If its me, a Norwegian cruise for two will be sufficient.Bengineer_92 wrote: ↑Tue Feb 24, 2026 8:06 pmThanks Sunfly that's really helpful. A replacement CPS seems straightforward enough to get hold of so I might replace it just to rule it if nothing else! I'm excited to see who's prediction's going to win...Sunfly wrote: ↑Tue Feb 24, 2026 2:06 pmIf it was recently starting poorly and running rough I'd suspect the Dizzy, but if it was running very nicely when you shut the engine off, I'd suspect the CPS. An engine running well in every other respect will never start with a CPS fault simply because it doesn't know the angle of the crank. The engine can continue running when a CPS goes rogue, mid journey, because the TDC sensor in the Dizzy tells the ECU where the crank is but it will NOT START without crank angle info from the CPS.
Follow Microns advice over the connector by the engine first, then check the CPS wiring hasn't fouled on the pulley, then change the CPS.
Good luck
All the best, Ben
V6 Ignition Issues
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Sunfly
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Re: V6 Ignition Issues
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Bengineer_92
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Re: V6 Ignition Issues
*UPDATE*
Spent all day changing the CPS to no avail (even had to de-pin the connector to get it behind the belt guard!). At least it can be ruled out. I didn't get a chance to look at the dizzy so at this point I don't see what else it could be. Correct me if I'm wrong but if it was the immobiliser, it shouldn't be able to start at all (I guess?).
As a side note, It did start today. Sounded like it was idling alright (maybe a little slow). But, the moment you give it any revs it splutters and stalls. I am wondering wether the dizzy is to blame.
If the dizzy is the issue does anyone know from experience whether just changing the cap and rotor might sort it? Or do these symptoms point towards knackered transistors in the distributor itself?
Spent all day changing the CPS to no avail (even had to de-pin the connector to get it behind the belt guard!). At least it can be ruled out. I didn't get a chance to look at the dizzy so at this point I don't see what else it could be. Correct me if I'm wrong but if it was the immobiliser, it shouldn't be able to start at all (I guess?).
As a side note, It did start today. Sounded like it was idling alright (maybe a little slow). But, the moment you give it any revs it splutters and stalls. I am wondering wether the dizzy is to blame.
If the dizzy is the issue does anyone know from experience whether just changing the cap and rotor might sort it? Or do these symptoms point towards knackered transistors in the distributor itself?
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Micron
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Re: V6 Ignition Issues
I would say that the ignition coil is breaking down. Get Ignition Car Parts to test and fix it if required.
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Bengineer_92
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Re: V6 Ignition Issues
On my list for this afternoon! It does something because my idle speed changes if I unplug it but that doesn't necessarily mean it's not faulty. I'm sure there will be a way of testing it in the Haynes manual.
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Bengineer_92
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Re: V6 Ignition Issues
The plot thickens... I think I've cracked it (though happy to be proven wrong!).
I had the MAF out - visually fine and bell tests were good. Out of curiosity I plugged my test LED into the diagnostic port and it threw up one fault: air intake temp sensor (IAT). After poking around for a bit for an obvious thermistor somewhere in the air box, I later learned that the IAT is part of the MAF assembly itself. This threw me off as I was expecting the IAT to have its own connector (but it's shared with the MAF... sneaky Mazda...thank you Haynes manual...)
The IAT pin in the connector looks off-colour to the others. I suspect a short which is upsetting the PCM and affecting the fuel air mix. I reckon a replacement MAF/IAT unit should do the trick. Fingers crossed.
I had the MAF out - visually fine and bell tests were good. Out of curiosity I plugged my test LED into the diagnostic port and it threw up one fault: air intake temp sensor (IAT). After poking around for a bit for an obvious thermistor somewhere in the air box, I later learned that the IAT is part of the MAF assembly itself. This threw me off as I was expecting the IAT to have its own connector (but it's shared with the MAF... sneaky Mazda...thank you Haynes manual...)
The IAT pin in the connector looks off-colour to the others. I suspect a short which is upsetting the PCM and affecting the fuel air mix. I reckon a replacement MAF/IAT unit should do the trick. Fingers crossed.
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Bengineer_92
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Re: V6 Ignition Issues
Hi all,
Cracked it. I can't say it wasn't a combination of several different things but after replacing the the MAF earlier in the week, it's running beautifully.
I tested resistance across the old MAF as well as the integrated IAT thermistor and it seems the IAT thermistor had failed and was sending confusing signals to the ECU. I reckon these bogus signal readings fluctuated each time I attempted to start the car which meant it was a random lottery as to whether the air/fuel mix was anywhere near correct each time.
Will follow up with an oil change and with plenty of driving to get the unburnt fuel out of my cat
Thanks everyone who made suggestions - I really appreciate it
Hopefully I can thank some of you in person at the NEC in a few weeks.
Cracked it. I can't say it wasn't a combination of several different things but after replacing the the MAF earlier in the week, it's running beautifully.
I tested resistance across the old MAF as well as the integrated IAT thermistor and it seems the IAT thermistor had failed and was sending confusing signals to the ECU. I reckon these bogus signal readings fluctuated each time I attempted to start the car which meant it was a random lottery as to whether the air/fuel mix was anywhere near correct each time.
Will follow up with an oil change and with plenty of driving to get the unburnt fuel out of my cat
Thanks everyone who made suggestions - I really appreciate it
Hopefully I can thank some of you in person at the NEC in a few weeks.
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Micron
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Re: V6 Ignition Issues
I’m glad you have it sorted, please use the discount code to buy your tickets
http://www.ukpoc.co.uk/forum/viewtopic. ... d580846e8a
http://www.ukpoc.co.uk/forum/viewtopic. ... d580846e8a
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Bengineer_92
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Re: V6 Ignition Issues
Thanks Trev. I'm actually sorted in that regard as I'm exhibiting my Probe on another stand in the show so already have wristbands, but I'll make sure to come over and say hi. It will be nice to work on some smaller, less dramatic jobs now that I know I can actually get there!Micron wrote: ↑Sat Mar 07, 2026 3:26 pmI’m glad you have it sorted, please use the discount code to buy your tickets
http://www.ukpoc.co.uk/forum/viewtopic. ... d580846e8a
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