autoserve Posted April 2, 2012 Share Posted April 2, 2012 hi all I have a 4.6 v8 engine running megasquirt, piper 270i cam, ported heads, twin plenum, and 45mm inlets. the engine has always run very rich on the right bank and runs slightly rough and missfirey at low revs since assembly, i have tried various tests to solve problem including recon injectors new plugs coils leads oxygen sensor but still no solution. i have tested injector feed using occilisciope both banks seem the same. i can see using a coulor tune (screws in spark plug hole to see combustion) that all cylinders on the right bank are running rich (orange burn RICH BURN) and left bank are all bunsen blue CORRECT BURN, i am running out of ideas please can someone throw some light on this problem??? could it be down to lifters not allowing valves to close on right bank? or the second hand heads that were already ported are ported incorrectly and 1 is flowing more than the other? the exhaust sensor was in the l/h manifoild when i had a straight balance pipe but then i fitted a x balance pipe and put sensor in the centre but still no change, was thinking of putting sensor in r/h manifold but if cylinder banks are running incorectly i cant see that this will resolve problem. Also all the inlet trumpets and manifold on right bank are wet and sooty on inside and l/h bank are dry. Quote Link to comment Share on other sites More sharing options...
Hybrid_From_Hell Posted April 2, 2012 Share Posted April 2, 2012 3 things : compression test on each bank PSIs ? Plugs -make / type and age ? Fuel pressurein rail in Psi ignition on and running ? Nige ?? Nige Quote Link to comment Share on other sites More sharing options...
Dave W Posted April 2, 2012 Share Posted April 2, 2012 Twin plenum ? If the fuelling is balanced are you sure the throttles are balanced ? Are the plenums split left/right or are they cross connected ? Quote Link to comment Share on other sites More sharing options...
autoserve Posted April 3, 2012 Author Share Posted April 3, 2012 new plugs fse fuel pressure reg running 36psi 170 compresions on all cylinders the twin plenum is 2 3.9 plenums cut in half and welded together, it doesnt seem to make any differance wich throttle body i use to rev engine it always runs rich on right side. could it be down to bad porting or maybe cam timing Quote Link to comment Share on other sites More sharing options...
Hybrid_From_Hell Posted April 3, 2012 Share Posted April 3, 2012 Sticking or weeping injector or injector having poor spray pattern will make it hard to ignite and will give symptoms of "Rich" Nige Quote Link to comment Share on other sites More sharing options...
Dave W Posted April 3, 2012 Share Posted April 3, 2012 So it's using twin throttles into a single plenum ? That should rule out any airflow balance issues. Is the fuel rail a standard fuel rail - wondering if there could be a pressure difference with a higher pressure on the RHS than the left. With a single cam I can't see a cam timing issue effecting one side only. Have you tried increasing the number of injections pre cycle in MS to see if it makes any difference ? Changing the injection events to 4 per cycle alternating will help even out any leaching across the plenum. Alternating helps balance the pressures out. Quote Link to comment Share on other sites More sharing options...
autoserve Posted April 3, 2012 Author Share Posted April 3, 2012 the injectors have just been roconditioned with good spray patterns and flow matched. i have a standard fuel rail that feeds the left bank first then goes round front of plenum to right bank. i have another fuel rail that feeds the other way perhaps ile try that one to see if theres a differance. i am currently waiting for delivery of a usb to serial port adaptor as my serial port lap top seems to have given up so i cant plug in at the moment but when i get it i will try playing with injections. the more i think about it the more i seem to think that the compressions are low on right bank when engine is running maybe due to lifter pump up and inlet valves arnt closing properly (this would explain wet black sooty stuff on inside of trumpets on right bank) i know that the lifters on right bank recieve oil first could there be some kind of blockage causing more oil pressure on right bank lifters? i have tried a cyclone cam in engine and also anaother new set of delphi lifters but it was still running rich and idle was not so good so ive gone back to the piper cam. the pre loads were set to spec. i am using old style front cover with gear driven oil pump running about 40 psi at idle. i tried lowering oil pressure using another weaker spring to avoid pump up but it just made lifters noisey. Many thanks to all that are helping me with this nightmare. Tom Quote Link to comment Share on other sites More sharing options...
autoserve Posted April 7, 2012 Author Share Posted April 7, 2012 Right then i have tried swapping injector wires from the rich lumpy right side to the other and the problem then changes to left bank. so i must have a fault with wiring, disconected ecu plug all seems fine carried out varios wiring tests and all seems good tried to start engine again and now no start carried out a few more tests to find that now my injector pulse wires from ecu arnt pulsing there just live all the time played around with injector settings but still no pulse. so now im thinking that this has been the intermitant fault all along and now its not pulsing so no start. i tried to scope the injector wires but they stay a constant 12v (earth when ignition off) have i got a fault in ecu????????? Quote Link to comment Share on other sites More sharing options...
Gs_John Posted April 8, 2012 Share Posted April 8, 2012 So your saying that the wires connecting injectors to the ECU are at +12v all the time? That's weird because MS grounds the injectors to fire them... Quote Link to comment Share on other sites More sharing options...
autoserve Posted April 9, 2012 Author Share Posted April 9, 2012 Yes that is the problem ms isnt grounding injectors i scoped the ms input from edis and a good pulse is there. must be fault inside ecu Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted April 10, 2012 Share Posted April 10, 2012 Undo the top case screws & post a picture of the insides. Who built the ECU? Quote Link to comment Share on other sites More sharing options...
TheRecklessEngineer Posted April 10, 2012 Share Posted April 10, 2012 What position are you reading this from? Checking at the ECU with the ignition on will read +12 as the other end of the injectors will be tied to +12. Quote Link to comment Share on other sites More sharing options...
Quagmire Posted April 10, 2012 Share Posted April 10, 2012 What position are you reading this from? Checking at the ECU with the ignition on will read +12 as the other end of the injectors will be tied to +12. Good point! Quote Link to comment Share on other sites More sharing options...
autoserve Posted April 10, 2012 Author Share Posted April 10, 2012 Hi I purchased the kit from Nige at megasquirt v8, i fitted kit with no problems but always seemed to have a rich misfire on right bank thinking that this was down to tuning i thought nothing more of it and carried on building car,wasn't able to road test as i hadn't finished building rest of vehicle. i have now finished car and was hoping to tune engine. started road testing but engine runs very rich on right bank i have tried swapping injector wires from the rich lumpy right side to the other and the problem then changes to left bank. so i thought i must have a fault with wiring, disconnected ecu plug all seems fine carried out various wiring tests and all seems good tried to start engine again and now no start carried out a few more tests to find that now my injector pulse wires from ecu aren't pulsing there just live+12v all the time played around with injector settings but still no pulse. so now i'm thinking that this has been the intermittent fault all along and now its not pulsing at all so no start. i tried to scope the injector wires but they stay a constant +12v (earth when ignition off) have i got a fault in ecu?? i think i may have a damaged injector transistor hoping that this has been the intermittent fault all along. also tried testing ecu output to injectors with injectors disconnected but still +12v no pulsing Quote Link to comment Share on other sites More sharing options...
autoserve Posted April 10, 2012 Author Share Posted April 10, 2012 cant seem to get hold of nige, perhaps he is on holiday Quote Link to comment Share on other sites More sharing options...
TheRecklessEngineer Posted April 10, 2012 Share Posted April 10, 2012 also tried testing ecu output to injectors with injectors disconnected but still +12v no pulsing Can I just confirm this: The injectors are disconnected (all 8) from the loom. There remains +12v on both pins on all injectors. When cranking, with the scope (or multimeter) probes connected across the injector pins (again, still disconnected) no activity is shown. If so you have: a) The wrong settings somewhere. b) A duff ECU (unlikely from Nige, but not impossible). c) A problem with the loom. Quote Link to comment Share on other sites More sharing options...
autoserve Posted April 10, 2012 Author Share Posted April 10, 2012 yes that is correct i have reset settings back to original map as supplied by nige wich it ran on before, i also playes with injector times etc and still no differance Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted April 10, 2012 Share Posted April 10, 2012 Nige was probably too busy faffing with his new engine to answer the phone Where are you swapping injector wires to move the fault, and what is your loom setup? Is it a flapper or hotwire loom that's been modified for the MS, is it one you built yourself, are you using a "pigtail" wiring connector to the ECU or did you solder the wires direct to the D connector? What happens if you run all the injectors from one channel? (You'll have to frig the injector staging to simultaneous to get it to fire them all at once for every squirt): TBH the most likely issue is a dry joint or something in the ECU build, things like that are hard to spot with the stim as it can't load up the driver circuitry as much as a real set of injectors etc., I've had a few that work perfectly on the stim but won't energise the fuel pump relay or something like that. Quote Link to comment Share on other sites More sharing options...
autoserve Posted April 15, 2012 Author Share Posted April 15, 2012 still cant get hold of nige! ive left a message and a email but no response so i sent ecu to eddie walsh at megasquirtuk (very helpfull bloke) he found 2 faulty transistors and also said that the jumper wires on board were unisulated and running very close to other parts of board he said he had never seen one assembled like this before and it was a very crude way of fitting wires. hope this will cure faults many thanks to all for your help Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted April 15, 2012 Share Posted April 15, 2012 still cant get hold of nige! ive left a message and a email but no response That's quite weird as Nige is definitely about, although I know he's been ill recently. so i sent ecu to eddie walsh at megasquirtuk (very helpfull bloke) he found 2 faulty transistors and also said that the jumper wires on board were unisulated and running very close to other parts of board he said he had never seen one assembled like this before and it was a very crude way of fitting wires. Eddie doesn't recognise enameled copper wire when he sees it then. Quote Link to comment Share on other sites More sharing options...
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