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Discussion Starter · #1 ·
Hi can anyone help me? I have got my Scenic back after a head rebuild following a cam belt snapping. as soon as I drove it back home I noticed a lack of power and bad mpg, I took it back to the garage who checked the ECU there was several codes all but two cleared EGR and MAF replaced the MAF and EGR as they were both faulty. After these were changed all codes cleared, still had the same problem tho.
I have replaced the turbo pressure release solenoid and had the ECU out cleaned the contacts on the plugs and sockets. Done the same around the engine bay all connections good and tight no error codes, still have a lack of power low mpg.
I have fitted a turbo pressure gauge inline with the MAP sensor and have the following results:
1250rpm 0.2bar boost
1500rpm 0.3bar boost
1750rpm 0.5bar boost
2000rpm 0.65bar boost
2250rpm 0.8bar boost
2500rpm 0.9bar boost
2750rpm 1.0bar boost
3000rpm 1.15bar boost
3250rpm 1.2bar boost
3500rpm 1.4bar boost
3750rpm 1.1bar boost
4000rpm 0.95bar boost
4250rpm 0.95bar boost
the boost does not drop off if for example climbing a hill and the engine is reving at 3500 revs.
Any ideas anybody
 

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Discussion Starter · #2 ·
I forgot to say that it has been serviced new air filter fitted I have checked this, there is no smoke what so ever the engine sounds fine and rev up ok too, What is the chance the CAT could be blocking up? Does it need the CAT?
 

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I'm having similar problems kirky. Only thing I can help with is when I fitted a new turbo yesterday I had to take the cat off. Thought it was a bit light and managed to push a bit of wire straight through.

So although theres no cat, theres still no power. So far I have replaced egr, map, maf, turbo soleniod valve, air filter, fuel filter, turbo, engine.

If you do fix it , please post your solution cos I'm running out of ideas :d
 

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Have you considered that the valves may not be properly bedded in yet so the compression may be down (or worst case they haven't been lapped in correctly and so may never seal correctly)
I'd advise a compression check to ensure this isn't the case.
 

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Hello kirky,

Mines fixed! :toast: It was my turbo, I must've knocked a vacuum pipe off the turbo solenoid thing when riving about in the engine bay.

I've had problems for the 8000 miles since i fitted the engine and have just worked through it 1 part at a time. All I can think with yours is if it was running great before the cambelt then it must be mechanical? Like andy says, valves bedding in, or maybe the timing is a tooth out? Or wires that were disconnected to get the head off have not been put back properly.
My next step was going to be replacing the camshaft sensor at the back of the head, maybe check this?
 

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Discussion Starter · #7 ·
pierrre, great news I will look at the camshaft sensor, I know that the renault service team only use the sensors codes as a guide they tend to use the live data for diagnosis.

Andy I never thought about the valves bedding in however it has now done about 1600 miles, how long does it take the valves te bed in, a compression test could be in order to get a better idea, I have been told the valve timing is spot on, the garage that did it said so? there is no problem starting it running it feels ok low down the rev range. when I get over the 2000 revs mark there is no power.
 

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Yeah they should have settled in by now, unless they weren't done right.
Over 2k suggests possible turbo issue or something between turbo and inlet leaking, maybe also egr valve (can't remember if you said you'd checked that) then again your boost readings are pretty consistent... could be turbo pressure sensor or perhaps maf. I did read on here somewhere someone was having trouble with no power over about 2.5k and it was the pressure sensor. If yours is the mk1 facelift like mine I believe it to be the unit on the right hand side by the bulkhead fed by a little pipe off the back of the egr housing. Also make sure this pipe isn't blocked, it can get clogged with black sooty gunk inside the pipe take-off on the housing.
 

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Discussion Starter · #9 ·
Thanks Andy will have a look at the pipe. I have checked and recheck all the pipes around the turbo will check them again now. I have been working around the fact the head has been taken off and looking for anything that could of been disturbed. It has had a new egr And MAF.
 

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Reading back over your original post, you said you fitted the gauge inline with the map sensor, which is the sensor I was referring to, is it would seem there isn't a blockage if you got a reading. Still could be the sensor itself.
Another thread i read on here regarding no power over 2k in a laguna dci turned out to be the wastegate at fault, but again, if this was your issue you wouldn't read any boost one would've thought unless it was stuck shut then you'd get too much... though i suppose it could be a bit open perhaps... wonder if a fragment of metal from the head carnage has fouled the valve in some way??
 

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Now if only someone could help me find the cause of the kangarooing at 2100 rpm... 2000 fine, 2200 fine 2100 its like someone is dabbing alternately on the brake and throttle. Could be any one of the sensors as far as i can work out, they could all cause this in one way or another :confused:
 

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Normally on a 1.9 dci engine when the cam belt brakes the camshaft sprocket has to be replaced as it snaps the locking key off and cam allow the valve timing to be out and it cam be out 2 to 3 teeth before a fault will flag up.
 

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Discussion Starter · #13 ·
Normally on a 1.9 dci engine when the cam belt brakes the camshaft sprocket has to be replaced as it snaps the locking key off and cam allow the valve timing to be out and it cam be out 2 to 3 teeth before a fault will flag up.
Yeah I remember the garage ringing me up telling me this only after I had priced and bought everything, it cost just over £70. I was bordering on scrapping it but the repair price it borderline. This was prior the EGR and MAF sensor replacement, guess am going to have to take it to Renault and ask them to do an engine diagnostic, ensuring they check the live data and compare it against the expected data. More money
 

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it may be a long shot but i had similar problems on my megane cc had every sensor checked defasor and cam belt done ......18 month later after hundreds of pounds it was a faulty fuel pump the fuel wasnt getting to the engine quick enough hence the lumpy and sometimes stalling problem plus my mpg went down to 14mpg very very low so its worth a mention good luck :)
 

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Hi Many thanks for the reply. I have changed the fuel filter ,but the fuel consumption is still only about 30 mpg and the engine does seem to lack power espically when changing from 2nd to 3rd, it seems ok when pulling away from a standing start.

Neil
 
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