URGENT! Help please. Car running super rough. Lambda/coil pack?

[Danith]

Right we've checked the diagnostics on a laptop with full blown 'snap on' diagnostics and it's showing no errors.

The brand new spark plugs we put in yesterday are black as anything which suggests serious overfuelling?

What could be the issue now? Are fuel pumps know to be faulty, fuel filter (surely it can't be something as simple as this - where is it by the way!?)

 

[mickstoke]

the plug leads should have numbers on them which should match up with the numbers on the coil pack and dont forget number 1 spark plug is gearbox end! coolant temp sensor can also cause overfuelling

 

[mickstoke]

also did you set the gaps on the plugs right before fitting?

 

[Danith]

where's that mate? Also, anyone got a pic of the fuel rail? Looks like some sort of plug is missing maybe at the gearbox end?!

 

[mickstoke]

the fuel rail is just what the injectors clip to! there looks like there is something missing on gearbox side but thats how they are. the coolant temp sensor is in the block its self! green i think and theres also a sensor on the thermosat housing. i know its a shot in the dark but try disconneting the battery leads (both) and hold the battery ends together for a minute then reconnet and try! its like a ecu reset

 

[Danith]

Tried all these things. I need to get it to a specialist but can't drive the car. f**king CBA.

There's a good autoelectrician in the village. gonna have to take it there.

 

[guysy]

So have you checked the plugs one by one for each spark?

Ruled out its not the injectors now? Cleared the on board fault finder, ran the engine and see if the t--- code has come back?

Im not a propper mechanic obviously but if it was me id go through the motions and hope to find something along the way thats at fault.

Might be worth writing down everything you've tried and changed now, also searching for over-fueling problems on here you might find someone else whos been in the same boat.

 

[Gavin J]

I'd buy a second hand fuel rail and swap the lot over, i got one posted off someone on here for a about £25.... and its so easy to swap them over. Your describing pretty much what was happening to mine, misfire, stinking of fuel and no warning lights - but one of my plugs was clearly blacker than the rest so pointed at an injector or coil pack prob.

 

[Danith]

Thanks for all your comments guys. Really is a great forum this. Unfortunately we've both come to the end of our tether with it. After 3 days of changing over parts and driving around the country for parts we've given in.

Replaced coilpack, plugs, leads.

Tried 2nd hand (but working) lambdas.

Took the injector rail off and appears to be working fine - also disconnected them one at a time to detect a faulty one.

Unplugged the coolant temp sensor to see if it was that at fault - no change.

ALL FOUR of the brand new plugs are covered in black soot, exhaust tailpipe is covered in it too.

Car is popping from the exhaust and generally misfiring but is revving up to the redline as it should.

Can't get the car to a specialist as it's undriveable. Diagnostic tools aren't giving an error and the engine management light isn't on.

Did check the fault code clearing mate sorry. Did disconnect the battery overnight and when we started it this morning it did very briefly sound ok.

Guessing its a sensor somewhere but no idea really. Gonna have to take it my local auto electrician and pray he can diagnose. SH!T WEEKEND!

Oh, but i did get a nice set of shiny anthracite turinis! So it looks very nice at least!

 

[guysy]

Quite a lot there mate, shame you havent found the problem yet, another thing ive thought of is possible the cambelt has slipped and the cars timing is now out?

Might be worth asking if this can be moved into "Engine,gearbox..." section but this is probably the right section to be in.

 

[Danith]

Don't think it will be the cambelt slipping mate, had the belts and dephaser done at Birchdown in Feb. They're supposed to be one of the 'cambelt gods'!?

Sick of thinking about it now. I don't use the car for commuting so just gonna ring the local auto electrician first thing.

Quite a lot there mate, shame you havent found the problem yet, another thing ive thought of is possible the cambelt has slipped and the cars timing is now out?

Might be worth asking if this can be moved into "Engine,gearbox..." section but this is probably the right section to be in.

 

[Nemesis16v]

Don't think it will be the cambelt slipping mate, had the belts and dephaser done at Birchdown in Feb. They're supposed to be one of the 'cambelt gods'!?

Sick of thinking about it now. I don't use the car for commuting so just gonna ring the local auto electrician first thing.

Mate - sorry I never got back to you from before. You say the new plugs are in and have blackened right away? This is a sure sign of continued over-fueling being the cause of the problem. First off you need to check there is no restriction in the air intake - check that the air filter and housing etc... are clear and there are no sign of air leaks anywhere round the intake manifold. If these check out OK then my money is on a faulty MAP sensor or the wiring to it - this controls fueling to the engine. These sensors are cheap and can be picked up for around £20 as far as I know (though Renault may have other ideas).

I am fairly certain it is a MAP sensor you have on your engine as opposed to a MAF sensor. I am open to correction on that - but either way - even if it is a MAF sensor that you have - this will also be the likely culprit given the symptoms you are describing as these sensors (MAF or MAP depending on engine) control engine fueling. Also be sure to check that the wiring and connector to the sensor is good.

Given the steps you have taken thus far this is where I would go to as the next logical step. Let us know how you get on.

 

[Danith]

Thanks a lot mate, good of you to write up the explanantion too. I'm always learning with cars, I sit at a desk all day so I only learn when faults appear!
I'll try that and let you know. Cheers dude.

 

[Danith]

No way, I've just googled a MAP sensor and seen one on eBay, is this the little plug that you see plugging into the inlet manifold on the right hand side (spark plug number 1) branch? I've noticed that it was loose so I guess the slightest air leak there will be the prob?!

 

[BIGASH]

No way, I've just googled a MAP sensor and seen one on eBay, is this the little plug that you see plugging into the inlet manifold on the right hand side (spark plug number 1) branch? I've noticed that it was loose so I guess the slightest air leak there will be the prob?!

I'm pretty sure that is where it goes yes mate, they are quite easy to break if knocked and also a PITA to take out in one piece. Hope this is a fix for you

 

[Danith]

Oh my god I will be so chuffed if it is this. Thanks a lot dudes, don't hold your breath but there's a motor factors next door to my mates garage and this is getting purchased tomorrow! It was definitely loose but we thought 'surely not'! It must've been knocked when we took the battery out to fit the gearbox mount!?
I guess that explains any leak of air into the inlet - it's in but feels really loose. Fingers crossed!

 

[BIGASH]

If you get stuck for one then I think I have one that I took out of my inlets that I sold so I could always try and dig it out if you can't get one locally

 

[Danith]

Cheers mate. Will be updating this as soon as I get on my lunch break I think (if I get a decent enough signal on my phone - they blocked CS on work computers! Probably for the best!)

 

[BIGASH]

Lol well good luck

 

[Danith]

Just thinking, IF the end has snapped off in the inlet, will I be able to get it out?!

 

[Russ_16v]

No way, I've just googled a MAP sensor and seen one on eBay, is this the little plug that you see plugging into the inlet manifold on the right hand side (spark plug number 1) branch? I've noticed that it was loose so I guess the slightest air leak there will be the prob?!

No, thats not the map sensor mate, the small one that goes in the inlet on the battery side is the air intake temp sensor, the map sensor is on the other side of the inlet at the top - a bigger black one.

I don't think this is your issue - it could be as anything is possible but I doubt it as iv had mine work loose and fall out and it didn't give the symptoms you have.

Have you checked for any wiring breaks?

It is over fuelling, so either you are not getting enough air or too much fuel.

Check the inlet, if there is no blockage then i would lean to over fuelling - if there is no fault codes i would lean towards something like an ignition fault - you say you changed the plugs, did you use the correct ones? My old 172 would barely run when i had to fit some bosche suprr 4's due to a proper plug failing

 

[Russ_16v]

Just thinking, IF the end has snapped off in the inlet, will I be able to get it out?!

If the end was snapped off inside the inlet it would have been sucked in the engine mate

 

[Danith]

Oh bugger. But if the air temp sensor isn't in tight then it would cause the overfuelling due to an air leak?

It had super 4's in it and I replaced them with the proper NGK PFR6 thingies. I've changed the inlet manifolds over and it's doing the same on both (I had a painted set I wanted putting on). We checked that the plugs are sparking on a piece of metal - out of the engine.

Sequence is correct? - as you look in the engine, 1 is bottom right on coilpack, 4 is top right, 2 is bottom left and 3 is top left. leading to: 1 is battery side of head and 4 is dephaser side. but this issue started before we tampered with any of the coilpacks/plugs/inlets.

 

[Danith]

If the end was snapped off inside the inlet it would have been sucked in the engine mate

Oh jesus. Meaning? I don't think it has, i think its just loose though - just saw it mentioned on another forum but there wasnt an answer!

 

[Russ_16v]

Yes the temp sensor not being tight could cause an air leak, but that would not make yours overfuel to the point of not being able to move mate.

Your plugs leads will be on right if it revs clean - it wouldnt start if they were out of sequence.

It could well be a number of things, but work from the basics again

engines need air and fuel.

Yours is getting too much fuel, so if there is not an air leak, then there must be something causing too much fuel.

No fault codes is a bummer, so work through the basics.

Try unplugging things one by one, see if anything makes a difference.

Does it struggle to start?

Could have jumped a tooth on the belt

 

[Russ_16v]

Oh jesus. Meaning? I don't think it has, i think its just loose though - just saw it mentioned on another forum but there wasnt an answer!

It wont have snapped and even if it had it is only a small bit of plastic on the end - dont worry mate.

Bear in mind they are not megga tight - even when i fitted a new genuine one on mine i could wiggle it.

 

[Danith]

It doesn't struggle to start at all. It revs (if you floor it) up to the redline as normal. I haven't even attempted to drive it as I don't want to risk conking out pulling out of a junction.
Would a quick check be to just take the temp sensor out and bung the hole up temporarily to see if it makes a diff or does it have to have that sensor in there?

We've tried pretty much everything mentioned on here.

If the cambelt slipped, wouldn't it run really rough all the way up the revs? I only just had the belts changed and it was done @ Birchdown too - I can't see those guys fitting a belt incorrectly as they're really highly regarded for them?

 

[Danith]

I was really sold on the MAP sensor but I really don't want to throw money at it anymore with guess work, but if they're only £20 or so and Nemesis' explanation seems very feasible? The diagnostic won't be too cheap I would've thought though? Plus it's getting the car down there and getting a slot cos they're really busy usually.

 

[Russ_16v]

No, belt slipped can cause other issues - nothing against who fitted it, it could have been an idler/tensioner that has failed and made the belt slightly slack.

Didit just happen when you were driving or did you fire it up one morning and it couldnt drive?


Could also be collapsed catalyst - had that happen on an escort where you could rev it fine on the spot, but under load it was blocking up.

 

[Russ_16v]

I was really sold on the MAP sensor but I really don't want to throw money at it anymore with guess work, but if they're only £20 or so and Nemesis' explanation seems very feasible? The diagnostic won't be too cheap I would've thought though? Plus it's getting the car down there and getting a slot cos they're really busy usually.

If you havent tried a map sensor mate then it is worth a try if you cant get it to a specialist - it could cause your issue, but alot of other things could and you could end up chasing your tail

 

[Danith]

No it decided to do this just by sitting in my mates garage while we fitted a new tailgate and steering wheel! However, if I'm honest, I have felt that the car has been feeling a little strange performance wise at lower revs - seemed to be less snappy but fine higher up the revs, but nothing really noticeable, just thought I was being paranoid or getting used to the car being quick. I've just put a Scorpion cat back on it (3 weeks ago) and that made a big diff to the fueling I think - I noticed the car seemed to take time to 'get used' to the exhaust as if the ECU was adjusting to it?
We thought about the catalyst too, is there any way to check this without buying another cat to test it?

With the belt, the tensioners would've been replaced at the same time. If it is the belts (which I really doubt it is - surely this would be covered under warranty?)

No, belt slipped can cause other issues - nothing against who fitted it, it could have been an idler/tensioner that has failed and made the belt slightly slack.

Didit just happen when you were driving or did you fire it up one morning and it couldnt drive?


Could also be collapsed catalyst - had that happen on an escort where you could rev it fine on the spot, but under load it was blocking up.

 

[Russ_16v]

Yes tensioners would be covered under warranty mate.

No real way of testing unless you unbolt it lol

the ecu would self learn quite quickly, it can calibrate itself for any minor tweaks with no problems.


It is an odd situation, with all the parts you replaced, could any have been faulty?

 

[Danith]

Lambdas maybe. Coil pack maybe - but we tested it and all plugs were sparking strongly. Both these parts were off a donor car. Plugs are from Renault and brand new.

The sound from the engine bay definitely suggests an air leak as it's REALLY throaty sounding, but then that's probs cos of the misfire.

Guess I'll just stick with the diagnosis from the auto electrician and see if my mate can borrow a MAP sensor from the auto factors next door

 

[Russ_16v]

I doubt it's an air leak - only because if air is getting in after the throttle body in theory the idle should raise up - and it should still drive. Silly question, when did you last put fuel in - not a bad batch of fuel?

 

[Gavin J]

We thought about the catalyst too, is there any way to check this without buying another cat to test it?

With the belt, the tensioners would've been replaced at the same time. If it is the belts (which I really doubt it is - surely this would be covered under warranty?)

Could you not just split the exhaust before the CAT and see if runs any better? as Russ said i've heard them breaking down internally and creating a blockage...

 

[Danith]

UPDATE!

I had it booked in tomorrow at 'Mission Control' in Burscough - really really good auto electrician with all the diagnostic tools.

Then I get a call from my mate - I mentioned the MAP sensor to him this morning and explained where it lives on the manifold - and he calls me back this evening to tell me he's played around with that and ITS THE BLOODY MAP SENSOR AFTER ALL!!

Not out of the woods yet but he says he did something with the sensor as it had snapped or something and it was running ok! So ordering a sensor from Renparts on Ebay tonight and getting it put on ASAP! Some places are charging £90 for it! £17.50 from Renparts with 3 months warranty so sounds like, by Friday it will be up and running again!

Big thanks to all involved! Not over yet but it's looking Very promising!!!!

 

[Christopher]

Good stuff mate!

 

[Danith]

Good stuff mate!

Absa-bloody-exactly!!!! Nemesis16v you absolute hero!!!! I'll do a full credits roll if I get it fixed when the new sensor comes!

Another MASSIVE thumbs up for CS!!

 

[Christopher]

£12 membership paid for itself again then. Let us know mate.

 

[Danith]

The £12 x 6 memberships paid for itself a long time ago when I signed up in 2006! Although I think it was only a fiver then? Seriously think that if it wasn't for this site, I wouldn't have bought my 2nd or 3rd RS.
Will post up a conclusion to this whole ordeal as soon as the part arrives. Only just paid for it from Renparts on Ebay now so guess it won't be here til Friday.