510 L20B EFI conversion - the project is finished!

[HRH]

The funny thing was it was dropping spark on 3 and 4, yet 1 and 2 were fine. Going to check my distributor cap in the morning too, make sure it hasn't taken a shit. I don't think so though. It ran fine when I parked it prior to starting this project.

[LenRobertson]

I dug out the resistor unit from the '81 SX I stripped, and tested it according to the factory manual - take an ohm reading from the center connector to each of the other 4 blades. Reading should be approx. 6 ohms. I didn't get this, so either I'm not testing correctly, my meter is bad, or my resistor unit is bad. If Matt or anyone who has one of these units has time to take an ohm test, I'd be interested in the result. I'm going to test with the meter at work, but it is a China cheapy, so who knows if it is any better than mine.

 

The next step in the factory test if the resistor checks okay is to test the harness. Didn't you say you had corrosion or something at some of the injector connectors? Or maybe I'm thinking of a different thread/problem. Still, doing a continuity test from the injector plug to the resistor plug, while twisting the harness wires a bit would be easy to do, and might show something. It is interesting it seems to be a problem with a couple of cylinders.

 

Matt, if you want to try the ECU and harness from this '81 SX, you can. However, it is designed for an O2 sensor, which I don't have. But won't you have to install an O2 sensor for any newer system? I think I've read there is a bung you can weld into any exhaust pipe to screw the sensor into, but it may be tough to do without taking the pipe out. But my '81 bits are virtually the same age as what you have, so getting newer stuff might be best.

 

Len

[HRH]

WTF? I just posted and it disappeared. Okay, now it's working. Weird. Anyway, thanks Len for the factory test info, I'll double check that. I have a good Craftsman multimeter. The other thing I haven't done is switched the injectors to OE Nissan injectors. I may do that just to eliminate another variable.

 

The ECU definitely won't work from '81 up, they put the resistor block in the ECU and the lack of O2. However, you can get a bung to weld on at any exhaust shop, and I think NAPA might even have them. It wouldn't be a big deal to weld one one. I haven't welded the pipe back on permanently either, so it'd be easy to yank it back off.

[LenRobertson]

Probably the resistor or wires from it to injectors isn't the problem, but is easy to check. Seems like it would cause it to run lean, but if the computer is getting a bad signal, it might be deciding it wants to run rich. Too complicated for me to understand, given my limited electronic knowledge. But it seems you are getting really close to having a good running system. Probably just one little component glitch to solve and you're there.

 

I'll be in Spokane Thursday for an eye appointment. I can bring any '81 pieces if there is anything you want to try.

 

Len

[Unclejesse88]

Link to the "Ghetto Efi" thread that shows how to install a KA distributor into an L series timing cover. Also, as far as I can tell, once Nissan went to the optical distributors, they all seem to operate the same.

 

http://community.ratsun.net/index.php?showtopic=2165

[HRH]

I think you're right Len, if that resistor block had corrosion (more resistance) it would lean out the injector voltage. I'm leaning towards the fuel injectors themselves right now. I know I mentioned that before but it's one of the things I haven't tried yet. Will be going at that in the AM or on Thursday. As much as I hope it's not that since they're new and from my store, I hope it is and the damn thing runs perfectly with the oe injectors. We shall see.

 

I'll be off Thursday, you should swing by my Datsun lair unless your pupils will be dilated! :)

[bilzbobaggins]

good luck man...cant wait to see how this turns out...

 

jefff :)

[LenRobertson]

I think you're right Len, if that resistor block had corrosion (more resistance) it would lean out the injector voltage. I'm leaning towards the fuel injectors themselves right now. I know I mentioned that before but it's one of the things I haven't tried yet. Will be going at that in the AM or on Thursday. As much as I hope it's not that since they're new and from my store, I hope it is and the damn thing runs perfectly with the oe injectors. We shall see.

 

I'll be off Thursday, you should swing by my Datsun lair unless your pupils will be dilated! :)

 

Yeah, probably not the resistor block, but it will be interesting to see what an ohm test shows, if you have time. If it doesn't have enough resistance, even in one cylinder, I suppose it might run rich. But I can't imagine what could cause a loss of resistance. I forgot to take my resistor to work and test it with the digi meter.

 

Thursday will be an interesting day. They need to do the same eye test each hour for 7 or 8 hours. So I'll probably have 45-50 minutes of free time between each. Not really enough time to go anywhere and do anything. So I probably won't have a chance to stop by, although I'd like to. The good part of the all day test is they don't have to dilate. I can't help wondering if this test is as much to milk the insurance company as anything. But not taking the test probably isn't wise either.

 

I've been wondering why Nissan added the O2 sensor to the system in '81. Maybe something simple like better lean running on deceleration or idle. Seems it would be smog control related, but maybe it helped the system run better. From what I've read, the '80 and '81s are almost the same components, except for adding the O2, and changes in the ECU because of the addition.

 

Len

[HRH]

The OE Nissan injectors helped a bit. Still running too rich, though haven't had it to operating temperature. Have a few ideas.

 

One is I'm running a Pertronix ign. Perhaps the ECU doesn't like the signal? I doubt it, but may switch to a matchbox to check.

 

Going to check continuity and resistance in all AFM circuits and ground circuits. My Datsun guru mentioned the only time he had major problems with richness was when he had a bad ground. My ground is grounded, but I'm wondering if maybe there's a break in the wires or corrosion or something.

 

That is all to report at the moment. Going hiking today, then will spend the afternoon dinking with the car.

[HRH]

Hey Len, do you have a factory setting for the throttle switch? (TPS) I have it engaged on 29 and 30 at idle, which from the wiring diagram is where it should be. Does it say anything about when it should switch to the other two? Like half throttle or open throttle?

 

Also am able to get it to continue idling with a thumb partly over the large vacuum leak, so I'm going to attach that to the air regulator valve in a minute. It seems with the large overlap that valve is quite necessary.

 

Still missing at steady rpm though, going to look at the coil and the dist next. Verified ground and most of the AFM connections, though there's not really a spec for them. Unless you have that info too Len?

[Sealik]

Hey Len, do you have a factory setting for the throttle switch? (TPS) I have it engaged on 29 and 30 at idle, which from the wiring diagram is where it should be. Does it say anything about when it should switch to the other two? Like half throttle or open throttle?

 

Also am able to get it to continue idling with a thumb partly over the large vacuum leak, so I'm going to attach that to the air regulator valve in a minute. It seems with the large overlap that valve is quite necessary.

 

Still missing at steady rpm though, going to look at the coil and the dist next. Verified ground and most of the AFM connections, though there's not really a spec for them. Unless you have that info too Len?

 

 

You should have continuity at idle with ohmmeter connected to 29 + 30.....Open throttle 4 degrees, should be no continuity.

Full throttle..(beyond 35 degrees) ...connect 1 of the probes of ohmmeter to a ground. With the other probe...touch 24, 29 then 30. The ohmmeter should have an infinite reading at each terminal. If not.....short circuit somewhere.

And or it's gonna rain.... :D .."hell or high water".... :)

[Unclejesse88]

For the grounds, I recommend load testing them. Sometimes measuring resistance isn't enough. To load test, use the ground wire you want to test as the ground for a light bulb (headlamp, stop lamp, etc). Power the bulb, and see if the ground you want to test will allow the lamp to turn on, and how bright is the lamp if it does turn on. If the lamp is normal brightness, then the ground is good. Attach to the lamp at the component end of the wire, not the chassis/body/battery end of the wire. All this assumes that you didn't already do this.

[LenRobertson]

I had a feeling today at the eye doctor that I should try to call you, or stop by. Not that I would know anything to help, but I did have the '81 SX manual with me. I brought it along to read up on FI. Oh well, I'll post the info, which is pretty much what Sealik said although there is an full throttle test too.

 

Idle contacts test: + ohmmeter lead to pin 29, - lead to pin 30. Throttle released should read continuity. Throttle depressed should read no continuity.

 

Full throttle contacts test: + to pin 24, - to pin 30. Throttle released: no continuity. Full throttle: continuity.

 

Insulation test: + lead to pins 24, 29, 30 in turn. - lead to "Body ground". Should read infinite continuity.

 

The test shown for the throttle switch component (unplugged from the harness, but still mounted on the engine) is "Connect ohmmeter between engine and terminals 24,29, and 30. Ohmmeter reading should be infinite."

 

Can't be certain the pin numbers are the same between this '81 manual and your '80 system, but I have a feeling they are. If you don't get all good readings, I can check the book and see if there are additional tests.

 

I finally checked my resistor unit with the digital ohm meter. Each of the four blades tested fine - about 6.4 ohms. I suspect this is one component in the system that seldom fails. But now I know I need a better meter than my old analog model.

 

Len

[HRH]

I did the ohm test on the resistor unit, mine were about the same. On the throttle switch, the 24,29, and 30 are actually marked on the tps near the connector, so it's really easy to find. Same for the AFM. I'm going to double check the TPS, then change out the distributor with a matchbox unit. Currently have a Pertronix, but it was working fine so why change it. However, it's the last thing in the system that is out of place. Everything else is the same, with the exception of the cylinder head.

[HRH]

Matchbox dist. vs. Pertronix.

 

So here's something funny. Started up the car with the matchbox distributor, didn't make any difference. Or rather, very slight, but still the same problem of missing, etc. Then I noticed I didn't have the TPS plugged in. I had forgotten to do that. Yet the car was still running. So I disconnected the AFM, and it still ran, but then tried to die, so plugged it back in, idled up high, then went back to loping at 400-500 rpm.

 

Pulled the TPS connector, probed for resistance and continuity, 29,30,and 24 all had continuity and marginal resistance. .3 on 200 setting. Considering I had to stick a pick tool in and alligator clip it, that's probably fine. Most of the other connections have somewhere around .3 also. I have not load tested it, as per unclejesse's suggestion. Will do that here eventually.

 

Sealik, would you do me a favor and let me know if you can start your pickup and unplug the TPS and see if it starts running crappy and missing if held at idle? This thing is just baffling me.

[Sealik]

Matchbox dist. vs. Pertronix.

 

So here's something funny. Started up the car with the matchbox distributor, didn't make any difference. Or rather, very slight, but still the same problem of missing, etc. Then I noticed I didn't have the TPS plugged in. I had forgotten to do that. Yet the car was still running. So I disconnected the AFM, and it still ran, but then tried to die, so plugged it back in, idled up high, then went back to loping at 400-500 rpm.

 

Pulled the TPS connector, probed for resistance and continuity, 29,30,and 24 all had continuity and marginal resistance. .3 on 200 setting. Considering I had to stick a pick tool in and alligator clip it, that's probably fine. Most of the other connections have somewhere around .3 also. I have not load tested it, as per unclejesse's suggestion. Will do that here eventually.

 

Sealik, would you do me a favor and let me know if you can start your pickup and unplug the TPS and see if it starts running crappy and missing if held at idle? This thing is just baffling me.

 

 

Can do....give me 5

[HRH]

Sweet! I'm just about ready to go to the wrecking yard and yank the entire harness and ECU out of that early Stanza with the CA20.

 

Oh, actually I meant if held at 2000 rpm let's say. I bet you'll do that anyway, but yeah.

[Sealik]

The idle drops ever so slightly......runs okay....but with a slight hesitation of idle.

But......The truck is cold.

I held it at higher RPMs with no issues.

Mine is a VG30E TB with a VG TPS plugged into the stock 200sx harness.

[HRH]

Okay, so that may not necessarily be the problem. Thanks! Think I may take a trip to the wrecking yard. The other option is yanking the entire harness and dismembering and checking every wire. The only other thing I haven't screwed with is the coil, but as Buddy my roomie keeps reminding me, then thing ran fine before I put the EFI on, so it stands to reason the problem is something I've changed.

[Sealik]

Okay, so that may not necessarily be the problem. Thanks! Think I may take a trip to the wrecking yard. The other option is yanking the entire harness and dismembering and checking every wire. The only other thing I haven't screwed with is the coil, but as Buddy my roomie keeps reminding me, then thing ran fine before I put the EFI on, so it stands to reason the problem is something I've changed.

 

 

Just 2 plugs are fouling still?

[HRH]

No, plugs aren't fouling now, replaced with a fresh set, but it's still running pig rich, even with a wide open air leak to simulate the air regulator and then some. Exhaust smell just sucks, my clothes are drenched in it. I've been having to start the fan before I run the car, just to blow it out of the garage. It's not diesel black, but not far off. I had less smoke when I had the dual SUs. Granted it's still on cold circuit, but holding at steady throttle the miss is still there. Won't hold the tach still. Wires are in good shape, but maybe I'll go down and get a new set, just for shits and giggles.

[Sealik]

No, plugs aren't fouling now, replaced with a fresh set, but it's still running pig rich, even with a wide open air leak to simulate the air regulator and then some. Exhaust smell just sucks, my clothes are drenched in it. I've been having to start the fan before I run the car, just to blow it out of the garage. It's not diesel black, but not far off. I had less smoke when I had the dual SUs. Granted it's still on cold circuit, but holding at steady throttle the miss is still there. Won't hold the tach still. Wires are in good shape, but maybe I'll go down and get a new set, just for shits and giggles.

 

I know about that smell.... :)

It's going to run rich without the air reg.....but should hold a steady RPM without.

Save a few bucks......Just check the resistance on the plug wires.?????

 

Actually I got NGK to email me all the resistance values on the Z24 wires.... :D

Because.... I was checking everything over on my EFI swap...also

Edited October 22, 2010 by Sealik

[HRH]

Here's a question. Wires seemed to help a little bit. Taped off the air leak halfway and let the thing idle enough to get it to 160, so well into operating range. Started holding at 3000 or so, and started getting better. Then it started puking out tanish-pinkish-whitish smoke. I mean like a smoke bomb times 100. I pretty much smoked out the whole alley. I'm thinking head gasket, but it doesn't smell sweet at all. I'm wondering if it's just burning out all the rich wet fuel, but jeezus it's bad. Like I don't want to run it anymore because someone will call the fire department bad. I've never run into this before motor still runs fine and isn't overheated during this smoking exercise.

 

Any thoughts?

[Sealik]

Here's a question. Wires seemed to help a little bit. Taped off the air leak halfway and let the thing idle enough to get it to 160, so well into operating range. Started holding at 3000 or so, and started getting better. Then it started puking out tanish-pinkish-whitish smoke. I mean like a smoke bomb times 100. I pretty much smoked out the whole alley. I'm thinking head gasket, but it doesn't smell sweet at all. I'm wondering if it's just burning out all the rich wet fuel, but jeezus it's bad. Like I don't want to run it anymore because someone will call the fire department bad. I've never run into this before motor still runs fine and isn't overheated during this smoking exercise.

 

Any thoughts?

 

 

Many...but probably none that actually pertain to your problem..... :lol:

Could be just burning all that crud off and out.

FYI........when I was driving real slow off road for....lets say 5-7 kms.

No air reg with NFG thermostat that didn't get the engine temp over 175.

When I punched it after the fact......I got the same color of smoke out my pipe.

[HRH]

Found the problem, I was emptying the crankcase through the pcv valve. Unhooked that, no more problem. I'm about two steps away from yanking this motor out and building an entirely different one.