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Discussion Starter #1
Hi,

My megane-s engine have intermittent power loss and while searching the cause of the problem I discovered that dephaser locking pin is not releasing below ~2000 rpm when engine is at operating temp.
After that I installed the oil pressure gauge to oil pressure switch port and the pressure was bad when the engine was warmed up(~40psi/4000rpm, 0psi/750rpm).
I took sump off and replaced the oil pump. Also added fresh 5W40 oil & new filter. The engine was really clean inside and oil pickup wasn't blocked.
After pump replacement the pressure went little bit better: ~47-50psi/4000rpm, 4-9psi/1000rpm, but 0psi/750rpm idle.
Then I took the sump off again and replaced main and big end bearings. There was light wear signs on the old bearings and crankshaft surfaces were good.
Unfortunately the bearing replacement didn't improved the oil pressure at all.
Cold start oil pressure is 50-60psi in rpm range from idle to 4000rpm. It can hold some pressure at idle about 20minutes while driving.

The power loss problem have been present more than 2 years / >20000km. Unfortunately the megane have that stupid oil pressure warning system which is activated above 1600rpm, so the oil pressure warning at idle is not showed.

The car is Megane mk2 1.6 vvt K4M 2006. Mileage is >250000.
The engine is not burning/consuming oil.
Coolant temp is in range 89 to 98C.
Also the thermostat gasket, dephaser pulley and solenoid are replaced. Oil is clean and there is no signs of oil in the coolant. There is no rattling or other bad sounds from the engine.

Is there anything else which can cause the pressure drop or some suggestions what to do?
 

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Is it possible that you have a oil pressure gauge with an offset? ........................thus you actually have oil pressure way higher than indicated.


I would first try another gauge
 

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Is it possible that you have a oil pressure gauge with an offset? ........................thus you actually have oil pressure way higher than indicated.


I would first try another gauge

Took the words out of my mouth.

Personally I reckon that gauge is reading 5-10psi low.
Though I would be interested in what Renault reckon you should have, very low at idle is no surprise when hot. Zero is a bit too low but you have done all the right things to improve.
 

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FWIW - Renault recons K4M with oil at 80C then at idle you should have 1 Bar (14psi) and 3000rpm you should have 3Bar (42psi)
 

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Discussion Starter #5
In the repair manual, there is min 0.5bar at idle and 3.1 to 4.1bar at 4000rpm for K4M engine. 4.1 bar / 60psi should be the oil pump release valve opening pressure. And the gauge show me that 60psi in range 2000 to 5000rpm when engine is cool and 50-53psi at idle. Maybe there is some reading error at low pressure end, but something is wrong because the dephaser is not working properly when the oil pressure reading is low. For example: 1800rpm ECU tries to adjust camshaft to 10.9 degrees, but measured cam position is between 0 to 1.1 degrees and solenoid actuator control signal is 99% When I increase the rpm over 2500 then the cam setpoint and measured position suddenly start to match and control signal is going to near 46%. When engine is cool and there is 50psi at idle, then dephaser control is starting to work instantly above 1000rpm.
Cam sensor is also replaced and crank sensor is cleaned and all wiring is checked and there is no starting issues.

I think this would be the cause of poor acceleration after gear changes and lower rpm. But some days the acceleration problem is less noticeable than others. Usually it's behaviour is changing while driving.

Near 3000rpm the pressure reading is between 30 to 38 psi when warmed up.
 

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I discovered that dephaser locking pin is not releasing below ~2000 rpm when engine is at operating temp.
So ito the original problem that I presume is still present despite the dephaser pulley replacement ..................... how did you EXACTLY "discover" that ..... just by monitoring cam advance angle in Clip or another scanner? (just interested in the method and not being a **** about anything) ............. or do you have errors getting logged?



There is an improved software update that you can install that addresses some control strategies of the cam advance (I have seen that with the old software Clip can demonstrate an extremely stepped and rough control method when monitoring cam advance angle, while with the new software, one can see a way more progressive cam advance strategy) ........... did you also install this when you replaced the dephaser pulley?
 

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Discussion Starter #7
My replies are coming with a delay because I'm new here. Some more info is in my previous message.

Yes, the pulley replacement didn't improved anything. The old solenoid went bad 2 years ago and started to show check engine light and codes P0010 and P0340. Then I replaced it. After that the ECU log-s sometimes intermittent P0010 and/or P0340.
3 weeks ago the check engine light appeared again(when I was driving uphill about 2500rpm/5th gear) with code P0010-actuator circuit open. After that I started to investigate the problem again and discovered that the dephaser is not moving correctly when the engine is warmed up. I took the solenoid off for inspection and there was a little bit of black debris on the filter mesh(looks like pieces of black paint) but the filter wasn't completely blocked. Solenoid looks fine to me(clean actuator and switching OK with 12V) and I cleaned the filter and put it back. Week after that at same pace and similar speed the "spanner" light appeared again with P0010. Then I installed the pressure gauge and discovered that low oil pressure issue.

Yes, I discovered the dephaser angle issue with OBD scanner, comparing engine rpm, cam angle setpoint, actual measured angle and solenoid actuator control data. I don't have a clip or access to use it. So I bought some cheaper scanner that can access to renault ECU-s. https://www.ebay.com/itm/Renault-COM-Bluetooth-Diagnostic-fit-for-Renault-Replacement-of-Renault-Can-Clip/113250165324?hash=item1a5e3c624c:g:eek:OIAAOSwFvZbnB6u:rk:6:pf:0
Unfortunately this scanner is not able to update the ECU software and I don't know is it updated or not.

Also I checked the signal with a scope connected to the solenoid wires and there was a constant battery voltage (13.xV) while the control signal parameter was 99% @ 1800rpm, engine warmed up, setpoint 10.9, measured angle 1.1. So the solenoid channel was fully opened to cam advance direction, but the dephaser didn't moved.
 

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Thanks - To me it sounds like you have taken a methodical approach to get to this point so cannot really fault your logic.


Let us know about the oil pressure meter change results ..................


Me? ............... I would start wondering where the oil pressure port you use gets its info from - is it fed pre or post filter? ................ iow if its post filter (I doubt) one could try to bypass the filter and see if anything changes. If its pre filter (just after pump - normally here) then you are sorta screwed - probably need to try thicker oil if you cannot find the cause - something like Porche's M1 5W50




Did you check the pinion driving the chain to the pump - teeth ok and truly gripping the crankshaft? (doesn't look like there is a key used there so its interference fit)
While down in the engine's backside - did you happen to notice all 4 those sprayer assemblies on the mains present?
 

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What about cam position sensor and/or its wiring? In my last 1.6 megane I had an issue with the wiring to the cam position sensor which meant the dephaser solenoid was always open meaning the engine would not idle when cold without throttle, and idled low when warm.

New cam position sensor and wiring fixed it.
 

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Discussion Starter #10
I forgot to add that the dephaser starting to move point is in a relation with oil pressure drop/engine temp increase. So when the oil is cold then it starts to change the cam angle instantly(~1000rpm) when the ECU is trying to change the cam angle. While warming up the cam angle change starting point moves to the higher rpm and reach above 2300 whe the engine is at operating temp. (that info is based on ECU OBD data)

What about cam position sensor and/or its wiring?
Sensor is replaced, wiring is checked, sensor/ ECU connectors are cleaned and sensor signal is checked with a scope. I didn't get any improvement after sensor change. The solenoid is not constantly open. There is a constant voltage only when the ECU tries to change the angle and dephaser is not changing it (low rpm(1000-~2300) and low oil pressure). I think that the dephaser release pin is holding it in it's default locked position while the oil pressure is low, but maybe I'm wrong?

I would start wondering where the oil pressure port you use gets its info from
The pressure sensor is in that hole where the original pressure switch was (at front side of the engine block) I'm not familiar with K4M engine lubrication channels. So I hope that it is after the filter.

Did you check the pinion driving the chain to the pump
Crankshaft sprocket teeth are ok, the chain is a little bit loose, but not that much to slip over teeth. When I was changing the main bearings then I pulled the chain from one side to get the top half of the bearing near chain sprocket out. Then the sprocket didn't moved on the crankshaft. I don't know what it is doing when the engine is hot.

did you happen to notice all 4 those sprayer
Yes, all 4 spray jets were there.

Let us know about the oil pressure meter change results
I have more acurate pressure sensors but I need to modify the gauge-s microcontroller software to be compatible with them. It takes some time but I will try to do that.
 

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You mate imo have a real problem there - you are making all the right noises so this is going to be interesting :wink2::crying2:
 

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Discussion Starter #12
Yes, the engine is probably reached to the end of it's life. The first owner of that car was security company, so I think maybe the engine have been on idle rpm a lot.

So where is the original oil pressure switch in the lubrication system? Is it before or after oil filter?
Which oil channels are going through the plastic thermostat housing? Is there only high pressure or both high and some oil return? (there are 2 separated oil channels)
Is it possible that the head gasket is broken in a way that there is a small passage from high pressure side to the oil return hole?
There is a thing called "backlash compensator" in the cylinder head above exhaust camshaft. Is it also working from engine oil pressure and can be broken and release the pressure?
There is a possibility that the cam bearings are worn too much but is there any other simple things which I have missed to check?

2 years ago I took the cam cover off because there was a oil leak to the spark plug hole. Then I wasn't aware of that oil pressure issue and didn't measured the cam bearing gaps, but there wasn't any noticeable scratching marks on the bearing surfaces. (dephaser issue was present at that time)


Which is the best oil filter for that engine? Should I try some bigger high flow filter with more filtering surface? (there is a room for longer filter)
What oil should I try next? 5W50? I don't wan't to use some 10W or 15W oils because here in Estonia the winter temp may be below -25C.
 

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Best filter? .............. no idea - never tried them all and would have to say the one that has lowest back pressure given your situation. (lowest back pressure does not necessarily mean its the best filter ito catching rocks and bearing and injector pintles though) :laugh:



I would be inclined to make up a filter bypass (yes its a lot of work mechanically to fabricate such an animal) but since you already mentioned a clean engine you basically need a single "hot" run to confirm if the filter is even involved or if you are barking up the wrong oil hole.


I would go with the Porsche 5W50 as an way forward - if ti gets you 10psi hot then that engine should be ok for a while still at the cost of expensive oil only
 

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Busy helping out a friend and since I also have a Renault-Com Bluetooth jobbie like yours sitting here I thought I would post the results shown from THAT on my K4MW761 ECU that I know is up-to-date via CLIP.


Dont know what those numbers all mean or whether ALL K4Ms get the same ECU software or updates but here it is anyway
 

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Discussion Starter #15
Porsche 5W50
Can you give me a weblink to the correct oil? Google showed me Mobil-1 for Porsche and Porsche classic motor oil...

yes its a lot of work mechanically to fabricate such an animal
Maybe I can make it from old oil filter without drilling it.
 

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Discussion Starter #18
No resolution yet.
1000km elapsed and the engine is not exploded yet.
Other oil gauge is showing also ~0.7PSI at idle.

ECU software is 8900 / #APR: 8200873673

Next I'm going to change the oil to 5W50 mobil-1 when the mileage is at least 2000km after bearing replacement.
Also the filter bypass test will be at that point before oil change.(because the old oilfilter was thrown away and it is covered with sand and I can't use it)

For the next oilfilter i'm thinking to use MANN W75/3 but if anybody have a better suggestion then let me know.
 

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Been joking with a customer that arrived here at my place crying that I have already answered all his questions on the forum under user "ints0000".........................................


Basically all the exact same symptoms on the dephaser/advance measured angle reported here - ie - when hot advance basically stops despite his assurance Renault them-self has replaced the camshaft sensor when they did the dephaser and also solenoid at exorbitant cost ................. all with no solution to the issue ............. and some similar expensive sounding noises being made about oil pump and oil pressure suspected:surprise:



So I decided to first check the cam sensor and confirm its replacement and condition......................:nerd:




Bingo!:smile2:


Dumbasses fitted a cheap no-name brand sensor and when monitoring with Clip or Autel, I could clearly see the advance work till engine reach around 80C ............... then boom - camshaft advance goes into fault mode and exactly ZERO advance no matter what the engine speed. No MIL on dashboard so owner doesn't even know about the issue - yet when you hang a Clip or other scanner off the car you find DF119 logged but not active - it gets removed from active to logged at engine switch-off ................ if engine cold next time engine is started, then cam advance will work again till engine reach about 80C





Now I have bumped into cheap sensors going funky at temperature on many vehicles before, so I ordered an original Renault (Valeo) part with the part number proudly displayed on it for 73 Euro .............:surprise:
Installed ............... problem solved - cam advance keeps running properly up to 110C (highest I saw on the vehicle):laugh:










So question to the OP ................ did you use an original Renault Cam sensor in your endeavors, and was your problem solved eventually? - I dont even feel the need to look at the oil pressure on this engine despite what all the previous Renault specialists have been mumbling about
 

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Discussion Starter #20
My problem is not solved.
I replaced the oil with a mobil 5W50, but I failed to make filter bypass test, because the filter's construction was really bad to make a bypass hole without making metal debris.
Now it take longer time to drop 0psi. It happens after highway drive with 5th gear, but the engine can hold 4psi at hot idle while driving in city.
3000rpm hot is still 34 to 40psi.
I use the car daily(drive 100km a day) and it haven't exploded yet and the engine is not making any strange noises. I haven't driven with obd diagnostics connected but so far there is no fault codes stored. The engine still have the same bad acceleration issue. It usually helps when I release the throttle few times while accelerating.

About cam sensors: First one was original Renault part, 2nd was some cheap thing whitch caused the MIL and cam sensor fault code(after that I put the first original sensor back) and the currently installed sensor is a new Valeo.
Compared cheap thing with original I noticed 2 differences: 1) the magnet is weaker. 2) There is something wrong in internal circuit(some sensor output pull-up or pull-down resistor is missing)


I could clearly see the advance work till engine reach around 80C ............... then boom - camshaft advance goes into fault mode and exactly ZERO advance no matter what the engine speed
My car's dephaser behave differently. When hot(89...97C) and I slowly rise the RPM(neutral gear) then cam measured angle is 0 degrees till ~2600rpm. Above that it will match with setpoint angle. But when there is a lot of oil pressure(not warmed up) then measured angle and setpoint will match in full rpm range above idle.
While the engine is warming then at some temp the angles mismatch appear till 1200...1300rpm and gradually moves towards ~2600rpm. There wasn't any fault codes when I tested the angles mismatch in neutral gear.

It looks like the dephaser locking pin is not releasing.

About week ago I found some other problem: The green coolant was brown, but there was no signs of oil in the coolant. It was replaced about half year ago with full system flush.
I replaced it again and it looks still green.
 
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