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[Solved] Renault Megane II stalling on low speeds


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Khaleal
Novice

Sep 6, 2014, 5:16 AM

Post #1 of 12 (7730 views)
  post locked   [Solved] Renault Megane II stalling on low speeds  

This is regarding a Renault Megane II 1.6 16v 2005 K4M760 Engine (Petrol)
This vehicle stalls and losses power on low speeds but performs very well on high speeds..
When driving this car on low speeds (lights/traffic) the EML starts flashing and the engine tends to lose power and stall (within 30sec-1m).. The only way to prevent the engine from stalling is to rev it up so the EML disappear.. This doesn't always work as sometimes its too late and accelerating won't make any difference as the engine lost all of its power. When this issue occurs the engine vibrates as it was misfiring.. I tried unplugging coils while the engine is vibrating.. And look what I've found.. Unplugging coils on cylinders 1&4 didn't make any difference.. while unplugging 2&3 stalled the engine.. So when this problem occurs the car is running only on two cylinders (2,3) while (2,4) aren't contributing to the engine power..
When the EML starts flashing and/or the engine stalls I can restart the engine and it starts with no problems and without the EML..

This is what I've done until now:
1. New set of BOSCH spark-plugs..
2. New set of VALEO GREEN TOP coils.
3. New TDC sensor.
4. New throttle body.
5. 2 injectors replaced (on cylinders 1,4).
6. New MAP sensor.
7. Compression test on cylinders 1,4 showed an identical compression of 150psi.

It has been connected to a Renault CLIP and it showed the following faults: DF022(active),DF131(active),DF061(pending),DF032(pending),DF010(pending)

What could be the problem? I'm thinking of a faulty ECU and/or Engine wiring loom.. But I don't want to play the guessing game as it costs a small fortune :)


(This post was edited by Khaleal on Sep 20, 2014, 2:51 AM)


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Sep 6, 2014, 6:40 AM

Post #2 of 12 (7716 views)
  post locked   Re: Renault Megane II stalling on low speeds  

This car not sold here so very limited for info so just wild guessing and observations.


So far you've discovered what items are NOT the problem and don't blame you for not liking the guessing game with parts. Seems this is an intermittent problem so need to catch it when doing this as you have seems to cut out cylinders #1+4 when this happens.


Probably coils do two cylinders each by your tests indicated that. Not sure if you are losing spark or fuel or if both associated with just those two and of course it would run like crap if at all and shoot out all kinds of codes that mean little IMO running on half an engine!


Too late now but when you've isolated two and items are the same next time try swapping items if you can't prove by testing and are the same items like injectors and coils.


This problem you could put an in line spark tester that flashes so you know it's not firing spark at #1 or 4 when it does this but since you unplugged coil to them with no change you about know it doesn't have spark.


That would lead me to look hard at the car's plug and wires right to that coil NOT the coil as now it's new and problem is the same so odds are not that end but the plug itself may show a clue or a wiggle test while it happens then if it snaps right out of that you know right where.


Speed seems to matter is a clue: Something that happens with speed is a constant load on engine/transmission is torqued with a given load - I mean tilting against mounts to limit of mounts if they are good (checking those is free) and just that tug on wires or plug could snap it out but only sometimes as you said.


I doubt a mechanical problem is doing this intermittently and would focus on the connections, wires that allow spark to the two cylinders known to cut out,


T



Khaleal
Novice

Sep 6, 2014, 8:52 AM

Post #3 of 12 (7708 views)
  post locked   Re: Renault Megane II stalling on low speeds  

I also doubt a mechanical problem is doing this because this car will start flawlessly when restarted.
I replaced the sparkplugs/coils as sets (total of 4 coils and 4 sparkplugs) so I don't think it's an issue with the parts themselves (coils/sparkplugs). (The coils have been replaced twice BTW.. First time with second hand ones and then with brand new ones)..
I've tested the wires going to the coils (Engine photo so you know what am talking about: http://goo.gl/k9tceZ) while the car was having the issue using a circuit tester like this: http://goo.gl/s8bxSo and the tester was indeed flashing so I think the ECU was telling the spark-plugs to spark..
I've connected the car to a scan tool which has live stats and I noticed that when the EML starts flashing the car goes to fuel open loop and short fuel trim values goes to a constant 0% until the engine completely dies (Or back to its normal readings if I can save the engine from stalling by reving up the engine).. Does that say anything?
This car is driving me crazy! What do you think should be my next step?


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Sep 6, 2014, 10:09 AM

Post #4 of 12 (7702 views)
  post locked   Re: Renault Megane II stalling on low speeds  

I feel your frustration! Can't make your pics show in that format but doesn't matter for the moment. Coils always blamed - twice now. Dagnabit silly rabbit makes me more worried about the harness they plug in to!!!! Maybe just the plug - can't know - you have to do the looking with a magnifying glass if need be.


I do find more crap with horrible symptoms because of stupid slight either misalignment or slight corrosion on plain connections. When it stalls it's giving itself the "wiggle test" by that I mean wiggle the connections that are suspect or wiring and if problem instantly happens or goes away you found the spot at least.


Default mode doesn't surprise me as it apparently is trying to save itself from damage. Know that raw fuel if being delivered without firing is nasty hard on converter up to killing it so don't let that happen and it will if neglected. Most don't just wear out over time but are killed by an engine that doesn't run properly for any reason.


If, if, if you find a connection that you suspect or reacts to that wiggle test or just unplug and back in again take a good look at it. Has to be a male/female something like pins or spades and you can sometimes tighten up one with tiny needle nose or perhaps dental like picks.


Side note is that I live in an area (lots of N. USA too) where they salt roads and every dang connection and thing can get soaked with salted water despite most are factory greased and sealed they lose it over time, heat, cold or just plain rains and throw in humidity when things get soggy like your windshield need a wipe because it was cold then warmer with humidity it fogs outside and so does every other dang thing in a car exposed to that.


OK - When at connections for anything and a bit fussy myself about it if unplugged I'll put a slight smear of dialectic (means grease for electrical things that is water resistant) or just a tooth pick of like even silicone spray or WD-40 type something still AYOR as I mean just the least possible so it isn't a problem from doing that.


FYI, not around all the time here. We volunteer only at this place and sometimes have some real something to do so if late with a response forgive me. My own vehicle I'm deciding now to do or not something not related to this just because I'm there - stupid as that seems I guess.


Off the topic again. Broke a guaranteed for life socket just now but that's a joke as they wont have one or the maker is out of biz so a waste to hunt down and hate that crap like anyone would.


Good luck. I think you have a better chance of finding this taking your time and NOT tossing things. Problem with that can become then you have to question new items being the source of the problem at some point which leads to pre-mature hair lossMad


Keep at it,
Tom



Khaleal
Novice

Sep 6, 2014, 11:58 AM

Post #5 of 12 (7695 views)
  post locked   Re: Renault Megane II stalling on low speeds  

This issue also occurs when the car is parked (not moving and the AT on P).. I tried unplugging the MAP sensor and trying to start the car without the sensor at all.. And look what.. The EML appears immediately when I start the car but now the engine won't stall.
Hmmm.. I'm confused to invest in an ECU or in a wiring loom as both are relatively expensive.. (As I'm familiar with decoding/cloning secondhand ECUs I personally see the ECU thing a little bit cheaper)
Anyways.. Thank you very much for your help! I really appreciate it :)


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Sep 6, 2014, 12:59 PM

Post #6 of 12 (7691 views)
  post locked   Re: Renault Megane II stalling on low speeds  

Arrrr! Unplugging MAP would set off a light but not sure why it picks on just two cylinders? MAP unplugged the car is making adjustments for more power or load probably but should be for all functions not just the two cylinders as said.


???? Add really checking out vacuum hoses and anything that seals vacuum to manifold like gaskets to head and base of throttle body may leak some. Why intermittent is messing up nailing this easily.


I know you want "done" with this but wouldn't be so fast for a wiring loom or ECU until more is ruled in or out.


Another maybe to look at is the air path from where it picks up on thru filter into throttle body should be tight and no defects in how it's all connected up,


T



Khaleal
Novice

Sep 8, 2014, 4:29 AM

Post #7 of 12 (7676 views)
  post locked   Re: Renault Megane II stalling on low speeds  

Hmm.. I found a hole in the hose near the air filter (under the battery).. But its before the air filter so I don't think its a problem..
See picture of the hole




(This post was edited by Khaleal on Sep 8, 2014, 4:32 AM)


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Sep 8, 2014, 7:20 AM

Post #8 of 12 (7669 views)
  post locked   Re: Renault Megane II stalling on low speeds  

Hmmm? Ok - pre filter that still needs be fixed and probably NOT the reason for the stalling but the result of it but if a back fire or flames caused that (looks like heat did that) from INSIDE but think it was from outside is now high on the list to find out why. Backfires should have harmed or wrecked the air filter so do take a look at evidence in there. More likely if burnt was fuel not engine oil that can get into that area in some designs.


So look for both reasons for external heat damage to this area that I would think would be exhaust pipe or manifold but surprised if any of that was close to this type stuff. It also should be replaced. High temp duct tape may be a test to see if stalling problem quits but doubt it by description.


If timing, valve timing or excessive fuel delivery is happening it could do this from inside but looks like from outside?


T



Khaleal
Novice

Sep 10, 2014, 6:28 AM

Post #9 of 12 (7661 views)
  post locked   Re: Renault Megane II stalling on low speeds  

Well.. The picture isn't very clear.. But I'm certainly sure it's broken by the previous owner and not by heat.
When I connected this car to Renault CAN CLIP I cleared to codes.. I've managed to connect the tool again to the car and those are the codes that keep comming:
DF080 - CAMSHAFT DEPHASER CIRCUIT - Phaser control outside of limits (Before it was: Camshaft phaser position error)
DF065 - MISFIRE
Wait! A faulty camshaft sensor may cause the car to run rough or even stall especially at low revs.. Do you think it worth changing the sensor?


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Sep 10, 2014, 6:58 AM

Post #10 of 12 (7655 views)
  post locked   Re: Renault Megane II stalling on low speeds  

Your pic again........

Even with my lousy eyesight that smacks of heat that caused that not trauma from something breaking it. Codes to a sensor don't mean that the sensor is the problem but info from it isn't right or that circuit has a problem.


If wires and things near it are also damaged that's the area to look by eye first for damage. Why do I suspect heat with this type damage not just a crack seems like MAYBE someone at some time used starting fluid or something to excess and it caught fire quickly but left that and perhaps more?


Just common sense I doubt this has a single sensor for just the TWO cylinders that demonstrate this problem while TWO others work so suggests the source problem is NOT the sensor. If cheap and easy enough go ahead and test or replace it but I doubt it so far,


T



Khaleal
Novice

Sep 20, 2014, 2:50 AM

Post #11 of 12 (7605 views)
  post locked   Re: Renault Megane II stalling on low speeds  

I tested (replaced) the camshaft sensor and camshaft dephaser solenoid valve from a junkyard and both were OK. But I was sure there is something wrong with the camshaft as it's the only thing that keeps coming after resetting the code.
I took the car to another mechanic (who is specialized in Renault cars) and has diagnosed it as a faulty camshaft dephaser pulley.
As he explained to me, this unit controls the valves in certain conditions depanding on the oil pressure.. He offered me to buy a new unit from Renault (which costs about 500$+VAT) or let him "fix" it.. As the unit is very over-priced I went on the second option.. He fixed it by making it stuck at open state as he claimed it wasn't able to fully open..
Now the car doesn't stall at all.. But the EML is constantly ON.. But I don't mind :) I will order a new unit from eBay soon (about 135$) and let him install it.. I'm OK for now with the "temporary" fix..
BTW, Is there any side effects of doing such thing to the camshaft dephaser pulley?


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Sep 20, 2014, 5:07 AM

Post #12 of 12 (7592 views)
  post locked   Re: Renault Megane II stalling on low speeds  

Glad it has been isolated and running but do fix it soon properly such that your "EML" (?Engine Management Light) stays off. It probably is still being harmful to converter(s) and they are expensive as the result of a problem not the cause most of the time.


I'll close out thread as solved as you seem to now know just what to do for the fix. YOU can ask any moderator to re-open this thread upon request,


T







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