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Apr 21, 2012 20:01:06 GMT
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Hey can anyone shed any light on this one?
I've ben trying to help my mate get his J-reg Astra GSi going today, its got the old 2.0 16v 'Redtop' effort.
The problem seems to be that it is overfuelling hellishly. It does start and run, but very quickly chokes itself to death on fuel and starts filling the sump up etc. We have had the injector rail out and when you crank the engine the injectors are at about 50% duty (thats my estimate of on-off ratio based purely on watching them squirting). They are pulsing like but they seem to be tipping a hell of a lot of juice in. Pressing the throttle during cranking seems to make no difference to the injector duty. Interestingly if you take the fuel pump fuse out, it will start and tick over very nicely, though it dies if you try to rev it to more than about 2000rpm or put a load on of any sort. it must just be able to suck enough juice through to keep itself going. If you pop the fuse back in while its ticking over it splutters to a halt almost immediately!
We have changed the Crank speed sensor (made no difference), the hot wire-type AFM (made no difference) and checked the TPS, which as far as we can tell seems to be working.
At the end of the day the injector duration is decided by the ECU based on what the crank speed sensor and the AFM are telling it, and we have subsituted both of those sensors for known good ones, but the problem persists. I'm a bit stumped to be honest, does anyone have any suggestions?
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1974 Lancia Beta Saloon
1975 Mazda 929 Coupé
1986 Mazda 929 Wagon
1979 Mazda 929 Hardtop
1982 Fiat Argenta 2.0 iniezione elettronica
1977 Toyota Carina TA14
1989 Subaru 1800 Wagon
1982 Hyundai Pony 1200TL 2-dr
1985 Hyundai Pony 1200 GL
1986 Maserati 425 Biturbo
1992 Rover 214 SEi 5-dr
2000 Rover 45 V6 Club
1994 Peugeot 205 'Junior' Diesel
1988 Volvo 760 Turbodiesel Saloon
1992 Talbot Express Autosleeper Rambler
2003 Renault Laguna SPEARS OR REAPERS
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squonk
Part of things
Posts: 864
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Apr 21, 2012 20:24:10 GMT
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Most injection systems have a coolant temperature sensor and this is what controls enrichment during warm up (ie by increasing the injection pulse duration and over fuelling). Can't say for sure about Vauxhalls, but on an RV8 if this fails it will cause over fuelling. If there is one fitted try disconnecting it. The ECU may default to a 'safe' value.
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2004 Chevrolet Avalanche Z71
2005 Mercedes CLK320 Cabriolet
1996 Mercedes C180 Elegance Auto Saloon
1996 Rover 620Ti (Dead fuel pump)
1992 Toyota HiLux Surf
1987 Range Rover Vogue (Rusty)
1992 Range Rover Vogue SE (More Rusty)
2006 Chrysler Grand Voyager
2008 Corsa 1.4 Design
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Apr 21, 2012 20:35:38 GMT
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Ideally you want to scope those injectors to find what duty they are running at - I find that the start strategy of most '90s EFi systems is to crank at 70-80% reducing quickly to about 10-20% and remaining there until the motor starts and the AFM/CKP/ECT sensor derived cycle starts (expect about 5 to 10% on idle)
Problem with direct observation is that you won't be able to tell the difference between an electrical fault causing the injectors to stay open and a mechanical fault like worn and leaky injectors or a stuck pressure release valve. Using the schrader valve on the fuel rail to read the system pressure might help... (you can use a tyre gauge for this but ffs be careful!)
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To get a standard A40 this low, you'd have to dig a hole to put it in |
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Apr 21, 2012 21:09:43 GMT
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check/change the coolant temp sensor, as it does it from stone cold I'd discount the lambda for now.
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Apr 21, 2012 21:13:51 GMT
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We did swap the entire fuel rail with another one actually, including the pressure regulator (forgot that!) which appeared to be chucking out the same large quantities of juice!
I certainly would like to scope those injectors, i reckon thats the thing we've got to cure. They do pulse regularly and in some sort of repeatable sequence mind you so the ECU is defo doing a calculation thats not completely random.
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1974 Lancia Beta Saloon
1975 Mazda 929 Coupé
1986 Mazda 929 Wagon
1979 Mazda 929 Hardtop
1982 Fiat Argenta 2.0 iniezione elettronica
1977 Toyota Carina TA14
1989 Subaru 1800 Wagon
1982 Hyundai Pony 1200TL 2-dr
1985 Hyundai Pony 1200 GL
1986 Maserati 425 Biturbo
1992 Rover 214 SEi 5-dr
2000 Rover 45 V6 Club
1994 Peugeot 205 'Junior' Diesel
1988 Volvo 760 Turbodiesel Saloon
1992 Talbot Express Autosleeper Rambler
2003 Renault Laguna SPEARS OR REAPERS
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Apr 21, 2012 21:21:23 GMT
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Just remembered something - make sure the fuel return line isn't blocked! I had a hell of a time with a cavalier once trying to suss a very similar problem but cured it when I noticed that someone had placed a jack badly and squashed the fuel return line completely flat.....
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To get a standard A40 this low, you'd have to dig a hole to put it in |
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Apr 21, 2012 21:25:44 GMT
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its not blocked! We checked that too.
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1974 Lancia Beta Saloon
1975 Mazda 929 Coupé
1986 Mazda 929 Wagon
1979 Mazda 929 Hardtop
1982 Fiat Argenta 2.0 iniezione elettronica
1977 Toyota Carina TA14
1989 Subaru 1800 Wagon
1982 Hyundai Pony 1200TL 2-dr
1985 Hyundai Pony 1200 GL
1986 Maserati 425 Biturbo
1992 Rover 214 SEi 5-dr
2000 Rover 45 V6 Club
1994 Peugeot 205 'Junior' Diesel
1988 Volvo 760 Turbodiesel Saloon
1992 Talbot Express Autosleeper Rambler
2003 Renault Laguna SPEARS OR REAPERS
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Apr 21, 2012 21:27:17 GMT
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Carp! It's deffo scope time then  |
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To get a standard A40 this low, you'd have to dig a hole to put it in |
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gruss
Part of things
Posts: 242
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Apr 21, 2012 21:27:29 GMT
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Have you checked for any dtcs? It does sound like a coolant temp sensor though...
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Daihatsu Mira TR-XX
Suzuki Alto Works
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Apr 21, 2012 21:34:53 GMT
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Whats a DTC?
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1974 Lancia Beta Saloon
1975 Mazda 929 Coupé
1986 Mazda 929 Wagon
1979 Mazda 929 Hardtop
1982 Fiat Argenta 2.0 iniezione elettronica
1977 Toyota Carina TA14
1989 Subaru 1800 Wagon
1982 Hyundai Pony 1200TL 2-dr
1985 Hyundai Pony 1200 GL
1986 Maserati 425 Biturbo
1992 Rover 214 SEi 5-dr
2000 Rover 45 V6 Club
1994 Peugeot 205 'Junior' Diesel
1988 Volvo 760 Turbodiesel Saloon
1992 Talbot Express Autosleeper Rambler
2003 Renault Laguna SPEARS OR REAPERS
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Apr 21, 2012 22:08:22 GMT
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diagnostic trouble code - on the astra it's likely to be bridge 2 pins on a socket in the engine bay and count the flashes on the MIL lamp on the dash then decode then find out it wasn't helpful.
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To get a standard A40 this low, you'd have to dig a hole to put it in |
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`state
Yorkshire and The Humber
Posts: 1,215
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Apr 21, 2012 22:37:40 GMT
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On the astra you can do the paperclip test by bridging 2 pins in the fuse box and counting the flashes of the eml.Search google for the toppbuzz site and theres a guide on there.
Although is the eml on anyway? Id go with the cts though as they play havoc when they knacker up.
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Look at all the plastic people who live without a care.Try to sit with me around my table,but never bring a chair.
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Apr 22, 2012 17:30:56 GMT
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Have a sultana, this problem has been cured now and the culprit was indeed an intermittently dodgy coolant temp sensor!!!! The astra is running SWEET. I am on the lookout for a cheap oldskool oscilloscope though if anyone stumbles across one in a field or whatever. Cheers!
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1974 Lancia Beta Saloon
1975 Mazda 929 Coupé
1986 Mazda 929 Wagon
1979 Mazda 929 Hardtop
1982 Fiat Argenta 2.0 iniezione elettronica
1977 Toyota Carina TA14
1989 Subaru 1800 Wagon
1982 Hyundai Pony 1200TL 2-dr
1985 Hyundai Pony 1200 GL
1986 Maserati 425 Biturbo
1992 Rover 214 SEi 5-dr
2000 Rover 45 V6 Club
1994 Peugeot 205 'Junior' Diesel
1988 Volvo 760 Turbodiesel Saloon
1992 Talbot Express Autosleeper Rambler
2003 Renault Laguna SPEARS OR REAPERS
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squonk
Part of things
Posts: 864
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Apr 22, 2012 18:51:03 GMT
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2004 Chevrolet Avalanche Z71
2005 Mercedes CLK320 Cabriolet
1996 Mercedes C180 Elegance Auto Saloon
1996 Rover 620Ti (Dead fuel pump)
1992 Toyota HiLux Surf
1987 Range Rover Vogue (Rusty)
1992 Range Rover Vogue SE (More Rusty)
2006 Chrysler Grand Voyager
2008 Corsa 1.4 Design
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Apr 22, 2012 19:46:47 GMT
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Yeah I cant claim to have any skills at all in using one but if I had one i'd fathom it out I reckon.
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1974 Lancia Beta Saloon
1975 Mazda 929 Coupé
1986 Mazda 929 Wagon
1979 Mazda 929 Hardtop
1982 Fiat Argenta 2.0 iniezione elettronica
1977 Toyota Carina TA14
1989 Subaru 1800 Wagon
1982 Hyundai Pony 1200TL 2-dr
1985 Hyundai Pony 1200 GL
1986 Maserati 425 Biturbo
1992 Rover 214 SEi 5-dr
2000 Rover 45 V6 Club
1994 Peugeot 205 'Junior' Diesel
1988 Volvo 760 Turbodiesel Saloon
1992 Talbot Express Autosleeper Rambler
2003 Renault Laguna SPEARS OR REAPERS
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Apr 22, 2012 20:13:19 GMT
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I've got one of them DSO nanos (mines a V2) and while they aren't really as good as a "proper" scope, they are dead handy on the car and once you put the new firmware on they are fairly straightforward to use.
They have an "auto" setting which works for most signals, but adjusting the volts/div and time/div is easy and probably all you'll need to do.
An old analog scope with a CRT with major image burn in is the easiest and probably cheapest way to get into this kind of thing, but they are big awkward sods so it's a hassle to drag the thing out every time you wonder what x signal would look like. You'd end up avoiding using it a lot of the time. They are great for working on a workbench in a lab though.
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Last Edit: Apr 22, 2012 20:15:53 GMT by cobblers
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Apr 22, 2012 20:31:29 GMT
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the schrader valve on the fuel rail to read the system pressure might help... (you can use a tyre gauge for this but ffs be careful!) Use a shock pump, rated a lot higher than a bike pump. I think my Fox one goes up to 600psi. |
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