Noddle Posted May 24, 2009 Share Posted May 24, 2009 Hi, I'm not sure if this belongs here or maybe the MS Forum My problem is on my Turboed "N/A L24" engine, it's running lean. my engine specs are: L24 N/A standard dish pistons, N47 head, N42 Manifold RB30 (200cc) injectors (low) EDIS Megasquirt II v3.0 board, v2.88 code Intercooler I'm running 15PSI boost, with 50psi fuel pressure at 5+K, at 6 - 7K, it goes learn I'm not sure if the injectors are up to supplying enough fuel, or it's some thing else, maybe some one else who has played with N/A L24 (TonyD) can give me a idea what size injectors they need for 15PSI, 7K rpm Nigel Quote Link to comment Share on other sites More sharing options...
jeffer949 Posted May 24, 2009 Share Posted May 24, 2009 You have to look at your duty cycle to see if you have any injector left. Have you tried tunning it out by adding fuel?? Honestly those injectors are pretty small so its very likely your running out of injector. Im probably selling my 460cc injectors with rail if your interested. Quote Link to comment Share on other sites More sharing options...
Brad-ManQ45 Posted May 25, 2009 Share Posted May 25, 2009 Nigel - your injectors are too small. Quote Link to comment Share on other sites More sharing options...
Arif Posted May 25, 2009 Share Posted May 25, 2009 Aren't those injectors smaller than the stock turbo injectors? IIRC the turbo injectors are 280cc. If the ones you have in the car are only 200cc then your duty cycle is probably at 100% at 15 psi. Quote Link to comment Share on other sites More sharing options...
Tony D Posted May 25, 2009 Share Posted May 25, 2009 I'm with the crowd here for more than one reason: Stock L28ET injectors are larger, and even THEY start to run lean at stock fuel pressures above 10psi and higher rpms. Add that intercooler and go above 12psi without added fuel pressure (and a pump capable to move it!) Even with elevated base fuel pressure of 50psi instead of the 36-40, you aren't making up for it. What you got is in essence a 4.8 L engine there, and most Mustangs are running 18 to 24# injectors... and that's with 8 cylinders, you got 2 less! that means a minimum of a 240, but more realistically a 320cc injector is the MINIMUM flow you want to have for that setup. Second, you neglect to mention which FUEL PUMP you're using. The stock internal bypass lifts around 60 psi... So you start at 50psi, add 15psi of boost for 65psi... The stock pump bypasses around 60psi... 65>60, you are running LESS fuel through the injector as a function of decreased delta across the orifice from 60psi on up. At lower RPMS you may not notice it, but likley 4500 is where you should use the most fuel, and it's only because of gawds grace you haven't blown anything running to 7K (though you DO pull fuel after torque peak, which is probably what is saving you!) BTW, you don't define what 'Lean' really is, nor your quantification stnadard. If you are running 13.8 instead of 12 like you wanted, your small injectors are simply pulling the fuel you should have been pulling anyway! You're just lucky, eh? The sizing is really dependent on your flow through the engine. JeffP is making like 465hp at that boost level. That requires a different injector size than someone running a stock engine and just cramming boost to it (likely a 450 would do then, instead of a 720!) With a Megasquirt, I'd say get some Mercedes injectors (450cc's) or some SVO squirters (370cc's), turn your fuel pressure back to a reasonable level and use the Fuel Management for what it's there for: controlling the fuel. Shoot for your duty cycle to be less than 80-85%. Realize there is latency in opening and closing an injector, the lower duty cycle you have the more time you have for opening and closing the injectors. The MS shoud easily control a good idle at 450cc injectors, or even 550cc injectors. That leaves you plenty of headroom for mods, flow improvements, or even fuel added as cooling....(digression beckons...) Man, I'm tired today, I'm hitting the hay. Flight is tomorrow at 6AM...BAH! Quote Link to comment Share on other sites More sharing options...
Noddle Posted May 26, 2009 Author Share Posted May 26, 2009 Second, you neglect to mention which FUEL PUMP you're using. The stock internal bypass lifts around 60 psi... So you start at 50psi, add 15psi of boost for 65psi... I'm running the standard N/A (MR30skyline) fuel pump, with the standard N/A fuel regulator, on vacuum the fuel pressure is 32-35psi, on throttle it's 42-45psi, under boost (15ish psi), 5+K and above it's 50psi, I originally though I was running out of pressure, so to check, I put a 'web cam' under the bonnet (watching the fuel pressure gauge), and recorded my 2 runs . BTW' date=' you don't define what 'Lean' really is, nor your quantification stnadard. If you are running 13.8 instead of 12 like you wanted, your small injectors are simply pulling the fuel you should have been pulling anyway! You're just lucky, eh?[/quote'] I noticed before I changed gears (1-1.5 seconds) the AFR went to about 16 -17, very lean. since I'm looking for injectors now, a side question, will the o-ring type injector physical fit into a standard N42 type manifold, I've never seen a o-ring type up close to compare them. Do they have the cir-clip grove for the 'holder', if not, I saw the 'holder' that Derek used on his cast manifolds, and though I could do some thing simular Nigel Quote Link to comment Share on other sites More sharing options...
Tony D Posted May 26, 2009 Share Posted May 26, 2009 An "0" sized drill bit or reamer would move the pintile hole to the large sizes, I think. They make drills especially for making pockets. But many o-ring - o-ring injectors fit the holes without doing anything. With 35psi at idle, 50 sounds low for 15psi, if you have 45psi 'on throttle' and that means "0" manifold vacuum, then you most definately are low on pressure. Best way to know what you should have is to take a 'static' fuel pressure test. Remove the sensing line from the FPR and see where your fuel pressure runs at---you can rev the engine slightly to keep it running if it goes way rich, it won't change with the line disconnected. If you can initiate the fuel pump without starting the car, that is the pressure you can refer to as 'Static'... For an EFI car, the pressure at the injectors must rise equivalent to boost. So at 45psi Static Fuel Pressure you go to 10psi boost you have 55psi fuel pressure, at 15 boost 60 fuel pressure, etc... What's the world coming to? Web cam to monitor fuel pressure. I've officially become a Dinosaur with my long fuel hose and big-numbered Fuel Pressure Test Gague Duct Taped to the windshield for speed runs. I'll probably bet you not only are running out of injector, you're out of pump as well. Take a look through the search on the Porsche 944 Turbo Pump, it should be available locally though a Bosch Vendor through the Bosch P/N. External pump, BTW. If you need an In-Tank pump, the Z32 pump works well, but it may have to be adapted. But you're right, 16-17AFR is 'lean' as in way to little fuel. Does it start dropping gradually, and linearly with the RPM rise as you have your foot in it at full boost? Quote Link to comment Share on other sites More sharing options...
Noddle Posted May 26, 2009 Author Share Posted May 26, 2009 Best way to know what you should have is to take a 'static' fuel pressure test. Remove the sensing line from the FPR and see where your fuel pressure runs at---you can rev the engine slightly to keep it running if it goes way rich, it won't change with the line disconnected. If you can initiate the fuel pump without starting the car, that is the pressure you can refer to as 'Static'... 28 psi, pump running, engine not running. (running on battery voltage 12 ish volts) 32 psi, engine running, vacuum line disconnected from FPR (about 1K rpm, I would assume battery voltage would be about 14 ish volts) For an EFI car' date=' the pressure at the injectors must rise equivalent to boost. So at 45psi Static Fuel Pressure you go to 10psi boost you have 55psi fuel pressure, at 15 boost 60 fuel pressure, etc...[/quote'] so, 32 psi + 15 psi boost, about 47 psi total, sound about right ? What's the world coming to? Web cam to monitor fuel pressure. I've officially become a Dinosaur with my long fuel hose and big-numbered Fuel Pressure Test Gague Duct Taped to the windshield for speed runs. My fuel pressure gauge is hooked into my supply line, so in the end this was the easiest way to check, since I use my laptop to tune my Megasquit, this was just a 'natural' thing to do. But you're right, 16-17AFR is 'lean' as in way to little fuel. Does it start dropping gradually, and linearly with the RPM rise as you have your foot in it at full boost? Honestly I'm not sure, I'm having issues with getting my wideband and megasquirt showing the same AFR reading, (the output of my wideband is doing something screwy), so all I have to go by is looking at the AFR display, the problem with that is, I need to watch the road as well I'll be installing another wideband soon, so hopefully I will be able to log it Just had a though, I'll set up my 'web cam' to show the RPM, AFR and my boost gauge.. and thank you, to all that replied, Nigel Quote Link to comment Share on other sites More sharing options...
Tony D Posted May 28, 2009 Share Posted May 28, 2009 Yep, when you datalog your MS, watch your battery voltage, that is a big jump running and not...the charging system may be marginal, and that can cause delivery problems if the pump is not getting sufficent voltage under highest load conditions. I ran a #8 line and used the stock relay to control switching of the power to the pump at the back. It gave me a large enough line for all sorts of power accessories at the back of the car from a common hot stud terminal...not that anything but the pump is back there right now...but it's well supplied off a #8 line from the battery, and then a short run of #10 from the terminal, to the relay, to the pump and then a large ground that is run similarly. It is not chassis grounded, there is a companion #8 wire (black) that goes along the frame rails front to back paired with the hot wire. What can I say? I'm paranoid about the drop. Plus, I kept thinking 'man, if I'd put my battery back here all this wouldn't be an issue...while I'm at all this, I should probably relocate it... About that time the wife yelled 'STOP THAT WHILE YOU'RE AT IT STUFF'... apparently my thoughts were also freely running out my mouth in stream of conciousness and she heard me. She knows what 'while I'm at it means'---two weeks over christmas vacation with no living room floor because I didn't like the floor crossbracing on the 4X4 section I was supposed to splice in and repair in a day... Quote Link to comment Share on other sites More sharing options...
Noddle Posted May 31, 2009 Author Share Posted May 31, 2009 But you're right, 16-17AFR is 'lean' as in way to little fuel. Does it start dropping gradually, and linearly with the RPM rise as you have your foot in it at full boost? I set my web cam up, a little rough though. as you can see in third from about 5k upwards the AFR rises. also this screen dump from megalogviewer not sure how to read the 'Duty Cycle' but it hits 186 Nigel Quote Link to comment Share on other sites More sharing options...
Noddle Posted June 14, 2009 Author Share Posted June 14, 2009 An "0" sized drill bit or reamer would move the pintile hole to the large sizes, I think. They make drills especially for making pockets. But many o-ring - o-ring injectors fit the holes without doing anything. I spent a bit of time searching on the net for some pictures of the o-ring type injectors to see what would and would not fit, but there not much out there that showed me the view I needed, (most still had the rubber seals on them, and at the time I didn't know it was rubber, and they were removalable). But in the end I brought some RB26DETT injectors (440cc), here are some pictures for others to see the difference between RB30 and RB26DETT injectors I think I will clamp hoses onto them for now, and maybe later get a Pallnet rail fuel rail, but that will depend on the cost to get it to me. Nigel Quote Link to comment Share on other sites More sharing options...
softopz Posted June 14, 2009 Share Posted June 14, 2009 Those pintle caps on the rb26 injector are almost identical size to the zx injectors and your rb30s *which are identical. Unlike the supra 440c there huge;however spray pattern looks better on the supras. Another bonus is injector clips are the same . I really recommend getting a an oring fuel rail the rb26 is an oring and needs that type of seal. Unlike your rb30 which are barbed inside that FI hose and tightened with an umbrella clamp .thats my o2 on that. Pallnet makes the 11mm and 14mm Oring rails. I got his o ring fuel for the supra injectors, and I gotta say its a nice tight fight with brackets to hold down to manifold. I havent gotten around to throwing them on Iam not sure If I have to increase the manfiold hole, use injector bodies? keep the bottem stock Oring that the injectors come with. Plus I still need the plugs first. So back to your setup. If I was to step up the injectors Id definatly do it right the first time. If you want to retain your stock rail than use a barbed style injector I believe mercedez benz 550 and jaguar injectors are identical. Goodluck Quote Link to comment Share on other sites More sharing options...
WizardBlack Posted June 16, 2009 Share Posted June 16, 2009 You see, this is why I don't like random numbers for a fuel map. What you need to do is take a datalog while it is recording actual pulsewidth. From there you can calculate what the duty cycle is at the corresponding rpm. Search for the formula; it isn't hard. I'm guessing you are maxing your injectors out; this will also cause some injectors to get flaky and cause inconsistent A/F ratios. Some get flaky as low as 80% duty cycle. With Megasquirt, all you really need to do is make sure the injectors fit and they're big enough. You don't need to (or want to) size them exactly for the power levels, etc. Fuel pressure should have nothing to do with rpm unless the pump or plumbing isn't up to the task. Set your curb pressure to 43.5 (ie., at idle with the hose pulled from the regulator) and simply add/subtract your relative pressure to determine what your instantaneous fuel pressure should be. In other words, with 15 psi and standard curb pressure, you should hit 58.5 psi fuel pressure and as long as your boost gauge is pegged at 15, your fuel pressure should be pegged at 58.5. Quote Link to comment Share on other sites More sharing options...
Noddle Posted July 8, 2009 Author Share Posted July 8, 2009 Hi, My fuel rail turned up today, so I will fit my o-ring injectors over the weekend, I'll also install my EGT probe into the spacer plate between the turbo and exhaust manifold. Nigel Quote Link to comment Share on other sites More sharing options...
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