EZ-E Posted May 25, 2005 Share Posted May 25, 2005 First Ill tell you about the car then go onto whats wrong with the car. It is a 1982 280zx turbo. Upgrades that I have done to this car are as follows. T3/TO4E turbo, .63 ar exhaust, stage 3 wheel, .60 ar compressor with a 57 trim wheel. 3 inch mandrel bent exhaust turbo back, dynomax straight threw muffler. SVO 370cc injectors 240SX 60mm throttle body Bosch fuel pressure regulator set at 43 psi static Pallnet fuel rail Walbro fuel pump Greedy (yes I said greedy) BOV Bar and plate intercooler from a porshce 944 (thanks to bumblezee) 2.25 inch intercooler piping (mandrel bent) NGK BPR7ES plugs NGK wires (not really an upgrade I know) Z31 LSD OK here is the problem The car runs fairly well but does have a bit of a idle problem which is expected due to the injectors and still running on stock electronics and ecu, with garbage flapper door afm. I have tightened the afm 18 teeth as per most here on the forum that have done this. What the car will do is run like a raped ape up till about 4000 rpms then it power will just fall off. From what I can tell is that I am able to run up to about 15 psi of boost without any problems at all till 4000 rpm where the fuel will go from rich and just fall straight off. I do feel it in the car and I know this sounds stupid as the readings I am getting are after all has happened but as it falls off the car does the same as well, with the O2 sensor hooked up the car will run and idle fine untill (watching the af gauge) it starts to go out of the stoich area. Then it will act up with the missing idle. Now before the upgrades to fuel and what not on the stock turbo boosting at 15 psi I had not one problem. With upgrading it seems that its just getting worse and all parts are new, well less the lsd of course. The plugs, wires, fuel filter, are all new. I dont understand why it will fall off like this at 4000 exactly, I know I shoudl be able to go to at least 5000 rpms. Can anyone understand what Im trying to put out here and give me the advice to try and remedy my situation. I know that the best thing for me to do would be to go to a stand alone system, but at the moment I just cant afford that. It just seems all that I do to make this car run better and a bit faster just makes it harder to get going properly, then again if I were doing it right maybe I wouldnt have such problems. I think I just need a stand alone to solve my problems and be done with it or sell the car and be done with all the headaches its currently giving me. Quote Link to comment Share on other sites More sharing options...
lifegrddude Posted May 25, 2005 Share Posted May 25, 2005 Try loosening up the afm by a few teeth, I had to set mine at about 12-14 when I had 370's. Otherwise it was like I hit a wall during acceleration. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted May 25, 2005 Share Posted May 25, 2005 Forgive me if I'm speaking out of my arse here but isn't 15psi of boost on a T3/04 too much for even 370 cc injectors? I know guys on this board run 15+ psi on the 'lowly' stock T3 with 370cc injectors on stock EFI and claim that it can run a little lean at higher RPM... of course you are flowing MUCH more air with a T3/04 at that same boost level. I don't have all the equations handy but you should try to figure how much air you are flowing or how much power you should be making and see if the 370's are enough to handle that, I think 370's are only good up to about 275-300rwhp? Garret 76zt is one member I know of for sure, who is running 15psi on the T3 with 370cc injectors and said it still runs lean on top, and was looking into getting an RRFPR to help take care of that. Jersey is running 18psi on his T3 and 370's and I think he has said he's running lean as well. Again if that's the case with a stock T3 it's only going to be that much more exaggerated on your turbo. You're probably running very lean above 4000rpm. Quote Link to comment Share on other sites More sharing options...
fl327 Posted May 25, 2005 Share Posted May 25, 2005 you might be running real LEAN... Quote Link to comment Share on other sites More sharing options...
Clifton Posted May 25, 2005 Share Posted May 25, 2005 If your fuel pump cannot supply enough volume your pressure will drop at higher RPMs. I would T in a cheap ($5) gauge and watch it at WOT. Quote Link to comment Share on other sites More sharing options...
Cody 82 ZXT Posted May 25, 2005 Share Posted May 25, 2005 Sounds to me like the car is running lean (possible slight detionation) and the knock sensor is getting a signal. The computer pulls tons of timing out to save you from yourself. Quote Link to comment Share on other sites More sharing options...
EZ-E Posted May 25, 2005 Author Share Posted May 25, 2005 I need to upgrade my injectors as well as my ecu, its as simple as that. At least im getting an idea of whats going on then. I would have thought with the bigger 370's that it wouldnt run as lean up top but then again I would guess also this has a lot to do with the stock ecu. I swear I would believe it really limits this car in so many aspects. Bastaad do you have any links on how to figure your fuel to air flow curve to know what size injectors you need to push x amount of compressed air from yoru turbo? What is weird is that with the stock T3 as far as I could see I wasnt having any problems at 15psi. , then again that was with a much smaller turbo, so this means its definetly time for SDS and bigger injectors What do you guys recommend? Thanks for all your replies as well. Quote Link to comment Share on other sites More sharing options...
Clifton Posted May 25, 2005 Share Posted May 25, 2005 I have seen 6 cylinder people put down the same rwhp as there injectors are rated at. I doubt you are over 350 whp at 15 psi with that turbo. Even if you were and you were starting to run lean it would still pull while gradually getting lean. Quote Link to comment Share on other sites More sharing options...
Cody 82 ZXT Posted May 25, 2005 Share Posted May 25, 2005 I have seen 6 cylinder people put down the same rwhp as there injectors are rated at. I doubt you are over 350 whp at 15 psi with that turbo. Even if you were and you were starting to run lean it would still pull while gradually getting lean. Lean or not it should still pull but, the 280ZX computer is very aggressive in pulling out timing if it even gets a hint of detonation. I had a similar setup at one time. It would do what your talking about at 11 psi. I added a RRFP and it soulved the proublem. Seemed like I could run 14 psi with any issues. I first thought I had a slipping clutch. Turned out it was the computer. I was pretty new at all this and was lucky the computer did what it does. I currently run no knock sensor (JWT w/ 85 computer) and have to always keep an ear on the sounds of the motor if I've running a little more boost than normal or testing a new tune etc. Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted May 25, 2005 Share Posted May 25, 2005 A quick and dirty formula for estimating how much HP an inj can support is as follows: (inj cc / 7) * # of cyls = HP @ 80% DC In the case of the 370cc injs in a 6-cyl, that is 317+hp, so he is not out of inj, IMO. First thing I would do is "hot-wire" the pump because if you using the stock pump wiring, you are lucky if you are getting anymore than 11-12V at the pump. Run a 10G wire from the batt to the pump through a relay. Run a 10G wire from the pump to ground. Use the original pump + wire to trigger the relay. Next thing is as someone else suggested, put a tee after the FPR and get a FP gauge on a long enough hose so you see the FP as the turbo is into boost. Nothing worse than not having enough fule volume or pressure under boost. Once you are assured the fuel delivery system is correct, then "fiddle" with the AFM, else you will be making adjustments at the AFM that will mask a fuel problem. Quote Link to comment Share on other sites More sharing options...
EZ-E Posted May 25, 2005 Author Share Posted May 25, 2005 Just a bit leary of having a gauge with fuel going to it flapping about at my window lol. I do have a relay hooked up ith the pump and it isnt the original pump its a Walbro, and Ive been reading that they are pretty good about 3rd in line next to Bosch's pump and the Pierburg pump. I do have a gauge on the rail but a lot of good that does going down the road. I dont think though that the wires to the pump are 10 gauge but rather 14 gauge, would this also cause a bit of a problem with enough juice getting to it. I noticed that when I had a battery that was dying and without charge to the alternator looking at my blitz TT, I like to keep it on volts to know what the pump or at least the system as a whole is getting that anytime it dropped past 12.9 volts you could hear the pump change its tune or hmm and it totally sounded different. Ill try and tape a gauge up to see what Im actually doing and report back. Thanks for the help folks. Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted May 27, 2005 Share Posted May 27, 2005 Come on guys! It's the classic symptom of loose or incomplete electrical connectors at the ECU and/or AFM. Clean them and use dielectric grease. Mine was falling flat on it's face at about the same RPM untill I reconnected everything. Check all the connectors while your at it. Try 10psi to get the car running right. Then and only then creep up the boost and add some fuel somehow. One more thing...be 110% sure you have no vacuum leaks. Quote Link to comment Share on other sites More sharing options...
EZ-E Posted May 27, 2005 Author Share Posted May 27, 2005 Well before putting it all back together, I did change all vacumn lines to new again, and I am a firm believer of dialetric grease on every connection. It cant hurt to try though but I am going to upgrade the power and ground wires to the fuel pump from a 14 gauge wire to a 10 gauge wire. Though now thinking that you mention it, I did have to move the afm a bit and the connection there might be a bit off, Ill make sure to check that as well. Thanks for the replies. Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted May 27, 2005 Share Posted May 27, 2005 I just thought of another issue I had that drove me nuts for a couple of days. After I upgraded to the TO4B Super V trim, The car was pulling hard to about 4000rpm full throttle and then it was like someone turned off the key. The car would coast down to idle and then I would have power again. The problem turned out to be a collapsing intake boot from all the suction of the new turbo. I am using the stock AFM-Turbo boot which is shortened to fit everything in the bay. Make sure the steel coil is inside the boot and it's not shifting around. Quote Link to comment Share on other sites More sharing options...
VinhZXT Posted May 27, 2005 Share Posted May 27, 2005 Perhaphs this will help: http://forums.hybridz.org/showthread.php?t=100844 Quote Link to comment Share on other sites More sharing options...
EZ-E Posted May 28, 2005 Author Share Posted May 28, 2005 Hmmm maybe not a bad idea, I do have some sputtering still but not hesitation, upgrading the wires from what was 14 gauage!! to 10 gauge wire really helped a lot. The fuel is now there but all I have left to do is verify by T ing in a gauge that I can see so I know for sure, but it does feel a lot better now. Ill look into that as well Vinh, Thanks. Quote Link to comment Share on other sites More sharing options...
Guest Zcarsmakemyheadhurt Posted May 31, 2005 Share Posted May 31, 2005 Try stock injectors. Quote Link to comment Share on other sites More sharing options...
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