RS 250 - Temperature Gauge, misfire and rev limit

So relatively new and so far happy owner of a 2010 RS250 Cup with 60k on the clock. First port of call after buying was to get it into a recommended main dealer and have it fully checked over and serviced.

Before dropping it in I had noticed a couple of things that did not seem right and let them know about them.

- The temperature gauge in traffic would sit just slightly below half way but on motorways it would drop to 1/4
- When driving the car hard it would hit what seemed like a very low rev limit of about 5800 rpm
- Car would misfire quite badly when under load at about 4800/5000 rpm onwards

On collecting the car I was told the temp moving about was "normal" and that after the service they said the misfire seemed to have been resolved. One of the mechanics also told me, when I asked about the low rev limit, was that the 6-7k rpm marked in red on the speedo was "bad for the engine"...it was at that point I knew I had picked the wrong garage and or mechanic!

So, the spark plug replacement (as part of the service) fixed the misfire when under load which was great but the temp gauge and the low rev limit were still present.

I had to bring the car back to them a week later as the rear discs and pads had to be replaced but they didn't have the parts at the time of my initial service. I bought a thermostat from them as I thought it was worth replacing seeing as how cheap the part is. Again they were adamant that the temp gauge was nothing to be worried about. The price they gave me for fitting the part made me say no thanks I'll do it myself.

Finally had the chance to fit it yesterday evening and wow what a difference!

Temp gauge now sits at half way whether in traffic or on the motor way. It also warms up faster. Looking at the one I took out it seems like the spring had rotated a bit and it meant it was sticking partly open all of the time. Added to the temp being fixed, the car now happily revs right onto somewhere around 6600rpm. It pulls harder than it has since I bought the car 2 months ago.

Next on the list is cleaning out the intake manifold and throttle body. Gaskets ordered and I should be able to carry out the work this weekend. I want the car to run as near to perfectly as possible, the car still has a slight hick/rough idle. No error codes are shown (have an OBDII connector and Torque). Maybe dirty injector or injectors but I will wait and see if cleaning the throttle body and intake manifold have any effect.

 

The fuel filter was replaced during the service. Regarding injectors, I assume over time even if an injector is not faulty it wont be optimal? As in year on year they just are not able to work as well due to deposits and general wear and tear.

 

So, quick (lengthily) update.

The rough idle/misfire is still present.

https://vimeo.com//220704488 Video where you can hear the misfire.

When sitting in the car you can feel it when idle and its noticeable when driving. It’s mostly noticeable while holding at 2k RPM at slower speeds, with light throttle, you can feel the car chug as it misses. Makes driving in slow moving traffic a little bit annoying.

Will add to this and say fuel economy is fairly terrible. Don’t get me wrong, don’t expect this to be a 1.6TDI Golf but 22/23mpg combined/mixed driving seems a bit excessive. Daily would be about 10km city (average traffic) and 40km motorway (average 75mph).

Issues/Symptoms

· Rough Idle/misfire
o Noticeable at idle and while driving.

· Bad fuel consumption
o 22/23mpg.

· Slight hesitation at times
o When depressing the accelerator (doesn’t have to be all the way) the car takes a second or two to respond. Noticed it over a bump once before. Could be traction control or possible knock sensor...?

· At speed in 4th, 5th and 6th gear (especially 5th and 6th) the car runs out of steam very quickly.

o I tested this recently. In a safe place (honestly!) a friend and I were side by side at 60mph, both at 3k rpm and floored it simultaneously. He pulled, 1 car length ahead pretty quickly, then 2 car lengths…and so on ahead of me. He was driving a Seat Ibiza Cupra 192 bhp. ☹

· Car loses power quickly as it heats up (not sure heat is the reason)
o I had the car on a DYNO and it first posted 243.2BHP then after 6 runs back to back with a minute between each it posted 186BHP. It dropped about 10BHP per run.


What I've tried -

1. Fuel from different garages:
There is a somewhat noticeable difference when filling up from different garages. But the rough idle/misfire does not completely go away. Thing is in Ireland now you can only get 95RON unleaded. Apparently 98RON fuels like Shell V-Power will be available soon.


2. Fuel System cleaning (simple steps):
I ran BG44k and Wynns Formula Gold through over a couple of weeks. While there seemed to be a noticeable, smother delivery of power, the rough idle/misfire was unchanged and once back on a normal tank of fuel it seemed to be not as smooth. Could just be me though!


3. Fuel System cleaning (more involved steps):
I removed the throttle body, intake manifold and injectors. Note: When reinstalling I installed new inlet and throttle body gaskets.

Image attached to show what condition the throttle body was in before and after
BEFORE: AFTER: .
I had this reset in Renault just in case. From what I’ve read here and elsewhere some say you should get it reset while others have said they had no problem.

Intake manifold was fine from what I could tell. Gave it a clean anyway.

While I had the injectors out, I performed a DIY cleaning method. Involves a 9v battery, alligator clips, a suitable injector cleaner solution and a silicone tube. My little makeshift setup.

Link below to a youtube video showing how to do it.

After all that, disappointingly I only noticed a slight drop in the misfire/rough idle. Which after a few weeks now has not only come back but is getting worse.

4. Main Dealer diagnostics:
I brought the car to a main dealer in Dublin to check for codes and to see if they could diagnose the misfire/rough idle. They sent me out with their lead mechanic for a lengthily drive and then he had the car for a further hour and a half in the garage.

All in all, he couldn’t pin point the issue. There were no error codes at all.

As the RS Megane was never really sold here (I believe there are probably less than 10 in Rep of Ireland) he recommended that I bring the car to one of the dealerships in Northern Ireland as they have in house mechanics that are trained and work on them. Fair dues to them, they did not charge me for what ended up being as near as makes no difference 3 hours work.

He did give me some print outs of some of the readouts/tests from my car. Attaching here just in case someone can see something in them he or I cannot.






5. Dyno Run:

I had the car do some passes on a dyno to see if they could help me find out what was wrong. They ran the car for 6 runs, minute or so gap between each. First run it posted 243.2 BHP. Not bad, thought it would be worse. I spoke too soon. Each subsequent run, the car posted 10 BHP less. By the 6th run it was at 186BHP…

They let the car cool for about 10 minutes and then did two more. First run was 230BHP then second was 218BHP.

I have yet to go back as they slotted me in on the fly and the car on just before me fried the exhaust temp sensor they use so I don’t have more info as of yet. Without further tests, they couldn’t say why the power was dropping so much so fast. They would expect it to drop but not by that much or that fast with each passing run.

Image of graphs from a video I took but be warned, awful quality.


So where do I go from here…

Well I’m about to book the car into Shelbourne Renault in Northern Ireland to get the timing belt, aux belt, rollers, water pump and the dephaser pully replaced as the car is at 64,000 miles and its 7 years old.

A little history on servicing, the same month I bought the car I gave it to Charles Hurst Northern Ireland with 61000 miles on the clock, asking them to do a full check and basically recommend to me any work that should be carried out. They never mentioned that the timing belt etc should be done at the time even though Renaults maintenance program states those should be done at 75000 miles or 7 years.

As I mentioned in another thread the thermostat was also faulty and they didn’t replace it and said it didn’t need to be. So, I bought the part off them and fitted it myself. Temperature problems sorted. Pretty disappointed in them to be honest so I won’t be going back. It may even be worth calling Renault customer service seeing as users on other forums state they received decent discounts on further serving work.

Anyway, tangent aside, while the car is in with Shelbourne getting the belts done, I’ll ask them to see if they can diagnose the misfire/rough idle. If they cannot diagnose it properly or want me to start throwing parts at it based on what has now turned into a wall of text, what would any of you that may have had or seen problems like I’m having, suggest I try first?

 

Should have mentioned, the car has new plugs since it had a full service within the last 2000miles. New plugs sorted a bad misfire under load while at high revs.

Why do you say coils? What are the main symptoms of those being faulty?

 

Hello all. Back again...


So, I've had a few more bits done to the car. Some done by others, some by myself. Would love to have done more but I just don't have the space or time at the moment. All work carried out so far is listed below.


Overall the car is more responsive and feels a bit "healthier" after the work carried out. The issue is, the bloody misfire/cough/hick still exists and is completely unchanged.


Hoping to be able to give the car into a specialist (a garage where they will properly attempt to pinpoint the issue) soon and hoping they can get to the bottom of it. Don't know when this will be though.


In the meantime, if any of you have suggestions as to what may be causing this or have suggestions on what I should try after reading the below, please let me know!


SYMPTOMS



· While car is idling you can feel it misfire and hear it cough/hick. Video linked in post 5 so you can hear the exhaust.

· Min/Max idle 700-780 RPM while idle and warmed up. The RPM fluctuates all through this range. When cold it is also misfiring. Revs are higher then but that’s expected when cold.

· While driving the misfire/roughness is most evident at 2000rpm (example - driving in 4th at 30mph and at 2000rpm the car will slightly cough and lurch as it misfires). Very annoying in traffic!

· While driving the misfire is not noticeable during load/heavy acceleration or holding at higher revs

· Car has cut out several times, seconds after starting the car. Only common factor I can think of it's when I've started the car after it's been recently driven - within an hour.

· Possibly related - Car loses power (maybe as it heats up?). Car was on a dyno, had 7 runs with a minute or so between each run. The power started at max 242 BHP and then dropped about 7-10bhp per run thereafter. Last run was down below 190 BHP. It was only a quick visit and I'm supposed to go back for a proper data logging session but not had the chance yet.



PARTS REPLACED

• New Spark Plugs (OEM)
  • Two sets used over 3 months (first set fixed bad misfire at high revs. Second set to see if first were faulty in anyway. They made little to no change)
• New Coils (OEM)
  • Between these and injectors the car feels slightly smoother and more responsive. Misfire still there and unchanged
• New injectors (OEM)
  • (same as above) Between these and injectors the car feels slightly smoother and more responsive. Misfire still there and unchanged
• New fuel filter (OEM)
  • Carried out while in for its first main dealer service/inspection after I bought the car
• New thermostat and coolant (OEM)
  • This fixed fluctuating coolant temp and low max RPM
• New throttle body gasket (OEM)
  • Carried out while I had the throttle body and intake manifold off for an inspection/clean I thought it best to replace these
• New intake manifold gasket (OEM)
  • Carried out while I had the throttle body and intake manifold off for an inspection/clean I thought it best to replace these
• New oil and oil filter (OEM)
  • Carried out while in for its first main dealer service/inspection after I bought the car
• New air filter (OEM)
  • Carried out while in for its first main dealer service/inspection after I bought the car
• New timing belt kit, water pump and dephaser pulley (OEM)
  • Carried out as second service by third party garage that came well recommend. No issues with work carried out as car drives/idles/runs exactly as it did before and work cost half what the main dealer wanted!
  • While in I asked them to check the software version on the car and make sure to apply any updates if available. Sure enough, there was an update. It seems to have sorted the knock sensor being over sensitive and pulling power when really pushing it, especially on bumpy/rough roads.

TESTS


Beyond parts being replaced and servicing carried out, I've also

• MAP sensors swapped around. No perceived change. No effect on misfire.
• Throttle body cleaned. Slight increase in responsiveness. No effect on misfire.
• Different unleaded tried. No perceived change. No effect on misfire.
  • Ran fuel system cleaners through a few times but no real noticeable change.
• Spark plugs looked to have a good burn on them. No carbon (black) or lean running (white) build-up of any sort. All looked identical.
• Error codes read. At all times, there are never any error codes thrown. I’ve had it read three times over 6 months in Renault. Small amount of Data logging as you can see in post 5 above from Renault.
• Dyno Run - Was a very brief run with no data logged as they had an issue with the computer but the readout on the screen was apparently correct for each run. As mentioned previously, the power on the 1st run was 242BHP max and then dropped to less than 190BHP by the 7th run.

Where do I focus next? I know a proper data logging session is in order but any suggestions beyond this would be great!

 

Not had a chance to dig further into this since my last post. Have had a full set of new tyres fitted (PS4's - i must say worth every penny) before the turn of last year and due to some utterly monumental pothole I had to replace two of them within a month due to sidewall damage sickened. Even so, now with a further 6,000 miles on the clock, the hick/misfire is no worse.

It's now due a service but wouldn't you know, it just had to throw its toys out of the pram about something. The bloody gearbox bolt sheared... I'm thankful it happened when I was coming to a stop (literally moving at 10 mph) on a quiet road so I could pull over right away and not drive any further. On inspection no damage to gearbox or anything else.

Spent last weekend pulling out the mount, drilling, re-threading and fitting a larger and stronger bolt. On my first attempt, the new M12 bolt turned in the mount as I tightened it for the last 1/4 turn! Back to the engineering suppliers yesterday, bigger drill bit, bigger tap and a M14 bolt. Didn't tighten as much this time but going to get the whole mount fully replaced with the newer versions. Supposed to be less lateral movement in it which diminishes the chance of further bolt sheering and sure it will stiffen things up a bit.

Regarding suggestions above, I'll defiantly give changing out the O rings and holding down the MAP sensors a go over the coming days. Should have what I need here. When it's in for a service I'll get the techs to check the fuel pump but if the part and fitting is not crazy I may just get it done. And while they are at it I'll ask them again to see if they can find out whats causing the miss fire. Not going to hold my breath.

Once all that's done, I'll get to a rolling road that has proper data capture facilities and see if that can help shed some light on whats going on.

I keep telling myself I could have worse things to spend my money and time on...

 

@Michiel - When you say the same issue, do you mean the rough idle and/or the misfire/hicking while driving? Would the actuator have any effect on idle?

Its funny that you mention the turbo actuator as I was beginning to think the turbo or parts directly linked to it had a role to play. Reason being is the misfiring/hicking (while driving) is at its worst at 2k RPM. Which seems to be around when the turbo would kick in. While driving if I have the revs at say 1500 rpm, the car drives much smoother. Little to none of the misfire feeling.

In relation to the MAP sensor O rings, I fitted new slightly thicker ones and it made no discernible difference.

Between a house move and other delays I'm only this week going to get around to a full service. While carrying it out I'll have a look at the turbo actuator as Michiel suggests.

 

Quick update on this. Full service done last week. Engine oil, oil filter, sparks, coolant change, gearbox oil, fuel filter, air filter and cabin filter. Also cleaned MAP sensors and throttle body. Must say, the pollen/cabin filter replacement was an absolute bastard! Was never installed properly when I last had it done by Renault. Thing was just squashed like an accordion.

Waited for a few days before touching the actuator as I wanted any "perceived" or real improvement after the service to stand on its own and not cloud any changes made by going at the actuator. The car felt a little smoother after the service. Biggest change was the gear changes. After going the gearbox oil its much smoother to change. Too much of a difference to just be in my head.

Anyway, went at the actuator on Sunday and it would not budge by hand. Ended up clamping a pair of pliers onto the bar and using that for leverage, all the while being careful not to bend/twist the bar. Took a while but eventually it started to loosen up. Got it to the point I could move it by hand and decided that was enough.

There is a very big difference in acceleration and noise (inductiony type turbo sound) now. Pulls much harder when on boost. What a change! Went as far to describe it to a friend as it feels like the car was tuned. Its way too much of a change to be in my only be in my head. Delighted! Although always a downside, the misfire/hicking/rough idle is still there. Unchanged as always. For another day...