Printable View
Quote:
Originally Posted by OlliesLRover
Yeah good call on this one OlliesLR and easily overlooked too. Sounds silly but I believe the fuel mapping relies on info from coolant temp sensor for part of its mixture calcs. At $30 its not going to break the bank to try.
Did you try Bee uteys suggestions with the fuel pressure??? This would be an excellent place to start you investigation. When it misbehaves, has it done it from both cold starting and hot starting??
Just checked and the fuel rail has the valve bee utey was talking about. I'm just about to head down to SuperCheap to pick up a fuel pressure gauge and then I'll check it. I'll let you know what it shows.
Thanks again everyone, greatly appreciated.
A failing fuel pump will give the symptoms you describe, combined with a sticking idle control valve. The high idle revs being due to the Idle controller trying to increase the idle speed when it is very low (due to a lack of fuel pressure) and then being unable to bring the idle speed back down quickly enough when full fuel pressure is provided.
I had similar symptoms when my fuel pump was dying.
Seems a fuel pressure gauge is hard to find. Supercheap don't sell them and two Autobarns and a Burstons were out of stock. Will call around a few places to find one.
I forgot to answer whether it happens cold start or hot start. I can't remember it ever happening first thing - eg after it has sat all night. Every time was when I had driven it for 20km or so and parked for 2 hours and then tried to start it again; and the few occasions it stopped in traffic.
Aside from the restart on those occasions, the idle seems to be perfect and it always has great power.
When i test the fuel pressure, is it possible that at the time i test it the fuel pump is working well but that it may cut out at different times (those occasions it has stalled or failed to start)? Just seems strange that it will drive really well for so long and then without warning stall and once it gets up and going again it drives fine again.
Sorry for not updating this for a little while. Was away for a few weeks.
Haven't yet bought a fuel pressure gauge (don't really want to spend $100 plus on one when I will likely only use it once) but have looked at a couple off eBay that I might get.
Anyway, tried to start the disco up after our holiday and had the same problem as I have outlined earlier in the thread. After quite a few goes (30 attempts to start over an hour or so having to pump the accelarator to keep it idling) it would idle rough by itself but never really kick in if that makes sense (always sounded like it was about to die and wouldnt respond to the accelsrator). I opened up the air filter box and just blew through it and cleaned a few bugs out and had a look at the maf (didn't do anything to it, basically just looked at it) and put it all back. Perhaps a coincidence but after i put all that back it then started first time and idled perfectly and has continued to run perfectly since then.
Sorry, I know the fuel pressure gauge is important to diagnose this problem, I'll get one, just need to find one that is an ok price. Also, I may be open to the possibility of buying a code reader. I know very little about that, so if someone could enlighten me as to whether I can get one for the disco (1994) that would be great.
Cheers again for all the help.
One of the best.... and thank god the cheapest of the 14CUX code readers is the ECUMATE..http://www.ecumate.com/. I think I paid 150 UK Pounds but check the site. They also have the fault code display but for the extra money get the actual ECU Mate diagnostic reader...it's worth it.
I made a very cheap and efficient fuel pressure gauge from a glycerine filled gauge available from some of more technical accessory shops here.
I then took it to a place who make hydraulic hoes and they fitted the appropriate hose and fittings.
With the 1 1/2 meters of pipe draped over the bonnet I can watch the pressure as I'm driving.