Why am I running so lean?
Thread Starter
Safety Car
Joined: Apr 2008
Posts: 3,908
Likes: 10
From: Charleston SC
Why am I running so lean?
I took the car to get dynoed today. I've been wanting to do it since buying it this past Christmas. Over these few months I've noticed that it smells very rich, and other people have confirmed that. Plus it leaves a trail of (black/blue) smoke at high rpm WOT runs. I figured the catless exhaust, ring blow-by, and rich tune might be causes..
But to my surprise, the car is actually quite lean! Ugh! I've been driving it quite hard since I bought it...wish I had known..
What could it be? Gasket? Vacuum leak? Tune?
I'll be taking it to a tuner sometime this week to get checked out..but input is appreciated.
Car:
'01 Z06, 35K miles, Halltech CAI, Tune, Bellanger Tri-Y headers, no cats, SLP Powerflo, catch can.
Conditions: Weather was cool, slightly overcast, probably 75*. Columbia, SC. Dynojet, SAE corrected. Dirty air-intake filter..
Here's the second run, which was slightly better, but not by much:
But to my surprise, the car is actually quite lean! Ugh! I've been driving it quite hard since I bought it...wish I had known..
What could it be? Gasket? Vacuum leak? Tune?
I'll be taking it to a tuner sometime this week to get checked out..but input is appreciated.
Car:
'01 Z06, 35K miles, Halltech CAI, Tune, Bellanger Tri-Y headers, no cats, SLP Powerflo, catch can.
Conditions: Weather was cool, slightly overcast, probably 75*. Columbia, SC. Dynojet, SAE corrected. Dirty air-intake filter..
Here's the second run, which was slightly better, but not by much:
Race Director
Joined: Mar 2001
Posts: 11,405
Likes: 26
From: Whippany NJ
CI 6-7-8-9 Veteran
St. Jude Donor '08-'09
NCM Sinkhole Donor
Yeah need more fuel in that sucker! Has it ever been tuned by anyone? Id stay away from WOT till you get her dialed in properly. The 01s always had a ring flutter problem. 
Also, maybe the fuel filter is clogged? When was the last time you changed it?
Also, maybe the fuel filter is clogged? When was the last time you changed it?
Last edited by Ikester; Apr 3, 2012 at 08:34 PM.
Thread Starter
Safety Car
Joined: Apr 2008
Posts: 3,908
Likes: 10
From: Charleston SC
I have been doing many WOT runs since Christmas...hope I haven't damaged anything..
Fuel filter is possible..I haven't messed with it, but bought the car with 28k miles. Where is it located?
Race Director
Joined: Mar 2001
Posts: 11,405
Likes: 26
From: Whippany NJ
CI 6-7-8-9 Veteran
St. Jude Donor '08-'09
NCM Sinkhole Donor
Yes, I believe the previous owner had it tuned...hence no codes or lights without cats..
I have been doing many WOT runs since Christmas...hope I haven't damaged anything..
Fuel filter is possible..I haven't messed with it, but bought the car with 28k miles. Where is it located?
I have been doing many WOT runs since Christmas...hope I haven't damaged anything..
Fuel filter is possible..I haven't messed with it, but bought the car with 28k miles. Where is it located?
Last edited by Ikester; Apr 4, 2012 at 12:08 AM.
Thread Starter
Safety Car
Joined: Apr 2008
Posts: 3,908
Likes: 10
From: Charleston SC
I've driven for 3 months like this without knowing, hard, WOT, autox, etc...how would I be able to tell if it has negatively affected the engine?
Last edited by Birdman; Apr 4, 2012 at 01:29 PM.
Thread Starter
Safety Car
Joined: Apr 2008
Posts: 3,908
Likes: 10
From: Charleston SC
As mentioned, it is tuned by previous owner(s).
I'm taking it to one this week to get checked out..
Drifting
Joined: Apr 2009
Posts: 1,898
Likes: 9
From: Morrisville PA
Numbers are in line for the 01 cam, but it is probably KRing like a bitch so most likely leaving power on the table.
If it is already tuned and the wideband is reading accurately, it sounds like the previous tuner did a "pe rape" tune. Which would have the AFR in line only for that particular day.
If it is already tuned and the wideband is reading accurately, it sounds like the previous tuner did a "pe rape" tune. Which would have the AFR in line only for that particular day.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
Thread Starter
Safety Car
Joined: Apr 2008
Posts: 3,908
Likes: 10
From: Charleston SC
What is "KRing"? And what is a "pe rape" tune? haha
Definitely had a tune I think...no codes or rear oxygen sensors/cats.
I'm far enough to not want to go there, lol. I'm in Columbia, SC..
Definitely had a tune I think...no codes or rear oxygen sensors/cats.
I'm far enough to not want to go there, lol. I'm in Columbia, SC..
Drifting
Joined: Apr 2009
Posts: 1,898
Likes: 9
From: Morrisville PA
KR = knock retard. The car pulls timing if it is knocking = power loss.
There is a table called Power Enrichment that is used for telling the O/S what AFR to run while at WOT. The correct way to do this is to set the desired AFR in this table and then tune your maf table so the AFR that is being spit out corresponds to the AFR you set in the PE table.
What bad tuners do to get a quick dyno tune, is they don't even touch the MAF table...they will simply "hack" the PE table until the AFR being spit out looks good. It basically removes a step. The maf table touches on various engine loads that takes a little longer to dial vs the PE table being only RPM based so it takes hardly any time at all. So a bad PE table would be commanding something like an 11:1 AFR but actually be spitting out 12.8 (for that day only!). The result is a maf table that is WAY THE **** OFF and when the weather or elevation changes, you get a ****ed up AFR.
If you were closer, I would fix your car free of charge but you are far as hell lol.
There is a table called Power Enrichment that is used for telling the O/S what AFR to run while at WOT. The correct way to do this is to set the desired AFR in this table and then tune your maf table so the AFR that is being spit out corresponds to the AFR you set in the PE table.
What bad tuners do to get a quick dyno tune, is they don't even touch the MAF table...they will simply "hack" the PE table until the AFR being spit out looks good. It basically removes a step. The maf table touches on various engine loads that takes a little longer to dial vs the PE table being only RPM based so it takes hardly any time at all. So a bad PE table would be commanding something like an 11:1 AFR but actually be spitting out 12.8 (for that day only!). The result is a maf table that is WAY THE **** OFF and when the weather or elevation changes, you get a ****ed up AFR.
If you were closer, I would fix your car free of charge but you are far as hell lol.
Last edited by mchicia1; Apr 4, 2012 at 01:13 PM.
Drifting
Joined: Apr 2009
Posts: 1,898
Likes: 9
From: Morrisville PA
An easy diagnostic test you can do is get a fuel pressure gauge. That will check if your fuel filter and/or fuel pump needs to be replaced. If the fuel pressure drops way down at WOT, you know you have a problem. Can rent them at autozone.
Race Director
Joined: Mar 2001
Posts: 11,405
Likes: 26
From: Whippany NJ
CI 6-7-8-9 Veteran
St. Jude Donor '08-'09
NCM Sinkhole Donor
Good to hear your getting a second opinion.
Thread Starter
Safety Car
Joined: Apr 2008
Posts: 3,908
Likes: 10
From: Charleston SC
I HAVE noticed that when in a higher gear (cruising) that if I step on it that I can hear a slight marble type sound.. Has done this as long as I've had it..
Is that what you mean?
Is that what you mean?
Race Director
Joined: Mar 2001
Posts: 11,405
Likes: 26
From: Whippany NJ
CI 6-7-8-9 Veteran
St. Jude Donor '08-'09
NCM Sinkhole Donor
Yup thats pinging. Get the tune cleaned up first then take her out. Car should feel strong.
Drifting
Joined: Apr 2009
Posts: 1,898
Likes: 9
From: Morrisville PA
Do not go WOT anymore and keep the engine load LOW! Meaning no lugging around at 1000 rpms...keep the rpms between 1800-2000 while cruising to put less load on the engine. Get that tune looked at asap.
The good news is that it is very hard to hurt an N/A engine. I still say since your power is in line, you probably didn't hurt anything. With detonation, if something goes, it is either going to be a ring land (more probable with boost) or a rod bearing.
Thread Starter
Safety Car
Joined: Apr 2008
Posts: 3,908
Likes: 10
From: Charleston SC
If you are hearing audible pinging, then it is pinging BAD!
Do not go WOT anymore and keep the engine load LOW! Meaning no lugging around at 1000 rpms...keep the rpms between 1800-2000 while cruising to put less load on the engine. Get that tune looked at asap.
The good news is that it is very hard to hurt an N/A engine. I still say since your power is in line, you probably didn't hurt anything. With detonation, if something goes, it is either going to be a ring land (more probable with boost) or a rod bearing.
Do not go WOT anymore and keep the engine load LOW! Meaning no lugging around at 1000 rpms...keep the rpms between 1800-2000 while cruising to put less load on the engine. Get that tune looked at asap.
The good news is that it is very hard to hurt an N/A engine. I still say since your power is in line, you probably didn't hurt anything. With detonation, if something goes, it is either going to be a ring land (more probable with boost) or a rod bearing.
Unfortunately the LSX tuner I had in mind that was local had his computer stolen so lost all of his tunes and software, etc. He said it won't be until next week...ugh..
I wish I knew of someone else in the Columbia area (~50m) that could fix this for me.
Race Director
Joined: Mar 2001
Posts: 11,405
Likes: 26
From: Whippany NJ
CI 6-7-8-9 Veteran
St. Jude Donor '08-'09
NCM Sinkhole Donor
http://forums.corvetteforum.com/c5-s...nly-149-a.html
Chances are Doug has a tune file for your exact combo. Just send them your PCM
