cygnusx1

Thanks guys. Great info. Looks like I need to start scouring cyberspace for a good deal on a wideband setup or time on a dyno or both.

Cast iron begins to glow around 1150 deg-F. Too much fuel causes combustion to complete in the exhaust. And too little fuel causes a hotter burn. So which will cause higher EGT's? What is an optimal EGT for an L28ET? Thanks, if anyone can add some knowledge.

Someone, somewhere in these forums or zcar.com has a good post about adding a variable resistor to the temp sensor circuit to fool the ECU into running richer over the entire stock fuel map. Of course you are eventually limited by the injector size and fuel pressure anyhow. Search for "resistor mod" or something like that.

I got the AFM to fit under the TB and Distributor. It sits just over the AC compressor. I mounted it on a home-made bracket off of the original mounting boss on the fender. The intake air comes up from towards the road via a 3" ovalized tube into a cobra-head elbow. There is a cone type air filter in the drivers headlight bucket between the light bulb housing and the inner fender liner. A 3" hose runs from the filter, under the framerail and up into the AFM. This was the original air supply but it got collapsed by the TO4B!!

This should be a sticky! Warning, a turbo Z conversion is highly addictive and may cause obsessive behaviors along with short quick spurts of mometary satisfaction. Generally these moments are accompanied by the desire to invite friends, spouses, and/or random strangers for a ride in the Z. Within hours of passing peak satisfaction, thoughts are quickly realigned towards seeking information, funding, and the nearest screwdriver in an attempt to reinforce the fixation with more boost. The only known cure is four days of honda civic. Note: the honda cure will only last two days once victim has returned to Z. Turn it up Baast!

It's close enough to a wash, I say. Aluminum moves heat faster. Both in and out. Aluminum can heat the air faster and cool the air than SS. So in your case it should be a wash. As long as the IC is aluminum don't fret. At least with SS you wont get pitting and corrosion.

Baast. I would connect the O2 and try to tune out the richness by using the AFM screw and spring just to see if it gets you anywhere. Mark everything first so you can go back. I have a 900rpm idle and factory timing. Actually what I do is set the throtte stop screw close to 900, screw in the AFM screw (rich) and then turn the AFM spring back and forth from lean to rich until I get a feel for how far I can go with the AFM spring. Then I go as lean as I can go without getting the bumpy idle on the AFM spring and then go like 1-2 notches richer from the leanest. Then I recheck the idle and start over if needed. I dont have a clue as to the AF ratio. I just get it idling smooth and it seems to cruise ok in that range. For reference, I can get a fairly smooth idle for about a 8-10 tooth section of AFM spring wheel. Within that section of AFM adjustment I can get the idle to rise and lower about 150rpm or so....oh and you can make black smoke come out of the tailpipe and you can also make it go away by turning the AFM wheel. When you have the AFM overall set too rich, after about 10 seconds of idling, rev the motor and you will get a black puff.

I can't tell what stock trend that is. Is that from Wall Street? Use a scanner.

Bast. Wow nice detective work! You have come a long way from the, "I give up!", you posted a while back. Great to see that you have reached your performance goals. I can't wait to get to a dyno and get some charts on mine. Oh, and thank the wife for us for letting you play and share your findings with us. I took my Z to work this morning and got pulled over I explained that I had no idea how fast I was going due to the different trans and wheels. The speedo was probably innacurate. His radar said 52 in a 40. I was polite and he let me off the hook. It was a barren straight peice of road...I could have been doing 125mph easily but I am semi conscious about safety. This car is just tooo fast. Funny thing is that he was a young cop who had probably never seen a Z. He read it off my registration which reads DATSU. He said, "Take it easy in your datsoo!" I almost laughed.

Bast, so you did get it back to another Dyno after the corvette place? What were the A/F numbers like and what were the RWHP and RWT numbers like this time with the FMU and 65psi fuel at what boost. Don't leave us hanging... By the way I took my friend out for a spin in my Z. He drives a Stage 3 WRX wagon dynoed about 300 Flywheel HP. After the ride he said that my Z would blow the doors off his Stage 3 WRX.

I have a Turbo XS race type BOV....(bypass valve http://www.turboxs.com/_images/RBV_H-34.jpg ). It IS supposed to be open at idle. That's the way its designed if it's the bypass valve model. That's why it has to be vented back into the intake tract. If you hear it between shifts and you are using the AFM, you are definately going rich. Make sure NO air is getting in or out of the intake system ANYWHERE ANYTIME. The only way IN should be the AFM and the only way out should be the Exhaust. Check for intake leaks. !!Clean all connectors!!

Bast. I wish I could tell you how mine is set but: 1) For two weeks, I havent had a good weather day to get the Z out of the shed. (I hate NY August weather) 2) I have no fuel map to correlate with the bleed screw on the Begi. Those bleed adjusters are not so precise that you can reliably count adjuster turns and have them all flow the same. The best way to get and index on them is to feed the FMU a known pressure from a compressor and log the resulting fuel pressure. This way you can build a "map" and put marks on the bleed screw knob. Try to get some "reference" marks on the knob before you get to the dyno.

Ahh cool so the stock regulator does react to boost and it does so in a logical way. It keeps the same pressure difference across the injector nozzles at all times. So if boost goes up 1psi fuel goes up 1psi. Vey cool.

Look again for vacuum leaks. Use a peice of hose as a stethoscope, probe around, and listen for hiss.

T4/T3, Stock dizzy, 2.5" IC tubes: http://hvmp.com/dc/76Z-IC-1.jpg http://hvmp.com/dc/76Z-IC-2.jpg Yes.

There are sooo many ways to do this. Its all a matter of money, understanding, and the willingness to match your build to suit your needs. I didnt go AIC because I am a Mechanical engineer and like mechanical things. I also like the simplicity of the FMU. I am always thinking long term. I envision doing a complete internal blueprint and balance in the future and adding a complete modern fuel injection system. As usual, I am being patient, going one step at a time, learning the turbo motor, and enjoying the ride. So far it has been 14 years on this Z. You can add an additional injector(s) with RPM and Boost control very cost effectivley. $45 adjustable RPM switch $?? ajdustable boost switch $?? (old Z injectors) AI $?? additional fuel line with adjustable valve for AI I bet you could do all that for under $150 No FMU or RRFPR needed.

An FMU is nothing more than a needle valve. The needle gets pulled UP by vacuum and pushed DOWN by boost. You can add springs, screws or air bleeds to adjust how far or when the needle moves. It is used to control fuel flow back to the tank after it goes through the fuel rail.

Hmmm Bast. you got me thinking now about the stock fuel regulator. My listed rail fuel pressures were taken at idle in the garage. I simulate the 14 psi boost to the FMU by hooking up my compressor to the FMU. In my method, I am NOT feeding 14psi to the stock regulator. In fact, the stock regulator is still seeing vacuum when I do this test. Soooo you are right. I should pull the stock regulator vacuum line off the intake and feed the 14psi to BOTH the stock regulator and the FMU to see my true rail pressure effect. Thanks for paying attention Bast. On a side note: I did NOT think that the stock fuel pressure regulator was able to act upon boost anyhow. It is only a vacuum device, isnt it? I'll try to redo my setup and take new pressure readings this weekend....if the rain stops.

Yes that was my idea. However it does not overcome the basic drawback of the FMU. To much fuel at low RPM and high boost. That's where the RPM switch would come into play.

I don't disagree with using off the shelf tech to make Hybridz run perfectly but there is a part of me that likes to use "Wile E. Coyote" technology to get similar results for much less dough. I'll admit, I did spend some money on my Z so far but I am trying to maintain some sort of a spending cap. I think that an AIC is a little too much money for my weekend fun driver. I would rather save up and put that dough towards a programmable with bigger injectors in a year or so. I know there is a cost effective way to install a 12v switch/valve that can be triggered by an RPM signal to feed boost signal to the FMU without going to space technology. Maybe I should consider that my Intellectual Property and go see a patent lawyer.. Oh well. No lawyers needed here..... check this out: Google RAWKS!!! http://www.rx7club.com/showthread.php?t=233381 RPM switch: $60 http://store.summitracing.com/partdetail.asp?part=MSD-8950&N=120%20301134 or $45.00 http://store.summitracing.com/partdetail.asp?part=SUM-830449&N=120%20302435 Wow, I can sell my FMU and use this in series with a boost sense switch to turn on an old Z injector I have laying around. Even less dough. LOOK OUT ROADRUNNER!!!! ACME AIC is coming!!!

Yes I think I solved the above: 1) FMU was set to high... gave too much fuel down low RPM. 2) Dirty FI Connectors...or whatever happens to them. 3) Vacuum leak at the throttle body gasket. (forced me to mal-adjust the AFM) FMU is good and bad. Good for running rich up top, bad for running rich all over. IF one could turn ON the FMU only at 4500RPM and up, it would be awesome.

Cartech/BEGI FMU 2022: A boost-reading FMU gradually "pinches off" the fuel return line as boost rises. By pinching off the return line totally, fuel pressure at the fuel rail increases to a maximum of the capability of the fuel pump. So, boost=return-line-pinch=fuel pressure rise. In the boost signal line that runs to the FMU there is a bleeder. The bleeder is adjustable. Wide open bleed, the FMU does NOT react to boost so the car runs stock fuel pressure based on the stock regulator. Close the bleeder all the way and the FMU fully pinches the return line when it gets boost to get MAX fuel pressure. What I do is leave the stock regulator intact to control fuel pressure in a stock way when not on boost. Then I pump my shop compressor up to 14psi and get the car idling. I connect the FMU boost feed line to the 14psi compressor and watch my fuel rail pressure. Then I adjust the FMU bleeder (onset) so that the rail gauge reads 45psi. With the Walbro, I can make it go as high as about 90psi. This does NOT gaurantee pressure at full throttle because if your fuel line is too small, you still may not get enough flow to maintain your FMU set fuel pressure. Summary: Engine Idle. FMU inline in the fuel return line, and connected to intake manifold for boost reference. Vacuum line is connected to stock regulator. Approximate-FUEL RAIL PRESSURES-at idle: IDLE FULL/VACUUM: 35psi IDLE/NO VACUUM: 40psi 14PSI BOOST TO FMU: 45psi (set by onset bleeder on FMU) The rate at which the fuel pressure goes from 40 to 45psi is linear with boost. Assuming fuel pump supply is adequate. Drawback of FMU.....Example: Reaching full boost at 3000rpm will lead to 45psi rail pressure which may be to rich for 3000rpm. FMU NOT RPM dependant. Neither is a RRFPR. whew...got all that?

On the leak thing.... Under vacuum, a leak would suck un-metered air in and cause lean. Under boost, a leak would let metered air out and cause rich. So if you are idling lean and going rich under light boost then I would say you have a leak. Does this sound right? I think it is correct.

Bast. well I know it would be nice to be able to blame the dynos O2 sensor but I know what you mean. It's an uneasy feeling. The only thing you can do is to test at another dyno to compare data. I wonder if your AFM spring is too tight and causes the lean conditions at the mid rpms. The fuel started to come back in at the higher rpms, possibly as the ECU was mapping around the AFM at that point. It could be. You can also try the resistor mod on the temp sensor circuit. I know there is a thread about that somewhere. It will move your entire fuel map richer (I hear). One thing we can say is that your injectors and fuel supply are NOT the limiting factors at 3500rpms; its the fuel map thats lean. Yes, I continue to weekend drive my Z at 13-14psi limiting myself to 5300 or so rpms. For those that are reading... It's a a stock 83 EFI, Walbro Pump, good I/C, TO4B Hybrid, and the FMU (fuel pressure 45psi reached at full boost). Food for thought. Historically the ZX Turbo motors are very tough and have been known to tolerate the evils we do to them. Therfore, it is difficult to tell when we have gone overboard without the proper diagnostic tools. DISCALIMER: I dont have any clue what my fuel curve looks like. It just runs good.

Check the basics, plugs, wires, cap, rotor, compression, fuel pressure. Look for vacuum leaks, cracked/loose rubber intake boot after the AFM. Then get a multimeter and check the resistance and continuity of all the FI component sensors and compare them to the manual. Make sure the connections are clean and shiny...AFM, Temp sens., TPS, ECU, Fusible Links, fuel pump, distributor plug, ground cables, relays.....do it methodically. Good luck.