510 L20B EFI conversion - the project is finished!

[datzenmike]

The 02 sensor input is pin 31 with the outer shielding connected to pin 16. The sensor grounds to the exhaust manifold so make dam sure the block and the ECU is well grounded or sensor inputs from the water temp/throttle position/AIS/ air box... everything! won't have a common return path.

 

 

Try your ECU on his truck!!!

[Sealik]

The 02 sensor input is pin 31 with the outer shielding connected to pin 16. The sensor grounds to the exhaust manifold so make dam sure the block and the ECU is well grounded or sensor inputs from the water temp/throttle position/AIS/ air box... everything! won't have a common return path.

 

 

Try your ECU on his truck!!!

 

 

Yes......I mentioned that a couple of times.

That was my problem...(grounds).....well 1 of them..... :)

[HRH]

A11-626-575 What does that number go to? I just put Joe's ECU in the car, it reacted the same. The ECU I was using was A11-629-575. Joe told me he's tested the spare ECU he had in his truck and it ran fine, unless he's remembering wrong. Considering he dug it out from the back panel of the truck I doubt it. His is 02-less as well.

[HRH]

I've tested the ground, let me yank it off, clip off the ring terminal and attach another wire to it, see if for some reason that's the issue.

[DISLEXICDIME]

What is your fuel pressure at ? Is the return line plugged. Is the fpr working ? Are you running a cts if so is it bad ? Is the cam so lumpy it is making the afm go all over the place at idol?

[HRH]

I rewired the ground, that actually seemed to help a little bit, but still too rich for my taste. Then again, maybe this system just runs a bit richer than traditional fuel injection. Fuel pressure at idle is 37-40 fluctuating which is probably due to the cam and the fact that it's running at 400 rpm. That I can handle. It seems to have gotten a little better holding at steady, so might have figured that out with the crap ground. The problem with idle is I need a bigger air leak than the air regulator can provide. But that may be because the orofice I'm using for the air regulator is roughly half the size of what's on the manifold. If I plug the air leak, she won't idle.

 

I'm also getting shocked occasionally if I mess near the dist cap, but reattached a plug wire, and looked in darkness for arcing which I can't see now. 50,000 feels good! :) Think I may go take her for a drive and see what the deal is.

[HRH]

Took her for a drive, did ok, just not what I would expect. Those of you with similar systems, do you have the ECU grounded?

[datzenmike]

Fuel pressure should be about 30 at idle and jump to 37-40 under throttle. Not sure how the fuel pressure is regulated either Throttle Position Sensor or vacuum. Anyway the idle mixture is set by the ECU assuming throttle closed and fuel pressure at 30. This may be hard wired in at the factory and ignores some of the other sensors. As soon as you step on the gas the TPS changes and sensor input overrides the factory settings. ???????

[Sealik]

Took her for a drive, did ok, just not what I would expect. Those of you with similar systems, do you have the ECU grounded?

 

 

My ECM is grounded....just bolted to the firewall though

[Sealik]

It's weird your engine does not die when you manually open the flap.......?

Something to ponder.

[HRH]

Grounded the ECU in addition to it's mounts. Didn't make much difference. I just talked to Joe and he thinks air leak, which again, I didn't find any, but I think I'm going to yank off the throttle body and maybe the intake manifold and take a second look. Something isn't right, this system should work. Joe has a big lumpy cam and his system works fine. I'm wondering if I have a lip on the head where the intake manifold isn't lined up correctly. I don't think so, but won't know without checking.

[HRH]

Where does your guys' fuel pressure regulator vacuum line go? I have mine hooked up to the top of the manifold.

[Sealik]

Where does your guys' fuel pressure regulator vacuum line go? I have mine hooked up to the top of the manifold.

 

 

Mine (stock placement).....is going to the side of the IM.

Put a vacuum gauge on the IM....see what you have......or don't have..... ;)

Should be the same as carbed....?.......around 20 lb

[HRH]

I'm almost beginning to question the manifold. If I had an air leak, then it seems creating a bigger one to let the car idle wouldn't make sense. Unless it's sucking more in, thus moving the airflow meter flap farther in making it rich. The other thought is turbulence from too large and intake going into too small a head port. I think I matched them pretty well, so I don't think that's the case, but you never know. Frick, I don't know. What I do know is the thing runs, but runs poorly so unless the harness is screwed, it has to be a vacuum leak of some sort or manifold problems. Going to make lunch and then go over to CDA to replace some shocks on a pickup, then up to the parents for dinner. Maybe I'll think of something else between then. Think I'm about to the point of tearing apart the intake and or trying a different throttle body, short of finding another wiring harness to try. Probably not going to be easy, though I should check Pull and Save and see if they have any 200sx's in there.

[Creepy Cruiser]

No, no Creepy, stay away from Matt with your KA ideas! LOL! I have a horror that if he abandons the FI project, I'll end up with the pieces. I have absolutely no time, energy, or expertise to mess with something like that. But that isn't to say I wouldn't think I should try. I know Matt is just one bad wire or sensor or something away from having this thing working.

 

Matt - Found the ECU from the '81 O2 version SX. Tag on it reads A11-626 575 on one line. Line below that reads 1323 Z20. I've wondered if you might have a ECU that needs an O2 input, even though it is supposed to be for a non-O2 engine. Probably not, but anything seems possible.

 

Len

 

No no no, I definitely think he should see this thing through to the end. And I totally agree, it's just one stupid little thing causing the issue. It's just a matter of trying anything and everything until you find it, lol.

 

 

You are too far along too give up now Matt, lol. So close.

 

I will bring my car by though (hopefully before the snow flies), just so you can check it out.

[Sealik]

I'm almost beginning to question the manifold. If I had an air leak, then it seems creating a bigger one to let the car idle wouldn't make sense. Unless it's sucking more in, thus moving the airflow meter flap farther in making it rich. The other thought is turbulence from too large and intake going into too small a head port. I think I matched them pretty well, so I don't think that's the case, but you never know. Frick, I don't know. What I do know is the thing runs, but runs poorly so unless the harness is screwed, it has to be a vacuum leak of some sort or manifold problems. Going to make lunch and then go over to CDA to replace some shocks on a pickup, then up to the parents for dinner. Maybe I'll think of something else between then. Think I'm about to the point of tearing apart the intake and or trying a different throttle body, short of finding another wiring harness to try. Probably not going to be easy, though I should check Pull and Save and see if they have any 200sx's in there.

 

 

Can't see the large intake/small head port being of issue...??....seeing that you matched them pretty well.

I have the round 200sx intake on my square Z24 head.....maybe up to 1/16 + inch in a couple of spots.

Need to get that air reg in place and or.

I also considered changing my ECM and harness.....but eventually concluded....that was never of issue.

[Unclejesse88]

Remember, if you have no O2 sensor, the car has no idea if it is rich or not. It only knows the basics, afm, throttle angle, rpm, and temp. If you have an air leak, the car has no idea of knowing it other than a lower afm reading, which in turn should make the ecu lean out the injectors. Less afm air flow, less fuel out of the injectors. This sounds like a fuel problem more and more. Have you tried using a vacuum pump on the fuel pressure regulator and applying 20" to it to simulate idle vacuum? Common fp regulators increase fuel when manifold vacuum to the regulator drops.

[HRH]

My dad mentioned that tonight when I was over there. I think tomorrow I'm going to clamp the rubber line to create a restriction and see if I can't clamp it to a slightly lower pressure, then see if it runs better. This is just for testing because it's the easiest. If that works, then I'll get an adjustable fuel pressure regulator. But yeah, I'm beginning to think the same thing. It should lean out if there's a vacuum leak past the AFM. So maybe the whole problem is just too much fuel pressure, especially considering it runs out okay.

 

I suppose I could also hook a vacuum pump to the regulator too as suggested. Will try tomorrow.

[LenRobertson]

The factory manual has a page on testing fuel pressure and vacuum. When I wake up a little more, I'll try to post a summary of what it says.

 

I'm still uncertain if you have the right ECU. Reading back through the thread, it seems Joe's ECU is a A11-626-575, which is the same number as the one I have from an O2 sensor system. datzenmike posted "A11 626 575 is for the '81 automatic 200sx. (non California)". You posted "The ECU I was using was A11-629-575." I don't know if this is an O2 sensor ECU or not, but datzenmike posted "Matt I just checked and I still have an 80 Auto ECU A11 609 571 (non California) This means that the ECU I sent is for the '81 with 02 sensor input." I probably shouldn't be trying to figure this out at 5:30 in the AM, at least not without a lot more coffee in me, but at the moment I'm confused. And I'm assuming an O2 sensor ECU must have an O2 input to run correctly. Maybe it doesn't actually need the O2 sensor hooked up, and Joe knows this from actual testing.

 

Len

[Sealik]

It looks like the (81 US models) ECU with the O2 sensor has a light on the side of it.

It's 'used' to diagnose a faulty exhaust gas sensor

[LenRobertson]

It looks like the (81 US models) ECU with the O2 sensor has a light on the side of it.

It's 'used' to diagnose a faulty exhaust gas sensor

 

Interesting. I have my A11-626 575 (taken from an '81 200SX) right here by my computer. Yes, there is a hole in the side of the steel case with what appears to be a little green light in there. I Googled for a Nissan ECU number list, but the only one I found didn't go back far enough. But my search skills are lousy, so someone else may be able to find numbers for the early '80s ECUs.

 

Len

[HRH]

Dammit, I hate when I lose all the form data!!! Typing this again. I think UncleJesse is onto something. I was ignoring the fuel pressure given the guage is old and it's 37-40 at idle, which I figured could be the gauge messed up, and the lack of vacuum due to overlap in the cam. But that's just it, I was ignoring the cause. Because of the higher pressure and the limited intelligence of this system, I'll bet the lack of vacuum is causing the problem. No vacuum causes the regulator to not regulate, thus bumping up the pressure. I'm going to put the vacuum pump to it this morning and regulate to 30 psi and see if that doesn't make it idle. If it does, that's likely the whole issue.

 

As far as the ECU, I don't think it matters. Joe had the other ECU in his non O2 truck and it ran fine, so there must be some latitude between systems.

 

I'll post up happily in a bit if I get the result I'm hoping for.

[datzenmike]

In the past I scrapped two 200sx cars an '80 and '81 both Canadian. One was a 5 speed and one an auto. I pulled both ECUs. I don't remember which one is which except that now I can look it up.

 

I have one in front of me, it's A11 609 571 which is for an '80 automatic. No green or any lights.

 

The one I sent Matt (I assume) must be for an '81 standard A11 626 575

 

 

I cannot locate A11 629 575 and must advise that the number 6 can be easily mistaken as a 9 in it's printed form.

[HRH]

Nope, it's a nine. Guarantee you. Where are you checking these numbers? Either way, I think it will work just fine. The one I have in the car now does have an LED, but it doesn't light up as far as I can tell. I know they made a big switch in '82, but I'm better there's some overlap from 80-81. Technically there's not, but you know how that shit works. Hollander only needs one thing different, and if the O2 sensor is in there but not necessary, they "won't work." I need to go eat breakfast so I can test my theory.

[Sealik]

Dammit, I hate when I lose all the form data!!! Typing this again. I think UncleJesse is onto something. I was ignoring the fuel pressure given the guage is old and it's 37-40 at idle, which I figured could be the gauge messed up, and the lack of vacuum due to overlap in the cam. But that's just it, I was ignoring the cause. Because of the higher pressure and the limited intelligence of this system, I'll bet the lack of vacuum is causing the problem. No vacuum causes the regulator to not regulate, thus bumping up the pressure. I'm going to put the vacuum pump to it this morning and regulate to 30 psi and see if that doesn't make it idle. If it does, that's likely the whole issue.

 

As far as the ECU, I don't think it matters. Joe had the other ECU in his non O2 truck and it ran fine, so there must be some latitude between systems.

 

I'll post up happily in a bit if I get the result I'm hoping for.

 

Ya...I was thinking that the duration of your cam/vacuum was creating some issues.

Thus the flap has no affect on engine when moved manually.

Maybe............ ;)