tracking down impossible missfire
tracking down impossible missfire
Recently I got the fly by wire back on, wanted to put it all back to normal so it had no eml and no issues before I slap a great big turbo on it in the coming few months. I set the tps to the correct voltage (according to the nz forum anyway) and after having the battery out for a while it idles ok and responds ok.
Sometimes, not all the time it will what feels like a misfire on moderate load at low revs (2k ish, bellow the power band) and around 4.5-5 sometimes all the way to 6.5 ish. Kinda bucks a bit and hesitates.
No eml although it has said fuel trim too lean a few times, Ill check if it brings that error up only after the misfire. Plugs are all good and the right ones. coils are ok Too bar 1 which is getting brown but it always has been brown. Seems to be worse on full throttle too, if I build gradually It doesn't do it as often. Fuel pressure is set right too, I was considering raising it a little just to see, would that damage the injectors?
Thanks in advance
As some of you may already know ever since I started modifying my altezza it's been problem after problem for the past year
Recently I got the fly by wire back on, wanted to put it all back to normal so it had no eml and no issues before I slap a great big turbo on it in the coming few months. I set the tps to the correct voltage (according to the nz forum anyway) and after having the battery out for a while it idles ok and responds ok.
Sometimes, not all the time it will what feels like a misfire on moderate load at low revs (2k ish, bellow the power band) and around 4.5-5 sometimes all the way to 6.5 ish. Kinda bucks a bit and hesitates.
No eml although it has said fuel trim too lean a few times, Ill check if it brings that error up only after the misfire. Plugs are all good and the right ones. coils are ok Too bar 1 which is getting brown but it always has been brown. Seems to be worse on full throttle too, if I build gradually It doesn't do it as often. Fuel pressure is set right too, I was considering raising it a little just to see, would that damage the injectors?
Thanks in advance
Have a bosch 44 in the tank so it shouldn't be struggling to deliver fuel. Have a universal cheapo fuel filter close to the fuel rail. It's low in the tank too and it will do it even on a full tank so I doubt it's struggling to get to fuel.
Ruled out an exhaust leak giving me incorrect lambda reading cos it would do it all the time so must be something with fuel delivery and its a lean out misfire. What are the dangers of a lean misfire? Bear in mind its only sometimes so it's not like the engine is always leaning off.
What do I start testing first? I don't want to put the standard pump back In so that is the last thing on the list after ruling everything out.
When it does it It throws up fuel trim too lean. Answered my own question lol
Have a bosch 44 in the tank so it shouldn't be struggling to deliver fuel. Have a universal cheapo fuel filter close to the fuel rail. It's low in the tank too and it will do it even on a full tank so I doubt it's struggling to get to fuel.
Ruled out an exhaust leak giving me incorrect lambda reading cos it would do it all the time so must be something with fuel delivery and its a lean out misfire. What are the dangers of a lean misfire? Bear in mind its only sometimes so it's not like the engine is always leaning off.
What do I start testing first? I don't want to put the standard pump back In so that is the last thing on the list after ruling everything out.
is your fpr a static one? is it dropping off at all?
another one could be battery voltage. that can effect the injectors/pump etc.
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Read my thread here: The Evolution of my Turbo Lexus from NA-Supercharged-Twin Turbo-Massive Single
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Sparkystav
01-02-2022, 10:56 AM #3Is the filter blocked? cheapo ones can clog up.
is your fpr a static one? is it dropping off at all?
another one could be battery voltage. that can effect the injectors/pump etc.
Read my thread here: The Evolution of my Turbo Lexus from NA-Supercharged-Twin Turbo-Massive Single
Please leave your comments.
Yes it's static, haven't hooked up a vac line as it didn't have one as standard. It does drop a tiny bit when I rev actually but it's a small drop, I didn't think that would cause such a big loss in fuel that it can't even keep up at 2k
I'll check the voltage across the pump when I get a chance
Wouldn't the filter do it all the time though?
Yes it's static, haven't hooked up a vac line as it didn't have one as standard. It does drop a tiny bit when I rev actually but it's a small drop, I didn't think that would cause such a big loss in fuel that it can't even keep up at 2k
I'll check the voltage across the pump when I get a chance
Haven't got a chance to test with multimeter but i can hear the pump change pitch on idle so something must be wrong somewhere. I think it's either too thin a wire or that crappy cheap filter. Plan is to make a little box to bolt down in the boot with a perspex access hatch for servicing and put the pump in there with a nice proper filter and run a braided hose all the way to the engine as a feed. was going to make a hard line but there's so many kinks it would be a nightmare to fit without making new brackets etc. Plan is to wire it from battery with a fuse to the front of the car to a switch then back to pump and to earth. Bearing in mind the battery is in the boot so I will need the wiring to go up and down the whole length of the car, what gauge would you recommend? And do I need a high amp switch or can I just use any on off switch? And what about the standard wiring? Can I just cut them and leave it dead or does the ecu need the efi circuit to be complete?
That's what I have.
Read my thread here: The Evolution of my Turbo Lexus from NA-Supercharged-Twin Turbo-Massive Single
Please leave your comments.
Sparkystav
08-02-2022, 07:35 AM #6Why not use the standard wiring to turn on a relay that activates the pump? That way you only need wire from the battery to a relay in the boot to the pump.
That's what I have.
Read my thread here: The Evolution of my Turbo Lexus from NA-Supercharged-Twin Turbo-Massive Single
Please leave your comments.
That's how It is now and it's not holding a steady voltage so I thought it might be from the standard wiring. Just d or ease really, have it on a separate circuit dont have to worry about it it's all nice and simple. I have a tendency to just re do it my own way when I have an issue
After some planning I've realised it's gonna be a pretty big job, will do at some point but for now I just wana get it working, might be boosted sooner than I thought! Voltage on the trigger wire and pump stays at 13.10v. Voltage doesn't drop when the pump randomly changes pitch so it must be from something else. When revving on idle it doesnt drop below 13v apart from once it went to 9 for a second and even 12.9 but I couldn't get it to do it again. I'm gonna get a nicer filter but a bit stumped on micron ratings, post pump needs a 10 or 40 micron? I'll get the car warm and try some full throttle tests to see if drops voltage
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