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Building an LN3 from spare parts plus a Supercharger


2seater

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4 hours ago, Ronnie said:

When you disconnect the battery cable and reconnect it resets the ECM. Then it goes through a learn process.  I don't really know anything about the learn process. I'm guessing, as it goes through the learn process it is operating on tables (standard perimeters) stored in ROM. Maybe something it learns in the learn process is causing the problem?

 

 

I had never done just the disconnect of the ground and then reconnect without changing the Memcal. I had previously guessed that it was just the reset that made everything happy again but that doesn't seem to be the case, at least not a quick off and on. The thing about that is the setup that previously screwed up was installed in a different ECM (the present one) and it worked perfectly until this morning. Grrr

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1 hour ago, DAVES89 said:

I would call GM Tuners

I agree with you. I just recently gave him a general update but no specifics of this bad behavior. This morning I did describe in detail what is going on and will see if he has any idea. He has been great to work with.

 

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Ryan suggests the possibility the adapter may be the problem, but the failure rate for it is very low, so no way to know for certain without an extended test. I am going to install an old Memcal that was programmed for my previous turbocharged engine. This will eliminate the adapter. It isn't optimum, but the injector constant is correct for the 30# injectors so it is safe to run, within reason. Until I accumulate a bunch of miles, there is no way to know for certain. He stated the pulsing check engine light usually indicates an internal ECM communication failure. I need to find one or more 1990 compatible Memcals to be able to program without an adapter.😢

 

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So far so good starting and running on a Memcal without the Moates adapter. Too soon to tell if that is the issue yet, and I wouldn't have posted that without adding some trivial information:

I found I had two spare ECM's in my parts pile at my cottage, one with an 88 ANBM chip, showing as a Delco remanufactured 16198264 service number and the other contains an 89 ANNH chip. The 89 ECM is sort of a mutt. The case is from my old parts car, also listed as the Delco reman, but the outside was covered in mouse pee, or something like that. We actually removed the guts, (which were clean), from the ECM and transferred them to the case from the red car #2 son has. In this case, the guts with the ANNH are now from a 1228253 ECM, which was the standard number. That's all sort of useless information but when I decided to save the contents of the two chips, and then compare, I found I couldn't read the 88 chip correctly. It requires a different decoder, in a manner of speaking. I guess this is one of the things that are different about the 88 vs 89. I did find the needed translator online and I just looked at a few things to see if the information was indeed different, and some of it is. The fuel cutoff RPM is 6000rpm, vs 5700 for 89 and the pulses per mile from the VSS is ten times higher on the 89. The display pulse divider is also ten times higher on the 89, so the ratio between them is the same. The pulse divider can be adjusted in the chip to correct the speedometer so finer adjustment is possible. I am sure there are other differences, likely unimportant, but it was interesting that the 88 is pretty much a one of a kind in more ways than one.

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I'm surprised they changed do many things between the '88 and '89 models. We keep stumbling across more of them all the time. 

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10 hours ago, 2seater said:

...interesting that the 88 is pretty much a one of a kind in more ways than one.

Thanks for the information about differences between the '88 chip and the '89 chip. I've updated my list of differences between '88 models and the later models.

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  • 2 weeks later...

After a couple hundred miles operating flawlessly with the Turbo Memcal, I decided to try an experiment to localize the problem child. I copied the PROM portion of the turbo Memcal to chip so I could reinstall the Moates adapter. This is the same information included in the Memcal, but split into two parts, if that makes any sense. I disconnected the battery to make this changeover. Upon startup, it stalled once but the second start proved to keep running and gradually smoothed out. I went through all the diagnostic data and everything looked good plus a short drive went well. Since the adapter also includes a chip change socket, I dropped in the SC chip I had burned and used previously and which seemed to work fine, but I think it has a flaw. The engine started and idled, but the check engine light came on and the temperature gauge was inoperative. Entering diagnostics showed no communication with the engine, again. Shutdown the engine and reinstalled the Turbo chip it was running on just a few minutes before and everything returned to normal. I did this once more and the SC chip acted up immediately. Apparently it is the culprit. I can change just the chip without disconnecting the battery every time and I did notice the check engine light flashes rapidly while in diagnostics for a while after swapping chips and does so until it has assimilated the new information, then it slows down to the normal slow blink. 

 

I ordered a handful of new chips as I have found I have a few used ones I have that will not completely reset under UV light, even after multiple exposures. Nothing lasts forever I guess. 

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  • 2 weeks later...

Update on the control system problem which pretty much confirms my previous post about the chip being bad or unable to communicate. Acting on Ryan's suggestion after receiving some new chips, I loaded the problem child S/C 1.4 tune on a new chip. After installing, the car started and ran perfectly. Going through diagnostics while the engine warmed up, everything looked normal. When it reached closed loop, there was a change in the sound of the engine, but it all went smoothly. I then shut down and installed the suspected problem chip and even though it started immediately, I could tell something was "off". Going to diagnostics showed "no ECM data" again, so I suspect it is running in a limp mode. According to Ryan, this means the ECM cannot communicate with the chip. All this chasing the tail of the real problem, looking in the wrong place and blaming the Memcal or the Moates adapter, was at least instructional although time consuming.

Maybe I can iron out some of the small details before it is time for it to sleep for the winter.👍

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  • 2 weeks later...

It continues to run well. In my quest to see where the knock bug exists, I tried various regimes to see what it does. I think I mentioned it climbs hills better with the S/C than the turbocharger under non downshift conditions. I was a bit surprised to find I could get 2-3psi of boost indicated if I roll pretty hard into the throttle with the trans in 4th gear and TCC locked. Lots of throttle but less than required to initiate a downshift. Something like rolling on the throttle at 60mph or so up to maybe 80mph, all the while showing a couple psi of positive pressure but never going over about 2400rpm. I figured only the turbocharger would do that, but I guess not. The best part was it showed no hint of knock.

 

In the trivia department, I have been looking at better ways to quantify what happens with the supercharger without beating things up and going to a dyno, which was never my purpose. I was looking for information regarding the Eaton M62 supercharger and found a few figures that maybe illustrate where and how it helps. This is a bone stock late M62 with the coated rotors but the coating is not pristine. Stock 3" pulley which gives about a 2.33:1 overdrive ratio for the supercharger. 5000 engine rpm is 11,677 S/C rpm, where it apparently requires 16hp if producing 5psi of pressure. Basic math calculates the engine requires 340cfm at 5000rpm @ 100% volumetric efficiency, something not close to reality in N/A form, which is more like 65%-75%VE. At that engine rpm, the S/C is capable of 380cfm, so I guess that is where the boost comes from. By definition, boost is actually resistance to flow, so I am sure it is possible to increase flow through other means and increase performance while indicated boost declines. 

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Last post on this, at least for the season I believe. I guess there is one little item I was tried to address before I took the car to storage, and that had to do with a bit of knock present at full throttle near the 2-3 shift. I normally don't beat on the car like that, but sometimes it needs to be. In any case, I made a new chip yesterday, theoretically identical to the one I have been running, just with a little less timing in the high load and rpm area. I tried it this morning so I could check it on my trip to storage but it gave me an instant check engine light and rough running. I removed it and reinstalled the one I have been using and it all settled right back down. Strange. There is a bright spot though. I was able to put about 350miles on a single tank of gas so I could get a mileage reading. It was right at 22.5mpg. Not great, but not bad either. About 70% highway, 30% urban. 

The car is now at storage, up in the air with the oil drain pulled since it was nice and hot. It will get new oil and the other detail stuff for winter storage over the weekend. Bittersweet

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15 minutes ago, 2seater said:

I tried it this morning so I could check it on my trip to storage but it gave me an instant check engine light and rough running. I removed it and reinstalled the one I have been using and it all settled right back down. Strange.

That is odd. Makes you wonder what is going on. Can you reprogram the problem chip with the same program that is working properly? That might tell you if the problem is with the chip or the with the programming.

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Apparently, operator error. I believe I had the chip that gave trouble slightly askew in the holder. I reinstalled it this morning and it functions just fine, as it should. Inserting a chip into an actual socket it must be aligned perfectly but the zero insertion force holder is a series of slots that are opened and closed via a lever on the holder. While it is easy to swap chips, it isn't foolproof if done in a hurry. 😖

 

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