Megane Running Problems - Fuel Pump ?

[RanjD]

Hi,

Wondering if anyone can help & advise me here as I haven't got much knowledge about the megane 225 engine / layout.

Problems have developed over the last 2 months, first noticed something was wrong as I would get misfires at high revs & max load. Then slowly the cars starting got worse, sometimes taking over 10 attempts before it fired up. When fired up & running, if you use the throttle lightly then the revs will rise but if you give the car throttle over about 30 % it does nothing, when you floor it at any rev range it does nothing - no acceleration at all - except misfire if you keep the throttle buried.

Suspecting Coil Packs / Spark Plugs I first changed these - Nothing improved at all. Then suspecting maybe a Flywheel sensor I changed this - No improvement.

At this point I bought a OBD2 scanner & started looking at the Fuel Trims and the fault codes.

DF054 - turbocharging solenoid valve control circuit - short circuit to earth
DF054 - turbocharging solenoid valve control circuit open circuit
DF072 - cylinder 1 ignition coil circuit open circuit or short circuit to earth
DF072 - cylinder 4 ignition coil circuit open circuit or short circuit to earth
DF065 - Misfire destructive misfiring

The cylinder 1 & 4 ignition coil circuit fault appeared when I removed a coil wire while the engine was running but its now connected up & the scanner wont clear the codes so I am presuming its there now.

I replaced the Solenoid Valve but the faults still show so it looks like a wiring problem.

I have looked at the wiring quickly & can see the Solenoid Wires & Coil Pack wires are in the same bunch, I have yet to trace where the go (lack of time at the moment )- Does anybody know where the go ? Do they go to a Relay or even the same Relay ?

The Fuel Trims are pointing me in the direction of the Fuel Pump but don't really want to replace this until the Above problems are sorted out as they maybe linked ?

The Long Term Fuel Trim is at 42.2% and stuck there, when driving under light Throttle the Short Term Fuel Trim goes up very quickly, up to 99% and then if I push further I get nothing and the STFT falls to 0 until I back off and let things settle , its like the injectors are maxing out - possibly due to not enough fuel being delivered or not enough pressure.

Anybody experienced fuel pump problems & a similar experience ?

Sorry for the long message.

 

[andybond]

That sounds almost exactly like the symtoms of a failing fuel pump. How many miles have you got on the car ? 80k+ ?

 

[RanjD]

The car has done about 95,000 miles now.

I was going to try a fuel pressure gauge on it but I couldn't find a test port nor could I find a suitable connector/adaptor to use at the Fuel Rail. Found a few websites selling the correct pipe attachment buts they were around £55 whilst a new fuel pump was around £80 (PWM - from eurocarparts) so didn't make sense to get the attachments.

Looks like I will drive it around until the fuel tank is nearly empty and then try to replace the fuel pump.

Anybody have a idea how hard it is to replace the fuel pumps on the 225 's ?

I have read the tank can distort but I don't understand why it would distort when its nearly empty & has little weight in it.

 

[Neal R19]

You don't really need to wait until it's empty.

If you go under the back seat there's a big rubber bung, take that out and you can get at the fuel pump sender assembly. It's held in by a plastic lockring and these can be a bitch to remove. Some people reckon you can tap them round with a bit of wood but I've never had much luck doing that - the plastic ridges just snap off for me. However you can buy (or make) a specific tool for the job.

Once the assembly is out you need to pull it apart to get at the pump. Again, on mine I ended up breaking the housing to get at the pump inside but it's obviously possible to dismantle it without breaking it as plenty of people have done it. I only wanted the pump and not the housing though so didn't put much effort in.

The tank might distort over time but unless you take your sweet time (weeks) doing the job I'm sure you'll be fine.

 

[RanjD]

Got the PWM fuel pump yesterday and it was a complete unit with the housing & not just the pump - So a good start.

Got a cheap tool from eBay to help remove the plastic lock ring as its very tight in there. A fit fiddly with the tool but it did manage to help remove the lock ring without damage and then out came the pump. Slotted the new pump in (only fits 1 way due to a cut out in the tank & plastic trim edge on fuel pump) and then begin the fun & games.

The new lock ring wouldn't go on straight no matter how i screwed it on - many times I tried to get it to sit flat but it just wouldn't, so i got it as best as i could & just tightened up as much as i could - there is a arrow on the pump & on the lock ring - looks like they must align & at the end. At the end of the tightening I wasn't really happy looking at it so went for a drive on some bumpy roads to see if it leaked - It DID !!!

BUT the car - WOW - what a transformation - It drove like it should, much better than I remember - you do get accustomed to slowly losing power over time - I don't even think it drove it like this when i bought it - especially at the top of the rev range - the kick felt like my R5 GT turbo at 24psi.

So back to the pump & lock ring once it all cooled down. Looking at it with more patience I could see it was crooked and looked crossthreaded. Undoing it now became a nightmare - it wouldn't budge - started snapping the plastic tabs - using a hammer & blunt flat screwdriver didn't work - only had few plastic tabs left but by luck it started shifting - after much swearing & time - it came undone but the the lock ring was shot.

I got the old lock ring & I tried threading that on without the pump in place & it wasn't going on straight - tried it all different starting positions but the same result - then I tried again, 1/8 turn and then using a rubber mallet I tapped the "high" side down over the thread & it clicked - started srewing on like it should - flat and square - so put the seal in place, pressed the pump down then got my wife to keep the pump pressed in using a the edge of a hammer - sprayed some wd40 on thee lock ring, slid the lock ring over the hammer and did the same thing - 1/8 turn - hammered the high side down & then I could screw the lock ring in by hand to to the point the pump was kept pressed in. Finished off the tightening using the tool & all is now well - PHEW !

I still have very high long term fuel trims - still at 42.2% but the short terms are heavily negative - I have drove it about 10 miles and was hoping to see the long term trims come down but nothing so far.

Anybody know how long they can take to adjust down ?

I have read on some makes that removing the battery helps reset so just removed the battery and will put it back on later on - does this work on the renaults ?

 

[andybond]

Has the trim changed at all ?

Reason I ask is I know you can stop it changing via the ECU ...

 

[RanjD]

It actually went up yesterday when I left it idling to about 50% then after I came back from the Drive it had reverted to 42.2% again but I would have expected to react much quicker to negative short term trims i am getting.

The long term trims were on about 25% when problems started arising but it had crept to 42.2% by the time starting had got very very bad so it does look like they are changing.

 

[Neal R19]

Those lockrings are a total bastard aren't they, I had an identical experience to you getting it back on!

 

[RanjD]

They are that Neal - You would think the thread would just wind on but it doesn't - There must some distortion on the neck so tapping the lock ring down with a bit of thread done by hand helped me - hopefully if others get stuck then try this way too.

I have reconnected the battery but the long term fuel trims are still stuck at 42.2% so will check again next weekend after a weeks worth of driving, memory for the trims must be held where the battery has no effect on the stored setting. On a plus note it clear my low pressure tire warning that wouldn't go away even with the scanner connected & clear faults.

The scanner is still showing the faults as above under "Injection", cant seem to clear them at all - definitely was not misfiring yesterday & was holding boost well. So will check them again next weekend to see where I stand.

DF054 - turbocharging solenoid valve control circuit - short circuit to earth
DF054 - turbocharging solenoid valve control circuit open circuit

If someone has experienced the above faults - Have you found a short somewhere & where did you find it ?