Used octane boost now car won't start :-(
- Thread starter Asiangunner
- Start date
pauljmcnulty
Active member
Lol, I wish I had a clue what they were talking about. [&o]
To me, as a technical novice, the DME relay is the little plastic thing that every 944 owner should keep a spare of in their glovebox. This was standard advice when I first entered the fold about 7 years ago, and most will have been replaced by now, but it's a £20 fix that is the first place to start when having fuelling issues. If it doesn't fix your problem it might help another owner one day. Carry a spare.
More recently, poor running, starting and even scary cutting out at speed have been down to the fuel pressure regulator.
One question: how old was the additive? I spend a lot of time at a garden machinery repairers, being a contract gardener. One of their biggest earners is people who put petrol in their machinery that's been sitting for months, if not years, and it's degraded. Could an additive degrade over time, and do the same thing? Certainly, if you put very old petrol in a two stroke it'll wear your arm out trying to start it. [
]
To me, as a technical novice, the DME relay is the little plastic thing that every 944 owner should keep a spare of in their glovebox. This was standard advice when I first entered the fold about 7 years ago, and most will have been replaced by now, but it's a £20 fix that is the first place to start when having fuelling issues. If it doesn't fix your problem it might help another owner one day. Carry a spare.
More recently, poor running, starting and even scary cutting out at speed have been down to the fuel pressure regulator.
One question: how old was the additive? I spend a lot of time at a garden machinery repairers, being a contract gardener. One of their biggest earners is people who put petrol in their machinery that's been sitting for months, if not years, and it's degraded. Could an additive degrade over time, and do the same thing? Certainly, if you put very old petrol in a two stroke it'll wear your arm out trying to start it. [
]
Fat Albert
New member
Rather than buying a spare DME relay to put in the glovebox, why not replace the DME relay with a new one and put the old one in the glovebox as a spare?
A lot less likely to fail and the benefit of nice new shiny contacts!
A lot less likely to fail and the benefit of nice new shiny contacts!
peanut
Active member
It is very complicated to explain I would probably refer anyone interested to read up on the Bosch website. I have tried to write it up several times and tied myself up in knots.
I am self taught and there are still many gaps in my knowledge but I believe I know sufficient now to fault-find most fuel ignition faults on n/a 944's
re the cranking speed it was a safety feature that Bosch introduced after several cars caught fire after accidents because early systems allowed the fuel pumps and ignition systems to continue to work after crashing.
Many 944's simply don't start because owners don't realise that their engines are not turning over fast enough.
peanut
Active member
good point Paul.
I believe the majority of non starting 944's are due to insufficient use and the fuel injector solenoids getting sticky due to additives in the fuel being left as a laquer residue in the injectors. Injectors are normally self-cleaning but need to be used fairly regularly in older cars to maintain operation.
pauljmcnulty
Active member
Actually I don't think I've got a spare in the new car, good example of not listening to my own advice! [&o]
I'd personally rather have the new one ready to go, and not take out something that is working perfectly well. Usually with me, and it's not uncommon on threads here, problems start with changing something on the car. I know a relay is a small thing, but I'm really useless. Even replacing my cassette box with a tray caused my ash tray light to stop working. [&:]
robwright
New member
At least then you would know it was working. I did at 120 mile emergency round trip to OPC in Cambridge as they were the only ones that had a DME relay I could get my hands on that day and paid over the odds to get a DME relay that was faulty and din't run the fuel pump [
] To top it all off I sent it back to them and after two weeks I had to take my car to them again to prove that it was faulty before I could get a refund!!! Are you telling me the so called technicians had no means of bench testing the relay with a battery and a multimeter. Apparently they needed a car to test it on []
peanut
Active member
ORIGINAL: robwright
At least then you would know it was working. I did at 120 mile emergency round trip to OPC in Cambridge as they were the only ones that had a DME relay I could get my hands on that day and paid over the odds to get a DME relay that was faulty and din't run the fuel pump [
where have all the wise, old, car mechanics gone from yesteryear? the ones that used to come out of their ramshackle timber garages and listen to your engine with a screwdriver on their ear and say with a knowing nod of their head ' uuurrrr that'l be yor balance shaft bush knackered that will'[
] They'd pull some part off a scrap car and have you running in 10 minutes flat and then not take anything for it. Come back Alf, Reg and Bert we need you
Super_Marv
New member
ORIGINAL: peanut
ORIGINAL: robwright
At least then you would know it was working. I did at 120 mile emergency round trip to OPC in Cambridge as they were the only ones that had a DME relay I could get my hands on that day and paid over the odds to get a DME relay that was faulty and din't run the fuel pump [
where have all the wise, old, car mechanics gone from yesteryear? the ones that used to come out of their ramshackle timber garages and listen to your engine with a screwdriver on their ear and say with a knowing nod of their head ' uuurrrr that'l be yor balance shaft bush knackered that will'[
Come back Alf, Reg and Bert we need you
You've brought a tear to my eye with that one! [
] [
]Oh and Paul - it usually says on the bottles for additive, to use it within 1 year of opening the bottle.
Fat Albert
New member
The SAAB independant I used to use was like that! Louis, the 5'0" Italian Master tech would hear you drive up and be able to tell you what was wrong sometimes! And yes I did pull in there at 8:00am in my 9000 Aero with an over-boost issue and he whipped an APC valve off one on the forecourt for me and sent me on my way without a bill.
My favourite encounter was when that APC valve blew a week later and I left the car with them, when I picked it up Louis lifted the bonnet and pointed to a load of new plumbing cable-tied to the old, with a brass cylinder and knurled knob, he then explained that he hated the APC so he had fitted a dump valve and a manual boost valve (similar to the Promax boost enhancer on my 944), he had set it to roughly the same as standard for now, but you turn the knob anti-clockwise to increase the boost....
My favourite encounter was when that APC valve blew a week later and I left the car with them, when I picked it up Louis lifted the bonnet and pointed to a load of new plumbing cable-tied to the old, with a brass cylinder and knurled knob, he then explained that he hated the APC so he had fitted a dump valve and a manual boost valve (similar to the Promax boost enhancer on my 944), he had set it to roughly the same as standard for now, but you turn the knob anti-clockwise to increase the boost....
Asiangunner
New member
ORIGINAL: pauljmcnulty
Lol, I wish I had a clue what they were talking about. [&o]
To me, as a technical novice, the DME relay is the little plastic thing that every 944 owner should keep a spare of in their glovebox. This was standard advice when I first entered the fold about 7 years ago, and most will have been replaced by now, but it's a £20 fix that is the first place to start when having fuelling issues. If it doesn't fix your problem it might help another owner one day. Carry a spare.
More recently, poor running, starting and even scary cutting out at speed have been down to the fuel pressure regulator.
One question: how old was the additive? I spend a lot of time at a garden machinery repairers, being a contract gardener. One of their biggest earners is people who put petrol in their machinery that's been sitting for months, if not years, and it's degraded. Could an additive degrade over time, and do the same thing? Certainly, if you put very old petrol in a two stroke it'll wear your arm out trying to start it. [
Paul, rob, Peanut,
I think you've got it spot on... I finally got a chance to tinker this morning and HOORAY the car has started.
I picked up my trusty Haynes manual after the DME fuse didn't make much difference when trying to turn over. I'm left wondering how long i can keep riding my luck with easy fixes, basically the first thing i tried fixed the problem.
I removed the fuel pump fuse to reset the pump and drain what was in there, turned the key and boom it started!
The octane boost has been in the garage for some time, easily over a year, so the car drove fine once i added it but then i left the car for 3-4 days so i think thats when the injectors have become stick as described by Peanut. I have put in half a bottle of Redex the other day to just help.
Many many thanks for all the replies, i'm glad i can get great advice so quickly.
Have a great weekend guys.
peanut
Active member
glad to hear its running again but I would strongly advise you do not use any fuel aditives particulary Redex. They are not intended for use with fuel injection systems.
Each of your injectors has a filter with extremely fine mesh .
Any crud that redex loosens from your fuel tank, fuel pump, filter, fuel lines or fuel rail will get trapped in the injector filters and make the situation 10x worse. !
Redex is fine for carbs not injected systems.
Each of your injectors has a filter with extremely fine mesh .
Any crud that redex loosens from your fuel tank, fuel pump, filter, fuel lines or fuel rail will get trapped in the injector filters and make the situation 10x worse. !
Redex is fine for carbs not injected systems.
Asiangunner
New member
Eeeek, hopefully it will not have sent too much crap through. I'm going to push the car a bit to use up this tank completely then just fill up again. It's a pain worrying if the car will run or not, luck for me I normally have another car or my bike spade when things go wrong.
Thanks for letting me know about the redex, I was planning on using when I next fill up.
Thanks for letting me know about the redex, I was planning on using when I next fill up.
peanut
Active member
I shouldn't worry too much , it wouldn't stop your car running by itself. Our cars are over 20 years old and lots of the poor starting and running problems are often due to poor earths , leaky vacumn system and oxidised electrical connectors. Best thing we can do is run them hard and use them daily[]
]
peanut
Active member
What Redex product are you using ? Is it an octane enhancer or a fuel system clearer ?
Bosch do not recommend adding fuel system cleaners to the fuel tank because eventually they can leave residue build ups on the injector pintles and valves . They recommend disconnecting the fuel filter and fuel injector rail and use compressed air to clean the piping and have the injectors professionally cleaned and the jets tested and reset by a specialist.
I'm sure occasional use won't do any harm providing the car is used regularly and not left sitting for extended periods
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