I was going to post this in the Adaptronic section but figured id get more feedback here. I finally got my car running again after 5+ years and I have been encountering an odd issue. The car runs and drives perfectly fine but randomly power will just cut out for a fraction of a second. It almost feels like you let completely off the throttle and back on. This will maybe happen 3 or so times out of an hour of driving.

I happened to catch this anomaly while datalogging for my tuner and dug into the problem a little more. According to the log, the ecu is losing rpm signal completely, which is followed by a lean spike in the AFRs, which would be normal if it thinks the engine isn't running. Thinking it may be the CAS at fault, I replaced it this weekend but I'm still having the same issue. The wiring harness is all new but I will be doing a continuity check between the CAS and the ECU when I have time.

Ive searched endlessly and did not come across anyone having an issue like this. I'm curious if anyone has any possible ideas on possible causes. Here is what the log reads; green is RPM, red is AFR.

S5 t2 streetport running on Adaptronic 440 select universal, stock cas, new engine wiring harness.

 

Combination ecu ignition circuit design and ecu firmware related..nippon denso 24+2 CAS has the 2 tooth triggers very close to the 24 tooth main trigger..toyota 3rd gen. supras , mr2's have issues also using the denso 24+2+2 CAS..aftermarket ecu's are not filtered/ optimized like the stock ecus.. adaptive circuits utilizing max 9926 IC's are supposed to be the best circuit...going to a crank wheel like a 36-1 is probably the best solution.

 

I understand the cas may not be perfectly matched for the ecu but there are thousands of FCs running this same hardware with no issues. That would be a last ditch effort for me; I would prefer to address a fixable issue on the current setup than go with the costly FFE trigger wheel and have to change the wiring all around.

Troubleshooting methods ive tried so far:

-replaced crank sensor
-replaced harness side connector for crank sensor
-tested continuity between cas connector pins and ECU
-regapped cas internal sensors
-confirmed case wiring is shielded to prevent EM interference

Next chance I get I'm going to also check for any continuity between cas wires and between the cas grounds and chassis in case of a short. Aside from that the only other idea I would have is running entirely new wiring from the ecu to the sensor.

 

The adaptronic forum would be your best bet to help get the issue sorted. there are a lot of factors to eliminate like the wiring harness...I just recently went for a ride in an S4 FC running an adapronic...Guy claimed to have no sync. loss issues but he was running a factory engine harness running along the original factory run location..Factory wiring harness is very well shielded. Does the adaptronic have any diagnostics ..like giving error codes for syn. losses? With megasquirts people have to run either a resistor or capacitor between the G+ and G- wires plus all 4 cas wires need to be separate all the way to the ecu and the cas shield ground at the ecu only .Unlike the S5 which combines the 2 Ne and G grounds before the ecu..these are just some things to think about .

 

Thanks for the reply. Unfortunately I've discovered that my ECU doesn't have the oscilliscope function and most of the other troubleshooting features the newer modular ECUs have. There is a 'trigger error' channel in the logging software, but it shows no change during the time the issue occurs.

I have been working with Adaptronic customer service and an Adaptronic FB group for ideas as well. Electromagnetic interference keeps coming up as a possible cause. I am currently using some 8mm MSD superconductor plug wires and a few people have raised suspicion about them, so I decided to swap them out with a cheap oe replacement set off Rock auto. Once I get them and install ill report back.

 

I tried installing the less aggressive spark plugs today but the issue still remains.

 

What about the condition of the CAS connector on the harness side? They are getting fairly old these days.

Is the CAS wire shield grounded only at the ECU end?

 

Thanks for jumping in Aaron. As far as I can tell, there are no cracks in the insulation or anything obviously sketchy about either of the CAS I tried. I did reject one that I bought off a guy on FB marketplace that had some pretty serious insulation holes upon inspection, so I do know what you mean.

As far as the shield grounding, I just pin probed the shielding and verified that it does have continuity to the same ecu sensor ground terminal that the 2 CAS grounds connect with. There arent any grounds coming off the engine side of the harness nearby so I'm fairly certain the shield is only grounded on one side, though I cant 100% verify without cutting apart the harness. I just purchased all the materials I need to replace the complete length of CAS wiring from the ecu the sensor. Should have everything I need by next weekend.

One thing I did notice when replacing the connector is that the guy who built my harness used 3 wires of the shielded core the entire length of the wiring, then right before the cas connector, he did a Y splice for both CAS grounds. I had read somewhere that certain ECUs like megasquirt needed the grounds to stay separate for the majority of the wiring length. Is this an issue for the Adaptronic? Either way I plan to run the new wiring in this fashion.

Also hoping someone can drop some knowledge on me as far as the proper grounding of shielded cable. Im quite clear on the fact it only grounds at one end, but Ive heard a good deal of conflicting information about the proper location of the ground. A number of people including my buddy who does a fair amount of motorsport electronics says the 0v ref/sensor ground on the ECU end is the correct place to ground. Others, including one proclaimed aerospace electrical engineer says that it should ground at the location where the most amount of electrical interference is generated, which in an automotive application would be the engine block. Is there any potential issue with tying electrical noise from the shielding in with the reference ground for critical engine sensors?

 

Well unfortunate update here. I replaced all of the cas wiring this weekend (new connector, new shielded cable grounded at the eco sensor ground only) and the problem still persists, so at this point, it has to be an issue with the ECU itself.

I bought it brand new when I started my build 4-5 years ago so Adaptronic won't do anything for me or even look at it because it's an outdated model. Pretty disappointing to hear and I'm now out $2k and countless hours. I will most likely pony up the money for a Haltech and will not be recommending Adaptronic to anyone in the future.

 

Yeah I think we all have a little bit of a bitter taste from Adaptronic right now