2002 Camaro SS w/ longtubes running rich/lean?
02-14-2014, 12:34 AM
#1
2002 Camaro SS w/ longtubes running rich/lean? Bought a 2002 Camaro SS.
It has the SS hoodscoop and SLP lid as factory options.
It has Kooks longtube headers, in to an offroad Y-pipe, in to the stock muffler, out the stock dual pipes.
The Y pipe is dumped, with a bolt on cap.
The car exhuast smells like gas. Its obviously in need of a tune. Whats the cheapest way to adjust for upgraded intake and exhaust?
It has the SS hoodscoop and SLP lid as factory options.
It has Kooks longtube headers, in to an offroad Y-pipe, in to the stock muffler, out the stock dual pipes.
The Y pipe is dumped, with a bolt on cap.
The car exhuast smells like gas. Its obviously in need of a tune. Whats the cheapest way to adjust for upgraded intake and exhaust?
02-14-2014, 12:36 AM
#2
The previous owner said the T-tops had been removed only once.
Its only ever ran premium fuel. All reccomended factory maintanence.
The car was kept in the garage except for weekends from 2002-2008 and only acrued 18k miles. (3k/year)
The car then was daily driven from 2008-now and acrued 70k miles. (12k/year)
The previous owner only installed the headers last year, I think it was then tuned to run dumped. (Which would explain why it runs rich/lean when capped?)
Other factory options included:
Hurst short-throw shifter (sexy as ****)
DAT MONSOON 500W
Its only ever ran premium fuel. All reccomended factory maintanence.
The car was kept in the garage except for weekends from 2002-2008 and only acrued 18k miles. (3k/year)
The car then was daily driven from 2008-now and acrued 70k miles. (12k/year)
The previous owner only installed the headers last year, I think it was then tuned to run dumped. (Which would explain why it runs rich/lean when capped?)
Other factory options included:
Hurst short-throw shifter (sexy as ****)
DAT MONSOON 500W
02-14-2014, 06:56 AM
#4
Nothing done there should require tuning to stop exhaust smell. Don't let a buddy try to "tune it out". More likely an issue with the O2 wiring extensions.
Might let somebody competent with a scan tool diagnose it for you.
Btw, no cats does smell different. Like exhaust smelled in the '70s, if your old enough to remember. LOL
Might let somebody competent with a scan tool diagnose it for you.
Btw, no cats does smell different. Like exhaust smelled in the '70s, if your old enough to remember. LOL
02-14-2014, 08:36 AM
#5
Thanks for the advice guys. Would the fuel enrichment adjust itself appropriately when going from caped to open? Or open back to caped?
What Im asking is, am I restricting performance with the cap on, or cuttinf efficiency with it off?
What Im asking is, am I restricting performance with the cap on, or cuttinf efficiency with it off?
02-14-2014, 08:51 AM
#6
You do not want it in closed loop with it uncapped. You will end up very rich. During the overlap cycle oxygen pulled back in the open collector will look very lean to the PCM when it sees the O2 measuring that oxygen. High oxygen=lean to the PCM. Racers, since open headers are used, normally don't allow closed loop until about 6000 RPM (or 500 or so above the 2 step) False lean indications at lower RPM, and the 2 steps screwing with O2 readings skew fuel corrections.
It's usually best to disable long term fuel corrections, or unplug the O2s while uncapped. Might reset your PCM to see if that fixes your smell. Could be still making bogus long term corrections is the headers were opened recently.
It's usually best to disable long term fuel corrections, or unplug the O2s while uncapped. Might reset your PCM to see if that fixes your smell. Could be still making bogus long term corrections is the headers were opened recently.
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02-14-2014, 10:35 AM
#8
If you unplug the O2s when you uncap it, the fueling won't go crazy. Cap it back up, plug them back in and you will only have O2 codes. No other isues. Won't learn anything wrong while unplugged.
Your tuning buddy can shut those O2 sensor codes off for you, then you would have to do nothing but plug them back in.
Your tuning buddy can shut those O2 sensor codes off for you, then you would have to do nothing but plug them back in.
02-14-2014, 01:13 PM
#10
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The stank at idle could be the usual cold-O2s-from-
long-tubes problem, false trimming. You can't do a lot
for this by tuning other than code suppression. It
wants hotter pipe / hotter sensors. Bogus trimming
does have performance downsides as well.
long-tubes problem, false trimming. You can't do a lot
for this by tuning other than code suppression. It
wants hotter pipe / hotter sensors. Bogus trimming
does have performance downsides as well.
02-14-2014, 10:02 PM
#12
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My preference would be to fit a decent aftermarket catback that flows well and sounds nice, and leave the dump capped, especially if it's a daily driver. It will always have a bit of a lawnmower smell with no cats though.
The predator is ok for what it is but no substitute for a proper laptop-based tuning suite (HPTuners/EFILive) and an experienced eye. Dirty MAFs and low fuel pressure are not uncommon on older cars and won't play well with a canned tune. You can view MAF airflow, fuel trims etc on the predator but it's much easier on a laptop.
Look for fuel trims within +/- 5% in normal driving, and 250-300 grams/sec MAF airflow at high rpm WOT, and O2 voltages steady around or above 900 mV at WOT. If O2 mV sag below this at WOT you probably have a fuel problem. If it passes these tests you might try the canned diablo tune...
The predator is ok for what it is but no substitute for a proper laptop-based tuning suite (HPTuners/EFILive) and an experienced eye. Dirty MAFs and low fuel pressure are not uncommon on older cars and won't play well with a canned tune. You can view MAF airflow, fuel trims etc on the predator but it's much easier on a laptop.
Look for fuel trims within +/- 5% in normal driving, and 250-300 grams/sec MAF airflow at high rpm WOT, and O2 voltages steady around or above 900 mV at WOT. If O2 mV sag below this at WOT you probably have a fuel problem. If it passes these tests you might try the canned diablo tune...
