Excessive KR

[Lostneye]

Car was running great on the OA tune. Lately it was feeling a little sluggish and after plugging in the X4 OAR was down. Lock it in 5th or 6th and it will add timing and OAR comes back up, could be 20 minutes or 2 days without issue before it happens again. Driving hard seems to have no affect, it usually happens when I am tooling around in traffic. Plugs are a couple months old with maybe 5k on them. Checked knock sensor wiring, no viable issues, added plastic flex loom on it no change. Stock tune it well see some KR occasionally but not enough to drop OAR, it's been -0.96 after the first drive after flashing it back to stock. Have an appointment at the dealer next week after waiting a month to be able to get a loaner but the issues doesn't seem to show up without the tune so not sure what they will be able to do.

How much KR is normal? Where do I look next?

 

[SaveMelMac]

Is it part throttle KR or WOT KR? Part throttle kr is normal

 

[krewat]

What octane gas are you using?

 

[Lostneye]

93. Have tried mixing 2 gallons of e85 in while tuned with no change that I can see.

 

[Lostneye]

Is it part throttle KR or WOT KR? Part throttle kr is normal

Doesn't seem to happen at WOT only part throttle. Not enough to drop OAR stock but will drop on the tune and depending how often as it's intermittent will bring it down to basically 0. If I'm watching a can immediately try and replicate can have not be able too, the car will add timing and OAR will creep back up until the next occurrence.

 

[b4black]

I found that aftermarket tuners switch the KR from Global to Per Cylinder. I monitor KR using an Aeroforce gauge, which only displays Global KR. With the aftermarket tune, I wouldn't/couldn't see any KR ever.

I set the KR back to Global so I could see what's happening as it happens instead of waiting for the OAR to change.

Can you back off your global timing a degree or two to see if the KR goes away?

 

[Lostneye]

I found that aftermarket tuners switch the KR from Global to Per Cylinder. I monitor KR using an Aeroforce gauge, which only displays Global KR. With the aftermarket tune, I wouldn't/couldn't see any KR ever.

I set the KR back to Global so I could see what's happening as it happens instead of waiting for the OAR to change.

Can you back off your global timing a degree or two to see if the KR goes away?

Not sure what Matt does, I will have to look further. I am flashing back to the AO tune and sending a log to GH.

 

[15SHOPP]

...you do realize the negative ignition correction on the X4 is actually positive correction, right?

Just how OAR is best when it’s a negative number, ignition correction is best when it’s negative (while monitoring on the SCT devices)

 

[SHOdded]

Check misfire counts and fuel trims.

 

[Lostneye]

...you do realize the negative ignition correction on the X4 is actually positive correction, right?

Just how OAR is best when it’s a negative number, ignition correction is best when it’s negative (while monitoring on the SCT devices)

Yes thanks. -0.96 OAR and typically adding timing with heavy throttle on stock tune. With the tune it randomly pulls a bunch of timing and drops OAR closer to 0.

 

[SHOdded]

could still be a partially bricked PCM or a knock sensor going bad, if a new tune file does not fix the issue. suggest pulling the connectors off the PCM and giving them a good look, cleaning & greasing, then reconnecting.

repeated tune revisions to the pcm has been known to damage them before.

 

[Angrymongoose]

I know I'm reviving a thread here, but how/did you get this fixed?

I just got my AO tune last week. Put it in and OAR started at -0.96, some knocking, all at part throttle, took it down to -0.50 over the course of a few days. I checked the plugs yesterday and made sure all the gaps were good, but then they only had like 300 miles on them anyway.

I just flashed her back to stock tonight and in a 10 minute traffic filled drive it had plenty of negative knock and the OAR started moving in the right direction again. Ill be emailing Gearhead with a datalog from when it was tuned and a datalog from the stock to see what they say.

Since it's the weekend though I don't expect anything till Monday. Figured I'd see if you had a solution.

 

[SM105K]

Negative KR on your SCT device is adding timing gentlemen. If you are seeing positive KR then timing is being pulled.

 

[Angrymongoose]

Yeah... I know. I had positive KR thats why my OAR went from -0.96 to -0.50

 

[b4black]

What fuel are you using?

 

[Angrymongoose]

93 Octane for all of this. When I very first loaded the tune I had just filled up with 93, and had about 1 gallon of 91 in that tank. It has been 93 ever since.

I thought about going and trying a few gallons 100 or 104 with the 93 to see if that helps. However since returning to stock has eliminated nearly all the knock I don't think it was the gas.

 

[Lostneye]

It’s not resolved. I did send a log to Matt. As it seems worse at part throttle/light load he’s convinced it’s either the knock sensors/sensor harness or metal on metal contact/rattling causing false readings. I poked around didn’t find anything loose that could be rattling and also zipped tied up the harness and tired to tied other wires hoses away so they are not touching without any real change. The car is under warranty but between a death in the family and the long wait for a loaner car it took a while to get it there. The dealer did not find anything wrong in the two days they had it. It can be pretty intermittent and OAR came up to -0.79 and has been there for a week. I am confident it is false readings and will end up just changing the sensors after the holidays or break down and just pay my local mechanic to do it.

 

[Angrymongoose]

Thank you for that. I'm going to send in my logs as well, but given that your issue is nearly identical to mine I'm hoping one of us stumbles on an answer soon.
Ill poke around and look for loose/rattling things. Ill see what he says next week, but Ill just plan on having to replace the knock sensor.

 

[b4black]

Don't replace the knock sensor if it doesn't knock on the stock tune. That's a clear indicator that the system is working.

 

[76FoMoCo]

so I had the same thing and had O KR until I put the AD trans mounts in. going to pull them on the next trans oil change to see if it corrects it as it is winter and I drop the e30 to 93. have added 110 gas and e30 to the mix well above what would be needed for the KR to drop and no change. the mounts are the only thing different.