disco-v8 Posted October 31, 2007 Posted October 31, 2007 ok just been messing with my V8 today to see why its not running right.... well just before the videos i made i took out all the plugs and did a compresion test and cleaned all the plugs up, look at some of these pressures all in psi 10.5........(8 7)........10.5 10.5........(6 5)........10.5 11...........(4 3)........10.5 10.3........(2 1)..........11 not bad for an engine with a compression ratio of 9.35 that what you get buying recon heads that have been shimmed, the compression goes up well fair enough i started it from cold and it may have been running at full temp but when i usualy drive it it gets hotter than this so some of the temperature reads are lower than i recon they do get, but doesnt matter cuz it still wasnt running right.... the sound on the video wasnt as good as i was hoping but just before i mess with the fuel pressure you should hear it back fire through the air box, and just after it does it aswell that cant be right!!!!! (DAMB VIDEO IS TO LARGE TO UPLOAD ON YOU TUBE WILL TRY SOMETHING LATER) ok here is another video which realy confuses me totaly, i thought while the engine was ruuning id take the lid off my airbox to see if there was any blockagies, but asoon as i started to take the lid of the revs started to die at first i thought that i might of been bending the inlet hose and blocking air flow but no this wasnt the problem, i tryed squeezing it to prove it..... every car i have had including this V8, when i take the air box off the engine usualy picks up abit as the air flow isnt restricted, but this does the exsact opisit!!!! the sound file is abit hard to hear as all you can hear is the suck of the air, so i filmed the power stearing pully spinning, and asoon as i lift the air box lid the wheel slows down!!!! http://uk.youtube.com/watch?v=DTAYq2lDmsk can anyone explain this to me cuz im lost Quote
FridgeFreezer Posted October 31, 2007 Posted October 31, 2007 Messing with fuel pressure? BTW what are the various tubes coming off the airbox top, if any of them feed sensors or things like fuel pressure reg then that could be an answer. Quote
disco-v8 Posted October 31, 2007 Author Posted October 31, 2007 Messing with fuel pressure? BTW what are the various tubes coming off the airbox top, if any of them feed sensors or things like fuel pressure reg then that could be an answer. i have a FSI boost vavle which i souly bought just to get my fuel pressure running at the correct 35psi, my old OME fuel pressure regulator was only running at 29psi.... my newer pressure reg has an imbuilt pressure gauge and i saw that it was running at 38psi, so dropped it down abit.... dont worry abot the air pipes off the air box, they are the breathers for the winch and a home made breather for the dizzy Quote
FridgeFreezer Posted October 31, 2007 Posted October 31, 2007 dont worry abot the air pipes off the air box, they are the breathers for the winch and a home made breather for the dizzy If you're applying a partial vacuum to the inside of the dizzy you may be affecting the timing, the vac advance is determined by the pressure difference across the diaphragm. Could explain why when you lift the lid (and remove the vacuum) it changes. Quote
q-rover Posted October 31, 2007 Posted October 31, 2007 And surely you would want to overpressurize the dizzy for protecting it against water ingress? Quote
FridgeFreezer Posted October 31, 2007 Posted October 31, 2007 And surely you would want to overpressurize the dizzy for protecting itagainst water ingress? Yes you would - mind you I just had the top chopped off mine and it doesn't miss a beat now Quote
disco-v8 Posted November 1, 2007 Author Posted November 1, 2007 i have a FSI boost vavle which i souly bought just to get my fuel pressure running at the correct 35psi, my old OME fuel pressure regulator was only running at 29psi.... my newer pressure reg has an imbuilt pressure gauge and i saw that it was running at 38psi, so dropped it down abit....dont worry abot the air pipes off the air box, they are the breathers for the winch and a home made breather for the dizzy hold it hold it hold it!!!!!!! first off the dizzy is NOT under any vacuum.... first off with having a 3inch snorkal attached to the side of the airbox its not going to have enough suck to suck throm my breathers, plus in the dizzy i have put another pipe in it which runs up inside my front windscreen pillor to the roof which fresh air is sucked in by from the air box.... in pipe in, one pipe out, no way can there be a vacuum in there..... and no i dont need to put pressure in the dizzy to keep water out, as i sealed the cap and whole unit up and have no problems keeping water out, its just i have proplems from condensasion build up inside it, hence the breathers Quote
Hybrid_From_Hell Posted November 1, 2007 Posted November 1, 2007 i have a FSI boost vavle which i souly bought just to get my fuel pressure running at the correct 35psi, my old OME fuel pressure regulator was only running at 29psi.... my newer pressure reg has an imbuilt pressure gauge and i saw that it was running at 38psi, so dropped it down abit.... I have read all now twice and don't realy understand what the problem is exactly ? FSI boost valves can be a PITA and IMHO a waste of money in anything other than a massively tunned V, the std PRV is enough for 280BHP/ less than 5500rpm, and too much pressue in the rails can lead to all sorts of probs Anyway, pleas clarify the problem ? Nige Quote
q-rover Posted November 1, 2007 Posted November 1, 2007 One thing I noticed, do you have a K+N filter in the airbox? If so get rid of it and stick to standard paper. Also having a clean engine bay helps with finding faults. Quote
disco-v8 Posted November 1, 2007 Author Posted November 1, 2007 hold it hold it hold it!!!!!!! first off the dizzy is NOT under any vacuum.... first off with having a 3inch snorkal attached to the side of the airbox its not going to have enough suck to suck throm my breathers, plus in the dizzy i have put another pipe in it which runs up inside my front windscreen pillor to the roof which fresh air is sucked in by from the air box.... in pipe in, one pipe out, no way can there be a vacuum in there..... and no i dont need to put pressure in the dizzy to keep water out, as i sealed the cap and whole unit up and have no problems keeping water out, its just i have proplems from condensasion build up inside it, hence the breathers ok i dont no my self what the problem is, all i no is that its strugguling to idle and is back firing up the airbox which IMO is BAD!!!!!!! if you see the video it shows that it trys to stall when the airbox lid is taken off like i said i only got the FSI valve just so i could tweek it to the correct pressure which my old standard one wasnt doing, i havent bought it so i can over pressurise the fuel rail and damage my injectors, just so i no its at the factory settings Quote
disco-v8 Posted November 1, 2007 Author Posted November 1, 2007 I have read all now twice and don't realy understand what the problem is exactly ?FSI boost valves can be a PITA and IMHO a waste of money in anything other than a massively tunned V, the std PRV is enough for 280BHP/ less than 5500rpm, and too much pressue in the rails can lead to all sorts of probs Anyway, pleas clarify the problem ? Nige im not trying to over pressuries the fuel rail just got the FSI to getting it running at the correct pressure.... how is the KnN going to make the problem worse, all it does is increase the air flow from the standard filter????? well if i have got an electrical problem i didnt realy fancy jet washing my engine bay and covering it in water so just left it for the time been Quote
FridgeFreezer Posted November 1, 2007 Posted November 1, 2007 how is the KnN going to make the problem worse, all it does is increase the air flow from the standard filter????? The oil from the filter deposits itself on the hot wire of the airflow meter, causing it to read wrong and even fail totally in some cases - there were a few examples in the Disco forum with TD5's IIRC. Also K&N's are not great at stopping dirt Was your old fuel pressure reg not working or just not reaching what you thought was the right pressure? You know the pressure changes with manifold vacuum, as the FPR's job is to maintain the same pressure relative to the pressure (or vacuum) in the plenum - so at high vacuum (EG idle) it may read up to ~10psi low relative to atmospheric pressure (as most pressure gauges would measure it). Quote
Hybrid_From_Hell Posted November 1, 2007 Posted November 1, 2007 ^^^ Wot he said If its backfiring then thats not right, 1st thing is to maybe work out when and where it started to do it - had anything be tweaked changed modified shortly before hand ? Then I would suggest using known good genuine or new genuine standard parts Air Filter (junk the K&N) / Dizzy cap /Leads / Rotor arm, check the timing both at tickover and then at high rpm is it moving back smoothly ? Use a Correct PRV bin the FSI one Are the plugs NGK BP6RES are they newish ? How old the fuel filter ? Any other "Mods" on the engine ? Have a lookie in the Tech Forum as I have shoved in there both diagnostic manuals for flapper and hotwire system Work through them once the above is OK, and then advise Nige Quote
disco-v8 Posted November 1, 2007 Author Posted November 1, 2007 The oil from the filter deposits itself on the hot wire of the airflow meter, causing it to read wrong and even fail totally in some cases - there were a few examples in the Disco forum with TD5's IIRC. Also K&N's are not great at stopping dirt Was your old fuel pressure reg not working or just not reaching what you thought was the right pressure? You know the pressure changes with manifold vacuum, as the FPR's job is to maintain the same pressure relative to the pressure (or vacuum) in the plenum - so at high vacuum (EG idle) it may read up to ~10psi low relative to atmospheric pressure (as most pressure gauges would measure it). well it only started to do this after last time i went off roading on sunday every other mod i have done to it never gave me any trouble but in creased performance ive had recon head, which are also slitly ported ive got the gems airflow meter KnN air filter timing is set to 10 degrees BTDC with great response from centre fugle advance and vacuum advance a FSI fule pressure reg piper torquer cam shaft the plugs are fine and only about 6months old spent £40 on a set of 8 my KnN has got the oil on it, i thought it was stupid to try and block the air flow with the oil... i no what the oil is for BTW so dont say i think i may have sourced the problem i took my air flow meter off and guess what, muddy water has some how manged to seep in past the plastic welds so took the thing apart and just have a look... i also made i little video again and you can hear it popping through the airbox still and take alook at these readings.... for the people who no what it is ment to read they will no that this is bad http://uk.youtube.com/watch?v=nF0abjWwbu8 here is another one and its running just aswell as it has been in the last few days and on sunday, stinks of fuel but runns sort of ok just struggles to idle, but that exsactly how its been running even with the airflow meter on http://uk.youtube.com/watch?v=_-xskY38CEw Quote
Coastcard Posted November 1, 2007 Posted November 1, 2007 muddy water has some how manged to seep in past the plastic welds They're called holes, not welds Quote
disco-v8 Posted November 1, 2007 Author Posted November 1, 2007 OPPPSSSS this is the video of the readings off the airflow meter when the ignition is turned on and the engine is not running it should jump to .5 - .8 and shouldnt take any longer than 3 seconds to drop to .3 other wise something it wrong..... well so ive read anyway http://uk.youtube.com/watch?v=PTlDDWZNlq4 Quote
q-rover Posted November 2, 2007 Posted November 2, 2007 To be honest you are better off taking the readings at the ECU, then you know what signal that is getting. Check the plug on the harness and make sure alll the wires are still connected. I had this fault happen to me, and was a bugger to find, as the plug looked fine. Make sure there is contact between the connectors and wires. The symptoms for my car were slightly rough running, very sooty exhaust, and fuel consumption like an ocean going oil tanker. Disconnect the battery for several minutes once you have checked everything and put it all back together. Then try again. Quote
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