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Title: Pretiming of injection during start. Post by: rufusgti on October 19, 2013, 10:38:29 PM Hi guys!
I have a little problem after I changed the fuel pump. The new pump is Walbro 255. When I start the engine speed increases to 1600-1800 rpm and then drops to idle. With old pump speed increases only to 1200-1300 rpm. After studying the documentation about ME7 I found that: "When the ignition is switched on, the main relay and fuel pump relay are activated during a few seconds. As soon as the ECU gets the cranking signal (from the crankshaft sensor) it initiates a coolant dependable fuel injection with all injectors simultaneously which ensures a fast engine start." The amount of fuel injected depends on the pump flow and injectors opening time. With Walbro the flow increases and this causes hight speed on startup. Now the only thing I can change is the injector opening time in pre-injection at start. ME7 have WEESTM map (correction of pretiming of injection during start). I think this is the map to be modified to solve the problem.I'm not so sure and that's why I want your help.And there may be other maps that need to be changed. Any help is greatly appreciated.Thanks! Title: Re: Pretiming of injection during start. Post by: terminator on October 20, 2013, 06:33:06 AM Your car has fuel pressure regulator, so it doesnt matter what fuel pump you use.
I installed Walbro 255 and Bosch 044 without any problem. Title: Re: Pretiming of injection during start. Post by: krazydbiker on October 20, 2013, 07:12:12 AM pretty sure terminator is right, unless your fuel pressure changed, it wont matter what pump you put in there, it will not change
is it much colder out? that would explain the idle change Title: Re: Pretiming of injection during start. Post by: terminator on October 20, 2013, 07:34:49 AM Maybe leaks also...
Title: Re: Pretiming of injection during start. Post by: userpike on October 20, 2013, 08:38:50 AM Change out the FPR and see what happens. Before that, check for vacuum leaks. Mess with the WEESTM map and see what happens after. You can always change it back to stock if things don't work out like you want them to. I personally have never heard of this happening, not here and not in the VWVortex forum. Not in my experience either. I'm running the Genesis pump purchased from Usually Sideways Rally Team, which is a higher performing pump than the Walbro 255 I believe.
edit: I just checked their site again and they claim the walbro 255 is good for 500BHP, so its rated for 100 more HP than the Genesis pump but still you shouldn't be having an issue. You most likely have a hardware problem. Title: Re: Pretiming of injection during start. Post by: hammersword on October 20, 2013, 03:40:30 PM Installing a bigger pump means that you need bigger returning fuel output from the FPR. Stock 3bar FPR of Bosch is too tight and the hole is too small.
Change to aftermarket one with 3bar FPR for performance use for high flow pumps so the FPR let the fuel easier to flow through it. By removing it and comparing it to a 4bar or any other performance one you will see what I mean This is your problem Title: Re: Pretiming of injection during start. Post by: rufusgti on October 20, 2013, 11:37:39 PM Installing a bigger pump means that you need bigger returning fuel output from the FPR. Stock 3bar FPR of Bosch is too tight and the hole is too small. You are right! that makes sense.Car is well maintained, no vacuum leaks.I'll by a 4bar aftermarket FPR and I will see if this solves the problem.Change to aftermarket one with 3bar FPR for performance use for high flow pumps so the FPR let the fuel easier to flow through it. By removing it and comparing it to a 4bar or any other performance one you will see what I mean This is your problem Thanks! Title: Re: Pretiming of injection during start. Post by: ddillenger on October 21, 2013, 12:11:41 AM Just measure your fuel pressure.
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