ROGUE TROOPER Posted April 25, 2006 Share Posted April 25, 2006 mumble mumble efi mumble mumble I hope its what we guess at and the battery is shot, hence not powering the EFi enough to make it fire. Anyone know what the voltage EFi needs to fire? Ta Rob Quote Link to comment Share on other sites More sharing options...
minivin Posted April 25, 2006 Share Posted April 25, 2006 no probs, at least I know the Diesel is useless for towing now as it won't pull past 2nd gear, bring on the V8 (carbed) Story is is that as we know it dies after a short trip of no more than a few miles, this time it died before it got back to my house after getting fuel. Brought my truck down to the end of the road and used it to jump start off my 95Ah battery supplied by a 90A alternator. Pretty much started after a crank or two from the V8, yet wouldn't do this on it's own battery. Once I towed it back to Rogue's, with the present battery it would be sat at 11.9V, but then drop down to 7V during cranking. Another odd battery from the S2 88 was then used in parallel which boosted it upto 12.5V and dropped to 8V during cranking. No start either time. Anyhoo, after pushing the S2 V8 by the garage, we put mine across it again, 13.8V charging, crank and not a single drop in volts and the V8 bursts into life. Pretty much what it sounds to me is that the EFi is sensitive to voltage drops, which I have also experienced on Bosch BMW EMU's that at the slightest hint of a discharged battery will not fire the injectors or the ignition system (naturally the ignition is Dizzy on Rogues, so it's the fuelling that is at question). So with Rogue's ticking over, I finally removed my battery and alternator from the equation, and the V8 sat ticking over at 12.5V~. Bringing the revs up the voltage stayed the same, until revved higher when it dropped a few decimal values. From what I can see, the battery is not holding a good charge and this is not helping the cranking, which further causes the voltage to drop during cranking and the injectors to not fire. Also the alternator is at question, but the battery is very old so this is going to be replaced first, to see if the alternator was being asked too much and may start to charge the system better. After that, alternator from the S3 88 and see what happens I suppose. Any other ideas? Quote Link to comment Share on other sites More sharing options...
Jon White Posted April 26, 2006 Share Posted April 26, 2006 12.5 volts and dropping when you rev it shouts knackered alternator to me! Should be chucking out 13.8 as soon as the revs rise above about 1500rpm, especially if the battery is flat! Even with a dead battery, the engine should still run happily as larry so long as the alternator is charging. Flat battery should only affect starting. I'd say in the first instance the alternator is knackered. Hence he gets the in the rangie, it drives for a while, then dies as the battery voltage gets too low to run the efi. Change the alternator first, and then see if it solves the problem. If not then change the battery. Jon Quote Link to comment Share on other sites More sharing options...
Fatboy Posted April 26, 2006 Share Posted April 26, 2006 Change the alternator first, and then see if it solves the problem. If not then change the battery.Jon FWIW I'd agree with that.. Quote Link to comment Share on other sites More sharing options...
RocKeR Posted April 26, 2006 Share Posted April 26, 2006 Same thing happened to me and my EFi Rangie. Went to see X-Eng and Simon supplied me with a nice Super-Power 120 AMP V8 Alternator. No more dead batteries or dying cars! B) Quote Link to comment Share on other sites More sharing options...
Guest diesel_jim Posted April 26, 2006 Share Posted April 26, 2006 When i had a 3.9 EFI in my 90, it used to misfire like bu@@ery when i did a heavy winching session once. i was looking at my voltmeter (which i'm not sure how accurate is) but it showed about 10volts, then engine ran like a bag of poo. Quote Link to comment Share on other sites More sharing options...
GBMUD Posted April 26, 2006 Share Posted April 26, 2006 Certainly says alternator to me too. Chris Quote Link to comment Share on other sites More sharing options...
minivin Posted April 26, 2006 Share Posted April 26, 2006 Another one I learnt today from my boss, the Lucas alternators have a tendency that the suppressor short-circuits and makes the alternator charge badly because it is discharging it's charge across the suppressor. By cutting the suppressor the alternator then sends all it's charge out and it works fine. With a new battery on I can test the battery properly, but the battery is badly discharged and not holding a charge properly so a proper diagnosis of the alternator is not possible at this time (could be brushes, could be regulator, could be a loose wire on the sense line, unknown till we can start it without using another vehicle or battery to get it going) Quote Link to comment Share on other sites More sharing options...
Jon White Posted April 26, 2006 Share Posted April 26, 2006 Its not worth buggering about with them these days - just shove a re-con or known good one on and be done with it if its anything more than stuck brushes. Mondeo ones are good value and work well - £15 or so down the scrappers..... If its been used off road at all my bet would be the brushes jammed up with mud. Most modern alternators you can drop the brush pack off the back by undoing a couple of screws without even removing the alt from the engine. Shove the brush pack in a bucket of clean water and work the brushes in and out with your fingers until they free off. Bolt back on and problem probably solved. Mine used to do this all the time. Everytime i sunk the thing in muddy water they'd get jammed up. The battery is a red herring. If you've got less than 13.5 volts with everything (lights heater etc) turned off with the engine running at 1500 rpm the alternators knackered, regardless of how good or bad the battery is. If you're that concerned its the battery take it down the motor factors and get them to test it with one of the heavy discharge testers. However I'll tell you again - the alternator is the first problem you need to fix! Jon Quote Link to comment Share on other sites More sharing options...
GBMUD Posted April 26, 2006 Share Posted April 26, 2006 If you're that concerned its the battery take it down the motor factors and get them to test it with one of the heavy discharge testers. However I'll tell you again - the alternator is the first problem you need to fix! Be aware that the battery needs to be charged before being "drop" tested. Chris Quote Link to comment Share on other sites More sharing options...
Cartman Posted April 26, 2006 Share Posted April 26, 2006 Rogius, If you need a battery immediately I have one at the back of the garage you can have for nowt. Paul Quote Link to comment Share on other sites More sharing options...
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