When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
My awesome tuner was able to pull off 449 hp and 403 lb ft. today on the dyno.
Had some issues almost immediately with the head bolts for ground not being fully tightened, possible poor injector performance through old 42# green tops, and the car running terribly rich (~10 AFR or less) and burning through spark plugs. We think the richness has contributed to the oxygen sensors going bad and not reading as they now don't read at all, so the numbers have been through open loop on the oxygen sensors.
The car has: *Everything in signature Plus: *Stock MAF
*FAST 36# Injectors
*Racetronix Fuel pump (I have the Hotwire & Ground but it is not installed yet)
*Removed AC (not from firewall)
Edit: Yes, stock clutch & rear end. And no, I don't race it lol
You had Green Tops before? Did you change the injector data? IFR at least? You can easily tune around it, but it seems like you might have been on the old tune for a while and it was running way rich?
Nice numbers btw. Probably more honest than a lot of numbers you see. 450 with a big cam, FAST, and ported heads isn't terrible. With the stock rear, you should probably make a little more... so the issue may be with your clutch. Could be slipping.
You had Green Tops before? Did you change the injector data? IFR at least? You can easily tune around it, but it seems like you might have been on the old tune for a while and it was running way rich?
Nice numbers btw. Probably more honest than a lot of numbers you see. 450 with a big cam, FAST, and ported heads isn't terrible. With the stock rear, you should probably make a little more... so the issue may be with your clutch. Could be slipping.
Thank you! Yes, green tops, apparantly an older style and they may or may not have been working properly. Yeah, I was on the old tune too long and it fouled out the plugs (twice) and possibly the oxygen sensors. I will need to buy new O2's, so if anyone has any suggestions!
Originally Posted by scotty2000ss
Nice numbers and set up. Maybe I missed it, but what gears are in the car?
Thank you! Stock gears, 3.73's. I didn't really want an aggressive tune anyways, so it's not too bad. Good enough for me!
Originally Posted by HCI2000SS
Great numbers!
Thank you!
I think I want a smaller camshaft though. It bucks/surges when you let off the throttle or at partial throttle. I'm not sure if that's because the oxygen sensor's are in open loop or what. I will be considering a cam swap to a smaller cam that doesn't have 19 degree's of overlap like mine does now. Maybe BTR Stage II?
If it were me I'd rule out the possibility of a tuning issue first. If that doesn't solve it then I might look at a cam that's still fairly aggressive though since you still want that awesome power I'm sure. That's just my opinion
My cam is right around 15 degrees overlap if I remember right and I get no surging or any of that
Lol just learn to drive around the surge. Gotta be quick with the clutch and throttle. Also, 3.73s never came stock in an f body. And maybe you haven't washed the cylinders down yet lol. But otherwise great numbers!
Maybe. But the camshaft is just so large, ya know? I wanted the power but wasn't aware of the poor drivability resulting from that.
Hey man, My cam has 22° of overlap. I have 3:90's in a M6 on stock 241's. Made 403/358 and traps 115.xx through a Fast 92/92. Man do I love it at the strip. Here's what I don't like...
1. 10 miles a gallon - I get about 160 miles out of a full tank. I think I got 190 when I did a little more highway driving.
2. Surging @ or below 1350 RPM's. - Even with 3:90s I can't really use 6th gear unless I'm going 70. Otherwise it will surge a little bit and it's annoying as hell.
3. Wear on the valvetrain - I'm not certain on this but I think I need to get the springs tested every 10,000 miles before I get into trouble.
Now people have told me driveability will get better with a bump in compression but, is that actually true? I dont know...
With all this being said, I love the power/sound the cam puts out but, if I had to do it over I would have went in the 228 range with a solid roller.
For those with surging... are you surging with throttle engaged or coasting? Typically, there are two kinds of bucking - surging with light throttle or when you take your foot off to speed match a car in front of you.
If it surges with slight throttle, you need to reduce the timing in those cells. Big cams hate timing at low load/low rpm. 20-22 degrees is what you need there. The lower timing helps force the car to rev up to compensate for the reduced power.
If it's bucking on decel, you are either running rich in your tune (if DFCO is disabled), if close loop is enabled, your O2s may not be switching properly or fast enough, or your follower table is adding too much airflow. Big cams and headers wreak havoc on O2s and you may need to spend some time tweaking the closed loop fuel adder tables. The follower table is a bit tricky to tune. All of it is related.
Greg Banish sums it up here:
Keep in mind that RAF and throttle cracker airflows are based on whatever airmass estimation you have coming from either filtered MAF or dyn_air (speed density VE or equations). ANY error in either of these models will make RAF and throttle cracker calibration that much more frustrating.
Taken a step further: Since most people aren't developing their air models based on actual flow bench data, but rather based on wideband feedback, the errors mentioned above will also now include wideband error and mismatches in the fuel injector values. This includes IFR, short pulse adder and offset.
Yes, you read that right. If you tuned your MAF and VE based on wideband feedback but didn't use the absolute correct short pulse adder or injector offset, it can make tuning the RAF and throttle cracker difficult. This is why it's so important to start with ALL of the right values for the actual injectors being used.
This may or may not be the case here, but it's one of the first questions I'd ask before getting too deep into trying to correct something that may not actually be wrong! Always make sure the fundamentals are 100% correct first.
So, if you didn't play with your injector data, that could be an issue.
I've found you can tune your VE around the wideband with no injector data. And the car will run fine. But it's the little things, like decel, cold starts, etc, that are off.
For those with surging... are you surging with throttle engaged or coasting? Typically, there are two kinds of bucking - surging with light throttle or when you take your foot off to speed match a car in front of you.
If it surges with slight throttle, you need to reduce the timing in those cells. Big cams hate timing at low load/low rpm. 20-22 degrees is what you need there. The lower timing helps force the car to rev up to compensate for the reduced power.
If it's bucking on decel, you are either running rich in your tune (if DFCO is disabled), if close loop is enabled, your O2s may not be switching properly or fast enough, or your follower table is adding too much airflow. Big cams and headers wreak havoc on O2s and you may need to spend some time tweaking the closed loop fuel adder tables. The follower table is a bit tricky to tune. All of it is related.
Greg Banish sums it up here:
So, if you didn't play with your injector data, that could be an issue.
I've found you can tune your VE around the wideband with no injector data. And the car will run fine. But it's the little things, like decel, cold starts, etc, that are off.
Jake, it will both buck/surge on light throttle and no throttle. When I'm in first or second, especially. It's terribly annoying and I'm already looking at smaller, more streetable cam profiles. Even when the clutch is pushed in, it will oscillate RPM's when coasting to a stop between 700ish-1200 (idle 900). But then again, I do have two bad oxygen sensors and they both need replaced.
If you're in Open Loop, the O2s aren't doing anything (hence open loop). I would recommend you run it in OL for the time being. Set your Closed Loop enable to 285 degrees to disable CL.
Once you get in running in open loop, lean out the idle some more 400-800-1200 cells, and zero out the follower tables up to 1600 RPM.
To lean it out, park it and let it idle. Play with the bi-directional controls (if you have HPT) and see where the idle improves. Turn off adaptive spark, and add .5 to the 14.7 number until it idles clean (and your MAP number starts to drop - adding timing also helps here - you may need 28-32 degrees at idle with that cam). However, as you lean it out, you'll notice you have no throttle response. Start reduced the number by .1 at a time (say you're at 16.1... reduce to 16 and so forth) until it's still clean and you have throttle response. If that number is 15.5 in the tune, then 14.7/15.5 is the number you need to multiply your VE table by in the 400-800-1200 cells (.95). Then you want to smooth into your next few rows in the 1600 and 2000 columns. Reflash and see if it does better. You're running rich on decel if you're bucking.
Also, like I said, you need to reduce timing as well if you're bucking on light throttle. I have a cam with 16 degrees of overlap, and I don't buck anymore. Getting the VE dialed in down low, adjusting the follower table, running in OL, and reducing timing all helped. See below for my timing map (notice the 1400-1800 RPM cells in the lower airmass areas):
Last edited by JakeFusion; 05-12-2015 at 10:41 PM.
Run it in open loop, lean out the idle some more 400-800-1200 cells, and zero out the follower tables up to 1600 RPM.
To lean it out, park it and let it idle. Play with the bi-directional controls (if you have HPT) and see where the idle improves. Turn off adaptive spark, and add .5 to the 14.7 number until it idles clean. You'll notice you have no throttle response. Start reduced the number by .1 at a time until it's still clean and you have throttle response. If that number is 15.5 in the tune, then 14.7/15.5 is the number you need to multiply your VE table by in the 400-800-1200 cells (.95). Reflash and see if it does better.
Also, like I said, you need to reduce timing as well. I have a cam with 16 degrees of overlap, and I don't buck anymore. Getting the VE dialed in, adjusting the follower table, running in OL, and reducing timing all helped. See below for my timing map:
Is there anyway to show this to my tuner without coming off as rude? I would assume he would do what you've suggested already and that the lack of driver-side O2 sensor is what is limiting him from a more proper tune. And thank you so much for the help!
If it's in Open Loop, the O2s aren't doing jack. Set the CL enable to 285 degrees if he hasn't. The O2s should be off at idle anyway with a cam that big. They don't read right at idle.
And this is why I tune my own stuff. You're at the mercy of a "tooner" and not a tuner it sounds like.
If it's in Open Loop, the O2s aren't doing jack. Set the CL enable to 285 degrees if he hash't.
And this is why I tune my own stuff. I ask questions. I get advice. I experiment. I learn. I built the car and tuned it myself. Then you know exactly what has been done to it.
I'm just wondering if when they're in closed loop, the surge would go away.
No, the surge would probably get worse. You have to play with your CL O2 settings (switch points, fuel adders, etc). But you're bucking because the timing and A/F are off. At least mine gets worse as my car prefers to be leaner than stoich at idle and coast down/light load. I do run in a hybrid mode tho where below 1600 I'm in OL and above, I'm CL. You do that with your PE table.
05-11-2015, 10:51 PM
1999 LS1 H/C/I 449/403 on Dynojet 
