Injector Related Queries (MK3 RS)

Good evening,

I have a number of injector related queries that I was hoping could be answered here. I've had a thorough (I think) search on the forum and Google, however have been unable to locate answers.

These queries are on the back of the car (MK3 RS) idling poorly when cold (vibration through the car), the issue being heightened when the car is left in "Normal" mode. Therefore, I always activate "Sport" mode upon start-up. The car actually sounds like it's struggling to stay running in normal mode when cold, although doesn't actually ever die.

1. Is an intermittent cough from the exhaust (no EML) likely to be causing any real engine damage? It seems like a lot of RS owners experience poor idling after a cold start. For me, this lasts around ten minutes, however only really apparent at idle. There is what sounds like an intermittent metallic noise from the engine (nearest the passenger side/injector 1), in sync with the cough from the exhaust. After driving for approximately ten minutes, the engine will then idle with no issues, unless driven hard - after which, when left to idle, the exhaust will cough for a good few minutes. No performance issues appear to be experienced as a result of this. The car can be driven hard and does not misfire when in motion. General Googling and forum searching appears to have pinpointed this to be injector related, specifically the seal.

2. The manufacturer of OEM injectors on a MK3 RS? There appears to only be Renault and Bosch injectors available - are the Renault ones re-branded Bosch parts? If not, does anybody have any experience with the Bosch ones? Given that injectors appear to be a real weak point in RS cars, I'm considering giving the Bosch parts a go. Although I've read that the cars can be a bit funny with aftermarket parts.

Not convinced with my formatting of this post, just trying to give as much information as possible, to help with any assistance that can be provided.

Cheers,

P.S. Apologies for the awfully long post.

 

Thanks for the information. I think that new Bosch injectors can be had for around 40 quid each online, as opposed to 60 for the "Renault" ones.

Truthfully, I've just read so much regarding how poor the OEM injectors are, that I think I'd rather just have them replaced and it cure any problem, than wasting time chasing it.

I believe that @Genty has resolved the "issue" for me. Many thanks to the both of you for your help.

Cheers,

 

To update, brand new injectors has made no improvement. Still a metallic clunk off the engine that can be felt through the entire cabin until the car reaches operating temperature.

Car as before - runs perfectly fine when up to temperature, apart from after a spirited drive, when there's a cough from the exhaust when idling. Considering replacing coil packs, thermostat (as it's now started dipping a notch when going round corners/bends, before returning to the centre) and the coolant temperature sensor.

To confirm, there's no engine management light on at any point in time. I'm now not sure whether it's just the typical poor idle from RS cars, or perhaps whether it may be low compression on a cylinder? The car never misfires when driving, pulls as expected and burns/uses no oil. I feel like it's chasing a fault that could turn out to be expensive and never actually "resolved" (if it can be). May just leave it and drive the car or try replacing the above three parts and then giving up.

 

Approx 54,000. Plugs have been changed with NGK iridiums and checked again yesterday - look fine.

 

It's been to a Renault dealer previously multiple times under warranty and they've said there's nothing wrong with it. They changed the plugs three times (don't ask, but I did make sure to ask for the old ones back in the hope of having some sort of proof that they were indeed changed, which I was provided) and the coil pack on cylinder 1.

 

It's had the 6 year service at a dealer (again, under warranty as it was claimed to have been done prior to me purchasing it and turned out not to have been), including timing belt, water pump and dephaser pulley. It's had the issue prior to this, therefore I don't think it's a timing problem either.

 

It's really not that much of a problem to me, in terms of I just know that it runs poorly for 10 minutes until it's warm. However, I'm more concerned about any potential damage being done to the engine as a result of the way it's running.

 

Technically, yes. However, I'd say no as I believe that the warranty is technically reset each time you have it looked at for that specific part i.e. it's been in for a misfire issue multiple times. I'm aware that if I took it back and complained about something entirely unrelated then it would be out of warranty. Truthfully, I just can't be bothered wasting my time. I've visited two dealers and they've both been utterly useless. At this point, I reckon I'll just keep it for the summer and then sell it.

 

This doesn't change my opinion of Renault cars, I still consider them to make the best handling/fastest (not in a straight line) hot hatches. However, I just don't really get to appreciate it that frequently as I use it as a daily driver for motorway commuting. I considered an Astra GTC VXR because I think styling wise they look great, shame they can't make gearboxes. Whilst I know it wouldn't have the handling etc of the Megane, again I don't track it or anything therefore unlikely to notice that much of a difference.

Although yes, Renault dealers are abysmal. They know nothing about RS models. They amount of nonsense I've had spouted to me is unbelievable. I'm not the type of person to let my experience tarnish the car. I'm well aware of how good it is, I just need to wait 10 minutes every day until it starts idling properly.

 

While I have no doubt that it's possible and I'm sure plenty of them do, there's also the other side well documented on here where people state that they've had numerous RS cars and every single one has ran poorly when cold. Even with MK3 RS's and apparently they've ran like mine when cold since new. It's not a very good reputation to have.

 

What I don't understand is how the engine management system isn't detecting a thing when it's clearly not running correctly - the thresholds can't be very sensitive.

In 7 months of owning the car, the engine management light has flashed on maybe 3 occasions? But never developed into anything. Even prior to the injector change, it hadn't happened in approx 2 months. It has never said check injection, although I'm assuming that's pretty much what it's saying. When I've connected a bluetooth reader and used the Torque Pro app it states P0301 - Cylinder 1 misfire pending, but never developed into a solid light. The light only ever flashes after it's been warmed up, driven and then left to idle though - never when cold, despite that being when it's at its worst. Even when the engine is coughing, spluttering and clunking when it's cold, there's nothing from the engine management system. Engaging normal mode makes it even more amusing, the car can barely run.

Unfortunately this still just points to a number of things and leaves me at the point of needing a independent Renault specialist, since dealers don't seem to have a clue - worrying. Thanks to everyone for their support. It's a shame that so many people have turned away from RS cars due to similar issues.

 

I'm not sure that this will go down well as I'm assuming that it's @Genty 's car (although I'm not trying to offend, as it sounds exactly like mine minus the loudness - mine has a mid box chop but not a decat), but particularly from around 1.15 onwards it sounds like the car is misfiring pretty considerably. With headphones on, I can hear the metallic/clunk sound from the engine through to the exhaust. It's particularly prevalent when the revs start to drop.

Upon reflection, mine is fine for about 30 seconds, then when the cold start (higher revs) begin to drop off, it idles poorly for around 10 minutes (fine when driving but noticeable after coming to a stop) as I said before. Maybe it is just the common RS cold start issue after all.

 

Finally posting a video...

https://streamable.com/4empf

You can hear the metallic clunk off the engine (best with headphones).

The exhaust smells very rich, almost like turpentine. Even with the car running as rough as it is, it will never trip the check injection light - that only ever happens after it's been left to idle for a few minutes when warm.

Does it give anyone any more of an idea? @bobsan

 

Vehicle test results from Torque Pro below (after a 25 mile drive).

O2 Bank 1 Sensor 1
Sensor period (calculated)
Min: 0ms Max: 1,300 ms
Current 370 ms

Catalyst Monitor Bank 1
Sensor period (calculated)
Min: 0Count Max: 5Count
Current: 655Count

Fuel System Monitor Bank 1

Min: 0.833 Max: 1.166
Current: 0.989

Misfire Monitor General Data
Misfire counts for last/current driving cycles (calculated)
Min: 0 Max: 65,535
Current: 133

CLIP test at Renault apparently showed no issues/faults.

The Catalyst Monitor Bank 1 test failed - although, I'm sure I've seen another member posting the same result and they didn't have any misfire issues. The only modification on the car is a mid-box chop.

The car runs perfectly fine when started for about 30 secs and then the cold start i.e. higher revs seem to drop off and it'll misfire until warm. The exhaust smells like pure petrol so it's obviously running rich. If I was to hold the revs at 3k for instance, then it wouldn't misfire.

If the car is driven hard and then left to tick over at idle, it'll cough which I think usually points to injectors. However, replacing them has made no difference. I literally just don't have the time to get it look at, at the minute. I'm close to just trading it in to be truthful and I don't think I want another one. The fact that a lot of Meganes' seem to run poorly when cold is not a good reputation. The car is phenomenal (thanks to the diff), but unless you're tracking it then I don't see much of a difference when compared with e.g. an Astra GTC VXR. The Renault dealer I took it to didn't have a clue. A real shame.

 

Any chance of a video of yours from a cold start? I checked the pre and post-cat O2 reading using Torque Pro and both of my sensors are operating as expected: the pre-cat sensor fluctuates from (if I can recall) 0.2 to 0.8 volts and the post-cat sensors sits around the 0.6 mark, which is as they should be.

Closest video that I could find online to mine is probably this:

I'm starting to genuinely believe that it's just the way that the cars run from cold. If it was that bad, the EML light would illuminate.

 

Can't see it unfortunately, it asks me to sign in.

I think the new injectors improved mine slightly, but nothing major. Would be interested to see more people uploading videos at least a couple of minutes long with a cold start of their Megane - there's very few on YouTube. People are either revving the nuts off it, or the video only lasts 30 seconds.

 

Cheers, I appreciate it. I've just not really found another video that I can say, yeah... that sounds exactly like mine!

Regarding your results, they look like the expected outputs to me. The test that fails for me also suggests a clogged cat, however the car passed a legitimate emissions test and it pulls like a train. I actually think it's making more than 265 bhp that it's rated, when comparing it to others cars I've went up against in a straight line.

 

Well, there it is. Exactly what my car sounds like inside the cabin whilst idling and it's from a Clio. No idea how Renault are even legally allowed to sell cars/engines that run so poorly when cold, and that's with a map trying to even it out. How it doesn't put owners off buying another one I don't know. It really must be just the F4R + T rough/lumpy idle trait.