High load low RPM KR and strange tune

[The_big_dill]

Hi all,

New to this platform, freshly rebuilt engine, have been doing a lot of reading.

I am running an OTS map for now (I know, they are far from ideal), but I have to run something with my mods: SRI, TIP, DP(catted),HPFP,VTCS delete,EGR,ACT FW. I am working on getting a custom tune.

1. Part throttle I see KR hover between 1 and 8 regularly, but only under low load. IF I step on it and go to red line, KR is always 0. I understand this is not a huge concern (fuel economy).

My concern is on the highway, I was in 6th gear and went WOT (high load, low rpm), KR was averaging 5: have a look at the logs.

2. Staring cold, once the RPMs settle (~10 seconds), my idle is kinda rough. Sometimes shakes the whole car (slightly). Vacuum, AFR and FP all look good. I imagine the tune can do this, but wanted to share the logs here to see if anyone sees anything abnormal?

Once the car is warm I can barely hear or feel the engine running - occasionally it will have a very slight stutter when warm, but this is likely the tune.

Thanks!!

Phil.

[SaveMelMac]

Don’t boost in 6th gear cruising or under 3k rpm. Low rpm and boost= unnecessary stress on the engine.

[The_big_dill]

Originally Posted by SaveMelMac Don’t boost in 6th gear cruising or under 3k rpm. Low rpm and boost= unnecessary stress on the engine.

I am not saying I plan to go full throttle in 6th at low RPM, but sometimes I need to pick up some speed on the highway, and I will end up demanding high load, low RPM conditions from the engine. When I do so, the KR will be pegged at 8.

I am more interested to understand if this may point to other problem area and if I should just ignore it.

[MSMS3]

Downshift to 5th or 4th. I would not go WOT in high gear unless I was going at least 100 mph. Downshift so your rpm puts you up in your fat power band. Going light throttle acceleration in 6th above 3,000 is fine though.

Show us a log like the others but 3,000 to redline in 3rd or, preferably 4th. I’d like to see if you have knock there. What fuel are you running? Do you have access to 93 or ethanol.

[The_big_dill]

Thanks for the replys guys, new to the platform.

From my understanding the car will pull timing for fuel economy under partial throttle, correct? (very low load I regularly see 6-8 KR)

(assuming the above is true), If go WOT typically I see the KR go to 0 all the way to red line. However, if I give it moderate load, It will decay the KR but slowly. One solution is to let off the gas and then re-apply and it goes back to 0 KR.

Any thoughts, is this normal?

Have a look at the log, pay attention to where I let off the throttle and re-apply it

[Vansquish]

That isn't quite accurate. The car will add timing for fuel economy reasons. It will do so until it reaches the knock threshold under part throttle conditions. Once the knock sensor detects knock, the car will start to pull ignition timing gradually until the knock disappears. Once the knock has dissipated, the car will start adding timing again.

This is entirely normal behavior. You should expect to see substantial amounts of knock at part throttle under normal driving conditions.

[The_big_dill]

Originally Posted by Vansquish That isn't quite accurate. The car will add timing for fuel economy reasons. It will do so until it reaches the knock threshold under part throttle conditions. Once the knock sensor detects knock, the car will start to pull ignition timing gradually until the knock disappears. Once the knock has dissipated, the car will start adding timing again. This is entirely normal behavior. You should expect to see substantial amounts of knock at part throttle under normal driving conditions.

I see - I have been searching around and there are all kinds of theories on PT KR. This makes sense though.

I should be able to confirm this by comparing logged ignition advance vs. the ignition map.

I also noticed that it follows the minimum load KR active map. Does anyone have experience with working with this map? I imagine it isn't advisable to mess with it, but am curious if this is a "safe way" to change when the ECU goes into this ign advance strategy.

[whatsabrooklyn]

are you referring to Lspi with the engine knock?

[The_big_dill]

Originally Posted by whatsabrooklyn are you referring to Lspi with the engine knock?

Not sure what you are referring to with Lspi?

[whatsabrooklyn]

One of the reasons behind breaking rods and ringlands

this link may help

[Jeff23spl]

loading the car in 6th gear before 3000rpm is one of the best way to destroy your engine.

for your rough idle cold, i would check for leaking injectors...if your remainint hpfp pressure isn't increasing and stay high for a while when you just shut down the engine is a good sign. and check plugs too...colder plugs doesn't like cruising around

[The_big_dill]

Originally Posted by whatsabrooklyn One of the reasons behind breaking rods and ringlands this link may help

Thank you it does. Lots to learn!

Originally Posted by Jeff23spl loading the car in 6th gear before 3000rpm is one of the best way to destroy your engine. for your rough idle cold, i would check for leaking injectors...if your remainint hpfp pressure isn't increasing and stay high for a while when you just shut down the engine is a good sign. and check plugs too...colder plugs doesn't like cruising around

Thank you for your info. I understand that low rpm High load is undesirable for these engine set ups. I just found it hard to believe that the manufacturer would allow damaging engine operation with just a push of the pedal. I guess the phenomenon wasn't understood at the time.

For my rough idle, I have been noticing it has been getting worse with cold, but I do not think it is a tuning issue, it seems like a mechanical, I will be posting a thread for that in the correct section of the forums with all the relevant details.