Narrowband O2 signal drop out - Chrome ECU v2

[Dougal]

Looks like I have been able to answer the question of why i am getting knock by simply reading a post I created here a year ago!

Its my knock sensor signal that's causing this knock.

I don't have any knock sensor signal as i can confirm no continuity from the sensor ecu side harness to the ecu pin 58.

So basically without signal its doing a 7,8,9 knock count dance.

I have no CEL for this? Which is a bit odd but then again i did not have a CEL for the o2 sensor signal either.

Upon inspection of the knock sensor wiring i can see that its a white wire with a mesh grounding cover around it.

I need to ensure that this white wire signal to pin 58 and that the grounding mesh grounds to chassis ground so it does not suffer any interference on the way through to the ecu.

Somewhere on this wiring circuit there is a break in connection or a really poor ground that is causing me issues.

I have my fingers crossed on this now as i have been around and around with this car for a couple of years now and its killing me that its not running well with all the sensors and there specific nuances.

[Dougal]

Been doing a heap of reading up on this issue.

So basically with the lack of knock sensor signal the ECU will go into limp mode at approx 3000rpm (perhaps over 100 ecuload)

I should have a CEL coming up however I have a feeling that because I have the Chrome Mod CEL on knock turned off that this might be why my CEL light is not coming on.
I tried checking DTC's but no codes came up but i got a J2534 Read Error. (Might need to see if i have the most updated Evoscan version perhaps)

[Dougal]

Life is good again!

Knock sensor online.

Wow that took some trial and error in that the wiring was very bad. Found one of those crimp things on the wiring all green and dirty. plenty of gunk on it.

Did a resistance test from the sensor back to the ecu pin and all good. Re-grounded the outer shield stuff too.

Good knock sensor signal now.

Also updated to evoscan 2.9.0100 and DTC's came back with no codes all clear.

Next up is a test drive and we shall see if the 7,8,9 knock limp mode is gone.
knock voltage evoscan.jpg

[cobrakiller1994]

I have a problem with my front o2 dropping out sometimes. When its working my trims are bouncing close to zero. My lows and mids settle around 4 in the front an -4 in the back. Then my front o2 will drop out randomly and make the front trims peak to 12.5 messing everything up. I changed the front to a new denso sensor and today out cruising around did the same thing. Car seems to still run fine but then i checked my trims they were maxed out. I was thinking about running it off just the rear sensor but it seems like the front would run a little lean then since the rear bank is pulling some fuel while the front is adding some.

[Dougal]

My issues were quite severe. The knock sensor drop outs caused by sensor grounds in poor condition and having high resistance. That really screws the signals the ECU is getting. Drop outs common.

Probing the wiring to locate the bad wiring was difficult. My wiring harness has been hacked up alot. Its a 25 year old loom ripped out of a half cut that had spent time in a snowy paddock in Japan. Then it was bent,twisted and forced into my Magna. Im surprised it actually ran my car at all!

I'm running with only the rear o2 sensor activated in my Chrome v2 ECU as my motor is a 92 JDM GTO that only used one single o2 sensor placed after the pipes have merged positioned in front of the Catalytic converter.
Im not too concerned about slight variance between front o2 and rear o2 for trims.
If i was able to use and log both front and back it would be nice however based of my current STFT my LTFT low and mid trims datalogged I know my tune is in the right region within 5%+/-
The more I fine tune them via MAF Smoothing the closer my actual Wideband AFR matches my High Octane Fuel table at various load and RPM point.

I think if your getting within 5% trims your in the area for both banks to be working well. Try switching to rear o2 only. Check your wideband as you go and see how the car reacts on idle and cruising.

How are you adjusting fuelling for your tune?