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Discussion Starter #1 (Edited)
Hello,
I'm trying to fix a RENAULT CLIO II 1.4 (75CH) from 1998 running on petrol. The symptoms are as following:
1) Can't idle (sometimes can). If I don't hold the acceleration pedal, it just dies. I suspect a bad IAC valve, but I'm unsure how to test it.

2) Rough running. At (supposed) idle speeds (below 1000 RPM) the car is really shaky. Accelerating it (in neutral) makes the shakiness go away to some degree, and it runs better once it reaches 2000 RPM. I can still feel it shaking, but much less.

What I did so far:
I looked at the fuel trims and basically, it indicates a vacuum issue, however, it could be something else too. The LTFT is maxed out (probably) at 30, an the STFT kind of fluctuates, but goes down when I accelerate it. I could post the graphs if needed.
I cleaned the throttle body, MAP sensor, and the IAC valve. The IAT sensors were 4, but I didn't clean them yet, and I don't have with what to clean them for a while either. The EGR valve (or what it seems to be that) was not cleaned either, as it was a pain to take out. The air filter seems acceptable. It could be possible for a leak between the intake and the throttle body, but would that affect it very much?

I checked the coils, and their resistance seems consistent, besides the last one (let's call it number 4), which has a little bigger resistance, but the wire is also longer, so it maybe could add up to normal.
I pulled out the coils one by one and started the car. It seems that the coils 1,2,3 affect the run (probably), but 4 does nothing.
I then pulled the coil 4 out while the engine was running, and then it made absolutely no noticeable difference. The coil does seem to fire, as I heard it firing when I plugged it out.

I'm unsure what the issue is for those symptoms. I'm guessing cylinder compression / blown head gasket / intake or exhaust valve? Coil misfire? Bad spark plug (I did not test it yet)?

Can anyone point me in the right direction?
Thank you in advance
 

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Super fantastic Mod Technical Supremo Nice Guy
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IAT sensors?

Would your Renault have an EGR..
Whats engine Earth reading ..
Has yours got that metal clamp that fits over the ECU just behind the throttle body..
If yes , check its not been allowed to bounce up and down, and cut through parts of the loom...
Really need to check your spark plugs, colour will reveal more..
 

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Discussion Starter #3
IAT sensor stands for Intake Air Temperature sensor, as far as I know. I noticed quite a few temperature sensors, unless I'm mistaking them for something else.... but they're on the intake, so I'm not sure what else could they be, although I'm not getting readings from all of them from the ECU. Probably not the right tools, or the ECU does not allow it.

It seems to me as it has an EGR valve, but I could be wrong. I will take tomorrow some pictures, maybe others know better whether it is or not. I will try to take the spark plug out tomorrow too, and test it by measuring its resistances and see if it has any issues. I'm not sure what else to check on it.

How exactly do I check the engine earth? Do I check the continuity between the engine block and the negative terminal of the battery?

As for the ECU, I'm not sure where it is located, but behind the throttle body it's just a wall (for sound reduction I think). I'll take a look tomorrow to see if I can take it off and see what's behind it. The engine supports theoretically are good as far as I observed them.
 

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Super fantastic Mod Technical Supremo Nice Guy
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Would normally only be one Intake air Temp..

Where are these situated on your engine

Do you have a K4J engine fitted - 16 valve
Or
E7J - 8 Valve fitted
 

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Discussion Starter #5
Not sure about the engine. It's a RENAULT CLIO II 1.4 75CV (BB0/1/2_, CB0/1/2_) (B/CB0C) (55KW)
Possible engines: E7J 780; K7J 700; E7J 634

It seems as if it is a 8 valve engine, but I'm not finding a lot of information about that. Given the engine power, I am inclined to believe that there's only 2 valves per cylinder.
I have also found some technical specifications that seem to fit the profile as far as I know: https://www.auto-data.net/en/renault-clio-ii-1.4-b-cb0c-75hp-10419

There seems to be a lot of sensors on the intake, which I find weird and confusing as well, since the car doesn't seem that technologically advanced to require so many of them. I might take apart the intake part tomorrow and take some pictures. They're basically behind the engine, after the throttle body. Above the throttle body it's the filter which is in a box taking most space from above, so I can't show them with it on. But after the throttle body there's the manifold, which has 4 of those sensors, looking like this: https://i.ebayimg.com/images/g/v9AAAOSwTc5b9vOw/s-l300.jpg. They look the same on my Laguna II, but I have only one there.
 

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E7J780 1.4 - 8 Valve
 

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Discussion Starter #7
I'm starting to suspect a leak in the cylinder. The spark plug which I took out was wet, but I'm not sure with what. Checking the oil, the color seems normal. The coolant is a darker color than what it should be, but I don't know if it's an effect from that, or just from it being old. A mechanic said a while ago that it has a stuck valve?

I'm repeating myself, but taking the plug wire out from cylinder 4, does not affect at all the way the engine runs.
I checked the ground of the engine and there's no issues with it. Supports are fine, and even if they weren't, they're not the issue that I want to fix. There is an issue with the engine in the cylinder 4, or at least there.

This is how the spark plug looks like:





I actually broke it when taking it out, but its resistance seemed fine. I was told that the spark plugs were relatively new.

This is the thing I thought to be the EGR valve, but I'm starting to doubt it now. It kind of looks like it, but as far as I managed to follow the pipelines going into it, seems like it has to do with the coolant. Not sure what it is, but even if it's not EGR, I'm still wondering what it is.


Behind the engine, I don't see any ECU or anything that would look like it... it's basically a wall behind a sound reduction cover.

I took the IAC valve out and tried to see how it's working, but I don't really see it operating. I managed to get it to operate once or twice, opening only a few millimeters (not sure if it's normal) but then it died again. Given that the engine would have a cold start, you'd expect it to open all the way to let enough air pass, but it didn't look like it would"ve been enough to let much air pass, although I'm not sure what to expect. The connection to it seems fine though.

In the next picture you can see the sensors I was talking about. They look like IAT to me.
 

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Super fantastic Mod Technical Supremo Nice Guy
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Have you tried another spark plug..

You will need one either way..
These do fail,

Compression test "might" reveal something, but if you are not using/burning oil.
Would go on the cheapest test first ( Spark plug ,, and lead )
Idle air control valve, refit it, now undo the screws so they are just holding it in place, now switch ignition on, Now screw it fully home.
Switch ignition on and off 5 times, this should reset it..
 

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Discussion Starter #9
Since a new spark plug is unavoidable, I'm getting one tomorrow and will see what happens from there, but given that I saw an oily spark plug, I don't think that's the only issue. I would want to check the other spark plugs too, but the one who put them in, tightened them way too much, so I will probably break them too in the process.
The spark plugs were replaced a while ago to fix this issue to no avail, so I'm not holding my breath. The car had this issue for quite some time now.

Thinking about it again, the spark plugs from my Laguna fit on this engine as well, so I took one and put it in the 4th cylinder. The problem is still there, and I'm quite sure that this spark plug is fine.
I'm planning to see tomorrow if any oil will be deposited on it while it stays overnight. If not, I will run it for a while to see if that will make the spark plug oily.
I believe that the previous one could've been fouled, but I don't see much of a difference with the spark plug from my Laguna, and I didn't have the time to do a more extensive test to see if pulling out the plug will make any changes in the running of the engine.

Sadly, I don't have the tools for a compression test, and in this country I don't think I can borrow those things from the mechanics. I might try to get the tools tomorrow if I have the chance. I'll come back when I'll have some advances on the matter.
Meanwhile, does anyone know what and where are the fuses for the fuel pump and the spark system so I can take them out when running the test? I don't think the car has the manual, but I'll ask tomorrow, although from my little experience with Renault manuals, they don't say those important technical things.

The IAC still looks pretty dead. I will try again tomorrow. I'm wondering if it's possible to open it up and fix it...
 

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Super fantastic Mod Technical Supremo Nice Guy
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If spark plug is not firing, you will get oil and petrol mixing..
The oil will drop down past the valve seal

Try a spark plug first,
 

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Discussion Starter #11
I did, I took one from my Laguna and put it in the cylinder 4. Running it for a little, I didn't feel much or any improvement with the good spark plug. I will see tomorrow if it's oily or not, or if it will get oily after running the engine.
 

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Discussion Starter #12
Ok, so with enough insistence, the IAC valve magically works again, and it seems to be fine for now.

The spark plug did not get wet while sitting in the engine for about 2 days. I ran the car for about 30 minutes and it didn't get wet either.
I performed the test again, pulling each coil out, and the result is the same. The coils 1,2,3 affect the engine (2 seems to do it the most), while the 4th doesn't make absolutely any difference, even with the good spark plug.

I managed to get a manometer, but I can't seem to figure out what are the relays for the fuel pump and the spark system. The manual does not provide any useful information on those things, and the relay boxes don't have any engravings or stickers on them. I only know that they're not in the cabin box.
Those are the relay boxes from the engine bay:

I'm suspecting the two 60A relays circled in red to be for the spark system.

I'm suspecting the one circled in red to be the fuel pump, but I could be wrong.
The big black switches are labeled L, M and H if I remember correctly and if makes any difference.

Does anyone know which relays are the correct fuel pump and the spark system?
 

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Super fantastic Mod Technical Supremo Nice Guy
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Coils or plug leads
Relay you have marked is fuel pump
Column of 3 fuses, smaller fuses I mean, top and bottom fuses control injection
 
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Discussion Starter #14 (Edited)
Today I did a compression check. The "dead" cylinder has a really good compression.
I also realized that the order they have is reversed, so the dead one is actually number 1 not 4.
Cylinder 1 (dead one): 180 psi
Cylinder 2: 150 psi
Cylinder 3: 150 psi
Cylinder 4: 170 psi

I've done a few tests, and this dead cylinder seems to reach 150 from 3 cranks. Pretty much all others do the same, but the final results are from 8 cranks. The rest of them seem to stay at 150psi (besides 4), but this one goes up to 180psi.
The engine sounds different when cranking it and checking the dead cylinder compared to when checking the other ones. As if it's working harder on the dead one.

The spark plug that I put a while ago in that cylinder got fouled, but the car was not driven much in the past weeks (less than 1km). Most of the time (95%) it was just sitting.

I reversed the firing order out of curiosity, but nothing changed.

So pretty much everything is tested besides the injectors and the exhaust of the dead cylinder.

Any other ideas?
 

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Discussion Starter #15
So I got someone to help me, and I kept cranking the engine until the pressure wouldn't go up significantly anymore.
Some cylinders took less turns, others took more, but in the end all reached 180psi under 8 turns or so. Cylinder 1 & 4 took less (4-6 turns), then 2 & 3 took more (6-8 turns). Overall, compression doesn't seem to be the issue.
I also checked the rhythm of the air being pushed out and it's the same for the dead cylinder as the others. I'm thinking that was a bit pointless as it does't say anything more than the pressure test. I checked the exhaust, and although it has rough air gushes, I didn't notice any vacuums pulling back in. I know now for sure that there's no valve stuck OPEN, but I don't know if it's stuck CLOSED.
I'm thinking to do a test on the intake, with no fuel and spark to the engine, but sealed with the spark plugs, and see if there's any air gushes pushing out, which would possibly indicate a closed exhaust valve.
My reasoning is that if the intake valve opens while the piston goes down, there should be pressure in the cylinder which would rather go out thought the intake before finally taking air back in. I'm unsure however if the vacuum created from the other pistons would make up for it instead and I wouldn't feel anything, or rather just a stop on the air taken in. Even that might be negated given that the pressure would go down as the valve opening would be increasing, which in turn could regulate the air pushed out in such a way that would not be noticeable.
It's all but an assumption, since I don't have any real experience with cars, so could anyone confirm me the expected behavior? Or maybe suggest some better tests?
 

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Super fantastic Mod Technical Supremo Nice Guy
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Not sure what to say Mike as you have compression.. .

Would now really be looking at an injector issue here..

Not sure how much the injectors are,as some injectors it costs more to have tested than replace with new ..


Just spray the base of the injector, where it fits in head/manifold with penetrating oil, to allow them to come out easy..
Then cover the 0.ring/seals you will see when the injectors are out , with grease to allow them to go back in with ease..
( Should you decide to swap from the other engine at this point)
Its always soak with penetrating to come out, cover the seal with grease to go back in..
WILL not come out DRY, dont try it will end in tears...
 

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So there is compression but the spark-plug fouls within 1km?............ this while engine can run on other cylinders and not foul other plugs? ...................implication is timing is right and there there is fuel as well as compression as a result of the actuation of valves via the camshaft



Somehow you need to confirm that at some stage during the 4 stroke cycle you end up with no compression


I would get a cheap boro-scope camera - few $ on fleabay hang it off your Android/Windows device, stick it in through spark-plug hole, and see if the inlet and exhaust valve opens and closes at the right times - if the exhaust valve never opens then your experience with dud cylinder taking more effort to produce same compression values is echo'd...........


Alternative is to rip off valve cover and physically see if rocker on the individual valve is actually moving the valve (look for loose/broken rocker or damaged cam lobe)


Perhaps an easier way to confirm if you feel adventurous:


Remove spark plugs, raise one wheel off the ground on a trestle, engage first gear, and with a socket on the center hub nut on the wheel, spin the wheel in reverse via an extension bar clamped in/attached to an electric drill with electronic speed control .............. you now have the engine working in reverse - ie the exhaust valves become the inlets and the inlet valves the exhaust valves - now do a compression test again - if the same cylinder is now reporting gaga compression you know there is a stuck closed exhaust valve
 

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S




Perhaps an easier way to confirm if you feel adventurous:


Remove spark plugs, raise one wheel off the ground on a trestle, engage first gear, and with a socket on the center hub nut on the wheel, spin the wheel in reverse via an extension bar clamped in/attached to an electric drill with electronic speed control .............. you now have the engine working in reverse - ie the exhaust valves become the inlets and the inlet valves the exhaust valves - now do a compression test again - if the same cylinder is now reporting gaga compression you know there is a stuck closed exhaust valve

Wont this FUBAR His cam belt/engine,

Never a good idea to turn an engine backwards, even a short amount , ..
 

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Still struggling on it being a stuck exhaust valve in the closed position, how is the compressed air getting out ..
 

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Wont this FUBAR His cam belt/engine,

Never a good idea to turn an engine backwards, even a short amount , ..
On this design?....................for the quick compression test cannot see why as long as the tensioner is in place and pulleys are all properly located/locked on their shafts . Can you describe a mechanism where you can see damage will result from? Have done exactly this on quite a few engines in the field where there is no space/facilities to get an accurate diagnosis without opening the engine was required to minimize downtime ............. as I said - adventurous.:wink2:



Still struggling on it being a stuck exhaust valve in the closed position, how is the compressed air getting out ..
From what I understand especially with the fouling of the new plug in very short distance (1km) - it never happens normally (compressed air gets out) - cylinder can get filled (first rotation after engine stood a while), compression stroke happens, and power stroke (down) happens, and as soon as the exhaust valve is supposed to open the rubbish in the cylinder is partially recycled in the cylinder and partially blown back up the intake soon as the intake valve opens ............. effectively recycling used combustion air on the 2nd and subsequent compression strokes (gaga misfires/ignition of poor air fuel mixtures effectively) .................will always have proper compression reading on a compression test if exhaust is stuck closed.................. that is off-course if we are told the whole mechanical story and its not simply a question of burning of oil
 
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