Ian C Posted March 10, 2005 Share Posted March 10, 2005 Goddamn it I thought things were going too well. Now that the weather is a bit better I've been using the car for longer journeys, about 100 mile round trips to see my folks. The last couple of trips though, on the way home, I've started to get a miss when under full boost. It starts off as a stumble that can be driven through (as the BOV goes parpaprparparp), and then turns into big gaps in power which throw you forwards. At first the car works fine, sometimes I can cane it and it's flawless, but once it starts with the big chugs I won't be able to cane it without it chugging I've checked the intercooler hoses etc etc and they are all OK and tight. I noticed when it stumbled I got black clouds out the exhaust - unburnt fuel... Now, last night I had someone in the car with me, so while I watched the boost gauge (check for air leaks) he watched the fuel pressure gauge. When it missed, the boost gauge was rock solid 1.3bar, but the fuel pressure gauge oscillated from around 58-59 psi to 40-45psi... Then, to my abject horror, there was a huge bang and flash out the exhaust, lighting up the rear view mirror, and the fuel pressure gauge's warning light goes mental as the fuel pressure drops to 3psi Everything else was running, no lights up, as the engine was kept going by the rear wheels, but the accelerator did nothing... I got a convenient layby and naturally the engine stalled as soon as I dipped the clutch. Feeling rather sick that I'd lunched the engine I checked under the bonnet for obviousness, nothing there, tried the ignition and it fired up and idled perfectly (we need a "phew" smiley). So despite nearly giving me a coronary I've got a heck of a symptom out of it. What would cause the fuel pressure to drop off to pretty much nothing?! I've got a dual pump setup, I'm gonna pull it tonight and examine it, maybe even knock it down to one pump as the twin setup has been shown as overblown. I figure it's fuel-delivery related, maybe the regulator is losing it's boost pressure reference and the chugs are the injectors only getting 40psi of fuelling with 19psi of boost in their faces. Maybe the big cutout wasn't the pumps losing power but the FPR not actually making a restriction in the fuel system anymore so pressure dropped to 3psi... They are big "clean" chugs so I don't think it's an individual cylinder issue, and they are deffo only occurring under boost so a loose connection isn't high on the suspect list. Thoughts please... I wanna get it working properly for the Bruntingthorpe bash -Ian Quote Link to comment Share on other sites More sharing options...
Guest Terry S Posted March 10, 2005 Share Posted March 10, 2005 Check your wiring to the pumps bud, the flow is very much voltage related. Did you keep the Pump ECU? If so wire them both 12v and try again. Quote Link to comment Share on other sites More sharing options...
Ian C Posted March 10, 2005 Author Share Posted March 10, 2005 But why would it be so intermittent? Why would it get worse as the journey goes on? Are things overheating? Would knocking it back to a one pump setup be a good idea? And why would it spit unburnt fuel out when it misses - perhaps not enough fuel is going in for even a lean burn so nothing gets burnt, hence the big misses rather than stumbles? It's a difficult thing to test unfortunately so I want to think everything through and get as many ideas together as possible, I'm not just questioning your response Tel I'm not into blind component-swapping because I don't work at Toyota -Ian Quote Link to comment Share on other sites More sharing options...
Nic Posted March 10, 2005 Share Posted March 10, 2005 Stock ECU fuel cut , cutting in? Quote Link to comment Share on other sites More sharing options...
Guest Terry S Posted March 10, 2005 Share Posted March 10, 2005 Chis honestly mate it could be anything, bad earth? The unburnt fuel is a funny one too, your ignition is OK? I will call you I think, be much quicker. Quote Link to comment Share on other sites More sharing options...
TRD3000GT Posted March 10, 2005 Share Posted March 10, 2005 Could it be the fuel filter needs replacing? Quote Link to comment Share on other sites More sharing options...
Ian C Posted March 10, 2005 Author Share Posted March 10, 2005 It's deffo not fuel cut. No warning lights on the dash, and the behaviour to fuel cut is totally different. The fuel filter is about 4000 miles old, it's an aeromotive inline one. Don't think it's that, but keep the ideas coming -Ian Quote Link to comment Share on other sites More sharing options...
Digsy Posted March 10, 2005 Share Posted March 10, 2005 I wondered why I couldn't get you on the phone last night. Sorry to hear about this episode mate. hope you get it sorted soon! If it wasn't for the 3psi indicated fuel pressure I'd suggest a rich misfire. Is there any chance the 3psi thing could be an instrumentation problem? Quote Link to comment Share on other sites More sharing options...
Nic Posted March 10, 2005 Share Posted March 10, 2005 E-manage injector harness? Quote Link to comment Share on other sites More sharing options...
Guest eyefi i Posted March 10, 2005 Share Posted March 10, 2005 what do the plugs look like? (not the ones in yr sink) Quote Link to comment Share on other sites More sharing options...
Nic Posted March 10, 2005 Share Posted March 10, 2005 what do the plugs look like? (not the ones in yr sink) Found on the end of a wire, usually white in colour, with 3 stickyout bits of metal..... where did I put me coat... Quote Link to comment Share on other sites More sharing options...
b_have Posted March 10, 2005 Share Posted March 10, 2005 Sounds electrical to me fella. Uh Oh...back to the footwell............... Although i would also look at the fuel regulator. That could cause the over rich (smoke) then somehow dumping the fuel pressure causing the cut out. Is it vacuum signaled or electronic? Quote Link to comment Share on other sites More sharing options...
Ian C Posted March 10, 2005 Author Share Posted March 10, 2005 Digsy - no chance of instrumentation error, the gauge (SPA digital) works fine, when it read the 3psi the engine didn't respond to any throttle position as it was effectively dead due to lack of fuel pressure. The gauge also showed the fluctuating fuel pressures when the chugs took place, and it read correctly according to boost or vac conditions at all other times, even after the event. Nic - the E-Manage taps into the injector lines, so they aren't ever actually cut (well, mine aren't ) so even if the connection to the E-M was lost it's underfuel one cylinder on boost, not cut what seems like all six at once... Eyefi - dunno mate, I only got in at midnight last night and I'm at work at the mo. I don't know what checking the plugs would tell me as it's an intermittent problem. I'm gonna try and datalog it at the earliest opportunity so I can check RPMs, boost pressure, AFRs, duty cycles etc to try and get more info on the fuelling front. Charlie - if it's electrical it ain't gonna be in the footwell I'm going to lose a fuel pump to see if it was the load of two pumps on the stock wiring causing problems with the fuel pump ECU or the stock wiring or something. Oh, and I'm gonna check out the FPR, I'll relocate my boost gauge pressure sensor to it's reference hose so I can see if it's losing boost reference even though the rest of the system is OK, and the Vortex boys have already volunteered me a spare to test because they are brill -Ian Quote Link to comment Share on other sites More sharing options...
Dragonball Posted March 10, 2005 Share Posted March 10, 2005 No fuel getting through - but loads sitting and unburnt at other times? Does it chug at full WOT - or just evry so often? FPR diaphram sticking open and then failing - alternating? Sparks OK? Fuel ECU signal? Wire loose with pump install? Bloody difficult - typical - probably something very simple and another one for the tech section! Hope you find it soon m8 Quote Link to comment Share on other sites More sharing options...
Ian C Posted March 10, 2005 Author Share Posted March 10, 2005 No fuel getting through - but loads sitting and unburnt at other times? Well, either none gets through or so little gets through it doesn't combust off the spark but is still visible in the rear view as black smoke after each chug. Either that or buckets get shoved in, enough to kill the mix. Does it chug at full WOT - or just evry so often? It chugs when under boost, kinda over 0.5bar. But it's intermittent, so I can rack through 3rd 4th 5th at WOT, 1.3bar sometimes without a twitch. Other times part throttle part boost causes stumbling or misses. It gets worse as the journey goes on. I haven't yet had it miss while driving off boost. It felt a little hesitant getting back up to speed on the dual carriageway after restarting the engine in the layby, and I *certainly* wasn't on boost then due to being very paranoid, but this may have been my paranoia making me feel it was hesitating slightly. FPR diaphram sticking open and then failing - alternating? I'm thinking this as well. Chopping in a different unit will be a quick and easy test. Sparks OK? As far as I know yes. It did it on my NGKs and I just put back in my IK24s and it's the same. Fuel ECU signal? Wire loose with pump install? I've had problems with the plug going to the pump cage before, where the pump(s) wouldn't start spinning until I bludgeoned the connector (those who saw me lose my rag at TOTB3 may recall this issue ) but I redid the pins once and for all and have had no problems with it since, and it also never manifested itself once the car was actually running. So, dunno really Something I'll be looking at when I pull the pump cage. Bloody difficult - typical - probably something very simple and another one for the tech section! Hope you find it soon m8 Yeah, hopefully it'll be something obvious like a melted wire or a split in-tank hose or something. As if -Ian Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted March 10, 2005 Share Posted March 10, 2005 Put the stock FPR on it, most aftermarket ones are junk, IMHO. The only one i have found reliable is the bosch Motorsport unit, but it's expensive. IMO there's no reason to change the stock unit. Now tell me you have a stock FPR on it, and I'll get my coat Quote Link to comment Share on other sites More sharing options...
Ian C Posted March 10, 2005 Author Share Posted March 10, 2005 Put the stock FPR on it, most aftermarket ones are junk, IMHO. The only one i have found reliable is the bosch Motorsport unit, but it's expensive. IMO there's no reason to change the stock unit. Now tell me you have a stock FPR on it, and I'll get my coat Stock on won't fit mate I've got an Aeromotive one, plumbed into a twin-entry HKS fuel rail. Does this sound FPR'ey to you then? -Ian Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted March 10, 2005 Share Posted March 10, 2005 Yes, sounds like the regulator could be the culprit, unless it's your trick pump installation. Quote Link to comment Share on other sites More sharing options...
Ian C Posted March 10, 2005 Author Share Posted March 10, 2005 I heard the disdain dripping off the word 'trick' then Seeing as I'm gonna concentrate on the FPR and the pumps (prob knock them down to just one) then I'm cheered somewhat by your input Chris, valued as always Now go buy a proper shotgun -Ian Quote Link to comment Share on other sites More sharing options...
Soop Dogg Posted March 11, 2005 Share Posted March 11, 2005 'Clean' chugs sounds more ignition related to me but I'd have to experience it. If it was as far back along the fuel system as the pump, i'd expect it to feel a bit more like when you run out of fuel. i.e. run on the pressure left in the fuel system for a little while until it just fades to nothing. Sudden loss of power just sounds to me like it's more in the area of the spark. Hope you get it sorted. You don't deserve all this again mate. Quote Link to comment Share on other sites More sharing options...
Ian C Posted March 11, 2005 Author Share Posted March 11, 2005 I know what you mean, but generally when you run out of fuel you are on 1% throttle trying to make it to the next petrol station. When this chugs I'm at full boost running 720's at a good chunk of duty cycle, so I imagine the fuel pressure would drop off a lot faster and any changes in power output be a lot harsher. However, yes, sudden massive ignition problems could be the culprit, I've got to check for error codes as I should have a 42 stored if it is indeed the problem. How ignition related misses could kill all the fuel pressure I don't know though... -Ian PS and thanks for the support All I ask for is a summer of fun with a fully functional Supra, please... Quote Link to comment Share on other sites More sharing options...
Dragonball Posted March 11, 2005 Share Posted March 11, 2005 Might be a shot - have you got racelogic fitted? Quote Link to comment Share on other sites More sharing options...
Ian C Posted March 11, 2005 Author Share Posted March 11, 2005 Yes and no, sort of, once I finish wiring it to the ABS sensors, but it did it before I started fitting it anyway -Ian Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted March 11, 2005 Share Posted March 11, 2005 I heard the disdain dripping off the word 'trick' then Seeing as I'm gonna concentrate on the FPR and the pumps (prob knock them down to just one) then I'm cheered somewhat by your input Chris, valued as always Now go buy a proper shotgun -Ian Thanks for the detailed gun info in the other thread ian, appreciated. As you know it's all but impossible to diagnose over the Internet, but if it were here i think I'd start by looking at the FPR and the pump set up. Maybe wire up a voltmeter to the pumps at the tank end, and monitor vac / pressure near the FPR plenum pressure nipple. Having said that if it were mine I'd not have removed the stock fuel rail or pressure reg in the first place Quote Link to comment Share on other sites More sharing options...
Dragonball Posted March 18, 2005 Share Posted March 18, 2005 Any update on this ian - did you find the culprit? ? Quote Link to comment Share on other sites More sharing options...
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