Factory tune incorrect for a 2000 with 241 heads?
Thread Starter
Joined: Oct 2004
Posts: 2,142
Likes: 9
From: South Windsor, CT
Factory tune incorrect for a 2000 with 241 heads? I have been chasing a weird issue with my new (to me) 2000 Z28 pulling timing at part throttle, and occassionally having a mildly audible ping at full throttle.
I know they changed to 241 heads from 853's sometime in the middle of the 2000 model year, and my car has 241 heads. The tune in the PCM is the same as any other 1999/2000 LS1 though and it's got me confused. The 1999/2000 stock tune has anywhere from 3 to 15 degrees more spark advance than the 2001/2002 tune has. I know the cam's are different (is mine though...if it got 241 heads, how do I know what cam it has?) and the intakes are different (definitely has an LS1 intake, not an LS6)...but thats a LARGE difference in spark advance...7 degrees difference at full throttle...which is where I become most skeptical...thats a MAJOR difference for full throttle spark for 2 engines with the same exact combustion chambers.
Has anybody ever run into this...is there an updated GM flash for 2000's with 241 heads?...was it factory installed but maybe mine was one of the first to get the heads and thus got the wrong tables in the PCM? I'm considering swapping in 2001/2002 spark tables just to see if the pinging issue goes away completely...I've run carbon cleaner through it once already, and all the sensors appear to be functioning properly...I plan to at least clean the MAF and replace the fuel filter and spark plugs...and maybe wires...but other than those 4 things...I'm kinda at a loss at this point (except for maybe trying another can of GM top end cleaner).
I know they changed to 241 heads from 853's sometime in the middle of the 2000 model year, and my car has 241 heads. The tune in the PCM is the same as any other 1999/2000 LS1 though and it's got me confused. The 1999/2000 stock tune has anywhere from 3 to 15 degrees more spark advance than the 2001/2002 tune has. I know the cam's are different (is mine though...if it got 241 heads, how do I know what cam it has?) and the intakes are different (definitely has an LS1 intake, not an LS6)...but thats a LARGE difference in spark advance...7 degrees difference at full throttle...which is where I become most skeptical...thats a MAJOR difference for full throttle spark for 2 engines with the same exact combustion chambers.
Has anybody ever run into this...is there an updated GM flash for 2000's with 241 heads?...was it factory installed but maybe mine was one of the first to get the heads and thus got the wrong tables in the PCM? I'm considering swapping in 2001/2002 spark tables just to see if the pinging issue goes away completely...I've run carbon cleaner through it once already, and all the sensors appear to be functioning properly...I plan to at least clean the MAF and replace the fuel filter and spark plugs...and maybe wires...but other than those 4 things...I'm kinda at a loss at this point (except for maybe trying another can of GM top end cleaner).
TECH Senior Member
Joined: Nov 2001
Posts: 7,036
Likes: 1
From: Lake Zurich, IL
no clue regarding your probs.... my 2000 was one of the last 2000's off the line.... (bought new July 2000)
if you would post scans it would be helpful......
swapping 01/02 spark tables w/out scanning your car... is um... we'll assume you hadn't thought of this....
post up scans w/your probs
if you would post scans it would be helpful......
swapping 01/02 spark tables w/out scanning your car... is um... we'll assume you hadn't thought of this....
post up scans w/your probs
Joined: Nov 2003
Posts: 6,216
Likes: 236
From: Wichita KS / Rancho San Diego
My 00 has 241 heads. I have some KR at WOT but no pinging or anything like that. The heads really don't make a difference with the tune. The cam is the same as any other 99/00 car. I'd be looking for oil in the intake besides the things you mentioned.
Thread Starter
Joined: Oct 2004
Posts: 2,142
Likes: 9
From: South Windsor, CT
Originally Posted by horist
no clue regarding your probs.... my 2000 was one of the last 2000's off the line.... (bought new July 2000)
if you would post scans it would be helpful......
swapping 01/02 spark tables w/out scanning your car... is um... we'll assume you hadn't thought of this....
post up scans w/your probs
if you would post scans it would be helpful......
swapping 01/02 spark tables w/out scanning your car... is um... we'll assume you hadn't thought of this....
post up scans w/your probs
I've NEVER seen a cam dictate an 8 degree timing change at full throttle in any engine I've ever tuned...I have seen heads dictate a fairly decent change though. From what I've seen (with sets of both sitting on the table in front of me), the chambers in 241 heads are indeed different from those in 853's...not a HUGE amount, but a good deal.
With oil in the intake...would that be PCV related? Worth upgrading to the LS6 style PCV?
Last edited by Mike454SS; Aug 17, 2007 at 08:05 AM.
Joined: Nov 2003
Posts: 6,216
Likes: 236
From: Wichita KS / Rancho San Diego
When I replaced my LS1 intake with the LS6 there was a lot of oil in it. I added a catch can, but you could do the LS6 valley cover & PCV - it's lot more involved, though.
There is a difference in the way the heads were cast, but not enough to cause what you're experiencing.
BTW, if you're scanning, I don't think it would be irresponsible to switch to the less aggressive 01 timing table for comparison purposes ...
There is a difference in the way the heads were cast, but not enough to cause what you're experiencing.
BTW, if you're scanning, I don't think it would be irresponsible to switch to the less aggressive 01 timing table for comparison purposes ...
Thread Starter
Joined: Oct 2004
Posts: 2,142
Likes: 9
From: South Windsor, CT
http://tis2web.service.gm.com/tis2web
I just went here and entered my VIN, and there are 2 part numbers that refer to "New calibration to reduce spark knock, enable enhanced EVAP diagnostics, and reduce occurences false setting of DTC P0175." one of them is 9358629 and the other is 9359027.
Has anyone seen these revised calibrations? I am wondering how much different they are.
I just went here and entered my VIN, and there are 2 part numbers that refer to "New calibration to reduce spark knock, enable enhanced EVAP diagnostics, and reduce occurences false setting of DTC P0175." one of them is 9358629 and the other is 9359027.
Has anyone seen these revised calibrations? I am wondering how much different they are.
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yea.. umm
i have HPtuners for 99s and 02s..
when i first started playing around with it i discovered this....
put a 99 timing table on a 02, and it will PING... no matter what.
i havent narrowed it down to the heads or anything exactly, but i know that you cant put the "more timing" 99 tune on a later model (01/02) LS1.. even if they're all stock.
why? i donno.. but it COULD be the 241 heads VS the earlier heads....
i have HPtuners for 99s and 02s..
when i first started playing around with it i discovered this....
put a 99 timing table on a 02, and it will PING... no matter what.
i havent narrowed it down to the heads or anything exactly, but i know that you cant put the "more timing" 99 tune on a later model (01/02) LS1.. even if they're all stock.
why? i donno.. but it COULD be the 241 heads VS the earlier heads....
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The high timing is in areas where the PCM expects there to be
EGR punking the charge out. If you delete EGR then the timing
will bee too high. If you have less EGR flow than expected (like
mods to exhaust, kink the tube, whatever) you may see this too.
Plus from what I've read the 2000 was biased the leanest of all
years for ARF which helps none.
EGR punking the charge out. If you delete EGR then the timing
will bee too high. If you have less EGR flow than expected (like
mods to exhaust, kink the tube, whatever) you may see this too.
Plus from what I've read the 2000 was biased the leanest of all
years for ARF which helps none.
Thread Starter
Joined: Oct 2004
Posts: 2,142
Likes: 9
From: South Windsor, CT
There's no EGR at full throttle...but it is 7 degrees more advanced there. The exhaust is 100% stock (the whole car is 100% stock except for a short throw shifter and better light bulbs in the stock lights...I'm waiting on delivery of the SLP lid and some other stuff for it to be "not stock") and the EGR tube is not kinked or clogged, and the valve is functioning properly. I'm pretty sure the car doesn't have the "revised calibration" and it clearly needs it...I'm convinced it's the heads. I gotta get the VIN off my other LS1 (though I don't think blocks have entire VIN's...anybody have an early 2000 that has 853 heads that they can run in that GM site and see what it says), because it's also a 2000 but it has 853 heads (had...it's all sorts of not stock and not in an f-body and not completely built yet...but it came out of a 2000 SS), and see what it comes up with on that website...my money is on it not having that revised calibration.
Originally Posted by jimmyblue
The high timing is in areas where the PCM expects there to be
EGR punking the charge out. If you delete EGR then the timing
will bee too high. If you have less EGR flow than expected (like
mods to exhaust, kink the tube, whatever) you may see this too.
Plus from what I've read the 2000 was biased the leanest of all
years for ARF which helps none.
EGR punking the charge out. If you delete EGR then the timing
will bee too high. If you have less EGR flow than expected (like
mods to exhaust, kink the tube, whatever) you may see this too.
Plus from what I've read the 2000 was biased the leanest of all
years for ARF which helps none.
that cant be it.
not only do the 99s im working on have !EGR, but theres litterally hundreds, if not thousands of EGR deleted 99 and 00s out there.
Thread Starter
Joined: Oct 2004
Posts: 2,142
Likes: 9
From: South Windsor, CT
Well...I still think it's worth looking at the spark tables in the updated calibration. I don't want to "tune" a 100% stock car, I just want to drive it and tune for it as I mod it (but right now I just want to drive it worry free)...I took the TB off today and I couldn't see any oil in the intake...it's not brand new looking in there (engine does have 87K on it and has EGR too) but it's not bad at all.
I guess I could keep whining to the dealer about it...I do have some extended warranty on it...but I'd rather just figure it out myself than have them take apart an engine that has nothing wrong with it.
I appreciate all the help you guys have given me, if anyone has a way for me to get the updated calibration without going to the dealer and begging (because I'm sure warranty or not, they'll figure out some reason not to do it without charging me a buttload for it)...anybody have access to a tech 2 or something, and a way to download the update? I'll gladly give you my VIN (I just don't want to post it on here...even though that probably doesn't matter).
I guess I could keep whining to the dealer about it...I do have some extended warranty on it...but I'd rather just figure it out myself than have them take apart an engine that has nothing wrong with it.
I appreciate all the help you guys have given me, if anyone has a way for me to get the updated calibration without going to the dealer and begging (because I'm sure warranty or not, they'll figure out some reason not to do it without charging me a buttload for it)...anybody have access to a tech 2 or something, and a way to download the update? I'll gladly give you my VIN (I just don't want to post it on here...even though that probably doesn't matter).