TD4 strange misfire and smoking
- Thread starter Kev80
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Skinny Mike
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Did you do what @guineafowl21 suggested, check the coolant temp sensor?
Mike
Mike
I Just had a read up Mike, and to be fair I had missed that, however, plugged in to the Snap On OBD computer the temp steadily rises on the live data.
Its all in bits at the moment, as I'm replacing all the vacuum and turbo hoses (they look tired regardless) along with a new PCV (I just washed it in petrol before). All stuff that needs doing anyway. I'm also looking at the operation of the VNT boost control solenoid and the arm - Figuring that if the Synergy is new it could have pushed it past its normal limit and got stuck on crud (Ron at Synergy suggested this in a fault finding guide).
I've replaced the MAF with a genuine new Pierburg - no improvement, in fact it runs a hell of a lot worse, so I need to check the wiring there (again, some suggestions to follow from Ron).
If all that fails to get any results, my next steps are likely to be air temp sensor, fuel pressure sensor, and coolant temp sensor (not in that order - will start with cheapest first).
Ultimately, I see me pulling the injectors and having them tested by a reputable company - and replace if required. Shame, as I got it cheap and its cost me a lot in bits so far!!
Its all in bits at the moment, as I'm replacing all the vacuum and turbo hoses (they look tired regardless) along with a new PCV (I just washed it in petrol before). All stuff that needs doing anyway. I'm also looking at the operation of the VNT boost control solenoid and the arm - Figuring that if the Synergy is new it could have pushed it past its normal limit and got stuck on crud (Ron at Synergy suggested this in a fault finding guide).
I've replaced the MAF with a genuine new Pierburg - no improvement, in fact it runs a hell of a lot worse, so I need to check the wiring there (again, some suggestions to follow from Ron).
If all that fails to get any results, my next steps are likely to be air temp sensor, fuel pressure sensor, and coolant temp sensor (not in that order - will start with cheapest first).
Ultimately, I see me pulling the injectors and having them tested by a reputable company - and replace if required. Shame, as I got it cheap and its cost me a lot in bits so far!!
Skinny Mike
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- 2,910
Fairy snuff.
Strange about the MAF. Could be worth chasing the wiring from the MAF back to the ECU, dodgy earth springs to mind.
Mike
Strange about the MAF. Could be worth chasing the wiring from the MAF back to the ECU, dodgy earth springs to mind.
Mike
Indeed - a good idea.
I had no instructions for the Synergy, but according to Ron (again!), it is possible to refit the MAF wiring loom back to front with the design I have... Embarrassing, but possible.
The whole charade is somewhat embarrassing - I've been a DIY mechanic for 20 years and have never had a problem that's so difficult to trace. At least I'm getting intimate with the inner workings of it!
I had no instructions for the Synergy, but according to Ron (again!), it is possible to refit the MAF wiring loom back to front with the design I have... Embarrassing, but possible.
The whole charade is somewhat embarrassing - I've been a DIY mechanic for 20 years and have never had a problem that's so difficult to trace. At least I'm getting intimate with the inner workings of it!
Nodge68
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You say you fitted a Peirburg MAF. Is that a Bosch spec replacement MAF. Or a Peirburg replacement that Ron recommends?
If it's the Ron recommended MAF, then the Syergy must have MAF compensation turned on.
If it's the Ron recommended MAF, then the Syergy must have MAF compensation turned on.
Skinny Mike
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On my rather battered synergy instructions, it's says,
" Mark the left hand end (flat end of the MAF sensor) before disconnecting it"
If you look in the socket, you can see one end is flat, the other is round.
Continues,
"The white mark on the synergy male plug is aligned with this mark on the plug"
So your flat end matches upto the white mark.
Believe me, it's still as clear as mud when you have the instructions
Mike
" Mark the left hand end (flat end of the MAF sensor) before disconnecting it"
If you look in the socket, you can see one end is flat, the other is round.
Continues,
"The white mark on the synergy male plug is aligned with this mark on the plug"
So your flat end matches upto the white mark.
Believe me, it's still as clear as mud when you have the instructions
Mike
To be completely honest, I think the MAF may well be a red herring - I only changed it as its the closest thing to the airbox, and fiddling around changing the air filter seemed to start the problems. I now have the Pierburg one from Ron, and MAF comp turned on. I've not bothered with it over the last couple of days, as I've been busy with other things and am waiting for some other parts to arrive so I can attack it all in one go. Last time I order vac hose off eBay - I've been waiting a week for it
Thanks for the continued guidance!
Thanks for the continued guidance!
Hi guys, thought I'd pop back here and lose this one out. Despite many trials without much success, I've now finally sorted it. It was indeed a vacuum hose to the little solenoid beneath the EGR fitting. All is now well, except the requirement for a bit of TLC and a new VCU!
Thanks for all the help!!
Thanks for all the help!!
Alibro
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- Northern Ireland
The one on the RHS as your looking at it always goes, at least it was on all three I've had but I didn't think it would cause smoking and missfire.
I think it has something to do with the turbo actuator, and it looked like I was stuck and hadn't moved for a while. I also freed off the mech, and changed all the vac lines. It ran fine after that, but I changed all the boost hoses anyway as I'd bought them already!
