cygnusx1 Posted June 6, 2004 Share Posted June 6, 2004 I just finished playing with the AFM wheel after installing a TO4B hybrid turbo, a good sized spearco IC, 240sx TB, Walbro pump, and Begi adjustable FMU. Stock 83 EFI, 83 Turbo motor, stock new injectors, all sensors working to spec and no vacuum leaks I can find. Before the FMU gets bashed, it is currently set to do nothing and my fuel pressure sits at about 33psi with vacuum connected and about 45 without. The car ran strong with the stock turbo but also idled a little ruff but not as bad. In order to get a real smooth idle, I have to richen the AFM by turning the wheel...the bypass screw is already all the way in. Once I get a rock steady idle I go for a spin and it seems to run rich. I think its rich because it bogs a bit and throws a bit black smoke plumes. If I lean out the AFM to where the car barely idles (like a hot cam) the car drives much stronger without the bog or the smoke. Any simple suggestions. I know the best thing would be to replace the EFI but..... One of my suspicions is that I had to mount the AFM on its side and that may affect the flap. Thanks Dave Quote Link to comment Share on other sites More sharing options...
Jersey Posted June 7, 2004 Share Posted June 7, 2004 What's you timing set at and vacuum reading? The AFM is a real pita in my opinion but, i did get it adjusted to run my cuz's Z with a T3/T4 pretty fairly good thoughout the rpm range so i would think you'd be able to do the same with your similar setup. When you lean the AFM out (tightening the spring - clockwise) can you raise the throttle plate stop screw to raise the idle and get it steady or does it lope? No problem with the way you mounted the AFM. Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted June 7, 2004 Author Share Posted June 7, 2004 Timing is set stock 83 setting, I believe its 24 btdc. I tried raising the idle via the stop screw and it smoothed out a bit at 1100rpm but after a minute it comes back down to 800 or so and begins to lope. I can remedy the stumble by pushing on the AF meter arm richwise about 1/16" I guess it's jst going to be a balancing act until I get rid of the AFM and stock FI. I also have ALL of the control gadgets on the intake manifold still connected and operational. Maybe some of those need to go but I'd hate to throw variables at variables right now. I suppose I can play with timing and mixture and idle speed but without an AF Ratio reading, I am shooting in the dark or am I? At idle, I can find the "too lean" and the "too rich" points and then set the AFM spring in between. I guess that's as precise as I can get without high tech tools. After all the "correct" mixture, it is a moving target as idle changes with AFM adjustments. Jersey...yes afm=pita. Any timing suggestions? Thanks, Dave (I smell like HC) Quote Link to comment Share on other sites More sharing options...
Jersey Posted June 7, 2004 Share Posted June 7, 2004 Your timing sounds good. You mentioned you just installed an IC. Did you pipe in a BOV? If so, is it vented to atmosphere? It could be leaking at idle causing your (HC) headache Just throwing ideas around. Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted June 7, 2004 Author Share Posted June 7, 2004 No blow off valve to leak yet. But I am going to hunt for vacuum leaks with a vengeance tomorrow. Lean at idle has leak written all over it. I just can't seem to find one but I'll try spraying tomorrow. By the way when I richen the AFM a bit to get a rock steady idle at 800-900 rpm , my boost gauge shows 20 inches of whatever for vacuum which is a good sign. When it starts to stumble with the "lean" idle mixture it reads only about 10-15 inches. More than you ever wanted to know about the AFM: http://www.roversd1.nl/sd1web/airflow.html Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted June 8, 2004 Author Share Posted June 8, 2004 I got it running pretty good today. Tonight we took it to Dunkin Donuts to get some ballast. When I started it cold, it idled ok and as it warmed up it seemed to slow down to about 1000rpm and steady smooth idle. As I drove away, is stumbled for a few light accell's and then it seemd to get better as it warmed up. I punched it in 3rd gear from about 2200 rpm and it built boost to about 14psi with pretty good power. When I let off the gas it kind of does that fwa-fwa-fwa air noise which I think is because I dont have a BOV yet and the air is "bouncing" off the throttle plate. After about 10 minutes driving it started to bog at over 5psi boost and load. I drove home for about 15 minutes at about 3k - 4k rpms and mid-throttle light boost. I pulled into the garage and shut it off minimizing the idle time. Here is a plug. What do you think? Mixtures have been ALL over for the past few days as I have been fiddling the AFM wheel. 83 Turbo, T04B, Spearco, 2.5" exhaust open, Stock Turbo ECU-AFM-Injectors, FMU brings 50psi fuel at 12psi boost, base timing 24btdc, 110K miles on motor. Dave Quote Link to comment Share on other sites More sharing options...
Jersey Posted June 8, 2004 Share Posted June 8, 2004 Plug looks good but a little white to me from the pic which would suggest lean, timing advanced too far and/or too hot of a plug. Which plugs are you using and at what gap? Do you have an onboard fuel pressure gauge that you can watch while running? If not, you may want to TEMPORARILY T tap one of your fuel lines between your filter and FMU, run it out from under hood to a pressure gauge and tape it to the windshield for a test run or two. It's best to do this with someone else in the car that can watch it and compare it with your boost gauge while you drive. Just a thought. And before i get bashed, no, it's not safe to drive around for a long period of time like this but, it's a pretty simple and inexpensive way to tell if fuel pressure is staying up with your boost. If your running 45lbs of fuel pressure with no vacuum attached to the FMU, you should be near 60psi @ 14-15lbs of boost. Should be near a 1 to 1 ratio. Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted June 9, 2004 Author Share Posted June 9, 2004 I'm running factory spec NGK plugs at the factory gap. I also set my FMU to bring 60psi fuel at 14psi signal. I must be getting close to "tuned". If I gently part throttle into boost it seems to load up and miss and blow smoke. If I hammer it, it stumbles a TINY bit and then build to 14psi by 3700rpm and HAULS!....it seems hit or miss and it seems to depend on how hard I slam the pedal down. My hunch is that it goes rich under mid throttle load and then when I go to full throttle after that its too loaded up and snorts and pops and makes smoke on the way to full boost. Hmmm. Weird. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted August 12, 2004 Share Posted August 12, 2004 Did you ever solve this problem Cygnus? This sounds just like the symptoms that were explained to me, would be expected when using the cartech FMU. Since the FMU will usually provide extra fuel any time it sees boost. Under light boost conditions the AFM is already providing plenty of fuel w/o the FMU, at stock fuel pressure and what not, and will do so up to some point where the AFM stops measuring accurately and the limits of the fuel system are reached, which is when you actually would want the FMU to kick in and give more fuel. But if the FMU kicks in before that point, which presumably it is and does, then you're going to run too rich in that transition period... the period when boost comes on but air flow is still well within the limits of the AFM to measure and supply fuel for, but the FMU is adding fuel to anyways. Sorry if you already knew all this or had already figured out the problem. I had been interested in the get go in the cartech unit, but after this was explained to me I've since been of the mind that it was NOT the way to go, as using it would give the exact problems you are describing. I'm amazed that no one seems to use, or even to know about, the slightly more expensive cartech unit that also has an adjustable ONSET of gain, which is to say, you can set at exactly how much psi of boost you want to have the thing start adding pressure. Hadn't you mentioned you were going to use a second grainger boost controller valve to block boost signal to the FMU until boost went above 7psi? I know someone did... I think that's a REALLY good idea if you don't have the unit that has that feature built in. I know this is an old thread but I wanted to see if you did ever get it figured out, I'm going to be buying an FPR tommorow, haven't yet decided on whether I want the cartech unit, or the much cheaper and easier to figure out MSD 2222, and just wondering what issues I might have to look forward to with either unit. Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted August 12, 2004 Author Share Posted August 12, 2004 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. Quote Link to comment Share on other sites More sharing options...
envmyz Posted August 12, 2004 Share Posted August 12, 2004 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' date=' bad for running rich all over. IF one could turn ON the FMU only at 4500RPM and up, it would be awesome.[/quote'] Get a AIC, I will have mine set for 3500 rpm turn on, running either two or three more injectors. Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted August 12, 2004 Author Share Posted August 12, 2004 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!!! Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted August 13, 2004 Share Posted August 13, 2004 Agreed... I dont want to spend that much either. So Cygnus it WASNT you that suggested running the grainger valve inline with the boost signal line to the FMU? This way you could set it to not come on until some set boost level... maybe 7-8psi. I still think that is a really good idea.... Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted August 13, 2004 Author Share Posted August 13, 2004 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. Quote Link to comment Share on other sites More sharing options...
envmyz Posted August 14, 2004 Share Posted August 14, 2004 How much was the FMU??? Over 200 right, well you can get a AIC the can control 4 injectors, plenty of fuel for around 300. And you wont run rich at idle, there is no problems with high RPM problems (like when on the highway, you wouldn't want the RPM switch dumping extra fuel if you are not boosting all the way) It's better on your stock fuel pump and lines. The nice thing about good AIC is that you can set it to come on, only when over a certain RPM and Lbs of boost. My brother has his set for when it hits 11PSI it automaticly fires up the two sub injectors to boost all the way to 16 PSI. This is great, because when he is running anything under 11 PSI, it's just stock ( idles great, runs great, never runs to rich) This is all my opinion, if I was smart and could figure out MSnS I would use it in a heart beat. I've just never been a big fan of FMUs. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted August 14, 2004 Share Posted August 14, 2004 Eh... I've heard just as many bad things about AIC's as any other method. Cronic on these boards uses an AIC and two injectors for extra fuel on his ZXT, said it gave him a very erratic A/F ratio. He's running the SDS AIC. And anyways, $300 is a lot more than $200... come on you guys act like that 'measely' $100 is just pocket change... well I wish I was as fortunate as some of you. And that's not even counting the price of the injector(s). And having a hole tapped. Then having to set up additional fuel line, running lots of wires.... Everyone has their own prefered way of getting extra fuel. For me, the little bit of extra fuel I need to get to my goal safely, the FMU is probably the best balance of cheap, easy to install and least effect on normal everyday driving. Agreed, if I thought I could pull it off w/o a hitch I would also have gone the MS route by now. Hell, I'd have even settled for a Z31 ECU swap by now if I didn't just see too much chance for me to futz up the wiring somehow and end up with a dead car. Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted August 14, 2004 Author Share Posted August 14, 2004 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. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted August 15, 2004 Share Posted August 15, 2004 well... too late already!!! heheh anyways I had already ordered my FMU on thursday, should be here by next tuesday. I agree that I also like mechanical things... much easier to figure out, diagnose, adjust, etc. I also liked the simplicity of the FMU... minutes to install, only one or two things to adjust... and I'm set. Unlike you though I really have no big plans for the future. I've said so many times, that before I even started this swap, I outlined exactly what I was going to try to accomplish with this car... and my goals were very modest. This was so that I could stay within a reasonable budget, have the car done in a reasonable time, and keep the car from being too crazy. I've always had a target of around 250hp to the wheels, staying as close to stock as possible. In such a light car I knew that'd give me all I needed to be faster than 90% of the cars on the road. The car feels plenty fast for me now, even though it's still a bit short on the hp... acceleration in any gear except for the extremely low 5th gear is impressive, and pushes me back in the seat. I'm very satisfied with the end result, and with the extra fuel, I've still got a few hp coming! There are still mods in my future... I'll be installing a full 3" mandrel exhaust asap and hopefully get rid of all the extra lag the I/C added, then just stuff like a Z31 ecu swap, and stuff to improve handling like larger anti roll bars... but after the exhaust they are going to be few and far between Quote Link to comment Share on other sites More sharing options...
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