Update on the M30 ECCS progress

[bemis]

Well, I've managed to get the Z tuned enough to drive around, but it is still pretty rich at idle and light throttle driving. I decided to use an "enhanced" VG30DETT tune available from ztechz.net, since it is already designed for the use of the Z32 MAS. So, I just needed to recalibrate the K value, TTPmin, Void, TTPMax and TP scales to represent MB 480cc injectors. With that setup, it runs, but really rich overall, especially at idle and light throttle driving. So I decided to start trimming down the TTPMax and Void time. I now have the void time at 00hex and the TTPmax brought down considerable at the lower end and it now runs alot better. Basically, the lower I bring the void, the better the idle mixture. but now i have run to the end of the scale at 00hex. Oh, the AFM reads 1.5v at idle, 800rpms. I wonder what i can do next in order to bring the enrichment lower. Maybe start lowering the fuel enrichment on the actual fuel map, but that is something that I shouldnt have to do. There seems to be a variable in the M30 ECCS that I have not been taking into account as it should not be giving me this much trouble. I have begun to think that maybe the fuel injectors themselves are at fault, as if they are sticking or have slowed down their pintle movement over the past 30 years. I have had them cleaned and flowtested with the results all coming back good. And I know for sure that they are not tied together as with what happens during the injector recall campaign. Also, maybe there is a voltage divider circuit for the AFM, of which im going to look into more to find out for sure.

So I ran down the AFM signal trace on the computer board and came up with this.



The AFM signal and CHTS are tied to each other through a voltage divider circuit. But, the AFM signal goes straight to an A/D convertor. I may cut the trace on the AFM signal trace going through the 170Kohm resistor and see if that makes any difference.

[Rick88ss]

What is your base fuel pressure ?

[bemis]

~38psi at idle, ~47 with no vacuum.

[Rick88ss]

Did you try a lower fuel pressure? You'l have to change all of the settings again but it might help

[bemis]

no, i haven't tried to lower the fuel pressure yet. but i will add that to my list of things to do.

[G-E]

with that much fuel pressure your 480cc k-value will be wrong.... remember it is supposed to be 37psi relative to the mainfold.... so if the manifold is in vac it should be less, and in boost it should be more

how much suck are you getting at idle? put the other injector settings back to normal and drop the k until you're just about right, then start fuxing with the others

[Stinky]

The injectors were flow tested at ~43psi. Bemis stated that his base fuel pressure is ~47psi. He could recalculate the new injector flow based on teh 4psi difference in fuel pressure.

Either way, I agree with setting the other things back to normal and playing with the K more.

[jeffp]

M30 box

I have been looking into this upgrade myself. I just got a second box, and this time I found a wire harness that had only the TPS connector missing. I got the whole thing. I can tell you this wire harness will fit the VG30 engine perfectly. All of the connectors are the same, same air bypass, and all that junk. The O2 is the same so it would be an excellent upgrade for the Z31 cars.
The Tuning, well here is what I suggest, set the TTP min to about 4 (convert to HEX) adjust the TTP MAX to 255, yes 255, then do the tuning. The TTP MAX is a redundant setting, and in some cases hurt the operation of the engine to get the correct AFR'S.
I would not worry to much about the K just yet, you need to decrease the latency of the injectors, to get the idle to match the fuel map. Then you can go and make the changes as you are required for the K

What kind of car is installed on? I cant remember, but if it is the Zcar this is an excellent upgrade.

[zmech]

M30 box

z

[bemis]

I fixed the problem.

While troubleshooting, I found out that the ECCS will run the engine with the EEPROM chip removed and if the data on the EEPROM is written in the wrong area of the chip. Must have an emergency back-up tune built in somewhere else. Also, if the AFM is giving an invalid signal, the ECCS will use the TPS scale to find the right mixture, but only letting the engine rev up to 2000rpms.

The Z runs beautifully now.

It starts up and idles perfectly, cold or hot, with just the idle set at the throttle body. Something that can be a problem with the Z31 ECCSs.

I'm loving the instant throttle response given by the use of the Throttle Position Sensor.

I also don't notice the "jolt" at ~3000rpms when the ECCS switches from sequential to batch fire, something that the Z31 ECCSs are also known for. This ECCS runs very smooth.

[G-E]

I know everyone is jumping on the 88-89 ecus, but I think what you're playing with is the way to go ... sequential and just as easy

how about the quest ecus? sure we need the quest distributor/cas but it's a direct swap, the temp sensors are the same, think there may be one more than a z31 but I doubt it matters... abs is irrelevant... it didn't come in stick but that shouldn't matter either... what else?

[jeffp]

The Z31 ECU

I am running the 88-89 Z31 part. I got very good results to 500hp. This last upgrade, now I am having problems. Seems the last mode of operation switches from one pulse to the injectors to a dual pulse scheme to get the duty cycle under extreme loads. This is where I am having my problems. When the ECU switches, the &2Lb injectors cant keep up with the dual short pulse width (duty cycle) so the car goes lean, then pig rich.
I have a complete M30 wire harness and can adapt that into my car easy enough. The thing I want to know for sure is if the M30 ECU also switches to the dual pulse width scheme for heavy loads. I have almost made my goal of 600hp with the Nissan box, but it sure is not running correctly, and it has cost me a set of pistons in the process.
The first thing the car did, (I was running low battery voltage 11.6 VDC to 12.5 or so) was run perfectly up to 5K rpm's and it would fall flat on its fact bad. Everyone thought it was a misfire, so I went and made sure it was not, tested the system, installed a Mallory Markll coil, threw the oscope in the spark plug and took a look at the pulse when the car did it's fall on it's face thing. The spark was good, the fuel was lean just like the wide band said it was(when a car misfires the O2 readings go to hell because of the unspent fuel and lack of combustion) By this time the engine was dust. The car did run very well for having 90psi in number 2 cylinder. What put me on to it was all of the smoke coming from the valve cover. I first thought it was my new PCV setup with the catch tank, so I tested it and that was not the problem. When I went to put oil on the engine, I took the cap off and noticed an excessive amount of smoke, kinda like a smoke stack. Well there was ONLY one place the smoke was coming from, and that is when I did a compression test, the engine was toast!
Now it is back and having similar problems, but to a lesser extent because I upgraded alternators and got the line voltage to 13.9-14.2 VDC.

Do you have the Service Manual for the 90 M30? If so could you look up the theory of operation for the unit and see how the injector firing scheme works? I don't think that I can use the dual pulse setup and get to where I want to go.
The sequential injection is much better, but for my application if it does dual pulse firing of the injectors any time I think I will be screwed.

[G-E]

I have i30 and j30 fsms but no m30

[Rick88ss]

Re: The Z31 ECU

jeffp wrote: I am running the 88-89 Z31 part. I got very good results to 500hp. This last upgrade, now I am having problems. Seems the last mode of operation switches from one pulse to the injectors to a dual pulse scheme to get the duty cycle under extreme loads. This is where I am having my problems. When the ECU switches, the &2Lb injectors cant keep up with the dual short pulse width (duty cycle) so the car goes lean, then pig rich.
I have a complete M30 wire harness and can adapt that into my car easy enough. The thing I want to know for sure is if the M30 ECU also switches to the dual pulse width scheme for heavy loads. I have almost made my goal of 600hp with the Nissan box, but it sure is not running correctly, and it has cost me a set of pistons in the process.
The first thing the car did, (I was running low battery voltage 11.6 VDC to 12.5 or so) was run perfectly up to 5K rpm's and it would fall flat on its fact bad. Everyone thought it was a misfire, so I went and made sure it was not, tested the system, installed a Mallory Markll coil, threw the oscope in the spark plug and took a look at the pulse when the car did it's fall on it's face thing. The spark was good, the fuel was lean just like the wide band said it was(when a car misfires the O2 readings go to hell because of the unspent fuel and lack of combustion) By this time the engine was dust. The car did run very well for having 90psi in number 2 cylinder. What put me on to it was all of the smoke coming from the valve cover. I first thought it was my new PCV setup with the catch tank, so I tested it and that was not the problem. When I went to put oil on the engine, I took the cap off and noticed an excessive amount of smoke, kinda like a smoke stack. Well there was ONLY one place the smoke was coming from, and that is when I did a compression test, the engine was toast!
Now it is back and having similar problems, but to a lesser extent because I upgraded alternators and got the line voltage to 13.9-14.2 VDC.

Do you have the Service Manual for the 90 M30? If so could you look up the theory of operation for the unit and see how the injector firing scheme works? I don't think that I can use the dual pulse setup and get to where I want to go.
The sequential injection is much better, but for my application if it does dual pulse firing of the injectors any time I think I will be screwed.

Hey jeff good work on your Z. What happenned to the first engine that was blowing smoke outta the valve cover? Did it make a hole in the piston or break the ring lands?
BTW what kinda Z do you have ? Any pics?

[bemis]

the m30 uses sequential injection up until ~3000rpms, then it switches over to batch fire.