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Building an LN3 from spare parts plus a Supercharger


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I am amazed by the quality control nowadays...

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You got lucky. You came close to needing a ride on a tow truck.

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This occurred over two days and I posted part of this incident in the lounge section previously. I am going to repeat the previous post with additional information here, so it is all in the correct thread.

 

After the repair of the vanes inside the balancer, the car was simply moved to a different stall and was not driven until two days later to come home. The engine started normally and without issue. After a short idle I started to back out of the garage and after only five feet or so, the engine stopped, just like the key was turned off. No warning. I immediately tried restarting the engine and it gave occasional signs of life until I held the throttle wide open to clear a possible flood and it started, but it ran very poorly. It did continue to run at idle but smoked black and was rough as can be. I noticed the check engine light was on, so I shut it off. I then checked diagnostics without starting the engine and there were no E codes, but there was a note that there was no E com(munication)? Something I never saw before or could find in the FSM. I took a different vehicle home.

 

I returned today to pick up items I had forgotten and decided to look at the car. I guessed either the ECM went bad or possibly the assembly used in place of the chip in the ECM. I disconnected the battery, popped the PROM and hardware assembly out and installed an older PROM from the turbocharger installation. I knew this PROM would operate the engine despite the tuning being off a little. With that in place, it fired right up and ran like nothing was ever amiss. I am now pretty confident the fault lies in some part of the PROM replacement assembly used for tuning. This consists of a Memcal (PROM), a 256k chip which is what gets programmed and an adapter that ties the two parts together. I left the car there and will have to get back to investigate further before trying it on the road. More to follow when that happens.

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You should check into the possibility that the PROM replacement hardware was displaying the "no E com" message. Maybe because it couldn't communicate with the ECM properly? I would check with the company that made it.

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I am not sure what to think here. I have a couple hundred miles on the combination that apparently failed? It is just a piece of hardware, a rather heavy duty version of a printed circuit, with no actual electronic parts. If you look at a stock Memcal, it is made of two parts, easily visible with the cover removed. There is a circuit board with many typical electronic components and at one end is the “chip”, in our case, a 28 pin, 256k integrated circuit. This is the part that we can erase and reprogram. The hardware piece has pins on one side that plug into the circuit board section of any MEMCAL and another section for a socket for the IC chip. Just dumb wiring to route the two items to the connection in the ECM. With no evidence to back this up, at least not yet, the most likely is the Memcal presently installed, is possibly damaged from the removal of the IC chip in the failed attempt to install a chip socket. 

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Brought the car home yesterday. I installed a stock ATYH memcal on the Moates adapter and my custom chip on the opposite side, same configuration as what had failed but with an untouched memcal. It started and ran but with the return of the cold start instability. It seems to be self correcting as it did before and it runs flawlessly once it warms a bit. This seems to confirm the previous memcal was damaged by being modified but only the passage of time and miles will confirm.

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Not strictly related to the title subject but it came with the donor engine. The 140amp alternator that came with the S/C donor engine stated making bad noises so I swapped it out for my original 120amp as I mentioned earlier. I opened up the 140 and found the rear bearing has destroyed the tip of the rotor. Probably the one part that isn’t readily replaceable🤨

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Another apparent failure today of the combination of Memcal/adapter/256k chip. The original failure was of a combination that I had used for many years where the Memcal was modified by installing a socket directly soldered in place. I attributed this to years of use and some abuse, but now I wonder. The next failure was as detailed above, and again this was a Memcal that had been attempted to be modified for a socket, and failed. It too operated for a couple hundred miles of trouble free and today, after working perfectly to drive about 30miles, when it came time to return, the engine sounded wrong. It surged up and down, the cooling fans were on and there was no temperature display on the IPC. This seems to be a common theme of all three failures, it occurs at startup, some or all of the engine data to the IPC is missing while other items activate that should not be. Essentially it appears to be an engine to ECM/BCM communication issue. In this case, I pulled the offending parts out of the ECM, installed a previously reprogramed Memcal from when it was turbocharged, and all the issues go away. Now I am in great need of a Memcal or two as backups. I have the files for a couple of stock '90 chips, so I can adjust them. One of the guys I was visiting, with much electrical experience, suggested I go over all the isolated power and ground lines to the ECM, to which I agree, there is a ghost in the machine somewhere.

 

Oh yeah, to top it off, the latch for the driver's seatbelt failed last Friday as well. The passenger's side has been swapped in temporarily. I am at least pretty sure that isn't related to the engine gremlins?

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That might be a hard one to figure out. Over my head.

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There are a number of 1990 Rivs at Gibsons. Would they work?

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2 hours ago, DAVES89 said:

There are a number of 1990 Rivs at Gibsons. Would they work?

The belt or the chip? I suspect the belt would be fine as long as it has the electrical connection for the belt warning, but that isn't strictly needed either. Memcals are a different issue. I can program them, but I don't know about the non programable stuff. I am not sure if the ones I have are fried or not either. Ugh, I have never had things like this and it has spoiled me🙂

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I have a number of ECMs as well. The latch end is the same and color doesn't matter as the plastic sheath comes off yours and goes on the replacement.

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I went over the power and ground connections, not expecting to find anything since they were not disturbed during the engine swap, all except the ground under the coils and the large stud at the passengers rear of the engine, behind the power steering pump on the non-s/c engine. I had to remove the alternator to get to that ground stud and while I could not easily move the connections on the stud, I was able to tighten the nut over half a turn. Maybe it will help?? No way to know for now. In any case, everything is clean and secure.

 

I have been making the assumption that the chip and/or interface device has been failing, so I tested that theory this morning. I installed the assembly that had run so poorly just a couple days ago into another ECM, which turned out to be my original one. The engine started, ran very briefly and quit. It did this five or six times in a row, then it started and continued to run on its own. It didn't sound very healthy with a seeming miss audible in the exhaust, but in less than a minute that cleared up and it settled down to a reasonable idle. I drove it a few miles and it doesn't miss a beat, but it has done this before. Why it had a hard time starting and running is a bit of a mystery. A flaw in the previous ECM being adjusted for in the Memcal or chip which came along for installation in a better ECM?? I just don't know. Of course, this begs the question of why installing a different Memcal in the previous ECM, twice, caused everything to return to a seeming normal. Maybe just doing a reset by removing battery ground and reconnecting would have done the same thing? Maybe tightening a harness ground to the engine helped? Only time and some miles will tell if this can be put to bed at last. 

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Now that you have lived a while with the SC engine, how do think it compares to the last turbo setup you were running as far as power and just as important to me, drivability? Do you feel like the SC engine is more reliable than the turbo?

 

 

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So far, everything is running as it should. I am hoping to get through one complete tank of fuel so I can get an actual mileage estimate. The weather has turned sour for the present with some low temperatures flirting with the thirties, high wind and rain. 

 

Power delivery has a different feel for sure. It is more immediate, which is pretty satisfying, although it lacks the feeling of power building as the boost reinforces itself. There is no doubt the turbocharger has the greater power potential, which is easy to see by observing the boost level. It isn't really a fair comparison there though as the two systems have different parasitic losses. The positives outweigh the negatives in my mind. The s/c is slaved directly to the engine so tuning is more straightforward, plus there are factory tunes available and everything is essentially bolt on. A little custom adaptation, but nothing very high tech. 

 

Given the constraints of the engine bay, which looks roomy but isn't where it counts, there is no doubt in my mind that the s/c is the best for making a nice cruiser. Given a more modern engine with variable valve timing, a more powerful computer and other modern aids, the turbocharger works extremely well as part of the whole engine package. Durability is probably a coin flip. A turbocharger is a very simple device and is easily capable of 100k miles or more as long as cared for properly. Over the road trucks are turbocharged, not supercharged, and the technology is the same. More moving parts inside and outside a supercharger.

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The bad behavior at startup has returned. A quick fifteen second disconnect of the negative cable to reset the ECM was no help. This probably wasn't long   enough so I am leaving the ground disconnected and going to the cottage for the weekend. Similar symptoms to previous; rough running and then stall. Smoky exhaust, check engine light flashing rapidly. I got about 170 miles on a tank of fuel, more than 1/2 tank indicated remains. I just don't get it. It seems like something in the control system, ECM, ICM? or something in the Memcal goes haywire after a certain amount of time. 

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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?

 

Any ideas Padgett?

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4 hours ago, Ronnie said:

Codes?

I will look after the weekend. I was rather irked that this keeps happening so I figured it's best to step away for a bit🙄

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