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12-14-2012, 05:20 PM | #67 | |
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As you increase boost you also increase the need for more pressure to pump the fuel, because the pump must fight against higher pressure in the cylinder. Granted this is not a turbo car and we're only looking at 8-9 psi, it definitely doesn't help the pump out. At 9 psi, the pump will have to create 9 psi more than on a NA motor to achieve the same pressure delta between the pump and cylinder. Leaning a mixture out is dangerous. Most tuners want no more than 12:1 at full throttle, because detonation at high rpm can be catastrophic. The extra fuel also serves to cool the mixture. Rated, I wouldn't run your car above 6500 rpm until you confirm that it's an inaccurate sensor. I would definitely install a wideband as soon as possible.
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12-14-2012, 09:14 PM | #68 |
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And that was a post 2002 untuned car?
Then the lambda sensor had to be dodgy. It is unpossible that a mixture gets too lean without the car's ecu knowing about it. If the pump can or cannot supply enough fuel has nothing to do with it. If the ecu wouldn't know the afr, it wouldn't know how much fuel it would have to give in the first place. This applies for all modern cars. So some sensor or mapping had to be defective. |
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12-14-2012, 11:19 PM | #69 |
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Nothing was defective, and this was an OBDII car... albeit a 1999. The engine was brand new.
Maybe it comes from my aviation days, but I never rely on computers to automatically tell me whether or not something is wrong. They fail, often with catastrophic results. I like having multiple methods of determining the state of operation. The last thing I would do is assume the car is fine just because there's no OBDII code thrown. "Too lean" has a different meaning once you add FI. The car may not be programmed from the factory to throw a code until the AFR reaches a certain value, but detonation can occur prior to that due to the extra heat introduced by the supercharger. Optimum FI AFR's, and what the car thinks it should see when naturally aspirated, differ. I'm admittedly new to the FI world, but I do know that nearly every tuner wants an AFR around 11.5 at WOT. I don't think anyone wants to see 14.7 at 8000 rpm on a FI car. I know that ESS said the VT550 would require a fuel pump upgrade, and the dyno that was posted showed the car running progressively leaner as it approached redline. I've seen firsthand what happens when the fuel pump is unable to provide adequate fuel, and there was no OBDII code thrown. I haven't seen any proof that the Z4M is capable of a claimed 570 hp without a fuel pump upgrade. Rated M is the first on this forum to do this, and with that comes risk. I'd pay attention to what that graph is telling me. Right now AFR's are leaner as the rpm climbs (right where detonation would be most catastrophic), and I wouldn't assume everything is good to go because the tail pipe sensor was sniffing the exhaust after the secondary cats had done their thing. I'd take the conservative route and not rev over 6500 rpm until you confirm that the fuel system is up to the task. After all, it is an increase of 60% over stock.
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12-14-2012, 11:45 PM | #70 |
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Still that car had to be defective at some point.
If obd2 protocols had been implemented correctly it would have known the engine had been running lean. It is required that by law that an engine light pops up (enviremental reasons). But what crap car comes stock from the factory that the fuel pomp cant deliver the projected amount of fuel?!? |
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12-15-2012, 01:09 AM | #71 | |
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Just because OBDII is required by law doesn't mean it actually works in all cases. I'm saying never rely on a check engine light to determine if you're running lean, or if the fuel pump isn't providing adequate fuel. I saw it first hand. OBDII is supposed to know these things... but is it an effective failsafe? No. It sucks in many cases. It's another tool to help identify problems, but a lack of a code is not a clean bill of health for a car.
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12-15-2012, 01:40 AM | #72 |
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When the ecu doesn't know the afr, it cannot provide the engine with the right amount of fuel.
You're talking about a defective car. For all you know, the engine light could have been defective too. If your car is working properly, the ecu will give a warning when the mixture gets leaner than expected by the mapping. Thats what p0171 (or p0174) is for. If the ecu wouldn't give a p0171, it wouldn't have the slightest idea how much fuel it would be putting in the enigne in the first place, so it's defective already. No warning light would have ment a defective ecu, not a defective fuel pump. The pump and injectors cannot provide what the ecu isn't telling the pump cq. injectors what to do. If obd2 and related protocols isn't a failsafe (or at least a warning), nothing is. Everything goes by obd2 and its (CAN)management: speedo, revs, coolant temperature, throttle..... Everything! Last edited by GuidoK; 12-15-2012 at 01:58 AM.. |
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12-15-2012, 03:14 AM | #73 |
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Not sure if it's a lack of pressure from the fuel pump just yet. I did some data logging on a couple runs and it appears that the injection timing is decreasing at a certain point causing the AFR to lean out. I'm not sure why the injection times would decrease; regardless of the pressure it seems the timing should continue to increase with the boost. Here are a couple graphs showing the decrease in injector timing and AFR change:
Z4m run3graph by M detaR, on Flickr Z4M run4graph by M detaR, on Flickr Z4M run5graph by M detaR, on Flickr Hope to hear back from VF after the weekend. EDIT: AFRs fixed... Z4MrevAFR by M detaR, on Flickr
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12-15-2012, 03:16 AM | #74 |
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Failsafe.
OBDII is not a failsafe. It can be a warning, but it is oblivious to many problems. No codes does not mean a properly functioning vehicle. Relying on OBDII to tell you if you're rich/lean is like waiting for your debit card to be declined to determine how much money you have in the bank. And yes, crap in = crap out. If your O2 sensor is giving crap readings, the car can be running lean but the ECU won't pick up on it until there is some other kind of catastrophic failure. If OBDII is telling me my car is running fine, but it's not, is it wrong? YES. Adding a wide band gauge adds another layer of protection. Can the wide band fail? Yes... but more than likely you'll recognize that the readings aren't making sense. You'll also have OBDII as a backup. The odds of both sensors failing simultaneously are so small they're insignificant. A light isn't instantly triggered when fuel is requested but not received. How many times must fuel be requested, how often, and for what duration before a code is thrown? I mean hell, I installed my MAF sensor backwards one time, and the car went crazy until I figured out what had happened... but no codes were thrown. After that, I had ZERO faith OBDII would catch a problem. Try it for yourself, and then tell me OBDII will save you from all your problems. Btw, every time the car is started, it goes through a light test. The check engine light worked. The O2 sensors are fine. The pump wasn't fine. OBDII didn't catch it. End of story.
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12-15-2012, 03:20 AM | #75 | |
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12-15-2012, 03:29 AM | #76 | |
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12-15-2012, 03:52 AM | #77 | |
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It's the same as that you have a failsafe gauge installed which is broken.... So what's your point? You cant trust instruments that are broken?.... Really? Maybe you should install a million backups... You know, just to be safe But the statement you made earlier that obd2 wouldn't pick up a failing fuelpump is definately not true, no matter how you put it. And that is the starting point of this discussion, so really you're trying to change the subject. If the diagnostics and ecu don't pick up a failing fuel pump, it means that both your fuel pump and ecu/sensors are broken. It's impossible not to detect the richness of the mixture, because otherwise the whole injection system with its fuel trims wouldn't work. If you think otherwise, you diagnosed the problem wrong. |
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12-15-2012, 06:45 AM | #78 |
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Can we please not turn this discussion into an OBD2 argument? we're actually not interested in your bickering not one bit.
we're interested in the VF kit, VF's response and that our mate ratedMRoadster gets this AFR thing figured out and his car up and running without worries. |
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12-15-2012, 07:11 AM | #79 | ||
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What you missed is that there are certain parameters that must be exceeded for the car to throw a code. You can look at a gauge and ascertain that the car has proper AFR. Without one, you rely on the ECU to decide when the mixture has been out of parameters long enough to trigger a light... and that light may not come on soon enough. The light doesn't show up instantaneously as soon as the lean condition exists. It may be X number of iterations, rpm, seconds, who knows... the point is, don't trust it to come on prior to damage occurring. With a closed loop system, the ECU will attempt to adjust, and the whole time it's trying to adjust, that lean condition still exists. At what point does it throw in the towel and say something's wrong? That point can be beyond serious damage, like what happened with my father's engine. But whatever, some people can't be told anything and have to learn the hard way. There's a reason so many people install wide band gauges into their modified cars, and it's not just to look cool. OBDII is slow. Most people don't even know what it is, judging by the number of people that post on here asking what their check engine light means without providing codes. They don't own code readers. The light is set to go off after the condition has existed for a while, so clueless people aren't bitching that they have to pay $115 to run a diagnostic check at the dealer every other month... and dealerships aren't wasting time looking for non-existent problems under warranty. Anomalies are buffered out. If you still don't believe me, try reversing your MAF sensor. See how long it takes your car to realize it. Then think about how much damage could take place at 8000 rpm and 175 hp/liter in that amount of time.
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12-15-2012, 08:04 AM | #80 |
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Gonna have to agree with Pokey on this.
You don't know the threshold (time or level)for the CEL activation. Lots of things can go bad fast, and the CEL may not catch it. Lots of cars on narrowband, it will not see much difference in lean / rich until it is way out of range. |
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12-15-2012, 08:06 AM | #81 |
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I am anxious to see what VF says, and hope it's a good answer / solution.
Again, I really like this kit otherwise, but don't want to hurt my car. I only have 7000miles on the engine, and it's a little too early in it's life to blow it up.... |
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12-15-2012, 09:36 AM | #82 | |
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this is perfectly said imo....... absolute truth here, this is why i love having the AFR in the car, do you guys remember fr8tdog, his gauge suddenly went into the 12s @ WOT high revs, his pump was letting on his higher milege car... great comment here pokey. Det is not nice......
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12-15-2012, 09:38 AM | #83 | |
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12-15-2012, 09:49 AM | #85 | |
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Bear in mind the first fuel pump failure happened on a vt2 500 car!!!!! That nearly ended in engine blow!!!!! i think ESS, VF, and G-power should be supplying fuel pump upgrdes imo! And NO the ECU did NOT pick up this failing pump, Fr8tdog picked it up on a unusual 12 AFR reading!!! no codes, not nothing. ill search back and link it!!
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12-15-2012, 10:55 AM | #86 | |
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12-15-2012, 12:42 PM | #87 |
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Rated, do you know what size injectors are being used???
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12-15-2012, 12:53 PM | #88 |
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430 cc/min (41lb/hr) at 3 bars
600 cc/min (57lb/hr) at 5.82 bars; which my ecu was telling me was the fuel pressure (not sure what the FPR is allowing though).
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