Unstable idle

[FishFart]

Hey everyone!

I have a problem with idle for quite some time, followed by engine light pulsing after I start the engine. The light goes on for 15-30 seconds and then just stops. This happens randomly, and sometimes 2-3 times in a row, and sometimes 2-3 times it doesn't appear at all.

Model 197 / 2008, 53000miles.

Recently I had it at mechanic, and on diagnosis it showed miss fire on cylinder #2.
- Changed ignition coils (yes, all of them), and was fine with engine light but idle was still unstable (falling up and down, all the way to 500-600 rpm and sometimes just engine cuts out.

Afterwards the same problem with diagnosis, but miss fire on cylinder #1.
- Changed spark plugs / all 4 of them, and there was no miss fire anymore.

Then the engine light keep appearing a few days after everything was fine (but idle was still unstable), and so I changed throttle body. After that everything was fine for 2 days.

Now I have same problem again and have no idea what could it be. Is it fuel pump? Is it ECU, electricity?

One thing that keeps happening is when I fill up the gas tank to 100%, and turn the car on instantly on the gas station, the car wiggles and the idle won't work normally (car cold/warm, all the same), and it just struggles to get to 800-1000rpm, loops around 600-850 rpm while choking.

And the pattern is the same every time:
1st time turn engine on: Choke like above
2nd time turn engine on: Choke like above
3rd time turn engine on: All works

But throughout the whole period of time described above, when I put the clutch in all the way, for example at at street while driving normally, I am stopping from 1st or 2nd gear, the engine chokes as the rpm-pointer drops down, and sometimes engine just dies.

Also when I drive in traffic, and just pressing gas a few times in 1st gear to move forward to traffic light, or I just park the car and go 1st/reverse/1st etc, the idle becomes so unstable by dropping that the car turns off.

Same goes for 2nd gear: 2 times I press gas pedal in short time period to get the revs up a bit, and when I don't press it next time, it drops and chokes the engine / gets turned off.

A friend had similar setup (raptor) to mine and had no such problems:

v6 airbox+K&N panel
ported intake manifold
ported head
toyosports exhaust manifold
akrapovic evolution
lightweight flywheel
lightweight crank pulley
remapped

Engine was re-built recently and has perfect compression on all 4 cylinders, as brand new.

Any input would be appreciated, thanks!

 

[FishFart]

I forgot to mention CatCams '402

 

[AmosMoses]

Map sensor isn’t stuffed is it?

 

[FishFart]

I will have it checked together with few other stuff, thx @AmosMoses

 

[youngarthur]

Ive had up/down idle, that was an air leak, and could well be map sensor.

 

[Dumdum]

Just an aside and not everyone knows how easy it is to find an air leak, use a decent brake cleaner, spray it round the various pipes, injector seals etc, if there’s a leak generally the revs will pick up/run rough for a second as the mixture goes rich

 

[Dumdum]

could also be a mapping issue of his is perfect yours isn’t?

 

[youngarthur]

Just an aside and not everyone knows how easy it is to find an air leak, use a decent brake cleaner, spray it round the various pipes, injector seals etc, if there’s a leak generally the revs will pick up/run rough for a second as the mixture goes rich

Very good point.

 

[Sherlock101]

Might be worth checking the lambda sensor is working properly? Mine went recently and it caused the car to idle really rough, had lots of pops and bangs when pulling away from cold (sounded awesome [emoji12])


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[FishFart]

Thanks everyone! Tomorrow I am leaving my car at mechanic so will take a look at those things.

@Dumdum will also go the the tuner to check on map, it is same tuner that mapped raptor's car but he had this setup 3 years ago so dunno atm.

The engine light keep appearing and blinking randomly, sometimes from cold start and sometimes when I turn engine on when still warm, it blinks for 10-30 seconds and then goes away. And sometimes it doesn't happen 5 times in a row, sometimes it does 3 times in a row.

The biggest concern I have is that pattern of not being able to start the car to work normally after I get the tank full at gas station. It is always 2 attempts fail at low choking idle RPM, followed by 3rd attempt which is successful. If I don't fill the tank to 100%; it is fine when I turn engine on (Except for that engine light appears randomly anyway).

If you have any additional thoughts, please post!

I will let you know on how it went this week as soon as it gets sorted out (if it gets sorted out) and I take the car back.

Thx

 

[Dumdum]

I’d check coolant temp sensor is reading correctly as it sounds like it’s over fuelling, and also air leaks with a can of brake cleaner

If the maps been on 3 years and ran correctly it’s doubtful to be that

 

[FishFart]

Still no information from my part, had the car on track the other day and it got worse while filling tank (on track and during driving was fine except it was 30-32 degree celsius outside so car wasn't as powerful as usual), now it didn't want to start after I filled the tank to 75%, 3 attempts to start and the car was dead, another 2-3 attempts and idle was choking as before, and finally then started normally.

Now the car is at mechanic's to check all mentioned above, including fumes, map etc.

Will report back as soon as I have any info.

Thanks everyone for your replies, highly appreciated.

 

[Dumdum]

id try disconnecting the tank breather (at the inlet manifold and block it off with some hose and a drill maybe) just incase the valve under the bonnet is knackered and somehow letting petrol vapour get pushed into the engine when its full, that's the only link I can think of between fuel level and the engine itself, it shouldn't effect fuel pressure but a set of gauges would be the next thing id check incase it was cocking up the pressure from the regulator in the tank...

 

[Dumdum]

or even if the breathers are connected wrong at the tank and somehow the engine is sucking fuel in, that would stop it starting asap!

 

[PaulV]

Hi, my 197 has displayed all these issues and run like a dog for a year and a half, luckily i broke the MAP sensor and replaced with new original renault sensor and the car is fabulous. Idles perfectly, no hesitation. Returns +5 to +10 improved mpg.

 

[Dumdum]

Hi, my 197 has displayed all these issues and run like a dog for a year and a half, luckily i broke the MAP sensor and replaced with new original renault sensor and the car is fabulous. Idles perfectly, no hesitation. Returns +5 to +10 improved mpg.

Could well be that but someone experienced with Clio 197/200 would know what it should read on idle and various throttle positions and spot it easily (Peugeot planet which I used extensively on various pugs sometimes have guide readings for various parameters... for example 210mb +/- 20mb on idle, 100+/- 25mb on wide open throttle and 700mb +/- 40mb on closed throttle at 3500 revs, this often made diagnosing sensors etc very easy, gave the same for lots of sensors inc lambda and the like, specs for idle revs and stuff, very handy indeed!)

 

[FishFart]

Thx everyone!

Last week I got brand new MAP sensor and replaced it. But still same problem happening. Mechanic is now away for holiday so can't do much around it, but was told that everything around hardware is now fine and I should check out with tuner to see the map and if there is any problem.

Last map was made with missfire issue on car IIRC. Could that make a problem?

 

[Dumdum]

Thx everyone!

Last week I got brand new MAP sensor and replaced it. But still same problem happening. Mechanic is now away for holiday so can't do much around it, but was told that everything around hardware is now fine and I should check out with tuner to see the map and if there is any problem.

Last map was made with missfire issue on car IIRC. Could that make a problem?

If You were mapping a car why would you do it with a misfire in the first place unless it was a generic map and not done on rollers, in which case it should be fine as it’s a generic to a degree, but if it’s a generic they probably won’t be able to change anything anyway, I’d be more suspect of an issue around sensors and engine management still, as presumably the car ran ok until recently??

 

[FishFart]

I left the car to be mapped and when I got back I was told car is mapped but had missfire on diagnosis. Was also told that missfire has nothing to do on high revs and mapping was ok. (pls note that I am no mechanic and I have no clue about this stuff).

And yes, the engine was re-built and then mapped, and since then this problem started first only after filling the tank to 100%, then afterwards randomly when filling tank only by percentage so not to 100%, and now it happens randomly when I just start the car after I was driving it for short or long distance without any re-filling tank (both driving fast or slow, doesn't matter).

 

[Dumdum]

I’d blank the venting valve for the tank to the inlet manifold, it could also be a blocked breather from the tank causing the tank to not release fuel via the fuel pump as a lack of fuel may also cause a misfire type symptom as well

I’d have asked him to put the original map back in to prove it wasn’t his map for as long as it would take... I don’t think I’d have accepted the car was fine before and misfiring after a map... that sounds fishy to me (mechanic of 12 years and many tweaked and tuned cars)