Rosco Posted February 13, 2011 Share Posted February 13, 2011 I'll start by saying I no enough about mechanic work to get me in trouble. I learn fast and have a pretty good understanding of z's but some of the abbreviations used throughout this site I don't get, but I'll learn. I have a 75z with a motor rebello racing built me. It has a 3.0 piston kit, 63 DI cam (what does this mean?),240sx turbo(2t) injectors, 2t throttle body, 2t mas air meter with the guts out of my 75 mafm, header, 2 1/4 exhaust, super tech intake hi flow valve, mild street port?, valve grind c&a?, adjustable fuel pressure reg on the rail and a modified manifold. They sent me the motor, I put it in and had a few problems with fuel.I narrowed it down to the tank so I dropped it, cleaned it and put this stuff from jegs that stops rust from coming back. Then I had to put a 280zx turbo fuel pump on it to keep up with the volume the injectors want. The next issue I had was flooding on cold starts so I unplugged the cold start injector, that helped but my 02 was reading 1.5 - 2 v. DO I WANT THE 02 TO READ .5 OR SO? If I get it to bounce between .7 and .5v it idles good but I loose throttle response because theres too much tension on the afm. If I drop the fuel pre. to 25 it leans out but I loose HP. I've found a pretty good spot it's fuel pre 32, .9v on the 02 and less tension on the afm. I'm still rich but I have HP and throttle response. I've seen a few post saying you can't put a cam in these motors without changing the ecu/efi but rebello says he has two other customers that have the same motor and they have no problems. My car runs great at full throttle it's just rich at an idle Now the question 1 is there any way to lean this thing out other than the afm? thank you ~Rosco~ Quote Link to comment Share on other sites More sharing options...
Tony D Posted February 13, 2011 Share Posted February 13, 2011 (edited) I have never seen a Narrow Band give more than .9V, if you are reading a WBO2 maybe... I'd start looking at your electrics for stuff fouled up. The rest of the post is so abbreviated I can't make heads or tails of it. If you have .9V on acceleration that is where it 'should' be, but using a narrow band is guessing. It should be switching between .5 .7 light and cruise. Closer to .9 if it even reads at idle (unheated single wire...) A three wire heated O2 will work at idle, but that's a step to nowhere. The AFM bypass will tweak the idle mix, but jump two paragraphs below to see you need more than a single wire O2 sensor to set it! Get rid of the hodgepodge mickey-mouse Bosch Licensed stock EFI crap and put proper fuel control on it and these 'compromises' will not be necessary. You will tailor the fuel to where it needs to be. But not with the O2 sensor you have in there, you need WBO2 at least, or a five gas analysis on the dyno even better. If you want to screw with the AFM, you will need at LEAST a CO meter to properly set the idle air bypass. If you're happy with partial throttle and it's only idle with the 'rich' problem now, this would be the way to do it. It's on the side of the AFM, and everybody I know of who tweaked it without having a CO Meter hooked up was sorry they did. You can try, but don't say you weren't warned! The problem is not with the mechanical part of the engine, it's the substandard hodgepodge of electrics you are tweaking and freaking to try and make it do something it wasn't meant to do. Get rid of that, and you will get rid of the fueling problems. Good Luck on the AFM tweak. Edited February 13, 2011 by Tony D Quote Link to comment Share on other sites More sharing options...
z-ya Posted February 13, 2011 Share Posted February 13, 2011 Going along with what Tony said: You will most likely never get that engine to run right with a mix of OEM EFI parts. You really only have three adjustments: Fake the coolant sensor with a series varible resistor (low speed mixture) Fuel pressure AFM You need tune-ability across the entire RPM and load bands. Since you probably have a lot into that Rebello motor, it would be a waste not to utilize it with the proper tune. Quote Link to comment Share on other sites More sharing options...
Rosco Posted February 13, 2011 Author Share Posted February 13, 2011 I have never seen a Narrow Band give more than .9V, if you are reading a WBO2 maybe... I'd start looking at your electrics for stuff fouled up. The rest of the post is so abbreviated I can't make heads or tails of it. If you have .9V on acceleration that is where it 'should' be, but using a narrow band is guessing. It should be switching between .5 .7 light and cruise. Closer to .9 if it even reads at idle (unheated single wire...) A three wire heated O2 will work at idle, but that's a step to nowhere. The AFM bypass will tweak the idle mix, but jump two paragraphs below to see you need more than a single wire O2 sensor to set it! Get rid of the hodgepodge mickey-mouse Bosch Licensed stock EFI crap and put proper fuel control on it and these 'compromises' will not be necessary. You will tailor the fuel to where it needs to be. But not with the O2 sensor you have in there, you need WBO2 at least, or a five gas analysis on the dyno even better. If you want to screw with the AFM, you will need at LEAST a CO meter to properly set the idle air bypass. If you're happy with partial throttle and it's only idle with the 'rich' problem now, this would be the way to do it. It's on the side of the AFM, and everybody I know of who tweaked it without having a CO Meter hooked up was sorry they did. You can try, but don't say you weren't warned! The problem is not with the mechanical part of the engine, it's the substandard hodgepodge of electrics you are tweaking and freaking to try and make it do something it wasn't meant to do. Get rid of that, and you will get rid of the fueling problems. Good Luck on the AFM tweak. I shouldn't try to keep up with your abbreviations I don't no what I'm talking about ha. I've had pretty good luck with tweaking the AFM it's simple more tension leaner, less tension richer. the 02 reads at an idle .9V and at half throttle it's reading 1.73V or so. What is a WB02? If the OEM EFI is Micky mouse what is the superman? and where do I get it? Quote Link to comment Share on other sites More sharing options...
Rosco Posted February 13, 2011 Author Share Posted February 13, 2011 Going along with what Tony said: You will most likely never get that engine to run right with a mix of OEM EFI parts. You really only have three adjustments: Fake the coolant sensor with a series varible resistor (low speed mixture) Fuel pressure AFM You need tune-ability across the entire RPM and load bands. Since you probably have a lot into that Rebello motor, it would be a waste not to utilize it with the proper tune. Have you ever heard of Rebello? It only loads up at red lights and it's vary cold natured. it runs good with your foot on the gas, as a matter a fact it puts you back in the seat at full throttle. I tried to run a resister in series with the coolant temp sensor and I set the resister before I started it and as soon as I start it the meter reads over the limit??? I tried running it with just my resister and no sensor and got the same results. I know I know change out the EFI but it is so close with out it. THANKS for the info ~Rosco~ Quote Link to comment Share on other sites More sharing options...
Rosco Posted February 13, 2011 Author Share Posted February 13, 2011 Has anyone ever heard of a N42 Head not having the ports for the injectors or the center bolt holes for the injected intake? Quote Link to comment Share on other sites More sharing options...
ctc Posted February 13, 2011 Share Posted February 13, 2011 (edited) Has anyone ever heard of a N42 Head not having the ports for the injectors or the center bolt holes for the injected intake? Some JDM (Japan Domestic Market), not sold in US, N42 heads did not come with the ports for injectros or the bolt holes for the injected intake. I have such a N42 head on my stroker motor. Works great with individual throttle body EFI on a Cannon intake. Think tripple weber, but EFI. Search ITB on this sight and you will find a few examples. Edited February 13, 2011 by ctc Quote Link to comment Share on other sites More sharing options...
Rosco Posted February 13, 2011 Author Share Posted February 13, 2011 thanks Quote Link to comment Share on other sites More sharing options...
NewZed Posted February 13, 2011 Share Posted February 13, 2011 This thread should help you - http://forums.hybridz.org/index.php?showtopic=48124 Since I'm here - what do you mean by "2t" in your description of your engine mods? Quote Link to comment Share on other sites More sharing options...
Rosco Posted February 13, 2011 Author Share Posted February 13, 2011 I was typing 240sx turbo tomany times so I typed 240sx turbo(2t) so I mean 240sx turbo sorry Quote Link to comment Share on other sites More sharing options...
Rosco Posted February 13, 2011 Author Share Posted February 13, 2011 thanks that helps I'll study it so I don't look like an idiot Quote Link to comment Share on other sites More sharing options...
z-ya Posted February 13, 2011 Share Posted February 13, 2011 Have you ever heard of Rebello? It only loads up at red lights and it's vary cold natured. it runs good with your foot on the gas, as a matter a fact it puts you back in the seat at full throttle. I tried to run a resister in series with the coolant temp sensor and I set the resister before I started it and as soon as I start it the meter reads over the limit??? I tried running it with just my resister and no sensor and got the same results. I know I know change out the EFI but it is so close with out it. THANKS for the info ~Rosco~ Uh, yes... Driven a Rebello 3.2 240Z with triple Mikunis. Dave knows how to build an engine. My point is that it will run only as good as your tune. There are hundreds of stand alone programmable ECUs out there. Anywhere from $500 (Megasquirt), to $4000+ (Motec). Quote Link to comment Share on other sites More sharing options...
Rosco Posted February 13, 2011 Author Share Posted February 13, 2011 I'll look into the megasquirt Thx Quote Link to comment Share on other sites More sharing options...
Tony D Posted February 14, 2011 Share Posted February 14, 2011 'I've had pretty good luck with tweaking the AFM it's simple more tension leaner, less tension richer. the 02 reads at an idle .9V and at half throttle it's reading 1.73V or so. ' OH, good luck with that then, you have a very special set of readings there. Quote Link to comment Share on other sites More sharing options...
Rosco Posted February 14, 2011 Author Share Posted February 14, 2011 There special? I have no idea what they mean. What is a WB02? Quote Link to comment Share on other sites More sharing options...
Rosco Posted February 14, 2011 Author Share Posted February 14, 2011 It sounds like I need to educate myself some more. Thanks for the help Quote Link to comment Share on other sites More sharing options...
NewZed Posted February 14, 2011 Share Posted February 14, 2011 (edited) WB02 means wide band oxygen sensor. It allows a higher resolution signal to be produced than with the narrow band, and with the right controller gives actual Air Fuel Ratios (AFR) over the useful range that you would expect from a well-tuned engine. Here's a link to one of the most popular units - http://www.innovatemotorsports.com/products/lc1.php Here's one with a gauge - http://www.innovatemotorsports.com/products/MTXL.php One more thing - the graphs in the link below show what you are probably reading, either narrow band or wide. The slope of the curves, negative vs. positive, is even different for narrow vs. wide. You should figure out what you have. http://www.carcraft.com/techarticles/116_0402_innovate_air_fuel_ratio_meter/photo_07.html Just one example. Not an expert, just stuff I've picked up here an there. Edited February 14, 2011 by NewZed Quote Link to comment Share on other sites More sharing options...
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