Huge post - Main problem is front four plugs are lean?
Thread Starter
Staging Lane
Joined: Mar 2007
Posts: 74
Likes: 0
From: Canada
Thanks,
Brad
Thread Starter
Staging Lane
Joined: Mar 2007
Posts: 74
Likes: 0
From: Canada
ok well theres some good info in here and it seems all the basics were coverd so ill ask some more unlikely things.......
did you check your valve train over?
any bent pushrods? bent valves? bad valve guides or bad springs?
basically anyting that could be hanging a vlave open?
also how about the ignition? cap and rotor in good shape not getting any spark scatter or transfer in the cap that shouldn't be there?
also....any debris in the fuel rails that may be causeing a volume drop between the entrance to the rail in the back and the crossover in the front??
again i realize these are rare problems im suggesting but it may apply here seeing all of the normal things havent solved it......
i cant see how the tune should affect it personally unless somebody screwed up the cyl. balance tables......
the car should be alble to idle at 15:1 afr withouht any crazy heat numbers i idle mine there to keep the plugs clean and its just fine......
you need to look for a place where extra un metered air could be getting into just those four front cylinders........or obveously a fuel delivery issue.
how about the intake manifold gaskets? sealed well? no leaks?
also exhaust? header gaskets good? no leaks? did you get any of the O2's wet with coolant or anything to foul them out?
just trying to bring some new ideas to the table lemme know...
did you check your valve train over?
any bent pushrods? bent valves? bad valve guides or bad springs?
basically anyting that could be hanging a vlave open?
also how about the ignition? cap and rotor in good shape not getting any spark scatter or transfer in the cap that shouldn't be there?
also....any debris in the fuel rails that may be causeing a volume drop between the entrance to the rail in the back and the crossover in the front??
again i realize these are rare problems im suggesting but it may apply here seeing all of the normal things havent solved it......
i cant see how the tune should affect it personally unless somebody screwed up the cyl. balance tables......
the car should be alble to idle at 15:1 afr withouht any crazy heat numbers i idle mine there to keep the plugs clean and its just fine......
you need to look for a place where extra un metered air could be getting into just those four front cylinders........or obveously a fuel delivery issue.
how about the intake manifold gaskets? sealed well? no leaks?
also exhaust? header gaskets good? no leaks? did you get any of the O2's wet with coolant or anything to foul them out?
just trying to bring some new ideas to the table lemme know...
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Verdad Gallardo Thread Starter
Staging Lane
Joined: Mar 2007
Posts: 74
Likes: 0
From: Canada
ok well theres some good info in here and it seems all the basics were coverd so ill ask some more unlikely things.......
did you check your valve train over?
any bent pushrods? bent valves? bad valve guides or bad springs?
basically anything that could be hanging a valve open?
did you check your valve train over?
any bent pushrods? bent valves? bad valve guides or bad springs?
basically anything that could be hanging a valve open?
I've pulled and replaced the intake manifold gaskets and had no change.
O2's have been replaced with new ones from the dealer. No change with the new O2's.
I appreciate the help. New or unlikely things are my only option at this point.
I drove the car home from the shop which is at least 30 minutes away. The thing runs like a top on the road. Lots of ***** and runs smooth. Even ran it on the emissions dyno (which it failed of course) with no problems. Brought it home and within a minute or two of pulling into the garage the cats where already orange.
I watched the cats on the emissions dyno and stopped and looked underneath on the road and they where fine.
Thanks,
Brad
Thread Starter
Staging Lane
Joined: Mar 2007
Posts: 74
Likes: 0
From: Canada
Thread Starter
Staging Lane
Joined: Mar 2007
Posts: 74
Likes: 0
From: Canada
May have found it:
CAT Overtemp Threshold (Low Baro) 801 deg. C
CAT Overtemp Threshold (Mid Baro) 813 deg. C
CAT Overtemp Threshold (High Baro) 828 deg.C
CAT Overtemp Baro Threshold 1 79.625 kpa
CAT Overtemp Baro Threshold 2 99.625 kpa
CAT Overtemp AFR 12.2 AFR
Hopefully that is the info.
Thanks,
Brad
CAT Overtemp Threshold (Low Baro) 801 deg. C
CAT Overtemp Threshold (Mid Baro) 813 deg. C
CAT Overtemp Threshold (High Baro) 828 deg.C
CAT Overtemp Baro Threshold 1 79.625 kpa
CAT Overtemp Baro Threshold 2 99.625 kpa
CAT Overtemp AFR 12.2 AFR
Hopefully that is the info.
Thanks,
Brad
May have found it:
CAT Overtemp Threshold (Low Baro) 801 deg. C
CAT Overtemp Threshold (Mid Baro) 813 deg. C
CAT Overtemp Threshold (High Baro) 828 deg.C
CAT Overtemp Baro Threshold 1 79.625 kpa
CAT Overtemp Baro Threshold 2 99.625 kpa
CAT Overtemp AFR 12.2 AFR
Hopefully that is the info.
Thanks,
Brad
CAT Overtemp Threshold (Low Baro) 801 deg. C
CAT Overtemp Threshold (Mid Baro) 813 deg. C
CAT Overtemp Threshold (High Baro) 828 deg.C
CAT Overtemp Baro Threshold 1 79.625 kpa
CAT Overtemp Baro Threshold 2 99.625 kpa
CAT Overtemp AFR 12.2 AFR
Hopefully that is the info.
Thanks,
Brad
801C = 1473.8F at approx. 6250ft. elevation ("Low Baro")
813C = 1495.4F at approx. 3325ft. elevation ("Mid Baro")
828C = 1522.4F at approx. 400ft. elevation ("High Baro")
79.625kpa = 0.785837651atm = 11.5518134697psi = (approx. 6250ft. elevation)
99.625kpa = 0.983222304atm = 14.4533678688psi = (approx. 400ft. elevation)
http://www.aa1car.com/library/map_sensors.htm :
"When the ignition key is first turned on, the powertrain control module
(PCM) looks at the MAP sensor reading before the engine starts to determine the atmospheric (barometric) pressure. So in effect, the MAP sensor can serve double duty as a BARO sensor. The PCM then uses this information to adjust the air/fuel mixture to compensate for changes in air pressure due to elevation and/or weather."
Pursuant to this line of thinking, what is the elevation where you are in Canada? What are your MAP values/ vacuum readings? Just looking for unturned stones...
i found this while searching was this ever cured?
im having this same exact proplem. front plugs are damn near snow white. rear 4 lookslightly darker than they should
quick run down on my combo which everything has 850 miles
stock GM short block
ported LT4 heads
230/236 108LSA lift is just under .600
about 11.4:1 compression
1.6 rockers
gold springs
edelbrock LT4 intake
AS&M monoblade
walbro 255 pump racetronix hot wire kit
FIC bosch 3 30lb injectors
55psi base pressure
gm opti
taylor wires
tr6 plugs gapped at .044
1-3/4 to 1-7/8 headers true 3"duals all the way to the bumper with x-pipe bullet mufflers
idles between 700-750 rpm
i never even knew there was a problem until i pulled the plugs to change them out before getting the final tune done
my BLMs are split at idle but are evened out by 1500rpm. throttle response from idle is ok. its really good above 2000rpm. drives great some surging/bucking on a real light load between 1500 and 2000rpm.
yesterday i took the throttle body off and modded the IAC housing so i could send all idle air through the IAC passage in the intake. BLMs are better but still will split if i let it idle more than 5 minutes.
i have never noticed any glowing headers but they are stainless
its deffently an air flow problem at idle i just havent been able to narrow it down
im having this same exact proplem. front plugs are damn near snow white. rear 4 lookslightly darker than they should
quick run down on my combo which everything has 850 miles
stock GM short block
ported LT4 heads
230/236 108LSA lift is just under .600
about 11.4:1 compression
1.6 rockers
gold springs
edelbrock LT4 intake
AS&M monoblade
walbro 255 pump racetronix hot wire kit
FIC bosch 3 30lb injectors
55psi base pressure
gm opti
taylor wires
tr6 plugs gapped at .044
1-3/4 to 1-7/8 headers true 3"duals all the way to the bumper with x-pipe bullet mufflers
idles between 700-750 rpm
i never even knew there was a problem until i pulled the plugs to change them out before getting the final tune done
my BLMs are split at idle but are evened out by 1500rpm. throttle response from idle is ok. its really good above 2000rpm. drives great some surging/bucking on a real light load between 1500 and 2000rpm.
yesterday i took the throttle body off and modded the IAC housing so i could send all idle air through the IAC passage in the intake. BLMs are better but still will split if i let it idle more than 5 minutes.
i have never noticed any glowing headers but they are stainless
its deffently an air flow problem at idle i just havent been able to narrow it down
i found this while searching was this ever cured?
im having this same exact proplem. front plugs are damn near snow white. rear 4 lookslightly darker than they should
quick run down on my combo which everything has 850 miles
stock GM short block
ported LT4 heads
230/236 108LSA lift is just under .600
about 11.4:1 compression
1.6 rockers
gold springs
edelbrock LT4 intake
AS&M monoblade
walbro 255 pump racetronix hot wire kit
FIC bosch 3 30lb injectors
55psi base pressure
gm opti
taylor wires
tr6 plugs gapped at .044
1-3/4 to 1-7/8 headers true 3"duals all the way to the bumper with x-pipe bullet mufflers
idles between 700-750 rpm
i never even knew there was a problem until i pulled the plugs to change them out before getting the final tune done
my BLMs are split at idle but are evened out by 1500rpm. throttle response from idle is ok. its really good above 2000rpm. drives great some surging/bucking on a real light load between 1500 and 2000rpm.
yesterday i took the throttle body off and modded the IAC housing so i could send all idle air through the IAC passage in the intake. BLMs are better but still will split if i let it idle more than 5 minutes.
i have never noticed any glowing headers but they are stainless
its deffently an air flow problem at idle i just havent been able to narrow it down
im having this same exact proplem. front plugs are damn near snow white. rear 4 lookslightly darker than they should
quick run down on my combo which everything has 850 miles
stock GM short block
ported LT4 heads
230/236 108LSA lift is just under .600
about 11.4:1 compression
1.6 rockers
gold springs
edelbrock LT4 intake
AS&M monoblade
walbro 255 pump racetronix hot wire kit
FIC bosch 3 30lb injectors
55psi base pressure
gm opti
taylor wires
tr6 plugs gapped at .044
1-3/4 to 1-7/8 headers true 3"duals all the way to the bumper with x-pipe bullet mufflers
idles between 700-750 rpm
i never even knew there was a problem until i pulled the plugs to change them out before getting the final tune done
my BLMs are split at idle but are evened out by 1500rpm. throttle response from idle is ok. its really good above 2000rpm. drives great some surging/bucking on a real light load between 1500 and 2000rpm.
yesterday i took the throttle body off and modded the IAC housing so i could send all idle air through the IAC passage in the intake. BLMs are better but still will split if i let it idle more than 5 minutes.
i have never noticed any glowing headers but they are stainless
its deffently an air flow problem at idle i just havent been able to narrow it down
Thread Starter
Staging Lane
Joined: Mar 2007
Posts: 74
Likes: 0
From: Canada
Nope I still haven't fixed the problem Bad94. 
I'd be interested in seeing how you make out.
I've taken my intake completely apart and cleaned all the IAC passages. Didn't make any difference in my case.
I've since stuck the car up on blocks and picked up a bone stock 2009 Z06. Some day I'll get interested in fixing this problem. Until then I am enjoying driving my new toy!
Later,
Brad
I'd be interested in seeing how you make out.I've taken my intake completely apart and cleaned all the IAC passages. Didn't make any difference in my case.
I've since stuck the car up on blocks and picked up a bone stock 2009 Z06. Some day I'll get interested in fixing this problem. Until then I am enjoying driving my new toy!
Later,
Brad
My 95 has the exact same problem. No glowing headers but the rear four cylinders are carboning up the header tubes. Read all the above and do not see any clear idea of what would cause this. Someone posted a picture of the front of the intake with the small hole ground off at an angle. What does that do? BTW: I also have a BBK throttle.
Al 95 Z28
Al 95 Z28
I will be honest, I did not read the whole thread.
Did you adjust the TB blades back to closed and drill an IAC bypass hole like the stocker had?? It needs to be sized correctly by trial and error for your combination.
Did you adjust the TB blades back to closed and drill an IAC bypass hole like the stocker had?? It needs to be sized correctly by trial and error for your combination.