bsmuwk Posted November 8, 2012 Share Posted November 8, 2012 To organize myself better I'll be starting a new post here. What has been done thus far, everything is NEW unless otherwise noted: - Cap and rotor - spark plugs - spark plug wires - 440cc Toyota Supra injectors - pallnet fuel rail - adjustable fuel pressure regulator [set to 35psi (or near there) at idle, unplugged goes to 40psi] - fuel filter - new fuel lines - timing set to 20* - 1985 300ZX ECU and MAF - throttle position sensor - GM HEI ignition module - completely shaved intake manifold - no egr, no idle controls, nothing. - O2 sensor - intake/exhaust manifold gasket - 2.25" intercooler piping to mitsubishi EVO 9 intercooler - Cylinder heat temp sensor - manual boost controller if there's anything else that i can think of that i've done, i'll be sure to post that up. Now my problem, From standing start, I go WOT, it'll set off normally and as soon as boost starts to build (2-3psi) my wideband goes pegged to full lean (22.4) and the car just stops reving, if I let off the throttle a bit it'll get going again but it'll be very lean (17-18 on wideband), if i ease throttle pressure through the revs, I'll build boost and i'll eventually get past the lean spot which occurs from about 2500-3000 rpm and i'll be on my merry way burning tires at 11psi of boost and the wideband showing AFR's of about 11-12 which is perfect. if i go WOT from a standing start and the lean spot hits, i'll shift into second right away and the problem still happens buck the car will buck. if i let my foot off the throttle really quickly and reapply WOT, the problem will go away and i'll be boosting away. doing a 3rd gear pull, the problem is less noticeable. it'll go lean, spike once or twice and then take off. shifting into 4th after a pull gives me no problems. neither does a 4th or 5th gear pull. trying to get a good baseline here. everything is adjusted like it should be, my fuel pressures good as far as i know (i don't know what it is while i'm driving). any ideas? Quote Link to comment Share on other sites More sharing options...
skirkland1980 Posted November 8, 2012 Share Posted November 8, 2012 I had a similar problem with a bad maf sensor. Do you have a spare you can try? Quote Link to comment Share on other sites More sharing options...
bsmuwk Posted November 9, 2012 Author Share Posted November 9, 2012 I had a similar problem with a bad maf sensor. Do you have a spare you can try? All 4 of my spare MAF sensors give me the same scenario. Chance of them all being bad lol One thing I thought of though, but it doesn't seem like Z31 guys have an issue with, is I am running my MAF after the turbo as a blow through set up. Might be fussing about with the readings with initial boost pressure? I could try setting up my MAF as suck though and see what happens. Quote Link to comment Share on other sites More sharing options...
skirkland1980 Posted November 9, 2012 Share Posted November 9, 2012 Yes, it seems to be maf related in my opinion. I haven't heard of running the maf that way. Are there people running it successfully this way? Quote Link to comment Share on other sites More sharing options...
Gollum Posted November 10, 2012 Share Posted November 10, 2012 I have seen blow through MAF setups run, but I'm not sure if you need a specific type of MAF to do it correctly. Idealy you want it to be post turbo so that your temperature readings are accurate. That said, the Z31 ECU is calibrated to run a MAF that's pre-turbo, and I'd suggest doing it that way just to keep the ECU happy. You're already running a hacked together setup (and I mean that in the most honoring way possible) mix matching an ECU on an engine that it was never designed to run, running non-stock sized injectors. There's all sorts of confusing already for an non-programmed ECU. To then throw in strange MAF readings for it just makes it worse. All that being said, I'm glad you have a wideband and I support experimentation. Before the days of tuneable ECU's we made do with what we had available, and I still support that notion whole heartily. I say, make it work and then let us know how it went and what you did. Quote Link to comment Share on other sites More sharing options...
rayaapp2 Posted November 11, 2012 Share Posted November 11, 2012 (edited) For giggles install your MAF before the turbo... See what it does then. The ECU isnt calibrated to read the MAF there. Measuring at that point its gonna confuse the ECU for what it's tables are written for. Atmosphere pushes air volume past the MAF in front of the turbo. On the other side of the turbo the pressure/volume and flow characterists are completely different. Even if you get it running well that way its not gonna be right without proper programming of the ECU tables and any corrections that need to be made to prevent turbulence through the MAF... and turbos make turbulence... lots of it. Some MAF's can be placed in that kind of environment but not a hot wire style. Thats as far as I will go without getting into how the hot wire MAF works, why, and why it wont work that way... that has been answered many times Start there then experienment with other ideas before you proceed. Edited November 11, 2012 by rayaapp2 Quote Link to comment Share on other sites More sharing options...
New 2 z Posted November 16, 2012 Share Posted November 16, 2012 (edited) For giggles install your MAF before the turbo... See what it does then. The ECU isnt calibrated to read the MAF there. Measuring at that point its gonna confuse the ECU for what it's tables are written for. Atmosphere pushes air volume past the MAF in front of the turbo. On the other side of the turbo the pressure/volume and flow characterists are completely different. Even if you get it running well that way its not gonna be right without proper programming of the ECU tables and any corrections that need to be made to prevent turbulence through the MAF... and turbos make turbulence... lots of it. Some MAF's can be placed in that kind of environment but not a hot wire style. Thats as far as I will go without getting into how the hot wire MAF works, why, and why it wont work that way... that has been answered many times Start there then experienment with other ideas before you proceed. I am sorry i HAVE to chime in. I am running a blow through maf along with a few other Z31 people. some making 200-450hp with that same blow through setup. so if he is running a Z31 afm i doubt that is the issue. just dont have it close to a bend as lots of turbulence builds at the 90 degree couplings and such. Edited November 16, 2012 by New 2 z Quote Link to comment Share on other sites More sharing options...
NewZed Posted November 16, 2012 Share Posted November 16, 2012 Looks like the Nissan factory setup is before the turbo, not blow-through. Quote Link to comment Share on other sites More sharing options...
New 2 z Posted November 16, 2012 Share Posted November 16, 2012 Looks like the Nissan factory setup is before the turbo, not blow-through. That does not mean you CANT run a blow through. join Z31 performance theres a few people running a blow through without a single issue. as a matter of fact my Z runs better with a blow through then a draw through. i know thats not the factory setup but the factory setup didn't have a intercooler either. Quote Link to comment Share on other sites More sharing options...
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