Cobb Stage 1 Engine Knock Issues

[TurboTJ]

I installed a Cobb stage 1 91 octane map and now there is engine knock. I can hear it when accelerating at wide open throttle and I log over 7 counts of engine knock on cylinder 3. Has anyone else encountered this? Does anyone else monitor knock after installing the Cobb?

it’s a 2019.

 

[SRPRACING]

Your gas may not be the best if your getting that much knock. When was the last time you checked your spark plugs?

 

[TurboTJ]

Your gas may not be the best if your getting that much knock. When was the last time you checked your spark plugs?

I’ve gotten the same results with two different tanks of gas from king supers and She’ll.

the truck just hit 10k so I’ve never checked the plugs.

 

[Chris Mies]

Contact Cobb. They are super helpful.

 

[COBB Tuning]

Feel free to send in a datalog of the issue for us to review. As previously mentioned, this is likely related to fuel quality, but we can double check a log to rule out any other potential causes. In the short term, the octane adjustment feature of the ECU should dial back timing and boost at WOT to accommodate for the inferred fuel octane.

For reference, we recommend that customers run fuel from gas stations that adhere to the Top Tier fuel standards. We also recommend that customers avoid ethanol-free fuel and stick to E10 blends. Assuming fueling meets these requirements, the engine may benefit from the installation of a catch can to avoid oil consumption. Oil vapors will have a drastically lower effective octane when they recirculate through the intake system, and a catch can will cut down on the volume of oil entering the combustion chamber.

 

[TurboTJ]

Feel free to send in a datalog of the issue for us to review. As previously mentioned, this is likely related to fuel quality, but we can double check a log to rule out any other potential causes. In the short term, the octane adjustment feature of the ECU should dial back timing and boost at WOT to accommodate for the inferred fuel octane.

For reference, we recommend that customers run fuel from gas stations that adhere to the Top Tier fuel standards. We also recommend that customers avoid ethanol-free fuel and stick to E10 blends. Assuming fueling meets these requirements, the engine may benefit from the installation of a catch can to avoid oil consumption. Oil vapors will have a drastically lower effective octane when they recirculate through the intake system, and a catch can will cut down on the volume of oil entering the combustion chamber.

What parameters should I log? It appears that I am getting knock across all cylinders from my drive across town just now even though I was avoiding hard acceleration.

Should I switch to the 87 octane map until I can get a fresh batch of fuel in there?

Also, is there any way to verify that the ECU is retarding timing? The knock octane modifier is still at 1.000.

Thanks for all the information!

 

[COBB Tuning]

What parameters should I log? It appears that I am getting knock across all cylinders from my drive across town just now even though I was avoiding hard acceleration.

Should I switch to the 87 octane map until I can get a fresh batch of fuel in there?

Also, is there any way to verify that the ECU is retarding timing? The knock octane modifier is still at 1.000.

Thanks for all the information!

Just use the default log list - it will be pre-configured. If you have already changed up the logging list, you can just reset to defaults.

Seeing some knock at low-load cruise is normal. The factory tunes ign. timing in these load and RPM ranges to be as efficient as possible, which means that sometimes knock will occur. As part of our commitment to maintaining factory-levels of efficiency and emissions quality, we typically leave these ranges of engine operation unchanged.

The key monitors to watch will be Knock Octane Modifier (KOM), Ignition Timing Corr. Cyl. 1-6, and Knock Count Cyl. 1-6. Note that most of these are actually not included in the default log list, as we have implemented a few custom monitors to take up less of the total datalogging "bandwidth". Ign. Timing Corr. (Lowest) is selected in the default log list, and will report the numerically lowest ign. timing correction of all of the individual cylinders. Knock Count Total is also selected in place of individual cylinder monitors to provide a cumulative count of knock events across all cylinders.

Note that ign. timing corrections can be both positive and negative. As we report these values, negative will imply that knock events are occurring, and positive corrections will generally indicate that knock is not occurring, or is only occurring to a small degree.

The extent to which ign. timing corrections go negative, combined with the load and RPM range at which this occurs, will determine whether or not a change is made to KOM. It will take a larger negative correction to drop KOM at light load cruise than it would at WOT, for example.

It definitely can't hurt to switch to the 87 octane map for the remainder of this tank of fuel, but without seeing a datalog of the engine's current state on the 91 octane map I can't speak to the urgency of this. Ultimately, some engine knock is to be expected. The ECU is equipped with the tools to adjust engine operation for knock, and we trust in that system to be on the conservative side.

 

[TurboTJ]

Just use the default log list - it will be pre-configured. If you have already changed up the logging list, you can just reset to defaults.

Seeing some knock at low-load cruise is normal. The factory tunes ign. timing in these load and RPM ranges to be as efficient as possible, which means that sometimes knock will occur. As part of our commitment to maintaining factory-levels of efficiency and emissions quality, we typically leave these ranges of engine operation unchanged.

The key monitors to watch will be Knock Octane Modifier (KOM), Ignition Timing Corr. Cyl. 1-6, and Knock Count Cyl. 1-6. Note that most of these are actually not included in the default log list, as we have implemented a few custom monitors to take up less of the total datalogging "bandwidth". Ign. Timing Corr. (Lowest) is selected in the default log list, and will report the numerically lowest ign. timing correction of all of the individual cylinders. Knock Count Total is also selected in place of individual cylinder monitors to provide a cumulative count of knock events across all cylinders.

Note that ign. timing corrections can be both positive and negative. As we report these values, negative will imply that knock events are occurring, and positive corrections will generally indicate that knock is not occurring, or is only occurring to a small degree.

The extent to which ign. timing corrections go negative, combined with the load and RPM range at which this occurs, will determine whether or not a change is made to KOM. It will take a larger negative correction to drop KOM at light load cruise than it would at WOT, for example.

It definitely can't hurt to switch to the 87 octane map for the remainder of this tank of fuel, but without seeing a datalog of the engine's current state on the 91 octane map I can't speak to the urgency of this. Ultimately, some engine knock is to be expected. The ECU is equipped with the tools to adjust engine operation for knock, and we trust in that system to be on the conservative side.

Thanks for all the information. I’ve spent a decent amount of time tuning Evo’s back in the day so I definitely appreciate all the detail you posted

Audibly, it sounds like unmistakable engine knock which is what has me so concerned. I can’t hear engine knock under any conditions other than WOT at fairly high RPM’s so I don’t know about the lighter load knock (it could possibly be phantom knock). Also, I never heard engine knock on the stock tune. Once I get down to the lower quarter of my tank, I’ll throw in some octane booster to see if the knock goes away and switch to top tier gas next tank.

I’ve already taken quite a few data logs with the default parameters. I will post them tonight.

Thanks for all the help!

 

[COBB Tuning]

Thanks for all the information. I’ve spent a decent amount of time tuning Evo’s back in the day so I definitely appreciate all the detail you posted

Audibly, it sounds like unmistakable engine knock which is what has me so concerned. I can’t hear engine knock under any conditions other than WOT at fairly high RPM’s so I don’t know about the lighter load knock (it could possibly be phantom knock). Also, I never heard engine knock on the stock tune. Once I get down to the lower quarter of my tank, I’ll throw in some octane booster to see if the knock goes away and switch to top tier gas next tank.

I’ve already taken quite a few data logs with the default parameters. I will post them tonight.

Thanks for all the help!

Roger that - send 'em over to [email protected] and PM me your email address so that I can find the message and review the logs ASAP.

 

[TurboTJ]

I picked up some octane booster on the way home to see if it was in fact real knock. Driving about 15 miles since then, the knock is *completely* gone. Most cylinders have a knock count of zero, some have a minor knock count of 1. This means it was not “phantom knock” and was the real destructive form of engine knock.

This leads to two possible conclusions - I have filled with bad gas on two occasions from two different gas stations or the stage 1 map has too much timing advance for local 91 octane gas.

It’s possible I got bad gasoline twice but at the same time, I’m disappointed the tune isn’t more resilient to that. We drive all over the continent in these trucks and fuel options will vary. This makes me wonder if I need to go back to the stock tune.

Will report back when I know more.