V1 Mikes Extended, Full Frame Goblin - 2009 Cobalt LS with 135k donor

[Robinjo]

How

I don’t see how moving the wheels out could change the stability much.

Alignment, better bushings in the rear control arms, adjustable eps, maybe rear sway bar.

The wider the track, the lower the amount of weight transfer. This means more grip. If you only widen at one end, then that end will gain traction and the other will not which changes the handling balance.

 

[Desert Sasqwatch]

Being stable on throttle and squirrely off throttle is indicative of an alignment issue. More specifically your toe, probably in the rear, is changing from okay when accelerating and cruising, but is probably changing (mostly likely toe out - more one side than the other) when the weight of the car shifts forward under deceleration. Did you change out the rear control arm bushings, replaced the donor rubber ones with something better? Is the rear tie rod crossbar installed in the correct orientation? Correcting for this changing suspension geometry issue must be addressed before going for any additional suspension/handling improvements - doing these first will exacerbate the problem.

 

[mike_sno]

So, I took the Goblin out for another drive, this time 2nd O2 Sensor behind the catalytic converter and the MAF Sensor worked. I want to say first I thought the knock would be reduced too, but looking at the log, it is still the same. I almost can reproduce the condition when the engine gets knock retard. It happens when I am off the gas pedal, below 2200rpm and get slowly on the gas. Like when I hit the point where the engine is not slowing the car down, but also not accelerating it. Also it fells like this power/no power oscillating when I get on the throttle is reduced a bit.

I noticed a new noise from the engine. Not sure how to describe it. Sounds like a snake when I am on half throttle.

Overall I wanna say I felt much more confident in the tune. It's the GM Stage 2 tune with some minor changes to idle rpm. It is not running lean anymore under WOT.

I noticed that my duty cycle for the Injectors are sometimes over 100%.

Question: How much knock is acceptable, if at all.

 

[mike_sno]

Being stable on throttle and squirrely off throttle is indicative of an alignment issue. More specifically your toe, probably in the rear, is changing from okay when accelerating and cruising, but is probably changing (mostly likely toe out - more one side than the other) when the weight of the car shifts forward under deceleration. Did you change out the rear control arm bushings, replaced the donor rubber ones with something better? Is the rear tie rod crossbar installed in the correct orientation? Correcting for this changing suspension geometry issue must be addressed before going for any additional suspension/handling improvements - doing these first will exacerbate the problem.

I guess I have to buy some aluminum and check it. I did not changed anything yet on the suspension. Was planning to buy the moog bushings but never did.

 

[Rauq]

Question: How much knock is acceptable, if at all.

I will occasionally see a degree or two if I'm actively tuning (clarification below), but stable tunes should be dialed back a little bit so that you should hardly ever see a degree when driving around. Make sure your knock sensor is clean and securely installed or else it may read knock when there's isn't any.

Then again, I'm not sure if it's my motor or LSJ's in general, but I actually see a decent bit of KR on shifts and quick throttle blips. It's like it's overly sensitive in highly transient situations, so my charts are typically filtered out to not log when the throttle is moving rapidly. The filter is [50090.156.slope(250)]>-0.1&[50090.156.slope(250)]<0.25 meaning only show when the rate of change in throttle position for the last 250ms is between -10% and 25%

 

[Robinjo]

Is the snake sounds just the intake sucking in air? It's right behind your head and is easier to hear when the SC isn't whining, like under normal load conditions. I hear mine the most when I'm just cruising at 50-60 mph.

 

[mike_sno]

Is the snake sounds just the intake sucking in air? It's right behind your head and is easier to hear when the SC isn't whining, like under normal load conditions. I hear mine the most when I'm just cruising at 50-60 mph.

Yes, I think it's coming from the intake. But it wasn't there when the MAF did not work. I will try to make a video and see if its possible to hear it. I hear it during normal driving, not WOT,...

 

[mike_sno]

I will occasionally see a degree or two if I'm actively tuning (clarification below), but stable tunes should be dialed back a little bit so that you should hardly ever see a degree when driving around. Make sure your knock sensor is clean and securely installed or else it may read knock when there's isn't any.

Then again, I'm not sure if it's my motor or LSJ's in general, but I actually see a decent bit of KR on shifts and quick throttle blips. It's like it's overly sensitive in highly transient situations, so my charts are typically filtered out to not log when the throttle is moving rapidly. The filter is [50090.156.slope(250)]>-0.1&[50090.156.slope(250)]<0.25 meaning only show when the rate of change in throttle position for the last 250ms is between -10% and 25%

Might be that this is the same for me. However, does it really matter when the engine is knocking? Is knock = knock or Is knock in certain situations less tow worry about than in others?

Just made a drive and logged the knock. I think due to the head being decked my engine is a bit more prone to knock. Will substract those values from the Sparc Advance high octance table.

Question how does the ECU know if it's a high octane or low octane fuel?? What decides which table is used?

 

[Rauq]

Might be that this is the same for me. However, does it really matter when the engine is knocking? Is knock = knock or Is knock in certain situations less tow worry about than in others?

It's not actually knock. The knock sensor is just a fancy sound sensor and the ECM interprets the vibrations it picks up and assesses whether it thinks it sounds like knock. The theory I read is that while it's pretty good at detecting the sounds of knock, or even the sounds that signal that knock is imminent, it's also fooled by highly transient states like a quarter-second throttle open-close-open cycle like you'd have on a shift. I guess it'd be worth clarifying that we're logging knock retard, or KR, and not actually knock. When we log KR, it's the computer saying it's pulled back X degrees here because it either thinks it heard knock or thinks it was going to.

Question how does the ECU know if it's a high octane or low octane fuel?? What decides which table is used?

I think excessive and pervasive KR leads the computer to switch from high to low. It will also use the low spark table with a MAF error.

 

[mike_sno]

Update from today. I stopped by at a racing fuel store and bought 100octane fuel. 5Gal for $90... oh well, its for the sake of diagnosis. Have not yet tried it, but getting more and more familiar with VCM Editor, Scanner,... Target for the moment, getting knock out of the system as good as possible.

I pulled back on the timing quite a bit. See pictures before.

I stopped by a local tuner and asked him if he would tune my car. He said yes, $800. Had done some slingshots before. He mentioned a few things:
- My current timing would be high for the boost.
- I should get rid of the cat and replace the exhaust with 2 bullets in series( I guess like the motorcycles have them?) I have never heard bullets, but google finds some. Cat and exhaust would not help getting the heat out of the engine and work against the SC.
- I should use NGK 3690 Sparc Plugs and gap them with a special gapping machine (which I have to buy of course) to 0.24 (What the hell a Sparc plug has to do with knocking, I don't know...)
- He asked if I had solid motor mounts. I don't. He is against them.
- Increased CR does not help at all... (Already knew that )
- He said Knock filtering should be increased ( I told him that's cheating IMO)
- Lastly he said best chances would be converting it to E85 (only). He mentioned immediately that the ECU would not allow that and that the tune had to be done in a way that it's at the lower range of the spectrum. Means if I get lower grade E85 that should be tuned for, if I get better the engine would just run a little rich. For that I needed 80lbs injectors and another fuel pump. I believe he mentioned 450 with an unknown unit.

All in all he said the odds are against me. To many factors are of disadvantage.

I will try the 100ocatane fuel at some point and see if that reduced the knock. IF I used the filter from Rauq some of my cells are not even filled.

I wanna say that the car was running smoother if that make sense. I might pull back a bit more on the timing and try to reduced the other factors to my advantage.

Attached my last logfile. Could someone of you post a logfile of a good running LSJ? That I have something to compare?

This is the LSJ Standard tune RPM over Airmass and Knock retard:

This is where I ended for the moment.

This is the how much timing I pulled back of the high octance sparc advance table in compare to the standard tune:

 

[Ross]

I keep a list of LSJ tunes in the first post of my build log... look for "Engine tuning resources". Turn your phone so you can see this post in landscape, then click on my signature line.

 

[mike_sno]

I keep a list of LSJ tunes in the first post of my build log... look for "Engine tuning resources". Turn your phone so you can see this post in landscape, then click on my signature line.

Just checked, I was looking for a log file. But the tunes are also very helpful

 

[Ross]

Oh, sorry, no log files... unless they are in the threads that the tune file was in.

 

[Rauq]

Did you ever verify that your MAF is fully functional? Your spark tuning is based off cylinder airmass calculated from the MAF only. Try creating a new Math Parameter like the below so you can tune for spark with Dynamic Airflow instead.

I don't think it works exactly per this explanation, as in there's other things going on behind the scenes that we can't see with an LSJ/P12 ECM, but as effectively as we can control it: the ECM meters fuel according to cylinder airmass. It has two strategies to calculate cylinder airmass, MAF and VE. MAF is fairly straightforward in reporting the airmass passing the sensor. VE fueling uses a combination of MAP, IAT, and volumetric efficiency (a percentage of the ideal fill of the cylinder achieved). On top of that, when Dynamic Airflow is enabled (restricted only by an RPM limit in the tune), the ECM uses some combination of MAF and VE to calculate cylinder airmass. I believe other ECMs can tell you how much of which strategy or the other are being used, but we can't. Furthermore, as far as I've been able to tell, what the ECM is reporting as Dynamic Airflow is what is being used for fueling, even if you've exceed the Dynamic Airflow High RPM limit set in the tune. So, under that threshold, if MAF is 10 g/s and VE Airflow is 9 g/s, then Dynamic Airflow should be 9.5 g/s... and the difference between 9.5 g/s and what it actually reports is unknown to us, but the ECM is metering fuel for a (9.5g/s / RPM / 60)*2 cylinder airmass. Again, theoretically, above the Dynamic Airflow High RPM limit, if MAF is 20 g/s and VE airflow is 18 g/s, then Dynamic Airflow should be 20 g/s... even though it doesn't always work out that way.

I'll add to that thought, fuel trims are one thing that skew Dynamic Airflow away from the actual average of MAF and VE Airflow.

All that to say, create a Math Parameter like below and either update your KR graph accordingly, or clone your KR graph and then update the new one for use with Dynamic Airflow. Normally I'd say I don't think you've hurt anything spark tuning with MAF only, but given that you also had MAF issues, I'm not sure where that lands you. Worst case scenario, you're removing spark advance in areas that don't need it because of lack of accuracy in your MAF curve. Ideally you'd tune for MAF and VE before spark tuning, but I understand the necessity here.

 

[Rauq]

I stopped by a local tuner and asked him if he would tune my car. He said yes, $800.

A little steep IMO but dealing with unknowns has a price. Worth it I guess if they actually straighten everything out.

- I should use NGK 3690 Sparc Plugs and gap them with a special gapping machine (which I have to buy of course) to 0.24 (What the hell a Sparc plug has to do with knocking, I don't know...)

If that's based off his experience, then that's great. ZZP, CobaltSS.net, and my experience all point to the NGK BKR7E being a great plug for mildly to well built, no further gapping needed. The wrong spark plug heat range, gap, and reach can all lead to hot spots/preignition or misfires, so they're not wrong that spark plugs and knocking can go together.

- He asked if I had solid motor mounts. I don't. He is against them.

Theoretically solid mounts can create more false positives on the knock sensors. Counterpoint, Goblins are built for solid side engine/trans mounts, and if you have rubber front/rear trans mounts, it increases stress on the side mounts. I don't think anyone's had issues with that yet, and I doubt they will, but it's just kind of the nature of the beast of a tube frame car.

He said Knock filtering should be increased ( I told him that's cheating IMO)

You both make valid points, however if we can raise knock thresholds then we can be more sure that the knock we're seeing is real and needs to be addressed. I touched on that earlier referencing a filter in the graph based on throttle position rate of change. I'll circle back to that in a second.

- Lastly he said best chances would be converting it to E85 (only). He mentioned immediately that the ECU would not allow that and that the tune had to be done in a way that it's at the lower range of the spectrum. Means if I get lower grade E85 that should be tuned for, if I get better the engine would just run a little rich. For that I needed 80lbs injectors and another fuel pump. I believe he mentioned 450 with an unknown unit.

42# injectors are definitely on the small side for an E85 tune, but I would be speaking outside of my experience to recommend what's appropriate. I will recommend you don't run 80# injectors without a boost reference fuel pressure regulator... and you see where this is going. I would estimate I've made mid-high 300s on a stock LSJ fuel pump and 80# injectors. I don't know the rating on a 2.2L fuel pump. I'm in the middle of an install of a 340lph fuel pump right now. I may have a stock LSJ or a compatible upgraded fuel pump available for you if you want one of them for cheap. You definitely don't need a 450lph pump.

 

[Rauq]

This is from a while back, compare these two graphs, with filtering:

Without filtering:

That 21° KR in the upper left of the second chart? That's hitting the throttle to get the RPMs up to start moving at a green light, indicated by the vertical white line in the chart and the current data readings. And the lower right cells in the second chart, 1.8-3.2 ish, is almost entirely in the area of chopping the throttle to make a crisp shift. You can see a little bit of that on the right side of the chart below. After this log, I pulled a degree out in the 0.64 cylinder airmass and 2800 RPM area. Pulling timing in the idle areas or because of KR caused by quick throttle cycling just isn't a priority.

 

[Gtstorey]

I'm not sure I would trust that tuner. I would definitely do some digging on his history first. Anytime they immediately point to different spark plugs and "special gapping" machine, I would get worried. Compare your heat range currently to what he recommends. If it isn't off by several steps, I call BS. Yes being off a lot can cause problems, but a step or two isn't likely to cause problems. And unless I'm missing something, you shouldn't "need" to go to E85 to get this to run correctly. You might have to pull some timing and keep it rich under boost, but shouldn't require it. And if it does, I would seriously think about going back closer to stock setup first unless you never plan on traveling outside of your home area. Without an E85 sensor, there will be a lot of places that you won't be able to get it, and you will be filling it up a lot.

 

[mike_sno]

Did you ever verify that your MAF is fully functional?

No, I was/am nervous that I had to much bad knock and needed to get that some sort of under control. But I have reason to believe that the sensor is ok and just needs to be calibrated. It's my understanding that a not MAF calibrated sensor leads to high short and long term fuel trims, which is kind of an on the fly calibration. Not ideal, but can life with that for the moment.

Worst case scenario, you're removing spark advance in areas that don't need it because of lack of accuracy in your MAF curve. Ideally you'd tune for MAF and VE before spark tuning, but I understand the necessity here.

That was my target for the moment. And tuning the MAF without having a wideband seems to be sub optimal as well.

$800 might also be the price if no competition is around Decking the head was a 2h drive to get it done! Florida is not Moresville NC.

I currently use this spark plug, just got them a couple of days ago. https://www.rockauto.com/en/moreinfo.php?pk=6276816&cc=1433737&pt=7212&jsn=3 Are they good to go or should I get the one you recommended NGK BKR7E ?

The part numbers for the 2.2L and 2.0L Fuel pumps are different, at least on Rockauto. So let me know what you have.

Regarding the graphs @Rauq are those numbers the maximum numbers? I can't see that on this snipping. Will study my log files now again. I know that I have a lot of the knock when switching gears, when I applied one of your filters It was reducing it also quite a bit.

 

[Rauq]

No, I was/am nervous that I had to much bad knock and needed to get that some sort of under control. But I have reason to believe that the sensor is ok and just needs to be calibrated. It's my understanding that a not MAF calibrated sensor leads to high short and long term fuel trims, which is kind of an on the fly calibration. Not ideal, but can life with that for the moment.

If you've not gotten a P0171 or P0172 then it's possible you're not too far off (outside of PE ranges). Not a top concern at the moment.

I currently use this spark plug, just got them a couple of days ago. https://www.rockauto.com/en/moreinfo.php?pk=6276816&cc=1433737&pt=7212&jsn=3 Are they good to go or should I get the one you recommended NGK BKR7E ?

From what I can read, an NGK 6 and Denso 20 heat range are comparable and are hotter than NGK 7 and Denso 22. I can't say whether it will solve anything, but ZZP, Intense, OTTP, and others use a plug with a heat range one step colder (NGK 7/Denso 22) than stock with their LSJ Stage kits.

Regarding the graphs @Rauq are those numbers the maximum numbers? I can't see that on this snipping. Will study my log files now again. I know that I have a lot of the knock when switching gears, when I applied one of your filters It was reducing it also quite a bit.

Yes those were the max numbers.

 

[mike_sno]

I tried to use the search function first, but it does not give me the answer I am looking for:

I am trying to get the alignment better, that I can make 4th gear full rpm range runs without ending in the ditch. I measured my rear axle toe in and calculated it to 0.963 degree for each side. I can't find what it should be. I saw some post and youtube videos talking about 1/8in. My question is what is 1/8in referring to? OR what should the toe in be?