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Fuel injected L20b with 200sx manifold.... Dies after warm up!!


rayven14

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Ok heres what I got,

 

L20 Stock form

200sx manifold Stock form

Rebuilt N58 head (I know I could do better) ported for fuel injectors

EI distributor (Thanks Hector)

MSD Blaster Coil ( - the ballast resistor) some people say I need it with this setup and some say I dont?

280ZX fuel pump set at 40PSI via the pressure regulator

New cap and rotor

New Plugs

Completely new custom harness built by your truly.

 

Plugs are set at .030

vlaves are set at .25 across the board ... if I remember correctly

 

SO! I reach for the key and this thing comes to life like its ready to jump on a track, I mean it literally fires up no problem!!!

It's a little high in the RPM range but it has yet to be set in terms of timing, TPS and it has open exhaust (just headers), although I dont imagine the timing is to far off.

 

Heres the problem: after roughly two minutes it starts to sound like the warm up regulator is doing its job and begins to idle down and down and down .... and it just simply shuts off. I can get it to start again, maybe even twice for ten / fifteen seconds but by the 3rd or 4th start up ... Nothing! not even like its trying anymore.

 

Okay so heres another odd thing, I go out there this afternoon (24 hours later) and reach for the key and bingo bango, starts right the hell up! and again it does the same thing as above.

 

So I pulled the plugs and they look either carbon fouled or oiled fouled (see pics) Im thinking carbon. With a heavy fuel smell that seems to evaporate pretty quickly in the open air. They clean up quick (see pic)

 

Sooooooo, what am I missing? too much fuel, not enough spark? bad timing? bad idea?

 

At this point Im in one of my "Im gonna sale this fu****** and go buy a volkswagen" stages But Im willing to slide someone some green fun tickets to fix it for me or some really good advice on what to do. Take into consideration Im a fabricator and not a mechanic so use apprentice terminology.

 

Oh BTW, I think its safe to rule out the fuel pump as the culprit for several reason: 1 I can hear it running, 2 FPR Says I have 40+ PSI on the rail, 3 I can here it via the return line in the fuel tank and if I crack open a line ...watch out!!!!

 

Oh ya Im trying to have this done before thursday sunnyvale meet .... I promised some folks I'd make it out there.

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Valve lash should be .008" and .010" hot, what is .25?

 

40 psi is for full throttle, but where is your fuel system regulated? You need to have it regulated at the fuel rail. The pump needs to be at 75-90 psi at the pump side, it dead heads at the regulator to maintain a constant 40 psi under full injector load. The excess pressure goes to the return line. If only 40 psi from the pump, you won't have enough pressure to open the injectors. At cold warm up it's a much richer charge which may account for why it runs so well, then just runs out of fuel after it reaches 160 degrees water temperature and switches to normal fuel map.

 

And Fuck VW, don't go buy one of those.

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.25 is in mm, the fuel system is regulated at the rail. So its set up for the pump to run through the rail to the FPR and then of course back to the tank.

 

Ok so what your saying (again Im a fabricator not a mechanic) is simply increase the FPR to 75-90 PSI?

 

Ok so question then, why would the plugs look carbon fouled? wouldnt that be because there is too much fuel? hell at this point I'll try anything.

 

LMAO whats wrong with a VDUB's? thats all I used to drive and I'm still a fan. Should I be admitting that here?

 

Thanks HRH

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Plug gap with an EI ignition is 0.038 to 0.042"

 

Matt .24mm is about 10 thou. so.... close enough.

 

Stock fuel pumps put out about 40 to 60 PSI

The regulator is set for about 36 PSI

 

As I see it the motor runs a rich mixture when cold. The air regulator is an external air source around the throttle valve to increase the idle. Just like a fast idle cam on a choke equipped carburetor. The air regulator is heated by power fro the ignition switch and slowly closes as the motor warms up.

 

Now the problem is that the engine is still getting the same rich mixture.... and without the extra air from the (now closed) air regulator, it chokes. Somewhere here the water temp sensor should be telling the ECU that the motor is warmed up and it should switch the O2 sensor into closed loop operation.

 

IMG_1186.jpg

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.25 is in mm, the fuel system is regulated at the rail. So its set up for the pump to run through the rail to the FPR and then of course back to the tank.

 

Ok so what your saying (again Im a fabricator not a mechanic) is simply increase the FPR to 75-90 PSI?

 

Ok so question then, why would the plugs look carbon fouled? wouldnt that be because there is too much fuel? hell at this point I'll try anything.

 

LMAO whats wrong with a VDUB's? thats all I used to drive and I'm still a fan. Should I be admitting that here?

 

Thanks HRH

 

VW is Hitler's revenge!! Evil!!! :D Not everyone feels that way here. I just happen to freely share my opinions and assholes. Ask DTP about that. Lol. Also, if you search my build thread, you may stumble onto some more information about your setup. Do a google search for "L20B EFI thread ratsun" Should come up. Lots to wade through. I'm eating dinner, can't think at the moment if there's any pertinent information in there. Oh, and to be fair, I hate Toyota too. ;)

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I'd 'eliminate' /plug the air reg......and if no improvement....check the resistance in the 'head temp sensor'(?)

 

 

 

 

EDIT

 

FWIW.......engine should still fire and run without the air reg, even in -30 temps

Just have to hold your foot into it till it warms up....doesn't take long if your locale is Cali

Edited by Sealik
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I'm curious what ECU you are using. From a 200SX? What year? With or without O2 sensor?

 

I was going to suggest finding HRH's FI conversion thread. Actually it more like a book. I think of it as the Ratsun version of "Moby Dick"! Fun read though.

 

Hey Matt, aren't Ford Rangers on your hate list too? Just a rumor I heard this morning!

 

rayven 14 - At least on my ancient Dell, your pics aren't showing in your post. I think you need to change your to to get them to show. Great pics and a beautiful car. Looking forward to hearing you get it running great.

 

Len

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:rofl: He barely got me Len! And with 500 more ccs and 1000 less pounds! I told him I'd race him in the Toyota, that wouldn't even be a contest!

 

The coolant temp sensor could definitely be suspect. It's just a simple switch, might be failing once it connects.

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Datzenmike: I gots no O2 sensor with this setup.

 

HRH: I will definately be looking for your thread

 

Sealik: I dont/did'nt make or have provisions for the cylinder head temp sensor,... Interesting thing though. While thining the harness I noticed the water temp sensor when closed went to ground. My plan was to simply ground this wire and adjust the throttle to compensate for the high idle.

 

Len: I have two ECU's one is 1980 and the other isnt labeled.

 

So before I go out and start blowing stuff up Ill wait to hear your thoughts, thanks guys.

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While thining the harness I noticed the water temp sensor when closed went to ground. My plan was to simply ground this wire and adjust the throttle to compensate for the high idle.

 

 

 

Would think grounding that wire would give the engine a full rich mixture?

Water temp sensor adjusts fuel ratio/ECU "modifies injector pulse duration" during warm up

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Would think grounding that wire would give the engine a full rich mixture?

Water temp sensor adjusts fuel ratio/ECU "modifies injector pulse duration" during warm up

Yes, so if its running rich cant I adjust TPS or idle adjustment to compensate? HRH seems to think I need to adjust the FPR to as high as 75-90 PSI, wouldnt this eliminate that need?

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No, not the FPR. The pump needs to provide 75-90 psi, but it should be regulated to 36 psi while running. The regulator has to be adjustable though. A factory regulator has a vacuum actuation. It goes to 40 psi on WOT, 36 psi at idle if I remember correctly.

 

Make sure you're using the 1980 or early ECU. Later ECUs with O2 sensor won't work with a non-O2 system.

 

Here is a link to my build thread. Lots of tidbits in there: http://community.ratsun.net/topic/22074-510-l20b-efi-conversion-the-project-is-finished/

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I forgot the '80 doesn't have an O2. But the temp sender is in the intake water passage on that year. On the '81 the temp sender in the head near the #2 exhaust plug for a faster more accurate reading.

 

Geez it's been a few years eh Matt?

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Haha, yeah, sad to say the 510 hasn't been running for about a year now. That will change this winter, but lots of work ahead. I should change my signature, but I'm too lazy. ;)

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Okayyyy,

 

So today I blocked off the warm up regulator and turned up the FPR to 60 PSI (seemed to work fine with alot less fuel going back to the tank) car started just fine at a litlle lower idle, lots of white smoke came out but cleared up quickly. It ran for about 2 minutes just fine and again slowly but surely started to die, along with that it lacked any throttle response (I couldnt keep it alive)

 

Any ideas? Im at that point of "Fuck it, its for sale" or finding a carb that will get me some pleasure out of this damn thing. If I had any money laying around Id get a megasquirt.

 

ARRRGGHHHH!!!!!!

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  • 4 months later...

matt, didnt you have the same issue almost?

 

didnt you have a yellow wire or something going to the wrong post on the starter for the power to the harness or what not? 

 

i remember you switched this wire from the main positive to the secondary one, and your rich issues were gone.. 

 

am i wrong?

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As a matter of fact, yes.  There is a cold start feature that enriches the mixture to 50% fuel dump or something.  The wire that goes to the starter (think it is yellow) must be on the COLD side of the solenoid to the starter.  It's only used while cranking for initial fire up.  Basically a big choke.  It shuts off at 165 degrees.  Prior to that however, it will choke the shit out of the motor and foul the plugs if left to 12v on.  It'll still run until they get so fouled they get annoyed.  With a stock cam, it may run longer.  With my big overlap cam it ran until the idle dingle on top opened up a bit more, then it choked.

 

And pardon me, I must go back and add pictures back into that thread as well.  Killed the website finally.  Tired of paying for basically photo storage.  Hadn't updated my website in over a year, just said fuck it, why pay, everything's on Ratsun anyway.  So I got a photobucket account.  Now I have to go back and edit all my damn threads, and there are a lot of them.  I started on the KAZ24 build on a little bit,  I'll look up the EFI one too.

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If it's slowly dying, I bet it's related to the temp switch. I didn't catch if it has a Idle Air Control Valve, if it does, then between the temp switch and the iac, I bet you'll find the problem.

 

I was trouble shooting a temp/time switch one time and to rule out either one, I bought a guitar amp volume switch. I hooked it up in place of the temp switch and then set the knob wherever it ran the best. I then measured the ohms across the volume knob and compared it to the temp switch to find a discrepancy.

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