Wow, that's a very odd one, I can't believe more than one guy is seeing this. The problems I have seen with the CAS doesn't look anything like that, it will put a vertical spike in the RPM when it goes back, not a back and forth type movement on the log. Wish I could help but if there is no misfire, I do not think it's CAS related.

 

I have seen similar things when logging a 1g ecu and I always assumed it was an issue with logging speed and/or precision since I can't log one of those bricks but a tenth of the speed of an evo ecu.

 

if that log is displayed in a line graph i bet the rpm plot will have low spots and the rest are clean.

 

its my vehicle and im at 102000 miles. I can say during that particular log it felt and sounded like a misfire but the odd thing is the plugs i put in like i always do br8es are fresh maybe 250 miles and i gap to .023

 

Yes, RPM is the parameter that's acting up. Below is the data vs time.

Ah. Since this isn't happening at lower loads, it sounds like this could be a simple issue of breakup. The lean fluctuations at the point of RPM flutter suggest this as well. You might want to try gapping down the plugs to something tighter (0.020"?) and relogging the last tune. Let's try that before going down the dying CAS road any further.

 

I can see the AFR blips and timing in that area is bit jumpy too, looks like it is breaking/misfire up in those areas...

 

will do THANKS mrfred

 

Inco9nito99 was referring to my car. Here’s a small snippet from a second to third pull in my car. My car “fuel cuts” in between quick shifts, and I’m wondering if I have a failing cas issue (?).

• Notice the fluctuation of rpm’s at 100% throttle (1).
• Notice the a/r (2) – I double checked the water/meth with the shop that installed and it works fine.
• Load also seems to fluctuate (3).

So I’m curious if this is a possible latency issue (I run 780cc injectors – not sure what brand, but I set them to Delphi 780cc latency values), or a faulty cas issue.

Any thoughts.

 

Kunal and Vernon, this might sound like a silly question, but is NLTS active on the car? (I'm guessing you're still running 96530006?) That looks exactly like what I'd expect if someone left their foot slightly resting on the clutch after a shift: bouncing RPM with a 0ms IPW, ie. fuel cut.

Perhaps try disabling NLTS and seeing if the problem goes away?

 

 

Ed, you were right, NLTS was my issue. I feel silly cause I asked Kris for that setting - stupid me. Lesson learnt.

 

Mrfred, did you ever find the cause of this issue? I am experiencing the same thing with a car now. When it happens it feels like fuel cut some of the time and sometimes you can't tell it is happening until you look at the log and see the rpm drop as much as 1000 rpm in the space of 0.2 seconds. Sometimes it results in very high knock counts, as the timing jumps also.

I assume it is crank or cam sensor related.

 

Yep, my intake cam position sensor was going bad. Life was good again after replacing it.

 

Ok thanks. This car is a IV, so no Mivec, but the exhaust cam sensor plug looks pretty dodgy.

I would have thought however that CAS would be responsible for the rpm signal though.

 

I think the cams sensor is still needed for sync. If there are no obvious fuel or spark problems with your Evo, I suggest swapping out the cam sensor. Its easier than the crank angle sensor.