Needing help with diagnostics!! :-(

DGF264 · Jan 25, 2015

Hey guys.. Shortest version..

Car developed a misfire. Progressively getting worse. Plugs, coilpacks, PCV, cam follower all changed..only ran on Vpower. Misfire is getting to the point where I would call it 'violent'! The car bucks, lurches & coughs. Revs 'hunt', car revs itself.

But only on light throttle..or maintaining a speed. On boost it's fine! I've removed the map (Revo) put it back on, changed settings etc.

It's been in various garages who (allegedly) checked fueling, checked the LPFP, checked the HPFP, air, blah blah..& because it's an 'intermittent' fault..couldn't find anything wrong!

I'm after your advice about a garage that will diagnose and fix this problem..ideally with a rolling road so it can be driven and logged on there as it's doing it..or just anywhere u think 'yeah that place is amazing' lol.. I'm based in the North East. But am willing to travel, drop the car off and leave it there for aslong as it takes!!

Please help guys!! Cheers. Car is a mk2 cupra running stage 2 with all supporting mods etc.

Darren

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locky · Jan 25, 2015

I would suggest contacting Richy down at Peterlee. (Richard Martin Automotive)

https://m.facebook.com/richardmarti...facebook.com/richardmartinautomotivesolutions

No rolling road, but he would be who I was calling at this point.

DGF264 · Jan 25, 2015

Locky.. I've already used him pal cheers Richie's exact words 'it's an intermittent fault, you are probably going to have to let it develop to diagnose it' but it's getting worse. To the point where it's popping in between gear changes as i think it's overfuelling that bad!! He's a top man.. Just couldn't find it!

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DGF264 · Jan 25, 2015

The other night it was literally undriveable! then the next day it'll be ok..then it'll start doing it again etc

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AlexK1 · Jan 25, 2015

Have you got any fault codes in the Ecu? I've noticed the one thing you haven't changed is a fuel injector and these seem to be failing recently, there's a fair few posts I've seen with no 4 injector failing I think it was. Could be an injector hosing but no way of testing that without getting it sent off.

You could check the resistances of them and see if the values are close. If there's one that's way out that's your problem. Only issue is how inaccessible they are

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DGF264 · Jan 25, 2015

Only fault code stored was a faulty DV valve.. So I changed that lol. It registers misfires across ALL cylinders when a friend looked at the misfire sum counter..
So Alex is that the only way to test injectors? Can't be done through vagcom?
I'm not that good when it comes to checking things I'll be honest lol.. How much would a full set of injectors plus fitting be? Rather then spending time sending one/them off for testing etc.. Do I just change the lot??

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DGF264 · Jan 25, 2015

But why doesn't it do it on full boost?? It's only ever light/partial throttle.. Nail it and it flys lol!!

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AlexK1 · Jan 25, 2015

Ah right I see, were the misfires logged under load or on idle?

Not sure what injector tests you can do on vagcom I'm afraid.

Bench testing injectors is usually around £100-125, a new single injector is around £80-100 I think.

To get them replaced would be a fair amount inc labour, I wouldn't recommend just fitting them unless you can guarantee that's the problem.

Have you tried running a fuel cleaner through like redex?

How many miles has your car done? Could be the inlet valves are coked up causing misfire if it's across all four cylinders

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DGF264 · Jan 25, 2015

Misfires where logged as we were driving.. And as said.. It logged misfires across them all.
I've used Millers.. Put a full bottle in over 3 tanks. A slight improvement..but may have just been placebo affect lol!
Car has done 71,000 miles..religiously serviced etc. yeah I read about inlet valves. Again.. How do u fix that lol

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AlexK1 · Jan 25, 2015

I tried getting mine cleaned using the terra clean forced inlet machine. But not convinced it actually done anything, best way is manifold off and get in there properly with cleaning agents and a brush.

The only other thing I can think of for low rpm driving is the inlet flaps, sometimes the motors play up and cause issues. Can test that by unplugging it as they default to the open position, if it drives any better then that could be one of your problems.

Be aware that it may bring your engine light on running with the inlet flap motor unplugged though

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DGF264 · Jan 25, 2015

Excuse my ignorance Alex..but if I did change injectors..could the inlet manifold/valves be cleaned then??
What are the inlet flaps? And how do I unplug them lol.. I'm open to try anything!! Anyone else think this is worth trying?? (I've never had the 'inlet flaps' mentioned to me at any garage so it's worth trying!) and once plugged back in will the engine light go off? Cheers

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DGF264 · Jan 25, 2015

Quick email to an eBay seller and x4 Bosch OE injectors are £300 delivered...

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AlexK1 · Jan 25, 2015

That's ok, yeah as you have to take the inlet manifold off to change the injectors they could be cleaned at the same time.

The inlet flaps are built inside the manifold, they are designed to help certain driving conditions, cold starts, and improve fuel economy among other things. The flaps can get coked up and cause them to stick, or the motor can go faulty.

I'll see if I can find a picture that shows where it is, if not I'll go out to mine and take a photo.

Not sure if the fault will clear, sometimes they do after a few ignition cycles but can't say for definite

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AlexK1 · Jan 25, 2015

Best picture I could get, it's the connector in the middle of the photo, bit tricky to get to

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DGF264 · Jan 25, 2015

Ok mate cheers I'll give it a try!! So by unplugging it.. They open.. And if the problem DOESNT happen, it points to the inlet flaps? Cool ok...

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DGF264 · Jan 25, 2015

Lol can u draw a circle round the connector that needs unplugging?

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AlexK1 · Jan 25, 2015

Yeah that's it dude, it'll be the motor at fault.

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DGF264 · Jan 25, 2015

Woah that is tricky.. Lol.. I'll go have a look in a bit! Cheers dude!

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DGF264 · Jan 25, 2015

@AlexK1 am I ok driving the car with it unplugged? Cos the fault was so intermittent I'm gonna have to go for a long ish drive lol.. What should/shouldn't i do? Or will it be ok? Cheers

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DGF264 · Jan 25, 2015

Been for a little drive (car didn't really get warm) round the block.. Car does actually feel a bit 'smoother' but it defo coughed still as I was driving it. So it points to inlet manifold..a combination of caked up inlet flaps, valves & injectors maybe? Hmmm I need a good garage to take it to!!

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Needing help with diagnostics!! :-(

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