running lumpy at idle! Help!!

[JoeRK]

Hi all, my Phase 2 172 FF has developed a lumpy/rough idle and up to about 3K then seems normal after that.

I've changed the coil pack, leads and plugs and there is still no change. When i removed the plugs there were no bad signs, they all looked ok.

I'm wondering if its anything else simple? like a sensor?! or a fuse lol

Any help appreciated!!

 

[Pedro]

Id suggest cleaning the TB or maybe a sensor issue more likely.

 

[TimR26]

They are lumpy at idle anyway so sounds normal but if it's really bad try cleaning the crank sensor. If you remove the airbox you'll see the t-shaped sensor on side of engine.

 

[JoeRK]

Advice to anyone having engine problems....get a diagnostic test!

After spending £135 replacing Coil pack, leads and plugs it turns out i have a faulty brake switch!

Gonna pick one up from Renault on Monday!

 

[JoeRK]

They are lumpy at idle anyway so sounds normal but if it's really bad try cleaning the crank sensor. If you remove the airbox you'll see the t-shaped sensor on side of engine.

I don't know what fuel your running on! Mine wasn't/isn't lumpy at idle, its quite smooth!

 

[Pedro]

TBH most clio's are lumpy from cold, especially if you have a decat.

 

[Tobs]

yh since i put a de cat on mine cold start is super lumpy with no power at all, then once warmed up its fine. also yh if u go over 3k it clears because it doesnt run on lambda after that, it runs off its normal map

 

[JoeRK]

Has anyone noticed any power gains thru de cat plus exhaust? im a bit reluctant to get anything at the mo cos im driving to Newquay from Kent in a couple of weeks (6hrs of exhaust note!)

I wouldnt mind some lumpy fast road cams at some point tho!

 

[J.B.]

Had a few of these threads lately haven't we? It seems to be really common these days. I had a lumpy idle which is now gone after I cleaned the TDC sensor, cleaned the throttle body and filled the car with BP Super instead of Tesco. I think the fuel actually made more of a difference than the rest. What fuel do you usually run it on?

Give the sensor and TB a good clean with some WD40 or Engine and Machine Cleaner. TB is a simple job, the TDC sensor is tricky to get at as the airbox needs to be completely removed. But as the airbox needs to be disconnected from the TB to clean that, you may as well do both jobs at once. Took me about 2 hours for both taking it slow.

Edit: Just seen you had said you had a faulty brake switch. Is that associated to the problem? It doesn't sound like it's related but I could be wrong.

 

[JoeRK]

Well I had it plugged in to a diagnostic machine and it had 3 fault codes about the brake switch sensor. He cleared the codes and when I started the engine it ran normally again. After driving it 3 miles home it very slowly started missing and eventually started running rough again. The mechanic said that the faulty brake switch will put more fault codes up until I change it. So hopefully tomorrow I'll chain the switch and clear the ecu and problem sorted!

I run mine on tesco momentum, seems ok. What does the TDC sensor do and look like?

 

[James23]

tells the ecu what position the crank is at and so when to fire. its a black plastic 'thing' on a curved metal bracket on the right of the engine as you're looking at it, under the airbox and near the gearbox. It has wires going to it you cant miss it.

 

[JoeRK]

b****cks!

replaced the brake sensor switch and no fault codes now, all electrics are fine.

Clio is still running wierd, cuts in and out every now and then, hesitant then pulls, very strange. Its as if the fuel cuts out then back in again, but its worse lower in the rev range and better higher up so i doubt its the fuel pump.

bloke who did the diagnostics said its defo a mechanical problem as he looked through everything on the ecu. He reckons its an air leak??

May have to take it to Renault...

 

[sideways danny]

all clios have a brake pedal switch fault logged.

Could be an airleak, but i'd suggest changing the plugs as a visual check will tell you very little unless they're completely wrecked. worth getting diagnostics done by someone who can look at live data and not just fault codes, a faulty lambda sensor almost never logs a fault code but causes terrible economy and bad running

 

[JoeRK]

Yeah he was looking at the live data, checking everything. I suggested the lamda sensor but he said it would be showing up on his screen. Sounds like you know your clios, possibly the lamda if u say it never shows up. could be anything, think i'm just gonna have to take it to Renault. £500 later! haha :S

 

[sideways danny]

where are you? plenty of better places than renault to go

 

[JoeRK]

Ashford in Kent. I just thought Renault might have a better idea on diagnosing the problem, plus its just down the road from me. £93 / hour tho!

 

[joshcliosport]

b****cks!

replaced the brake sensor switch and no fault codes now, all electrics are fine.

Clio is still running wierd, cuts in and out every now and then, hesitant then pulls, very strange. Its as if the fuel cuts out then back in again, but its worse lower in the rev range and better higher up so i doubt its the fuel pump.

bloke who did the diagnostics said its defo a mechanical problem as he looked through everything on the ecu. He reckons its an air leak??

May have to take it to Renault...

sound like that could be a blockage in the fuel pipes

 

[Soot1e]

Judging by previous threads on the rough idling problem, everyone has changed the usual plugs, leads, coil, lambda etc. and still had the same idling fault. I believe its a fuel mapping problem, possibly overfueling at idle as all other times the car drives smoothly. One other part that may cause problems of this sort is the throttle potentiometer, could I be on the right track?

 

[JoeRK]

A friend has told me it could be the automatic choke?? someone he knew had the same problem and this was playing up! would this not show on a diagnostics? god i'm at a loss!! Its booked into a Renault specialist on Friday.

I do think it may be fuelling issues tho...

 

[Pedro]

Judging by previous threads on the rough idling problem, everyone has changed the usual plugs, leads, coil, lambda etc. and still had the same idling fault. I believe its a fuel mapping problem, possibly overfueling at idle as all other times the car drives smoothly. One other part that may cause problems of this sort is the throttle potentiometer, could I be on the right track?

Ive thought the same. Im hoping this remap off JMS will fix this issue.

 

[Soot1e]

Love to know the outcome Pedro.

 

[Soot1e]

I love to know the outcome of this. And Pedro's remap.

 

[Pedro]

Ill keep you posted. Im in talks with JMS about a date at the moment.

 

[JoeRK]

Mines had a group N remap from JMS. Before the recent problems started it ran smooth at idle and had a better torque curve, it pulls really well from low revs all the way round.

 

[JoeRK]

I took the car to a Renault specialist today for some answers...his diagnostics picked up a fault with the main Lambda sensor or the wiring to the Lambda.

He is going to check the wiring next Thursday before we change a sensor that might not need changing, although i want to check it over myself and see if I cant find a dodgy connector or something....

Has anyone ever had a problem with their wiring or is it most probably just the sensor??

 

[Mike@Rentech]

Oxygen sensor is probably the most important sensor on the engine management system, tells the ecu what is coming out of the exhaust and the ecu adjusts furling accordingly.
So if it's faulty then car is never going to run correctly.
Change it see how you go, remember it's the upstream sensor that's the important one.

 

[JoeRK]

Yeah thats what the fault code was saying...the upstream oxygen something! (Paperwork is at home!) I could change the sensor myself, dunno whether to risk it or get it checked out on thursday.

Bearing in mind i've already spent £200 on changing unnecessary parts! lol

 

[dannothevts]

im having the same problem

 

[FlansS14]

seams a very common problem? has anyone changed the fuel filter?

 

[JoeRK]

It was actually the downstream oxygen sensor (after the CAT) that was diagnosed. Had it changed and now i'm not getting any fault codes but the problem is still there, although it has made it 50
% better and more drivable. I'm gonna swap the lambda sensors around tomorrow to see if it is the upstream sensor thats faulty....

 

[my leige]

Would love to know if this fixes it.

I have a similar problem with mine. I think it may be an exhaust leak or a sticking injector. Exhaust makes a noise similar to a minor leak at low revs. Injectors are noisy and when they are gummed up they tend to stick open and make the fuelling erratic.

 

[Soot1e]

Gummed up injectors tend to ruin the spray pattern of the fuel entering the combustion chamber and can cause uneven ignition, usually an ultrasonic clean is all that is needed. The machine that cleans them also measures the amount of fuel that passes through the injectors and of course they should all be the same. Gummed up injectors doesn't stop the switching on/off, the timing off the injectors is controlled by the ECU and that rarely goes wrong.

 

[my leige]

Would love to know if this fixes it.

I have a similar problem with mine. I think it may be an exhaust leak or a sticking injector. Exhaust makes a noise similar to a minor leak at low revs. Injectors are noisy and when they are gummed up they tend to stick open and make the fuelling erratic.

Fixed now It was two very light exhaust leaks; one at the cat to centre section joint and one at the centre section to subframe sleeve. These were the tiniest of leaks and if you're not experienced at finding them you could easily miss them. Also, the standard renault sleeve that joins the centre section to back box is utter crap. This was replaced with something more suitable.

The tickover has a very gentle 'throb' or pulse. I expect that this is the normal uneveness that people report. Before the fix it was close to cutting out at times, less so at others.

 

[my leige]

Gummed up injectors tend to ruin the spray pattern of the fuel entering the combustion chamber and can cause uneven ignition, usually an ultrasonic clean is all that is needed. The machine that cleans them also measures the amount of fuel that passes through the injectors and of course they should all be the same. Gummed up injectors doesn't stop the switching on/off, the timing off the injectors is controlled by the ECU and that rarely goes wrong.

I agree but I would also add that it's not unusual for injectors to get crud between the pintle and the seat. In other words, the injector 'leaks' as it can't shut off even though the ECU and injector solenoid are working correctly. This was a possible symptom I suspected and referred to above. The injectors have really quietened down now the exhaust is fixed, probably because the ecu is no longer making such sweeping changes to the outputs because the feedback it's getting is much more linear.

 

[rory182]

Fixed now It was two very light exhaust leaks; one at the cat to centre section joint and one at the centre section to subframe sleeve. These were the tiniest of leaks and if you're not experienced at finding them you could easily miss them. Also, the standard renault sleeve that joins the centre section to back box is utter crap. This was replaced with something more suitable.

The tickover has a very gentle 'throb' or pulse. I expect that this is the normal uneveness that people report. Before the fix it was close to cutting out at times, less so at others.

Bit of a bump but I'm getting some hesitation when I pull away and its noticeable if I short shft into a higher gear e.g. 4th or 5th at say 20mph it stutters, hesitates.

The coincidence is I have a new renault exhaust centre section, tailpipe and sleeve fitted with new cat gasket. I shall take it to an exhaust place to get it checked tomorrow and report back!

 

[rory182]

Well my exhaust isn't to blame, suspect plugs / leads / coil so have ordered all of the above, will report back next week

 

[MicKPM]

A friend has told me it could be the automatic choke?? someone he knew had the same problem and this was playing up! would this not show on a diagnostics? god i'm at a loss!! Its booked into a Renault specialist on Friday.

I do think it may be fuelling issues tho...

Automatic chokes!!! LoLz, we've not had those on cars since the 1980's matey (Well, since EFi became standard fitment at least to petrol engines). Fuel lines and fuel itself are rarely an issue these days so I doubt it is a blockage... plus, if it's okay pre and post 3k rpm its isn't fuel supply.

As above, H02/Lambda sensor is the most likely cause along with possibly the coolant temp sensor but a proper session on decent diagnostics will settle that argument. Would also be worth scoping the injector triggers to see what's occuring there also.

Mick

 

[JoeClio1.6]

Hello everyone

I am new here and just found the cause of an idle related problem on my clio 1.6 16v K4J engine, the car starting fine in the cold of the morning but as the day warm up then the rev began to drop to 500 rpm and all the symtoms described on this thread, after searching and searching on the renault sites didnt found nothing, after checking technical values of the engine sensors, found that the IAT sensor was faulty, this sensor must have a resistance of 25K ohms at 20 degree celsius, and about 1.2 k ohms at 40 degree that is pretty hot air, as soon as my car began to idle roughly, pull out of the road and measure the IAC sensor resistance and was 0.7 K! then measured in cold engine ambient temperature and it gives the 25K Ohms, but these devices fail weirdly, so the ECU was receiving wrong info, then sending wrong info to injectors and spark, and the oxigen sensor making correction, maybe thats why the revs seems like oscilating, so if you have this problem check that sensor, you can put a 1.8 k resistor across the sensor cable connector while buy the spare part. Hope this helps

 

[Xanda73]

Hello everyone

I am new here and just found the cause of an idle related problem on my clio 1.6 16v K4J engine, the car starting fine in the cold of the morning but as the day warm up then the rev began to drop to 500 rpm and all the symtoms described on this thread, after searching and searching on the renault sites didnt found nothing, after checking technical values of the engine sensors, found that the IAT sensor was faulty, this sensor must have a resistance of 25K ohms at 20 degree celsius, and about 1.2 k ohms at 40 degree that is pretty hot air, as soon as my car began to idle roughly, pull out of the road and measure the IAC sensor resistance and was 0.7 K! then measured in cold engine ambient temperature and it gives the 25K Ohms, but these devices fail weirdly, so the ECU was receiving wrong info, then sending wrong info to injectors and spark, and the oxigen sensor making correction, maybe thats why the revs seems like oscilating, so if you have this problem check that sensor, you can put a 1.8 k resistor across the sensor cable connector while buy the spare part. Hope this helps

Interesting, if a little strange first post. Welcome along; introduce yourself in the relevant forum section.

 

[MicKPM]

Also any decent diagnostic live data session would show the IAT as being like the inside of an over or simply not recording with those resistance readings to not to mention the H02 sensor would be all over the shop trying to compensate for driving on the surface of the sun.

There's nothing wrong with checking sensors out with a multi-meter, I like to do this to confirm what the live data is showing, but don't always believe the values that software like Vivid and AutoData gives you for them... your metering device itself won't be 100% accurate even if it is brand new or has just been calibrated.