Chasing a lean spike I get at WOT followed by knocks ("84 Crossfire Vette, 383 Stroker, Renegade, 80# Inj, VRFPR @ 28psi, EBL ECM,). Nothing I do seems to have any affect on the spike which occurs momentarily from a standing stop WOT action. In fact increasing AE time and strength has a negative impact on 0 to 60 times and added a second lean spike shortly after AFR enriching, go figure. Anyway, I noted the injector duty cycle % are 50% or less during the initial leaning out event. Duty cycle increases rapidly there after and AFR's shoot up from 16:1 to ~10.5:1. Thinking I've got to those injectors working harder at the initial moment of WOT- right? How do I do that? BPC values? VE tables? __ ? Have jacked VE's that also seems to have a negative impact on performance. BTW overall I have it running rich and am reluctant to drop it because of the knocking... Graph - (Before AE jacking)

 

Follow up - Well looking at the spike it appears momentarily to start enriching then leans out fast. Told it's the thirsty Renegade surface area which requires a good shot of petrol at the lower KPAs and that makes it an AE fixable issue. Tried that and it resulted in poorer performance and no improvement in the leaning. . Below is spreadsheet that illustrates the values I'm playing with. The "USE" column represents the attempted BIN value fix while the "Gold" column represents the baseline. Green highlights, I believe, are the operating areas where things go bad. So, just soliciting some advice from anyone who has been down this road before. Also wondering if my vacuum referenced fuel pressure regulator is contributing like in not reacting fast enough. Maybe I should try running it without the vacuum function. Jump in, cuz I'm running out of things to try... Thanks.

 

What stall is your converter?

GD

 

2500

 

You don't have enough AE to get up against the converter. RPM's are climbing much higher than stock and there's not enough AE to support this. I have a 3000/3500 10" converter and I had to add about 500% more AE and use the filter tables to both increase/adjust the AE size, duration, and delay. If it bogs then you have too much AE too soon. It needs what it has now but at the start but it is running out so you need to make the AE last longer. Also double check that MAP AE is working for you - I don't know about the cross-fire, but if you are running it in "port" mode to accomplish the cross-fire tuning there is a bug in the EBL that has been fixed..... it was causing the MAP based AE to zero out in port mode operation. If that applies to you RBob has a fix for it.

I needed a surprisingly large increase in AE PW and AE duration. And remember the AE tables are based on PW not corrected for injector size so do your injector size corrections to the PW tables first.

GD

 

Thank you, will do and post results.

 

"And remember the AE tables are based on PW not corrected for injector size so do your injector size corrections to the PW tables first."

Not sure how to approach this since I'm not sure what injector size the baseline values represent in my BIN. My baseline is from a borrowed BIN of a similar set up that ran the best.

I did however play with AE values, initially I aggressively doubled the uSEC times and cut the filters in half. Resulted in bogging with minimal TPS ~ 15%. Then created three bins with incremental adjustments of 10% up to 30% (decr on filters). Similar bogging occurred with the lowest (10%) incremental BIN @ ~25% TPS. Baseline BIN runs the best but still gets that lean spike. Laying out side by side comparisons on a spreadsheet for analysis right now.

Also tried something else - went back to my baseline BIN with the base AE values and aggressively raised the VE values in the higher KPAs (60+). VE's were set at near 100% at 95 KPAs. Still got the spike but this move reduced the knocking considerably. In fact only got two knock counts on three standing WOT events and that just on the first one - after that no knocks. Did experience some poor running though in certain areas.

Still chasing.... jump in... comments welcomed. Thanks.

 

Went back and double checked my BIN values to make sure the values I wanted ended up in the right BIN found some glitches which may have skewed the results - fix in progress will post results. Unfortunately it's pouring here... so no test runs today.

 

Values corrected but issue remains the same - a lean spike with subsequent knocking.

Below is a snapshot of my log. I really need help understanding those AE values. Seasoned tuners are telling me to jack AE's unfortunately the slightest (5%) increase to the TPS AE's results in bogging (too much fuel) and playing with MAP AE's doesn't improve the leaning event. Wondering if there isn't a mechanical issue behind this??? Recommendations? Thanks.

 

That much pulsewidth is over double your high rpm fueling pulsewidth which is showing very rich. I think you got wayyy too much ae and its drowning spark. You are reading a false lean. Thats what it looks like to me

 

Thanks. So, back-off PW's... That would explain bogging with the slightest increase. Suggestions on where to start ? Like drop both TPS and MAP values 20%? More?

BTW - would that also cause knocking?

 

Orr has a good thought on the AE. I was thinking that the fuel pressure may be dropping off due to the high demand.

As for the knock, that may be due to tire spin setting off the ESC system.

RBob.

 

Not sure how much to drop it but i would certainly try it. Overly rich may create some knock counts. But those counts are occuring well after the ae event it seems. The timing retard may just be from being rich but i would leave timing in and keep coming down on ae to see what the wideband does

 

The knocking does not seem to correspond to the lean readings. Since the O2 is going to lag any lean knock events being downstream in the exhaust it does not look like the lean condition is causing the knocking.

It might be false knock - the way it goes up and back down and then up again..... if that were real detonation at WOT like that, the detonation would tend to continue and get worse till you backed out.

GD

 

Good feedback.. thanks. Will post....

 

Adjusted AE's @10% and 20% reductions (increase on filters) - still getting the lean spike. Here's comparisons of the log data. I tried to line it up by similar TPS and MAP deltas. All are at 100% TPS from a standing stop a moment into the event. Should I continue to drop AE's? MAP vs TPS differently?

 

Try the opposite, lower the filter values to extend the duration of AE. Along with lowering the AE TPS & MAP PW tables. The lean spike is lagging the throttle opening, which points to the AE ending too soon. And with too much AE at the initial throttle opening.

After trying that, can try changing the launch mode (LM) SA table: SA - Launch Mode

With the high stall speed converter it may be helpful to add SA via the LM table to bring the engine up against the converter faster.

RBob.

 

Thanks - will do and post. Detoured - Chasing bad reading speedometer issue right now.

 

Well, well this is where I left things last year. Appreciate everyone's time and input. Speedometer fixed this year turned out to be a bad VSS and now O2 sensors are working properly so I'm back on this nasty lean spike and knocks. Will post results of tweaks as suggested above...

 

Make sure in the main fuel map you are ramping in the fuel in the transitional areas where the ECU will rapidly sweep through the map..... so low RPM and high MAP.... when rapidly opening the throttle the ECU will shoot up through the MAP values but the engine RPM hasn't caught up. You need to ensure that there is enough fuel in these transitional areas. The opposite area of where the WOT is - similar MAP values but low RPM. That is the first line of defense against rapid throttle opening enleanment.

See in your logs how you are at 1000 RPM and 97 MAP? What does that area of your fuel map look like? I am betting that area is insufficient. You are getting AE (a TON of it by the looks of the PW... probably far too much). But when the AE runs out, you are still too lean in the 1000 to 2500 RPM high MAP area of your fuel table. Remember that area is only going to be used for transition to WOT.... you don't cruise at 97 MAP...... so adding fuel here is going to help you a lot I think.

GD

 

Assume main fuel map = VE tables?

 

Here's my VE Table @ High KPAs and Low RPMs - Is this where you are suggesting I add VE? Jack it 50% or less?

 

Yeah exactly. It wants more fuel.... in that column for 100 kpa try adding 20% more fuel and see what it does. Just +20 the whole column from 900 to 2400 and see what happens. You're engine probably breathes significantly better, revs faster and higher due to the higher stall than what that map was designed for.

GD

 

Raising VE's in those areas did not help. I'd say I jacked em a good 30 to 40% (was before I saw your 20% recommendation). One thing I noted during this logging was the knocking did not come into play until things got rich - low 12's and 11's, so definitely looks like rich knocks. I'm going to continue to play with AE per above suggestions and see what that does. As always I appreciate all suggestions and your time.

Snap shot of what's going on now -

 

So where it's 15.3..... I wouldn't be worried about that number as the engine is essentially under no load. All of those data points from 1162 to 4600 RPM are occuring in *less* than one second based on the time stamps. Don't worry about 15/16 AFR during the run-up against the converter. It's almost unavoidable. Mine still does a little of that but it's not an issue in practice. You can't feel it and the engine is perfectly happy.

The "knocking" isn't happening till over 3k..... what stall is your converter?

It's not going to knock from being that rich. The AFR's are good. Mid-high 12's are good. Shouldn't be detonating at that. Pull 10 degrees up there - does the knock go away? What's your timing? I don't see it logged. Remember good heads need less timing.

Get a couple 5 gallon cans of C16 and make sure this isn't false knock. Can you hear it? Is it showing up the spark plugs? Mine has false knock also and I just ignore the knock sensor. Unfortunately that's all too common with built engines. Too many loud engine components, headers, etc.

GD

 

2,500 stall. A while ago when knocks started I found silver specs on the plugs. Had me convinced they were real. What confuses me though is sometimes I get no knocks under the exact same conditions. I run Shell 93 octane exclusively.