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Discussion Starter · #1 ·
Hi all

I've owned my 59 plate ST225 since 2014 and never had any issues with it....until last few months.

About 6 weeks ago the engine light came on and was running rough but it was intermittent. Engine light was sometimes blinking, sometimes solidly on, sometimes off. Took it to a garage who said it was misfiring on 4 out of 5 cylinders. They changed the plugs (which were due anyway) and all was good. I asked why 4 plugs would fail at the same time and they didn't really have an answer. Mentioned they had had loads of issues with people moving over to new E10 fuel but I said I normally use Tesco Momentum which is still E5.

Had no problems since then until the other day when the same thing happened but this time it was running really bad, a lot worse than before. Engine light blinking and it was happening constantly not intermittent as before. A different garage said the same thing, 4 out of 5 cylinders misfiring.
Told them about the plugs being replaced and whether something else could be going on and they want to replace the coil packs and plugs (at a cost of £500+).

As with the plugs it feels unlikely that 4 would go at the same time. Garage said that if one goes it puts the others under pressure? It feels to me like something else is going on and I don't want to waste the £500+ only to have the problem pop up again in a month.

Only other thing that happened was about 2.5 months back the alternator needed replacing. Not sure if that would be relevant.

Car is completely standard.

Cheers
 

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Can you get a code reader on it and read the codes yourself? Or even better, get a modified ELM cable with laptop and read the codes using something like Forscan?

I'm not saying the garage doesn't know what they are doing but they will have a generic approach to what appears to be a complex problem. When faced with a problem like this, 9 times out of 10 just changing the ignition parts such as plugs and coils will fix the problem but I don't think that's going to work for you. Also, £500 is way overpriced anyway.

I think you probably have an intermittent fault in the crankshaft or camshaft position sensor circuits but you really need to know the stored codes.
 

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Discussion Starter · #3 ·
Thanks
I'm going down to pick it up shortly as I'm not paying to change anything until I'm confident it will fix it.
I'll ask them what the exact codes were but I remember him saying there were loads.
I don't have a code reader so wouldn't be able to do it myself.
 

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Mk3 ST Sabre 350R
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I'll ask them what the exact codes were but I remember him saying there were loads.
I don't have a code reader so wouldn't be able to do it myself.
If you've already got a laptop, then for approx. £21 you can access all the codes to your hearts content from the comfort of your own garage/driveway (order via Amazon and it could be with you tomorrow) then you could familiarise yourself with it over the weekend. Just an idea....

 

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Has it had a clutch done? Reason I ask is that the crankshaft position sensor bolts onto the engine block and sits in a small recess on the gearbox bellhousing, a clumsy removal/refitting of the gearbox can damage it or the wiring.

The other thing that can give loads of error codes is a simple battery failure.
 

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Discussion Starter · #11 ·
Has it had a clutch done? Reason I ask is that the crankshaft position sensor bolts onto the engine block and sits in a small recess on the gearbox bellhousing, a clumsy removal/refitting of the gearbox can damage it or the wiring.

The other thing that can give loads of error codes is a simple battery failure.
No, nothing has been changed on it like that. Alternator replaced a couple of months back.
 

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Discussion Starter · #12 ·
I'd start by looking at the Crankshaft Position Sensor as it plays a crucial role in the process of detecting misfires.
What am I looking for? I can do basic things (like the alternator replacement) but no good at diagnosing or any major repairs.
 

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Start by looking at its physical condition, particularly the connections.
Check also the wiring as far back into the loom as you can manage. The other end of the wire is connected to the PCM.
The only way you can functionally test it is by replacing it or watching live output data on a suitable diagnostic instrument.
 

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Discussion Starter · #14 ·
Just a thought but if there were problems with the crankshaft or camshaft sensors would it still run ok but produce error codes?
Mine is running like an absolute dog so definitely misfiring.
I'm no expert but think 4/5 cylinders misfiring at the same time must point to something other than plugs/coilpacks.
Weird thing is that the last time this happened changing plugs fixed it, for a while.
 

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Nick - Mk3.5 FL ST3 Moondust Silver
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Yet again a misfire issue exactly like I had on the ST500!! Is the age of these cars starting to show up a trend? I would check the ECU plugs/pins as that is what had started to fail on my car. The ECU signals were getting corrupted & causing all manner of weird running issues. I too checked plugs, coil packs, sensors, MAF & everything to no avail. Sometimes it would be fine & other time not. Until one day I happened to just knock the ECU plug & the engine started up fine - then quickly started misfiring again to the point the car would not run at all! I sent my ECU to these people & they found the plug connections on the ECU damaged & corroded.

https://the-ecu-doctor.co.uk/

A reflash onto a new ECU & everything was fine & running better than it ever had before! They can test the ECU if you send it to them & if it needs fixing I am sure the test is then free.
 

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Just a thought but if there were problems with the crankshaft or camshaft sensors would it still run ok but produce error codes?
Mine is running like an absolute dog so definitely misfiring.
I'm no expert but think 4/5 cylinders misfiring at the same time must point to something other than plugs/coilpacks.
Weird thing is that the last time this happened changing plugs fixed it, for a while.
Take the black plastic cover off the top of the engine and check that the 8mm bolts securing the ground points on the loom are all tightened down onto the cylinder head cover.
 

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Discussion Starter · #17 ·
Take the black plastic cover off the top of the engine and check that the 8mm bolts securing the ground points on the loom are all tightened down onto the cylinder head cover.
The mechanic that looked at it took the cover off and said everything was ok with wiring and earths
 

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Discussion Starter · #18 ·
Yet again a misfire issue exactly like I had on the ST500!! Is the age of these cars starting to show up a trend? I would check the ECU plugs/pins as that is what had started to fail on my car. The ECU signals were getting corrupted & causing all manner of weird running issues. I too checked plugs, coil packs, sensors, MAF & everything to no avail. Sometimes it would be fine & other time not. Until one day I happened to just knock the ECU plug & the engine started up fine - then quickly started misfiring again to the point the car would not run at all! I sent my ECU to these people & they found the plug connections on the ECU damaged & corroded.

https://the-ecu-doctor.co.uk/

A reflash onto a new ECU & everything was fine & running better than it ever had before! They can test the ECU if you send it to them & if it needs fixing I am sure the test is then free.
Hmm. When I changed the alternator I had to move the ecu to get the airbox out. I just took the bolts out so I could move it slightly to one side. That was about a month before the first misfires. I'm wondering whether that has damaged ecu. I will give them a call.

Thanks
 

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Hmm. When I changed the alternator I had to move the ecu to get the airbox out. I just took the bolts out so I could move it slightly to one side. That was about a month before the first misfires. I'm wondering whether that has damaged ecu. I will give them a call.

Thanks
It might just be that the plug has loosened, can you check it yourself?
 
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