grillhands Posted October 12, 2015 Share Posted October 12, 2015 I've been driving my conversion for a few months now at 5 psi with no problems. My a/f stays around 11.1-11.6. I bumped the boost to 8psi and the car will turn off like it's not getting fuel. For me to be able to start it again I would pop the hood with the key on and manual prime the fuel lines by moving the flap by hand. Sometimes I can't hear the fuel coming in so I would have to do it twice or more. I have all stock l28e components. My initial thoughts is fuel pump but I don't see the a/f creeping up when it happens. Could be possible that I'm outflowing the afm? I do have the l28et afm handy and a spare l28e afm that I could try. Any suggestions would be great. Thanks Quote Link to comment Share on other sites More sharing options...
Tony D Posted October 12, 2015 Share Posted October 12, 2015 The AFM is out of the equation doing nothing once you are WOT and on boost over about 3,000 rpms. It is only active in part-throttle situations and lower RPM's. The stock N/A's "outflow the AFM" at aroudn 3,500 when the box goes to a preprogrammed fueling curve. it's not a MAF sensor, it is NOT active through the whole load scalar range of the engine giving source feedback for the fueling of the engine. It opens, the ECU/ECCS is "open loop" and on a preprogrammed curve. Quote Link to comment Share on other sites More sharing options...
grillhands Posted October 13, 2015 Author Share Posted October 13, 2015 (edited) Ok. Thanks Tony. I'm gonna fiddle around a little more to see what the issue could be. I plan on replacing the fuel pump because I think it's the original from 75. The car only has 90k and by the looks of the pump I would bet it was never replaced. Edited October 13, 2015 by grillhands Quote Link to comment Share on other sites More sharing options...
Leon Posted October 13, 2015 Share Posted October 13, 2015 If your AFR stays in the 11s, it's not a fuel problem. Quote Link to comment Share on other sites More sharing options...
jeffer949 Posted October 13, 2015 Share Posted October 13, 2015 Do you have the Turbo intake manifold? If so it could be that your pop off valve is opening and maybe is sticking open or something. Quote Link to comment Share on other sites More sharing options...
Brad-ManQ45 Posted October 13, 2015 Share Posted October 13, 2015 Please describe in detail the conditions that you engine shuts down under (ex: WOT passing xxxx rpm, etc.)...and is it a complete loss of power? Quote Link to comment Share on other sites More sharing options...
grillhands Posted October 13, 2015 Author Share Posted October 13, 2015 Partial throttle or wot it doesn't matter.The rpms are around 4.5-5k and it's a complete loss of power. I usually set myself up on a dead road so when it turns off I won't affect traffic. The only way I can get the car to start again is to manually move the afm flap until the fuel pressure builds back up in the system. Once I do this the car is fine. There are no signs of sputtering or misfiring. It turns off abruptly. Quote Link to comment Share on other sites More sharing options...
NewZed Posted October 13, 2015 Share Posted October 13, 2015 If you drop the boost back to 5 the problem disappears? Might just be coincidence. If you have a manual transmission, watch the tach when it dies. If you're still in gear with the key on the tach should still show spark when rolling. If the tach drops to zero while rolling, that would be a sign of an igntion problem, maybe with, maybe without, a fueling problem. Also, you said L28E, not ET, for engine management. Is this a cobbled together turbo setup? Quote Link to comment Share on other sites More sharing options...
grillhands Posted October 14, 2015 Author Share Posted October 14, 2015 I'll take a look at the tach next time to see what it's doing. My setup is stock l28et manifold with turbo, front mount intercooler, locked n/a distributor at 28 degrees. I also have a spa fmu with a adjustable range of 1:1 to 12:1. I have to double check to where I set it Quote Link to comment Share on other sites More sharing options...
Tony D Posted October 14, 2015 Share Posted October 14, 2015 Oh my... Quote Link to comment Share on other sites More sharing options...
grillhands Posted October 14, 2015 Author Share Posted October 14, 2015 I know it's a crude setup but some people here had some success with it. Quote Link to comment Share on other sites More sharing options...
Tony D Posted October 14, 2015 Share Posted October 14, 2015 I did with Mikuni Carb Blow Throughs too, but I wouldn't recommend anybody follow that route! LOL "I see a megasquirt on the horizon..." Quote Link to comment Share on other sites More sharing options...
grillhands Posted October 14, 2015 Author Share Posted October 14, 2015 Every winter I do something new to the 280z. First was the auto to manual conversion. Second was doing the turbo with the n42 block and p79 head. This winter I want to do floors with rails along with fender flares. Megasquirt will be soon once I get the ba**s to do it. Quote Link to comment Share on other sites More sharing options...
Pac_Man Posted October 14, 2015 Share Posted October 14, 2015 Like was previously mentioned, the stock l28et manifold has an emergency pop-off valve which will vent excess boost pressure at a certain point. Enough that I removed mine in order to run an 8 psi spring. It was a while ago, but I know that I removed it because it would have caused issues at 8 psi if I left it on. It basically creates a boost leak, which would make the car lose power and stumble until the pressure goes back down. Quote Link to comment Share on other sites More sharing options...
grillhands Posted October 14, 2015 Author Share Posted October 14, 2015 That's on the intake manifold,right? Quote Link to comment Share on other sites More sharing options...
Tony D Posted October 14, 2015 Share Posted October 14, 2015 The Emergency Relief Valve should pop at 10psi, and if you wire your wastegate shut it will lift on a stock turbo and run you along happily at 10psi all day long. Which is, incidentally, where the stock ECCS Mapping ends... Which is why when you take a stock ECCS and start cranking up boost (with the ERV Plugged) it will not make any more power after 10 psi and start running progressively leaner. At 10psi the stock ECCS is around 14:1 at 5,000 rpms....which is fine, but.... At only 8psi it will not make you slow down and stop as described. I would still plug it, but I doubt the issue is the ERV. I wired my wastegate shut on my 84 Skyline and ran it on the ERV for about two weeks to see if bad things would happen. It survived. Then I sold it to a guy from WV. He seemed to enjoy the stock boost. Meh. Quote Link to comment Share on other sites More sharing options...
TimZ Posted October 14, 2015 Share Posted October 14, 2015 (edited) I'll take a look at the tach next time to see what it's doing. My setup is stock l28et manifold with turbo, front mount intercooler, locked n/a distributor at 28 degrees. I also have a spa fmu with a adjustable range of 1:1 to 12:1. I have to double check to where I set it I don't think that this is your immediate problem, but the stock fuel pump has an internal pressure relief that I believe was set to ~55psi for non-turbos. So your rising rate FPR likely won't add nearly as much fuel as you might expect. For instance, as I recall your stock base fuel pressure is 37psi, and as Tony pointed out the ECCS mapping ends at 10 psi boost, at which point your "normal" fuel pressure would be 47psi. Fuel flow increases with the square root of pressure, so the most additional fuel you'll be able to add will be about 8% over what was available at 10psi. If you want to use the FMU as intended you really need to go to a pump that can supply the additional fuel at the pressures you'll require. It might not be your immediate problem, but it will be soon... Edited October 15, 2015 by TimZ Quote Link to comment Share on other sites More sharing options...
grillhands Posted October 14, 2015 Author Share Posted October 14, 2015 Thanks Tim. I'm going to order a walbro and then take it for spin once it's in. Quote Link to comment Share on other sites More sharing options...
grillhands Posted November 20, 2015 Author Share Posted November 20, 2015 Fixed the problem. I got a new afm harness because apparently the vibration at higher rpms would rattle the connection just enough to cut fuel. I bought a new 7 pin connector on ebay and now the car runs, idles and boosts much better. Fuel pump is still going in soon. I didn't want to just throw parts at it lol Quote Link to comment Share on other sites More sharing options...
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