Boothy Posted August 4, 2009 Share Posted August 4, 2009 For a few weeks now my 4.2ish V8 has not been a happy chappie and has been a bit down on power and not as responsive but hey ho its a challenge only vehicle and hasn't caused massive issues, and was due a rebuild closed season this winter. Its had a habit of late of fouling up plugs and not revving quite so cleanly as it was, but Sunday at West Harptree doing the Howlin Wolf it was a case of "no go" stick it on the trailer and take it home for an early bath, bittery gutted after a 460 mile round trip. Whilst I was there Sunday I changed the plugs again for a new set (NGK at 1mm Nige) but was surprised when 3 and 6 were squeaky clean and the rest heavily sooted. So change the coil packs and introduce the spare one, rotate them, then start on the spare leads, check the injector plugs, get very hot hands, get totally frustrated, get knotted and take it home its now worse by some margin and will hardly run. When home today checked with the lap top what and nothing appeared amiss except for the MAP which came down to me being clumbsy and knocking the vacuum pipe off whilst rooting with the injector plugs probably. So checking the plugs by removing the leads from the coilpacks didn't prove anything really but showed all were sparking when it got near to coil pack, the 2 clean plugs didn't change the tone of the engine the rest did. When metering the injectors it became apparant one was completely duff and needed changing, so stripdown and all out, cleaned the connectors which were filthy and then put them back onto the fuel ring to leak/drip test them, all ok, so now to test the flow and all appeared ok and consisitant, this was done with a spare plug with 12 volts on it and by turning the ECU to start the fuel pump, the fuel pressure by the way is 38 PSI. I was now happy that all the injectors are consistant and are letting fuel through, so back into the engine and fit everything back on. A engine compression test was done about a month ago to check for a valve problem and all cylinders were about 130PSI but the engine was rebuilt last year with all new rods, pistons, bored, camand followers, rocker shafts and rockers etc, just about everything really. The general condition of the engine is great and its runs very quiet and no noisy tappets etc, with good clean oil and pressure. So restart it and it runs much smoother and tick over is up a mile to nearly a fast run but its still missing and backfiring intermittantly down the exhaust when you rev it, now if I pull the middle injector plugs of nothing appears to alter even the middle 2 together on the same side doesn't seem to affect it but the outer ones definitly alter things. Its seems to run much smoother but is far from right, in theory its got to run smoother its had a duff injector replaced. Last test tonight was to meter both injector circuits on Ohms and they both come in at about 5 to 6 Ohms which is right to the book, and pulling each plug off when watching on the meter clearly shows they are all in circuit. The plugs that were clean last night are now a biscuity colour as they should be, but bear in mind its not left the workshop yet and is still early doors into whats wrong with it. So boys whats up with it, thoughts please ????? Quote Link to comment Share on other sites More sharing options...
Hybrid_From_Hell Posted August 4, 2009 Share Posted August 4, 2009 Whats the coolant Temp sensor saying ? E-mail me a datalog, and the soft southern barsteward will have a lookie, and with some luck then be able to take the **** Nige Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted August 4, 2009 Share Posted August 4, 2009 You are dealing with a slight unknown here - if the injector's been dead for some time you might have inadvertently tuned the engine to run nicely on 7 I had a similar problem when the pins on several of my injectors corroded due to deep wading and effectively shorted out each bank so all the injectors were slightly open all the time. How it ever ran at all was a miracle, but it went all the way to Russia & back like it running sweet at one point I tweaked the REQ_FUEL up because it seemed slightly down on power and running a little lean Ultimately I only fixed it at Billing 'cos it finally manifested itself as a misfire, bought an inlet manifold for a tenner and swapped 2 or 3 injectors out and bob's your uncle. It did reiterate the fact that RV8's will run quite well with fairly major faults, so pulling an injector plug off may well not give a noticeable misfire. Quote Link to comment Share on other sites More sharing options...
Hybrid_From_Hell Posted August 4, 2009 Share Posted August 4, 2009 "corroded" Oh right, ........... that's the 'word' for it / the state of it - is it ? Thats like saying Hitler was "A bit Driven" :rofl: Nige Quote Link to comment Share on other sites More sharing options...
Boothy Posted August 4, 2009 Author Share Posted August 4, 2009 The reason it more or less stoppped running Sunday was probably a mixture of the duff injector and no doubt the pipe to the ECU coming off in the middle of things, causing it to run stoopid rich and blacken up the plugs I hold my hands upand accept that. A combination of a duff (open circuit) injector and some sh&tty connections since dipping it deep at Kirton certainly didn't help but there is I feel something else wrong. Coolant temp last night on the screen matched exactly the mechanical gauge to the letter, but there was a difference with the air tempsensor of about 5 or 6 degrees, which I observed because the thing had sat untouched in the garage for over 24hours so I presumed they would have been very similar until obviously it had started. I forgot to add I swapped my spare ECU over as well to see if it was a faulty, but I was fine and exactly the same missfire. I don't thimk its in the Megasquirt but I am running short of idea's. And Iamtotally happy allinjectors are in parrallel and are being seen by the ECU, I have also studied the fuel pressure for consistency to watch for fluctuancies of which none were seen. Its always had a habit of poppin the exhuast (which is a straight through single box) when revved and let off, a bit of a poppy grumble that sounds well, but now its a proper backfiring which puzzles me a bit. Maps one you sent me Nige a while a go and was left untouched, I've no stick here to swap it of my old laptop (serial port) but will bring one or two home from work tomorrow and will ping it you, this ones USB only and I need another lead. Thought the "Megasquirt mayhem" would wake you up. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted August 4, 2009 Share Posted August 4, 2009 Double check the VR sensor connector, they're pretty damn good but seeing how deep you've parked it it's not impossible you've got water in there or maybe damaged the wire. Quote Link to comment Share on other sites More sharing options...
Boothy Posted August 4, 2009 Author Share Posted August 4, 2009 Yep Nice one, when you say check as in sit on it with a timing light to visually see if its not jumping around, and luckily I have a removable link on the EDIS so can easily go to limp mode, with my limited knowledge it appears all steady on the laptop. When I said I was dissing injectors with no effect, I unplugged at the same time the 2 middle injectors on the left hand bank with no audible diffence to the running on tickover, the 2 right hand ones I left alone to be honest because they're a bit harder to get to. What I haven't done is spayed some WD40 or similar around to see if I've introduced an airleak when I've put it back together. The think tank method is a fantastic tool, I love joint thinking it always resolves most problems. I gave up at about 8.30 tonight, the new neighbours have a toddler and I don't want to rock the boat really, just yet..... Quote Link to comment Share on other sites More sharing options...
Aragorn Posted August 5, 2009 Share Posted August 5, 2009 What are the plugs like on the two cylinders that you say you can pull the injector leads off with no change? Quote Link to comment Share on other sites More sharing options...
Jon White Posted August 6, 2009 Share Posted August 6, 2009 Boothy - are you absolutely certain you've got the plug leads on in the correct order? I've managed before to get the two to the middle two plugs transposed, and it still ran fine, just not quite right and down on power. I'd also disocnnect every plug to all the sensors etc and check that they're all nice and clean. Including crank sensor, temp sensors etc etc Jon Quote Link to comment Share on other sites More sharing options...
Boothy Posted August 6, 2009 Author Share Posted August 6, 2009 Well here's the update, after a lot of testing, I'm hopeing to have solved it but may have to wait a wee while, 1, Without shadow of a doubt I have had a completely electrically duff injector, problem is I may always have had it from the rebuild, 2, I have dirtied other injector plugs following repeated dunks in deep water and may have introduced intermittant faults, this may have been a major contributry factor, these have beenproperly cleaned and refitted with lashings of silicon grease in the plugs, 3, During the rooting/diagnostic process I accidentally pulled of the MAP vacuum pipe, this will not happen again it is now an unbeliavebly tight fit, 4, Sparkplug leads were checked with the plugs out in fresh air, this is not the perfect test as under load conditions they may breakdown and not deliver a adequate spark, plugs leads have susequently been renewed, 5, Being a big clumbsy sod I stripped the thread on No 4 clyinder last night and are currently waiting for a mate to call and helicoil it with the head in situ before re-testing, the plug was still clean but soaked with fuel when we took it out, following the new lead and subseqent explosion and flame, smoke, noise etc when it blew out I can only presume it is now firing and squirting, shat myself, 6, Before blowing the plug out of the head, the tickover had shot up by over 350 rpm without any adjustments, leading me to think the injector/s may have made a vast difference to tickover fuelling and has always ran a bit down on possible power, and I have checked for air leaks of which there were none, but it was still missing this is the point we removed the plugs found the clean one and changed the lead, then after the plug shot we have not re-tried it, 7, The backfiring down the exhuast is being caused by the missing cylinder that is now fuelling putting fuel out into the exhuast system that is being lit from other cylinders, 8, The mate I loaned my timing light to 2 weeks ago is in hospital awaitng a Kidney scan, is stopping me from checking my timing and I wish him a speedy recovery, so I have not really been able to check the VR sensor. I feel that after the plug is re-threaded that most of the problemswillbe cured and it will be time to start the Megaquirt settings from the start again, with datalogging etc. Problem is with it being a competition car only and driven maybe once or twice a month off road only and usually with a 15 mph site limit some underlying ineffiencies are not really noticed as they would be with a vehicle that goes up motorways and dual carrigeways daily, and 70% of the power available from a well tuned all firing and all squirting V8 is ample and will sound well. If I was trying to beat 2 litre BMW's off from the lights every morning I may have noticed earlier. I will keep you all posted if your still interested, and thanks for help and suggestions so far. Quote Link to comment Share on other sites More sharing options...
steve_d Posted August 6, 2009 Share Posted August 6, 2009 I feel that after the plug is re-threaded that most of the problems will be cured and it will be time to start the Megaquirt settings from the start again, with datalogging etc.Problem is with it being a competition car only and driven maybe once or twice a month off road only and usually with a 15 mph site limit some underlying inefficiencies are not really noticed as they would be with a vehicle that goes up motorways and dual carrigeways daily, and 70% of the power available from a well tuned all firing and all squirting V8 is ample and will sound well. If I was trying to beat 2 litre BMW's off from the lights every morning I may have noticed earlier. I would not worry about only being able to tune when off road. If that is the only place it is driven then the map boxes seen will be the only ones that matter. The only thing to watch for is that boxes just outside those visited in the datalog will influence the tuning so if you can see they are way off then manually adjust them to something close to the boxes visited. Steve Quote Link to comment Share on other sites More sharing options...
ThreeSheds Posted August 7, 2009 Share Posted August 7, 2009 I will keep you all posted if your still interested, and thanks for help and suggestions so far. Well I didn't read this far not to know how it all turned out - Sure we are interested! The only thing to watch for is that boxes just outside those visited in the datalog will influence the tuning so if you can see they are way off then manually adjust them to something close to the boxes visited.Steve An important point I completely missed on my Megajolt setup until a couple of weeks ago! Quote Link to comment Share on other sites More sharing options...
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