510 L20B EFI conversion - the project is finished!

[LenRobertson]

Okay, I'm about as awake as I'm likely to be today, so here is fuel pressure/vacuum test from The Book:

 

With fuel press. gauge installed between filter and fuel rail (vacuum gauge not installed yet), and engine running. "At idling" approx 30 psi. "The moment the accelerator pedal is fully depressed" approx 37 psi

 

Unhooking vacuum line to regulator from intake manifold, and replace with "variable vacuum source" (book shows drawing of vacuum gauge on hand squeezed vacuum pump). Disconnect alternator field plug and oil pressure sending unit wire (On stock system these are part of safety shut-off that I don't think you have, so you can ignore this).

Turn key on, but don't start engine.Then:

 

With vacuum pressure 0, fuel pressure should be 36-37 psi

Vacuum 5 inHg, fuel 33-35 psi

Vacuum 10 inHg, fuel 31-32 psi

Vacuum 15 inHg, fuel 29-30 psi

Vacuum 20 inHg, fuel 26-28 psi

 

Then it says "Fuel pressure must decrease as vacuum increases". If not replace regulator. I know you have a new regulator, but I wonder if it is possible to T a standard vacuum gauge into the line to the regulator and watch it while running the engine?

 

I'm still studying the ECU light and O2 sensor, but it looks like if the harness wire is unplug from the O2 sensor, the light stays off.

 

Len

[HRH]

So I just went out and woke up the rest of the neighborhood who should already be up. It's amazing how much fuel pressure has to do with smooth running. Just using the vacuum pump, I got exact readings since there wasn't any fluctuation from the manifold. Ran it high at 37ish, ran well. Idled it at 30 psi, idled better. Still had to leave an air leak open. Ran it around 36ish or so at steady throttle and got rid of the miss/wum wum wum!

 

Then I had an epiphany. I haven't messed with the idle screw on the KA throttle body, mainly because it's screwed all the way down and that's it. And I realize if I hold the throttle at 1000 rpm, it holds steady. Normally this would be bad because the plate is open too far, but I forgot, this isn't a carburetor. It probably needs the plate open more because the cam is so lumpy! On a stock KA with stock down low cam, it wouldn't need to be open much at all to achieve idle.

 

So I'll put a longer screw in the idle stop to fix the idle issue. Then I think an adjustable fuel pressure regulator is in order. I was able to get it much leaner this morning, so that it would even start popping from lean backfire. I think if I do the throttle thing and then install the pressure regulator that I can tweak with, I should have this thing down.

[Sealik]

So I just went out and woke up the rest of the neighborhood who should already be up. It's amazing how much fuel pressure has to do with smooth running. Just using the vacuum pump, I got exact readings since there wasn't any fluctuation from the manifold. Ran it high at 37ish, ran well. Idled it at 30 psi, idled better. Still had to leave an air leak open. Ran it around 36ish or so at steady throttle and got rid of the miss/wum wum wum!

 

Then I had an epiphany. I haven't messed with the idle screw on the KA throttle body, mainly because it's screwed all the way down and that's it. And I realize if I hold the throttle at 1000 rpm, it holds steady. Normally this would be bad because the plate is open too far, but I forgot, this isn't a carburetor. It probably needs the plate open more because the cam is so lumpy! On a stock KA with stock down low cam, it wouldn't need to be open much at all to achieve idle.

 

So I'll put a longer screw in the idle stop to fix the idle issue. Then I think an adjustable fuel pressure regulator is in order. I was able to get it much leaner this morning, so that it would even start popping from lean backfire. I think if I do the throttle thing and then install the pressure regulator that I can tweak with, I should have this thing down.

 

 

I mentioned that without a AIS...idling would be of issue.

Now you are opening the plate to compensate

Anywho....here no there.

The longer screw might change the function/settings on the TPS....?

 

FYI......I have no clue....just trying to understand :blink: :)

Edited October 24, 2010 by Sealik

[Sealik]

Correction....IAS

The IAS is part of the idle by-pass system for the intake air.

[HRH]

Hmm, forgot that system had that. That would explain why it needs the extra air inlet sort of, I can't remember how that works. Still only idles at 400-500 rpm though. Just went around town, go figure it's Sunday and the two stores that might have had EFI pressure regulators weren't open.

 

Here's the other thing I though about trying. Joe's truck does use the 280zx throttle body. It has a smaller opening which would also increase vacuum being it's a smaller orifice to suck through. On the other hand, Katherine's roadster uses the KA/SR throttle body......oh f I don't know.

 

It seems odd to me that the FPR can't operate within the correct range even with the lumpy cam. I'm wondering if I move the vacuum source to the throttle plate (where the dist vac. adv is currently hooked up) if that might be a better vacuum source?

 

Oh and I thought about the longer screw, I can adjust the TPS out I think so it would be normal.

[Sealik]

Hmm, forgot that system had that. That would explain why it needs the extra air inlet sort of, I can't remember how that works. Still only idles at 400-500 rpm though. Just went around town, go figure it's Sunday and the two stores that might have had EFI pressure regulators weren't open.

 

Here's the other thing I though about trying. Joe's truck does use the 280zx throttle body. It has a smaller opening which would also increase vacuum being it's a smaller orifice to suck through. On the other hand, Katherine's roadster uses the KA/SR throttle body......oh f I don't know.

 

It seems odd to me that the FPR can't operate within the correct range even with the lumpy cam. I'm wondering if I move the vacuum source to the throttle plate (where the dist vac. adv is currently hooked up) if that might be a better vacuum source?

 

Oh and I thought about the longer screw, I can adjust the TPS out I think so it would be normal.

 

 

Like the air reg.....the IAS just bypasses the TB.

Fuel damper? Suppresses any pulsations in fuel line from pump.

[LenRobertson]

Like the air reg.....the IAS just bypasses the TB.

Fuel damper? Suppresses any pulsations in fuel line from pump.

 

Yeah, the Book shows a fuel damper on the side of the fuel pump. Different than the pressure regulator. Maybe your Subie pump (isn't that what you used?) has this built in, or doesn't need it, but since there seems to be a fuel irregularity, it is something to be aware of.

 

Could General Store on Division have an EFI regulator? I've seen V8 "speed" junk there in the past, but maybe they only cater to the V8 carb guys. Reg might have one, if he is home today. I've lost track of his Honduhs and what he has in them. I think one of his 510s has an adjustable regulator, but it is at the farm, far, far away.

 

Len

[HRH]

Nope, shit's all fucked up. I've lost patience. I'm going to go to the wrecking yard and see what they have for a different setup and put that in instead. For some reason I can't make this damn thing work. Or rather I can make it work, but it runs too rich. Ran it lean for a while, zipped it up to 200 degrees with flames out the pipe, fixed that. Ran it almost out of gas, that makes neat lean popping noises too. Filled it back up with the gas can. I almost wonder if my motor is messed up and I just couldn't tell with carburetors? It's back to the point where it will run okay but if held makes a nasty oscillation and I can tell by the color of the smoke out the pipe that it's too rich. Car is fully up to temperature. Maybe I'm just asking too much of this older system. Hence why I'm going to go find something else to wire up that may work better.

[LenRobertson]

I hate to see you give up on this. I can get the factory manual to you at some point. There is way more testing and trouble shooting info than I've posted. I suspect you can find the solution, but I also realize you are getting sick of it. But will changing to a newer system be less work? Really don't know. Way back on page 9, #175 Bill from Bonners made a good case for a throttle body system. The big advantage there is using stock manifold. Don't know about performance potential through stock manifold, though. And Bonners is close enough you could go look at what he has.

 

Or how about adding an O2 sensor to the system you have, and see what happens? But only if you are going to need it for a newer replacement system. I don't know if O2 sensors are standard on newer FI or not. But if the problem is full regulation or something similar, an O2 probably won't make any difference.

 

Len

[HRH]

Well, here's what I looked at. The 2.4 is a much better choice simply due to how much my 510 is going to weigh after rollcage and skidplates. I already have everything to put it together besides the harness and ECU. Finding that off a hardbody pickup shouldn't be too hard. While the 2 liter was fun, it certainly isn't as fast as I'd like. With very little effort I can probably make the KA even with sohc and truck EFI run harder than the 2 liter, with a lot more torque. Now the only question is to either swap the head on the 20B, or weld up the holes, and put it back to carburetion for sale. Or pull it apart and sell block and head separately.

 

The thing is I know the EFI swap works. Enough people have done it. Why I can't get it to work well enough is irritating, but I just don't care. I want the thing to run super reliably yet fast. The only way to do that is to add displacement.

 

I'll make you a hell of a deal on the motor Len! :)

 

Most of the work is already done, and I can use the same pump for the 2.4 if I remember correctly. Creepy can probably answer that, but I don't think it's that much more pressure. I haven't fully decided what I'm going to do yet, I'll mull it over this afternoon.

[Creepy Cruiser]

I understand where you're at, but you are so close dude, lol.

 

I also understand the bigger displacement.

[jovial_cynic]

Just so we're on the same page before you abandon ship on this project... can you fully describe the symptoms your car is having? You mentioned it was running pig-rich, but you stated that your carb setup had you running rich as well, so it might be good to rule out some things that can cause your engine to run rich in both a carb and EFI setup.

 

List out the symptoms, and then list out the specific things you've done to address those particular symptoms.

[datzenmike]

Josh! You have a efi don't you?

[jovial_cynic]

I don't at the moment, but I'm building one up right now. I was actually cutting away at a L-8 intake manifold early today. But there aren't that many parts involved, and if the only symptom is "running rich," it doesn't seem like there's too many things that can be wrong.

[HRH]

Haha, you funnie guy! :D Yeah, that's what I keep telling myself too. That's why this is so annoying. Not to mention I probably have a hemorrhoid, for which I have a doc appt later next week. This vacation has been soooo fun! ;) I went for a walk with the dog and thought about it the whole time. Haven't arrived at any eureka moments.

[jovial_cynic]

Well, like I said - list out all the symptoms. This thread is 15 pages long, and it'd be nice to have everything in one spot so we can help diagnose.

[Icehouse]

HRH have you thought about just ditching the factory ECU's and running Megasquirt? After hooking one up I wouldn't bother with any other EFI systems on an L series. It's amazing on Dave's car how much smoother it idles compared to before even with a big cam, it's pretty damn impressive, and it's not even fully tuned! I have a vid I need to post on his thread. From meeting you at Canby and reading all your posts I don't think it would be to tough for you to do. I have an version 1 processor you can have if you want. Get the V3 circuit board and the 12' wiring harness they sell and you'll be set! Just an idea.

[HRH]

That might be an idea. I haven't dabbled with Megasquirt yet, this is actually my first venture into fuel injection as far as making it work. It's easy to fix factory prepared stuff. Have known a few people to play with them. I'll have to do some research, but maybe that's an option. The other likely is to do the 2.4 swap, but I'd be just as happy if I didn't have to yank the motor out. I've even come close to thinking of s.....nope, don't even want to think it. In fact, I thought of putting a banner across the car stating "Failure is not an option." It's really hard not to just go with something new sometimes. Particularly after I've had the car down most of the year. I have more blood sweat tears and money into this car than I'd care to say, and it's still not where I want it.

[Icehouse]

Hey don't get down. If it was easy everyone would do it. I know tinkering with EFI can be frustrating. I read most of the pages but can't remember have you monitored the "door" when you are under the rich conditions? I check the voltage output maybe the return signal is off for some reason. The FSM may have some standard voltages you can cross reference.

[HRH]

Well I was halfway through yanking a harness of a Stanza with a CA20 at the wrecking yard, when I realized it had a dual coil setup and even though it probably would have worked, I remembered something odd about that not liking not having dual coils even though you could do it.

 

So then I thought (in the middle of a rainstorm) this is stupid. I need to either

 

A: Find out what's wrong with the EFI on the car.

B: Yank the head, weld up the holes, and save up for a new manifold and single sidedraft 44 Weber which would be much more tuneable than the SUs.

C: Scrap the whole idea and build the 2.4 and use a megasquirt.

D: Sell the whole thing.

 

Since I spent the time to wire in the fuel pump and the car is ready to go for EFI, B is not an option. Since I will never get my money out of the 510, D is not an option.

 

So I think I'm going to yank the intake manifold off and look for issues. Even though the cam shouldn't be it, I may try a stock cam for ease of tuning, then put the rally cam back in.

[INDY510]

.

Before you do ANYTHING ........... I would try a different ECU ........... my KA24 was running like crap.... and I tried EVERYTHING.......... but a used ECU fixed the problem ..... (it might be worth a try if you can find a good one for cheap)

[HRH]

I'd love to, but finding ecus isn't easy for these anymore. Both the local yards don't have any. May call up to a few others, but not very easy to find. Most 79-81 200sxs have already been crushed, I know of a few still in operation, but even more rare than 510s.

[HRH]

Hey Datzenmike, did you ever find anything on that ECU I have that is a 9 but not listed? Len, does your FSM list any ECU serial numbers in it?

[INDY510]

Varying prices for used 79-81 200sx ECUs:

 

http://cgi.ebay.com/...=item19bc39a2b2

 

 

http://cgi.ebay.com/...=item51843ea7c2

 

 

http://cgi.ebay.com/...=item518f280212

 

 

http://cgi.ebay.com/...=item19bc780a42

 

 

http://cgi.ebay.com/...=item4aa12d9f30

 

 

http://cgi.ebay.com/...=item27aa63d6ff

 

 

http://cgi.ebay.com/...=item29fff24537

 

 

http://cgi.ebay.com/...=item19b3e7ad86

 

 

 

 

 

Hey Datzenmike, did you ever find anything on that ECU I have that is a 9 but not listed? Len, does your FSM list any ECU serial numbers in it?

 

Could not find it listed anywhere.

[INDY510]

.

Before you spend that much for a used ECU ........... I still think the fuel pressure regulator sounds like the problem..... .. what pressure is Icehouse running on daves car?