Thumper
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Posts posted by Thumper
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I think its been a month now that I've had this problem. It all started after a night of tuning at 20 lbs of boost and getting the revs above 6k rpm. All went perfect, until the next morning while dropping it into 4th to take an exit. I felt a stumble. Also that morning my turbo (holset) started smoking. Rebuilt the turbo that week no more smoke but the stumble is still there.
Let me define the stumble. It feels like I'm hitting a rev limit. and seems to only happen above 14lbs of boost. But sometimes it does not happen at all. If I lower the boost to say 12lbs, the car will rev to 65k rpm. During the stumble the tack stays in place does not jump around, fuel psi builds and holds steady does not drop off, wide bands goes LEAN during stumble, but the injector pulse width and duty cycle hold steady.
Sometimes it will pull through, so rpm holds at say 48k rpm, fuel builds to say 50lbs and holds. But then boom the car takes off as though nothing was wrong.
I've changed the cap and rotor with Nissan parts. check the plug wire ohm's, new plugs. put a test light on fuel pump before and after the relay. test light on coil, neither losses power.
Nothing has changed from that tuning night a month ago. I've ohm'd the injector wires, signal wire from dizzy, TPS wire, put noise filters on all 12+ going to megasquirt. And I've rewired the CLT and IAT sensors with shielded wire.
I'm left thinking its my turbo? I rebuilt it but did not have it balanced. I've done that before on my other holset but I've checked EVERYTHING and thats what I'm left with?
Sounds like you are blowing out the spark. Especially the part where you can run lower boost and not higher. Tighten the gap to something very small.
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Yepo it is a stock boost gauge sender. Thanks for your help. And it in no way effects the stock ecu. So when you get an aftermarket gauge remove it:-D
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Im no expert on the zxt's but if there was such a box that told the ecu how much boost its running it would be included in the zxt to z turbo swap, and well i think we all know that its not. It might be part of the cruise control if i recall right there is alot of the sensors on the drivers fender by the coil that has to do with the cruise.
Its labeled boost solenoid and has a vacuum hose connected to it. With no vacuum/boost it sends out 2.21 volts. At maxium lip suckage it gets 2.1 volts at maxium lip blowage it gets 2.34 volts. So it definetly is sending different volts to the ecu. My question is does the ecu actually use this? and what is normal volts for this sensor? Thanks
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I'm working on my friends 280zx turbo 82'. I remember reading way back then about the boost reference device over by the ignition coil. If my memory serves me correctly it supposedly tells the ecu it is running more boost. My question is does anybody know what this thing does? and do you know how to test it to see if it is good or bad? I game my factory manual to my friend and its now lost so no go there. Thanks
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Would be kinda cool to see a stock l28 dynoed and tuned through the afm.
I dynoed tuned my ghetto beast (crappy 280zx turbo) on the dyno with adjusting the afm. But it only ran great at full throttle and it changed afrs every day. Get a standalone and you will be much happier. Megasquirt with all extra parts can be done for $400.
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That's a tough call. It could go either way. Also, what are the odds that all the injectors are clogged evenly? Pretty low. Unfortunately, you can't tell if one injector is causing a lean reading or all of them are.
Is the regulator maintaining a constant fuel pressure differential under vacuum and load? Disconnect the regulator vacuuum line at idle and the FP gauge should jump up. Blow into the regulator with a bike pump or compressor at 10psi and the fuel pressure should go up by 10psi. A ruptured or sticky diaphram in the fuel pressure regulator will cause you to lean out under boost and run rich under vacuum.
The regulator is fuctioning correctly. It moves up 7psi when the vacuum is diconnected while engine is running. And it goes up 1psi for every 1 psi of boost. And it holds a vacuum when I put a vacuum pump on.
I'm going to try and get some more stock injectors and i'll take the fuel rail off and see the spray pattern of the ones i have currently.
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Well, then I would check over the entire FI system with the factory manual and then have the injectors flow tested.
I was thinking the same thing but if the injectors were clogged somehow wouldn't the car run lean all the time? or just at high rpms?
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You need to increase the fuel pressure with an FMU or get larger injectors and tweak the AFM, or get larger injectors and a engine management system.
I have a really nice Begi FMU (probably the best) that I am willing to sell. PM if interested. With a Walbro fuel pump I ran 14psi boost with the FMU making 60psi of fuel under boost (stock injection). It was reliable and had more in it. I put down 265rwhp/300rwtq with it.
I ran 13 psi on my ghetto beast (stock 280zx) with just a intercooler upgrade and only ran out of fuel at 13psi so I know the stock injectors are suppose to handle more power than 9psi can put out.
The stock ECU is the problem - it simply cannot deal with increased boost pressures - it runs off preset figures in open loop type mode - so it doesn't add enough fuel for the boost you're running.Anything over 5-7 psi and you simply start starving for fuel.
As someone suggest a RR FPR is one way to go' date=' but an aftermarket ECU would add MUCH more driveability over the stock system.[/quote']
I know the stock ecu system/ fuel system can run more boost I have done it and so has many people on this forum. And i'm trying to stay away from aftermarket ecu for my friend but I've installed atleast 6 of them and tuned ALOT more.
I know something is wrong in order for this to be happening. The stock fuel system and ecu can handle more power. Any other thoughts on what could be causing this? Thanks
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I'm working on my friends 280zx turbo automatic. We are having the problem at high rpms above 4500rpm it will slowly lean the micture out. It will start at 11.5:1 and work its way up to 13.5:1 by 5700rpms. We put a new fuel pump, filter, and have varied no fuel pressure drop via fuel pressure gauge so its not a fuel supply problem. We put a new afm on and I loosened the spring inside of it so that is was running 9:1afr at 4000rpms and it still went to 13.5 by 5700rpms so its not the afm. The only thing I can think is the problem is the injectors are somehow clogged or the ecu has a problem.
The car is bone stock except intake and no exhaust. It has a greddy ebc that is turned off but it still raised the boost to 9psi instead of the stock 6psi. If we turn up the boost the problem happens earlier in the rpm range due to we are moving more air earlier. When the car is cruising or building boost the afr's seem to be ok so it only seems to be a problem at high rpms. What do you guys think is causing the car to run out of fuel? Thanks
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Click, click, click is no good. Read up on the safety pop off valve. It could be that. Or something totally different. 99.9% sure someone has had your problem before so you should be able to find it.
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So it shouldn't be leaning over that much? I'm following the other thread as well, thanks.
Currently I have the stock front sway and no rear.
I was running tokico illumina's and springs and had a fair amount of body roll. When I upgraded the sway-bars it drastically reduced. So unless your struts are bad I would first upgrade the sway bars. Makes a huge difference.
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Happy B-day
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Wow I wish the office who just gave me a ticket would have made this many mistakes. Oh well still funny.
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But if you go 90mph you get there faster so the engine is not running as long.
Does that make your brain hurt?LOL yeah the wear and tear on the engine. You have to consider that in cost oh and your time. Time is money and you spend less time driving more time doing other things. But then you have to factor in.... oh NM
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Since the gas has go up in my area lately and I just did a 1600 mile trip its got me thinking what is the best speed to go for best gas mileage.
I know efficiency will go up higher in rpms and in speed, but at some point load becomes to high. But even if its 150% more efficient at 2000rpms then at 1000rpms you are still squirting fuel 200% more of the time. But then again you are going faster at 2000rpms vs 1000rpms so hmm. Well I found an article explaining alittle bit of it.
http://auto.howstuffworks.com/question477.htm
So what I gathered is a 280z will be most efficient at about 50mph due to its poor aero, but its light weight. While lets say my new car a Z4 Should be efficient at 60 due to is much better aero, but slightly heavier. Then a Hummer will be best at 40 because of heavy weight, and poor aero drag. So for every mph we go over 50-60mph we are getting worse gas mileage.
I'm still not at the point where i'm going to change my driving habits or buy a hybrid but I might go 75-80mph instead of 80-90mph to get my extra 2mpg or more.
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Phil,
You should be able to get an extra 10hp from leaning out the gas on the big-end but at the same time get the lean spot 11.8:1 taken car of as well. Its right at your torque peak so that makes since. Then you will be able to add timing. Remeber the main thing extra fuel does is slow the combustion down alittle so its just like you retarded timing. It also cools off the combustion alittle bit but its returns are reduced at a certain point. So get the a/f's line steady and you should be able to pick up a good 10hp. Also don't know if you know this but you can add timing after torque peak to pick up top-end power as well.
Too give you an idea at DNI getting Gabes a/f's from lows 11's to high 11's and adding 4 degrees of timing he picked up 3-4?mph in his traps. Which is about 15hp.
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Hey Gabe,
Glad you got her running reliably. Did you thermocoat your exhaust manifold? Oh and if I have too I'll lend you my god-like tuning skills friday night if you want. Seriously when it comes to tuning megasquirts I'm better than average. Just FYI.
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Looking good Gabe. Now you can can't complain but i'm only on a stock turbo...
Can't wait to see it at DNI. -
You could always run a new relay real quick for it. Find the ground wire coming from the ecu (wiring diagram) and wire up a relay from the bat. Bypassing all the stock crap. Might save you lots of time and money.
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Do you have pictures of it from the side with those wheels on?
Thanks
Sure do lots of pics in the my hybridz album.
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Does the car start if you push the pedal all the way down. If you have your tps calibrated it will cut all fuel. Also how does your tach look, injectors timing, and map look through megatune? It could also be a stuck injector. Pull them real quick and see the spray patterns. Make sure its not something mechanical before you start messing with your settings. My money is something is not hooked up right or injectors stuck. Good luck. 832-444-4540 Ted
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If you search my screen name and holset it should pull up a write up I wrote awhile back. Should get you started. The rest can be found fairly easily. Good luck.
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iat's affect ignition timing, not afr.
Nope afr's adjust fuel as well as timing. If you look at your injector opening time and then warm up your iat it will decrease. And vice versa getting it cold.
Prox, I did a quick search about a month or so ago and didn't find anything as well. So can't be much help there. Sorry.
Does that make your brain hurt?
Can't wait to see it at DNI.
can't get rid of stumble MSnS??
in MegaSquirt
Posted
FYI 1. When the spark plug gets too hot it can adjust its gap by itself. If this happens get a colder plug.
2. What Thumper says is always right:twisted: