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Renault Megane F7R 1998 - Cutting out under load #

Posted by Nigel Bennett on January 31, 2009, 8:16 pm

Year of Manufacture *: 1998
Engine Code or Type *: F7R 710 150 BHP ( IDE )
( Optional ) ECU Type: Fenix
( Optional ) Scanner used: DEC

Hi all above vehicle has severe and total loss of engine resulting in immediate stall. No fault codes stored all serial data looks right.Fault is difficult to reproduce in work shop while hooked up to scope and four gas etc.
Fuel pressure sits around 2.7 bar but does swing wildly about each side of this when stall is imminent
as does the rev counter.
Today while under test the rev counter flicked around now and again while this occurred I took this Trace. (see following scope frames )Is this a fault of the coil or ECU control?Regards Nigel.

Re: Renault Megane cutting out under load

Posted by George Cameron <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5426' width='330' height='300' border=0 style='border:none;'> on January 31, 2009, 11:27 pm, in reply to "Renault Megane cutting out under load"
George Cameron

Have you checked the vac pipe to the map sensor
common for splitting at manifold

Re: Renault Megane cutting out under load

Posted by brian cowan <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5585' width='330' height='300' border=0 style='border:none;'> on February 1, 2009, 12:04 pm, in reply to "Re: Renault Megane cutting out under load"
Brian Cowan

There is a common problem with earth cables snapping on rear of cylinder head drivers side, worth a look. brian

Re: Renault Megane cutting out under load

Posted by Kevin Apps <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2589' width='330' height='300' border=0 style='border:none;'> on February 1, 2009, 1:12 pm, in reply to "Re: Renault Megane cutting out under load"
Kevin Apps

Nigel
I agree with Brian.
Kev.

Re: Renault Megane cutting out under load

Posted by lee mackintosh <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1348' width='330' height='300' border=0 style='border:none;'> on February 1, 2009, 1:12 pm, in reply to "Re: Renault Megane cutting out under load"
Lee Mackintosh

on the 1st scope pattern you seem to have some oscillations when the coil is switched to earth to build up charge (dwell angle i think) which i'm not sure is normal so maybe an earthing issue or the ecu not grounding coil good enough.

Check all earth cables for corrosion.

others with more experience with scopes will know exactly what's wrong.

thanks
lee

Re: Renault Megane cutting out under load

Posted by Sean Mc Gettigan <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5291' width='330' height='300' border=0 style='border:none;'> on February 1, 2009, 1:43 pm, in reply to "Re: Renault Megane cutting out under load"
Sean McGettigan

Hi Nigel, its normal ECU current control for this system.
Regards Sean

Re: Renault Megane cutting out under load

Posted by Michael Whitworth <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5568' width='330' height='300' border=0 style='border:none;'> on February 1, 2009, 5:33 pm, in reply to "Re: Renault Megane cutting out under load"
Mike Whitworth - Administrator

I agree with Sean,

Looks to me like the difference in the two patterns is dwell and current control governed by the ECU.

Mike

M.O.M. Miserable Old Manc

Re: Renault Megane cutting out under load

Posted by Nigel Bennett <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5463' width='330' height='300' border=0 style='border:none;'> on February 1, 2009, 11:51 pm, in reply to "Re: Renault Megane cutting out under load"
Nigel Bennett

Hi all and thanks,all power and grounds at ECU are good.I agree that the topping of the coil current is due to ECU control but,why is it having to apply this strategy? It appears to be switch the coil to ground too early or holding the firing point latter than it expected? I have been re-vieuing the live data and you can see the stall coming,I'll try to post it.

Megan 2.0 16v IDE Stall

Q: How does the ECU decide when to starting charging the coils so there is sufficient voltage at time of discharge?

Re: Renault Megane F7R 1998 - Cutting out under load #

Posted by Dave Hill <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2783' width='330' height='300' border=0 style='border:none;'> on February 2, 2009, 9:19 pm, in reply to "Renault Megane F7R 1998 - Cutting out under load #"

Hi Nigel

Is it possible that you could take a scope capture of ignition primary & injector voltage with lots of time on screen & the sample rate turned all the way up.

This way you you could monitor what drops out & when (in great detail). If neither ignition or injection drop out, then maybe fuel pump current could be monitored??

Dont be blinkered into just taking the "classic" 1ms/div injector or ignition captures, when Pico is capable of displaying great detail with long time bases set.

here is an example....

http://www.londonroadgarage.com/images/secondary%20trigger%20lead%201%20vs%20primary.psdata

Use pico to establish what falters first & then set about finding the cause.

Regards

Dave

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