Gotcha.

Well looking back at my logs, here are my spark advance tables for the runs as well as a scan from the summer.

605s

103s

Summer


Looking at those tables and the log during WOT the spark advance seems to be pretty similar between all three, peaking at about 11-12 degrees during the run. Also here is the IAT spark advance table I currently have, I don't think I have changed this at all yet.


Yeah, I still want to do E85 so I might bump up how soon I buy the 60# injectors and get those in there to see if there is any change. I have read that big injectors struggle with low pulse width and some people have said 60# without E85 might cause idle problems but I don't know for sure. As for the plugs, do you mean throw a brand new set in, run a quick WOT then pull them and see? Would I be looking for differences between them? When I pulled the 605s which I had in since summer none looked different from the rest.



Hmm interesting. I don't know how much boost I was making since the MAP sensor on these cars gets maxed out

 

When I read post #48, I had the same thought as you. It sounds like something is wrong with one or more injectors. You could take them to a local shop and have them flow tested.

Something else you could look at while trying to diagnose this issue is misfires. I have all six cylinder misfire history PIDs open in my scanner.

One thing I noticed when I was looking at your spark advance table is you're running 35-40 degrees of spark in about half your table. That's about double the stock timing in those areas. Is there a reason for that?

You may have mentioned it already, but are you sure the knock sensors aren't going bad? Cause it seems like this issue is getting worse and worse over time.

 

I can see about having a shop flow test them, but if its going to cost more than $100 I might as well just buy new injectors, they've got 176k miles on them and I want to run E85 anyways.

How do the misfire history PIDs work? Right now the only misfire stuff I am logging that actually works is the 6 Misfire Current Cylinder PIDs. I tried making a misfire table but it doesn't work at all. I will say that at idle my Misfire Current Cylinder #4 occasionally reads 2, which for reference was coincidentally (or maybe not) the same cylinder that ate a sparkplug real badly in this thread https://montecarloforum.com/forum/en...k-plugs-61426/. I can hear and slightly feel a miss occasionally, although with the new plugs its less frequent. I had the old 605s at perhaps a bit too small of a gap and that might be why I had misses sometimes, or maybe its Cylinder 4 who knows.

No there isn't a good reason. TBH I'm not really sure the best way to tune spark in that regime, so its been slowly creeping up as I add a few percent to the whole table and then pull timing where knock occurs. I probably should go back and revert that left half to stock.

No, I'm not sure. Do you know of a way to test them? Last summer further up in the thread I put some race gas in and it cleared up the knock, although I only tested the WOT. The lower RPM high airmass region where I see knock climbing hills wasn't tested. It is real knock at WOT at least though. Back then I was focusing more on why my WOT timing needs to be so low, and well it seems like I need to drop it into the single digits after these tests this winter so something seems to be getting worse. For reference, if I pulled the timing out of my tune from these recent WOT runs I would have cells dipping down to 7-8° at WOT. That's why I'm suspecting injectors, since it makes sense to me at least that I could have one gradually having a worse spray pattern or even flowing less from buildup after all these miles. I'm far from a good mechanic though so its just a guess.

 

The way I have mine set up is just logging the misfire history for each cylinder, and the total misfires on the left where all the other PIDs are. I don't have a graph or anything setup. I have an intermittent misfire on cylinder five that I haven't found the cause for, but I'm going to be upgrading the ECU, coils, and spark plug wires here in probably a month, so if its any of those, I'm not too worried about it.

A quick google search on testing one wire knock sensors said to connect one lead of a multimeter to the knock sensor, and the other lead to ground. It should have continuity, and read more than 10 ohms. I would definitely try testing or replacing the knock sensors. They're about 55$ each new. Also, I don't know what your goals are with the car, but you can get 80lbs injectors for 20$ more than 60s off ZZP.

 

If you suspect injectors at all and planned to upgrade anyways, I wouldn't hesitate to throw the 60s in there. Should be zero issues getting the 60s dialed in to run fine on gas; 3800 folks have been doing it for a long time now (especially turbo setups that don't have access to E). I ran 60s from the day I swapped my L67 in (which at the time was a 3.4" M90 also on pump gas) and had no issues getting it to idle and run fine.

To your point, you could easily spend half their cost getting the existing ones cleaned and flow benched so it doesn't make much sense to sink much into them. About the only thing I'd bother with on the old injectors is swapping them around (if you happened to be able to isolate a specific cylinder causing the issues) to see if the problem moved or not.

There's a ton of info that can be gleaned from plugs depending what you're looking to learn. Given your issue seems to be at WOT, ideally you install them, make a pass, and then kill the engine before it gets back down to sit at idle.

Below is a pretty good article:

https://www.crankshaftcoalition.com/...ng_spark_plugs

One tricky part is that normal driving / idling can skew the appearance of the area used to read WOT. If they all looked identical though, it does make me a bit skeptical of uneven fueling unless its some kind of oddball problem that's only showing up at high rpm. You'd think any mechancial issue would be constant though and wouldve shown some kind of difference.

You're maxing out a 2 bar MAP on a 3.4?

I wondered the same thing before. But he stuck in race gas at one point and all knock went to 0. So I think that would rule it out as a malfunctioning knock sensor as it would have no way to know what fuel was in the car and should've continued to produce 'false knock'.

 

Yeah I think I'm just going to do that. I've finally graduated from college and have started actually making some money so I can afford them finally :P


Wow thats a good website, thanks! I don't know that I'll do that unless my issue doesn't clear up with new injectors, but its good info just in case.


Uhhh well going back and graphing my Manifold Absolute Pressure no I'm not, its reading correctly and maxing out at about 10PSI (~25.0 PSI absolute). The reason I thought I was maxing it out was because anything close to WOT immediately jumps into the furthest right column of cells, both in the spark table where the columns are MAF Cylinder Airmass and in the VE tables with the columns being Manifold Absolute Pressure. I don't have to be WOT, looking at the logs I reach these cells with only 50-60% TPS and higher. I've actually been wondering if that's normal and how exactly people tune WOT well on these cars because you can get very different conditions in that rightmost column. I guess maybe its just a problem with having such a coarse table?

Here is what I mean

Keep in mind I only really tested WOT cells, I didn't do much cruising up hills in the lower RPM and high airmass region, so that area could still be false, and I've got some pretty low timing cells in there as well as WOT. But yeah it did clear up the WOT knocking.

 

Could I take a look at your current tune file and the latest log file?

 

Sure, attached them.

 

Here are things I noticed looking at the tune and log files:

-The spark knock table only goes to 105kpa. Since you aren't trying to conform to your knock graph to your spark advance table which locks you into MAF Cylinder Airmass, you should be able to continue the y axis of the map reading in kpa. Cause all the knock info above 105 kpa is no longer useful really. You can't use that graph to directly copy/paste over to your base spark table, but it could help identify when exactly the knock is happening.

-To me, it looks like most of your knock is happening at part throttle/high load. Look at 6 mins and 45 sec into the log you attached. From there TPS increases from 9% to 42.7%, rpm barely claws its way from 1500 to 1700, MAP goes from 69kpa to 126kpa, vehicle speed doesn't really increase, timing advance is 31* at the start and goes down to 7*, and you get up to 5* of knock. I'm curious what the engine thinks its calculated load is at that point. You don't have it logged. This keeps happening up until your TCC unlocks. Then your RPM increases like you'd expect at 42% TPS



-I've never tried to read TCC Slip before, but in that log, at 6 min 47 sec, there's a spike of 2.5* knock, right before that, the TTC Slip spikes at 132 RPM while the TCC is locked. I really don't want to say that I found your issue, but that TCC smells fishy to me.

-Your wideband looks like its reading stoich, which makes me wonder why your LT fuel trims are showing lean. Try zeroing out your fuel trims, since I'm not sure if you ever have. To do so, connect to vehicle in the scanner with key on, engine off, go to vehicle controls and special functions. It's the little green power button. In I believe the tab is labeled fuel, if not, search around and there will be an option to zero out the fuel trims. You may have to adjust your MAF Calibration after doing so.

-Do you have an aftermarket boost reference fuel pressure regulator, or stock regulator from an NA or SC engine?

 

I'm not sure that I follow. My knock retard table is the same axes as my high/low octane tables in the tune, and that's where I have been taking knock readings and subtracting from the octane tables. My AFR error VE table has MAP readings in kpa, but it goes up to 140kpa, the same as my primary VE table in the tune.

Yeah that's the high airmass low RPM region I've been mentioning. It along with WOT is where I see knock, and the above mentioned race fuel test I did only verified the WOT cells as being real knock, I didn't go and test those lower RPM cells. That particular region at 6:45 is a hill climb with cruise control on. I can take it out and log calculated load in that scenario if that would be helpful. Further up in this thread, starting at post #39 we discussed unlocking the TCC earlier so I never enter those cells and bypass the problem. I did that and made the changes, but for some reason the car doesn't follow them when in cruise. Off cruise control nearly any small incline results in the TCC unlocking, but on cruise control it acts exactly as stock. Maybe there is a setting or a table I am missing for when the car is on cruise control, but honestly I am probably going to revert those TCC changes, I don't really like it locking and unlocking all the time with small TPS changes, and cruise control ignores my changes anyway. Plus, I don't really want to resort to just bypassing the problem altogether, I'd rather enter those cells and solve the knocking issue there.

I don't really know much about TCC slip either, but yeah I see what you mean. If its locked it shouldn't be slipping at all, right? If so a jump in slipping that corresponds with a TPS rise does seem a bit odd. Hopefully the TCC isn't on its way out Like I said above I am going to revert back to the stock TCC settings. It still knocked under them though so that's not the source of the problem.


That's a good catch, yeah I'll zero the trims and check my MAF calibration. I need to go back and tweak it a bit anyway, plus my VE table needs some work.

I'm honestly not really familiar with them but I haven't touched anything fueling related so its the stock one (if they even have one stock? Don't know anything about them )