Hey guys, so I think I finally have got my tuned dialed in correctly. I went and did a few 1/4 mile pulls, using HPTuners Track Addict to time them, and I'm coming up pretty slow, right around high 14s to 15.0. Something clearly isn't right, as my car with the mods I have on it shouldn't be that slow. I was wondering if anyone familiar with HPTuners could take a look at my tune and see if you notice anything wrong. I've got timing adjusted so I'm not knocking, my only guess right now is that maybe I am running rich and losing power. I tried leaning out a bit, but it didn't seem to make any difference and I wasn't comfortable going leaner until I heard what you guys thought. I plan on taking it to a dyno and doing some runs there to compare to my previous numbers when I got my dyno tune done, but I want to see if I can fix it before I pay to do a run on the dyno. Any advice?

Edit: I also added my latest scan

 

Dont use HPT, but I've got a few questions:
-What are you actually seeing for max WOT timing?
-How about boost? No belt slip or anything?
-Whats the 1/4 mph you're seeing?
-Whats the wideband AFR at WOT?

TBH, assuming the ET is accurate, that seems even slower that your previous dyno graphs would've indicated. I'd have expected pretty low 14s at high 90s with the numbers you had before.

I wouldn't worry about trying to gain power by leaning it out. Unless its single digit AFRs, you're not really going to gain noticeable power going from say 11 to 12.

 

My WOT timing is between 8-9 degrees and I'm seeing about 10.5psi for boost according to my MAP readings. I'm not sure if there is any belt slip, what would be a sign of that?

As for my 1/4mph, I don't remember off the top of my head, and the track addict app is crashing when I try opening old runs so I'll have to go do another pull when its not raining.

My AFR starts at 0.85 EQ / 0.82 Commanded at the start of the pull and goes as low as 0.79 EQ / 0.78 Commanded. I agree that it is slower, assuming the app is correct. I have slips from the strip when the car was stock that were 15 flat, so either the app is just off, or something isn't quite right.

Something I should mention is that after my dyno tune last summer, I had a longer glasspack installed, and I distinctly remember a kind of grainy, static-y sounding exhaust sound coming from what sounded like behind the lower dash area when WOT. I thought it was just a tiny leak somewhere, but as I was tuning timing, the less knock I had, the more the sound went away until I was left with no KR and a smooth sounding WOT engine note. It seems as though what I was actually hearing was KR the whole time, and I remember it becoming apparent when I got the longer glasspack installed. I'm wondering if that glasspack didn't affect my tune enough to cause KR and the source of all of my problems like the melting plugs? If it did, I'm wondering if maybe my exhaust flow is being restricted and I'm losing power because of it.

 

Wow, that timing is REALLY low. Is that necessary to keep it knock free? Theres definitely some power to be picked up there once you get things straightened out.

Belt dust around the pulley, erratic boost levels.


Couple things on this-

First, is this all commanded AFR or actual via wideband?

Second, TBH I had no idea what EQ was as I use AFR or lambda. I looked up a conversion chart and this topic of the HPT board makes .8 ish EQ = to almost 18:1 AFR (which is clearly impossible as the engine would've melted down on the first pass)

https://forum.hptuners.com/showthrea...Eq-Ratio-Chart

Is that post wrong or am I not reading one of the two right?



At least that's an easy theory to test. I'd just drop the catback, grab some earplugs and go for a few rips to see how it responds.

 

Yeah, anything higher and I knock on 91 octane. Would I be making more power with a larger pulley and bumping up the timing? What range should I be looking to be in?

I haven't noticed anything, and my MAP reading stays fairly constant so I don't think that is an issue.


The first number I gave, the EQ ratio, is the wideband reading and the commanded is what lambda the tune is commanding. You've got the ratio backwards, you should multiply lambda by stoich to get the AFR, so in my case I start out with the wideband reading 12.5 and ending the pull at 11.6.

See I would do that but everything from the downpipe to the tips are welded lol

 

Wow, what size pulley? I thought you had quite a few mods too, so I'm surprised to hear that.

I'd probably either pulley up one step or add some mods to let you run more timing. The upside to going to a larger pulley is that the blower gets more efficient. You'll lose some boost, but you'll gain power back with more timing and a cooler air charge and usually make more power than by running more boost and tanking the timing.

Ideally, I like mid-upper teens for timing. 20+ seems to have limited gains, so it's not worth pushing that far on this platform IMO. But I'd definitely do something to get that timing up higher without knock.

That's a good sign. It would be apparent something was wrong if it was slipping on the MAP.


Ah, I knew something wasnt right, lol. Those AFRs seem good though.

Wow, that's got to be tough to deal with. Being you suspect something wrong in the exhaust, I'd be real tempted to grab the sawzall and hack it off somewhere logical. Then when you go to weld it back up, just stick a flange in there. Or maybe add a cutout if that was on the future mod list?

 

Yeah I do my next mod on the list is an intercooler. I have a 3.4" pulley on a ported blower. That's why I'm wondering if its an issue with the glasspack restricting the flow. Its a 2.5" louvered core, 24". I might have a shop cut it out and weld in flanges for a 2.5" resonator instead.


Yeah I didn't think there was anything wrong there.

 

Yikes, scratch going to a larger pulley then. That's really unusual to have to crank timing that low with as many mods as you've got. I see why you're thinking there may be a problem, like with the exhaust or something. I get some cars are more knock prone than others, but I'd expect to be able to run full timing on a 3.4" with all the stuff you've got done.

Curious - do you still have a cat? Is it possible its starting to plug up (perhaps from a previous issue)?

 

I do have a cat, its the ZZP hi-flow one on their 3" downpipe. I installed it summer of 2017, so its about 3 years old at this point. Do they plug that fast? Does detonation make them plug up faster?

 

I just ran some 1/4 pulls, trackaddict is reporting im running 15.5s. I don't know that I trust the app to be super accurate, but that is far too off for me to explain it by the app being wrong. I cleaned the air filter but that didn't help anything. I'm not sure where to go from here, I suppose my first step might be having a shop cut the 24" glasspack I have out and seeing if that clears it up. I don't think its the cat being plugged because it runs fine, no choking or bogging down or anything, it just doesn't seem to be making much power.