envmyz Posted July 13, 2005 Share Posted July 13, 2005 Hello, I'm having some problems with my MS (or could be engine) after driving the car for a while, turning it off, then starting it within 1/2 hour. It wont idle, and rev's worth a crap, sounds like it's missing, the whole nine yards. After I tach it out through first gear, it runs great like normal. Anyone else having this problem? I already set the startup enrichment to 25 from 50 and that didn't help. running extra_21, MT 358 Thanks Chris Quote Link to comment Share on other sites More sharing options...
mobythevan Posted July 13, 2005 Share Posted July 13, 2005 I would suggest using the newer code like 024s9 becuase it allows after start enrichment to vary based on engine temp. The earlier codes only allow one after start setting that is used all the time and causes problems with warm start. The new code will allow you to have almost no after start enrichment in these cases. Quote Link to comment Share on other sites More sharing options...
TimZ Posted July 13, 2005 Share Posted July 13, 2005 Hello' date='I'm having some problems with my MS (or could be engine) after driving the car for a while, turning it off, then starting it within 1/2 hour. It wont idle, and rev's worth a crap, sounds like it's missing, the whole nine yards. After I tach it out through first gear, it runs great like normal. Anyone else having this problem? I already set the startup enrichment to 25 from 50 and that didn't help. [/quote'] Just a thought - those are classic vapor lock symptoms. Quote Link to comment Share on other sites More sharing options...
midnightzxt Posted July 13, 2005 Share Posted July 13, 2005 Just a thought - those are classic vapor lock symptoms. That is what i was going to suggest.. vapor lock. Try letting it idle for about 2 min after you drive it, then turn it off and try again within a 1/2 hr Quote Link to comment Share on other sites More sharing options...
z-ya Posted July 14, 2005 Share Posted July 14, 2005 Ditto, fuel rail is hot, and vaporization is happening. Same thing happens on my Megasquirted track 240Z. Just let it idle a minute, and it smooths right out. Pete Quote Link to comment Share on other sites More sharing options...
TimZ Posted July 14, 2005 Share Posted July 14, 2005 You might also try running fuels that don't contain alcohol - these seem to vaporize at lower temps than regular fuel. Other solutions - insulate the fuel rail with thermal wrap if you use an electric fan, wire it to run off a thermo switch after the engine is shut off on the 280ZX, Datsun started using a small fan that mounted on the passenger side with a duct that went over the valve cover and blew cooler air directly on the fuel rail - if you can find one of these it should bolt right up - again, you'll need to wire it with a thermoswitch. Quote Link to comment Share on other sites More sharing options...
envmyz Posted July 14, 2005 Author Share Posted July 14, 2005 allright, thanks for all that helped. I will be trying a few of the sugestions, at least I know it's not ONLY my car that is doing it...lol Quote Link to comment Share on other sites More sharing options...
mobythevan Posted July 14, 2005 Share Posted July 14, 2005 for an experiment could you cycle the ecu on and off maybe 5 times before warm starting to let 10 seconds of fuel run through the rail. Then if it starts OK you know for sure its vapor lock. Seems like 10 seconds worth of fuel flowing would cool the rail and remove air in the rail?? Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted July 14, 2005 Share Posted July 14, 2005 My FPR and pump have no valves in them to retain fuel pressure when the engine is off. I always have to turn on the ignition and wait 5 seconds for the fuel to start circulating and pressure to build. Better that than cranking the engine for the same amount of time waiting for it to start. i don't have MS, just a factory ECU, but I thought it might be applicable. High pressure recirculating fuel systems seldom have actual vapor lock issues as the fuel is pushed under pressure from the tank, and the FPR will pass any air locked in the lines. Quote Link to comment Share on other sites More sharing options...
Tony D Posted July 14, 2005 Share Posted July 14, 2005 I would have to agree with Moby and Sleeper. I would cycle the fuel pump for several cycles BEFORE starting it. If you had a fuel gauge in the rail, it would help. Many times the stock fuel rail will actually either bleed down, or boil the fuel in the rail. This is why the ZX's started turning the fuel pump on for 3 seconds every time the igniton was switched. Early 280Z's have a habit of having thos symptoms in a very narrow window of time AFTER a hot shutdown. Mine will be fine for 5-10 minutes after a hot run with the hood closed. But try in the key at 15 to 30 minutes and it's stumbling until I get that hot fuel out of the system! By "priming the fuel system" you cover both bases from bleed down due to check valves, and boiling from alcohol fuels and heat soak. Vapor Lock is not "technically" what it is, but it's what everyone understands, so that nomenclature works. I have actually seen people put in BYPASS switches to the "s" terminal for their early 280Z and ZX's so they can hold the key to "crank" without turning over the engine, yet start the fuel pump. Simply turn to crank while holding the bypass switch, and like Sleeper mentions, after say 5-10 seconds let the bypass spring back to normally closed, engage the starter, and away you go! Quote Link to comment Share on other sites More sharing options...
midnightzxt Posted July 15, 2005 Share Posted July 15, 2005 something I want to add.. the fan that goes over the valve cover is a nissan bandaid, not a complete fix.. there are better ways as have been suggested to fix the vaporlock problem if it is what it is. Quote Link to comment Share on other sites More sharing options...
z-ya Posted July 17, 2005 Share Posted July 17, 2005 My MS does run the fuel pump for around 10 sec when I first turn it on. It still does this when hot. I suppose I could turn the ignition on and off a number times to flush all of the warm fuel out and get the pressure out. Anyone know if the fuel pump "prime time" is adjustable easily in the MS? Seems like to could increase this time to maybe fix the problem. I suppose if you wer setup to compile the firmware you could adjust it easily. Pete Quote Link to comment Share on other sites More sharing options...
Tony D Posted July 19, 2005 Share Posted July 19, 2005 If you are a brave code hacker, you could post the request on the MSEFI forum, and someone there (Probably Bruce of Al) would tell you where in the code you would have to go in the routine to snip that portion of code and replace "XX Seconds" in the routine, to whatever you wanted, and then burn it to the chip. That really would be all you needed to do. Programming wise, it should only be a subsititution of the runtime number... Quote Link to comment Share on other sites More sharing options...
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