy enough swap having managed to set spark plug and old skool distributor gaps in the past.

Got a new sensor and reading Haynes I am getting the picture correctly or otherwise that the engine needs to be tdc see I st pic, and the sensor needs a .5 to 1.5 gap to a crankshaft pulley tooth.

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However at tdc no pulley tooth is in sight see pic 2, have I misunderstood something or am I doing something wrong ?

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TIA for any response

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The ‘teeth’ you’re looking for are like the one at 10:00 in the first photo:

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Just turn the crank until one is opposite the sensor then set the gap. Some people advocate checking all 4 teeth.

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That white mark on the plastic timing belt covers that you’re using is not TDC, look at the marks to the right of the water pump pulley for TDC.

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Thanks for clearing that up Robbie, will have a look this morning and post more pics when it is done.

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Thanks got the new sensor fitted but alas no joy when I went to start Madge. Engine turned over much as before.

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I couldn’t find a set of feeler gauges so I used a pair of small Tesco loyalty size cards, very tight with two relatively easy with just the one, the gap was the same on all four teeth.

How critical is the accuracy of the gap, I am reasonably confident it is between 0.5 and 1.5 ?

I charged the battery overnight so I doubt that was the issue.

I don’t have an odb2 yet but I do have a multimeter somewhere, other than using it to test a few batteries 20 years ago I have never used it, is it worth checking the new sender is working ?

If so what do I need to do ?

Thanks for your patience feel I can stretch my skill set to fix this, hopefully before next Sunday but if not I have nothing to loose by persevering.

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Thanks MisterG1, I bought a feeler gauge and wireless obd2 code reader this morning and downloaded the car scanner app . Despite references to that strange WAP and LAN stuff I appear to be able to get some info from the car to my phone.

I rechecked the crank sensor - tooth gap and all 4 teeth were spot on without any further adjustment required .

Tried to start the car and it turns over with no hint of firing.

The code P1345 came up and since I know a new sensor is fitted I tried clearing and no DTC’s are now showing but still no hint of the car firing up despite no codes showing.

Any recommendations for next step more than welcome. TIA

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Not sure what to suggest, really. Until an expert comes along, these are suggestions off the top of my head (in increasing order of desperation!)

  • Make sure that the connectors for the crank sensor are free from corrosion and pushed together tightly
  • Check the wiring on the crank and cam angle sensors for damage (the P1345 code could apply to either AFAIK).
  • If the old crank sensor wiring was damaged, check fuses.
  • Maybe move the crank sensor slightly closer (nearer to 0.5mm than 1.5mm)?
  • Check for error codes from the Mazda diagnostic connector in the engine bay (I think your car will have one - requires an LED and a jumper wire).
  • I don’t know whether the immobiliser would allow cranking but prevent sparking, or if it would disable cranking completely, but make sure there aren’t any immobiliser issues and you’re using a ‘known good’ transponder key, nothing around the ignition key hole, etc.
  • Check whether you’re getting a spark by removing the plugs, reconnecting them to the HT leads/coils and laying them on the cam cover such that the plug bodies are in contact with it, then crank the engine and check for sparks at the plug gaps.

And… Good luck! :slight_smile:

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Thanks MisterG1, should keep me busy for a day or so :sunglasses::+1:

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I got a tip from Steve at MX5 Restorations in Ilkeston that the problem of not starting might lay with the cam position sensor. Plonked a new one in, cleared the P1345 code and hey presto Madge started. I have not had a chance to drive her yet but feel mighty relieved to have heard Madges engine running again.

Fingers crossed a test drive tomorrow will give me the confidence to compete in the Sprint at Llandow on Saturday and put Madge on the MX5 Restorations of Ilkeston stand at Compton Verney on Sunday.

Thanks to everyone who has helped Madge along the path back full health.

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