So really, if your 2001 WS6 was...
06-08-2011, 12:35 PM
#1
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So really, if your 2001 WS6 was... ...running like a dog what would you try first?
I can't seem to find a clear concensus on what to attack! Read TONS of threads here and on HPT and other LS related forums but no clear answers emerge. It seems many have had these issues, many different opinions and potential solutions were voiced, and many threads died with no final responses. Only hanging questions and theories.
If your 2001 WS6 (with CAI, SLPlid, P&P MAF, smooth bellows and that's it, nothing extreme yet) with 20,000 miles was knocking and pinging like mad at tip in once in closed loop, O2 sensors check out, no vac leaks to find and overall still running strong in open loop and higher RPMs. She has all LTFTs at 25 but other standard config PIDs look good to my amatuer brain. Only started the rattling after CAI and lid install. Logged and compared to a forum members 2000 Z28 and noticed much greater and quicker KR at tip in than on the WS6. Even looks like the TA isn't always giving all the KR commanded as the red background bar shoots up to 10 and the green KR is only hitting 2-4 degrees of retard at times. The Z is hitting KR full on, fast and often at tip in. Of course, knock sensor rot wouldn't explain LTFTs but KR response was the only other obvious difference in the logs. Both cars have similar mods and stock tunes other than fan settings. Both running right about 200ECT.
So would you:
1- Yank the manifold and check the knock sensors...
2- Adjust the VE table to address LTFTs (and what would you do there?)...
3- Re-calibrate the MAF freq to address LTFTs (and again, how? Or is this now the old, debunked first step to lean/rich conditions as some have told me?)...
4- Assume I missed a vacuum leak or mechanical issue so tear everything off and inspect, seal it up and re-torque?
I guess technically it's a poll, but it's informal and I type slow, so no button voting today.
Thanks for your time.
I can't seem to find a clear concensus on what to attack! Read TONS of threads here and on HPT and other LS related forums but no clear answers emerge. It seems many have had these issues, many different opinions and potential solutions were voiced, and many threads died with no final responses. Only hanging questions and theories.
If your 2001 WS6 (with CAI, SLPlid, P&P MAF, smooth bellows and that's it, nothing extreme yet) with 20,000 miles was knocking and pinging like mad at tip in once in closed loop, O2 sensors check out, no vac leaks to find and overall still running strong in open loop and higher RPMs. She has all LTFTs at 25 but other standard config PIDs look good to my amatuer brain. Only started the rattling after CAI and lid install. Logged and compared to a forum members 2000 Z28 and noticed much greater and quicker KR at tip in than on the WS6. Even looks like the TA isn't always giving all the KR commanded as the red background bar shoots up to 10 and the green KR is only hitting 2-4 degrees of retard at times. The Z is hitting KR full on, fast and often at tip in. Of course, knock sensor rot wouldn't explain LTFTs but KR response was the only other obvious difference in the logs. Both cars have similar mods and stock tunes other than fan settings. Both running right about 200ECT.
So would you:
1- Yank the manifold and check the knock sensors...
2- Adjust the VE table to address LTFTs (and what would you do there?)...
3- Re-calibrate the MAF freq to address LTFTs (and again, how? Or is this now the old, debunked first step to lean/rich conditions as some have told me?)...
4- Assume I missed a vacuum leak or mechanical issue so tear everything off and inspect, seal it up and re-torque?
I guess technically it's a poll, but it's informal and I type slow, so no button voting today.
Thanks for your time.
06-08-2011, 12:47 PM
#2
first thing i would suspect would be the MAF....
you could unplug the MAF, forcing it into SD mode.
then seeing if it still knocked on throttle.. if it doesnt, that doesnt mean its not the issue, as you will be on the secondary spark table.. you could always overlay the secondary table to match the primary to test, but thats a lot of work for no reason.. just seeing if it knocks in SD may tell you if its the MAF or not...
you could unplug the MAF, forcing it into SD mode.
then seeing if it still knocked on throttle.. if it doesnt, that doesnt mean its not the issue, as you will be on the secondary spark table.. you could always overlay the secondary table to match the primary to test, but thats a lot of work for no reason.. just seeing if it knocks in SD may tell you if its the MAF or not...
06-08-2011, 01:02 PM
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I'd begin with fuel pressure, especially across tip-in
and at WOT. Filter service if needed. Your fuel
pressure is an -assumption-.
Then look at the misfire current cylinder counts 1-8
to see if you maybe have an injector imbalance,
weak coil / wire / plug which might only be "exposed"
at higher cylinder pressures.
and at WOT. Filter service if needed. Your fuel
pressure is an -assumption-.
Then look at the misfire current cylinder counts 1-8
to see if you maybe have an injector imbalance,
weak coil / wire / plug which might only be "exposed"
at higher cylinder pressures.
06-08-2011, 03:20 PM
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I replace a good 20 ETC Throttle Body's for every 1 MAF sensor. I have seen many customers replace the MAFs only to find out that they have an Intake Leak. Yeah the fuel trims come right back in when you disconnect the MAF, but it isn't the fix
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06-08-2011, 03:23 PM
#8
sure the system corrects it with fuel trims for the most part, but its also one of the big parts that can make car X go faster/slower then identical car Y.
not to mention every one of them has a MAP sensor thats more accurate and reliable...
im just not a fan of wire based MAFs.. or MAF systems in general.
06-08-2011, 03:40 PM
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therealhitman -
If it's running good and strong in open loop, but having issues in closed loop it could be something as simple as o2 sensors or IAT sensor. Is the +25 LTFT showing up for both banks? Your PCM is adding a ton of fuel based on your mods. Fix this problem correctly (do not try adjusting your tune to compensate for a problem - though a ported maf will want a little tweaking).
Things to check/try would be:
o2s
recheck for any vacuum leaks-if both banks are showing lean then look at hoses and related items, if only one bank is lean look at the manifold seals/gaskets.
check for any unmetered air - i.e. a leak or poor seal around your bellow (or anything else between the TB and MAF)
check fuel pressure
barrow a stock MAF if you can find one and throw it on your car, data log
recheck all sensors via log data
If it's running good and strong in open loop, but having issues in closed loop it could be something as simple as o2 sensors or IAT sensor. Is the +25 LTFT showing up for both banks? Your PCM is adding a ton of fuel based on your mods. Fix this problem correctly (do not try adjusting your tune to compensate for a problem - though a ported maf will want a little tweaking).
Things to check/try would be:
o2s
recheck for any vacuum leaks-if both banks are showing lean then look at hoses and related items, if only one bank is lean look at the manifold seals/gaskets.
check for any unmetered air - i.e. a leak or poor seal around your bellow (or anything else between the TB and MAF)
check fuel pressure
barrow a stock MAF if you can find one and throw it on your car, data log
recheck all sensors via log data
06-08-2011, 06:18 PM
#10
Start there ... You obviously left something unplugged, or a loose coupler connection that is making the car run lean. Ensure no vacuum leaks around the MAF and Throttle Body. Also ditch the P&P MAF if you have not tuned for it. Fuel Trims should be a little lean, say +10 or so, but not +25. I have seen P&P MAFs and resistored aftermarket MAFs go +25 lean, with no other changes.
06-09-2011, 02:20 AM
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Overwhelming. What a great forum this is. Thanks for your time guys.
I will drive the car tomorrow and log for misfire count per Jimmyblue's advice (I hoped you'd weigh in). BTW I changed out the fuel filter right off the bat along with the other 'obvious' things like trying a different MAF, blocking off the CAI and bypassing the PCV weeks ago. Once I'm warmed up I'll try unplugging the MAF to force OL (thanks Mr Dude) to test the possible bad MAF versus potential intake leak theory. I am going to try swapping out my O2s as 99TALS16SPD mentioned. I'm guessing that showing good voltages doesn't necessarily mean they are switching correctly. And I am in full agreement with CalEditor that it still could be a sneaky manifold leak. Carb cleaner didn't reveal it, but the back end is tough to get at in an Fbody. A friend says the propane wand will get back there, so I may drive her out to his shop to have a pro double-check my leak diagnosis.
This is not my first rodeo guys, just first problem with an LS ever. My C6 runs like a dream and so did this one until recently, just a bit underpowered was all. Either way, I've got lots a muscle car builds under my belt the last twenty years, so the real obvious 'ya left something unplugged' or 'what kinda dumbass are you portin yer MAF' stuff isn't helping me much lol. Thanks anyway though.
I'm gonna get this figured out and I'm sure all the guidance from you guys will get me there faster. Thanks for the constructive ideas, I hope (most of) you can drop back to brainstorm once I run through this first batch of things you've given me to test tomorrow and Friday.
I will drive the car tomorrow and log for misfire count per Jimmyblue's advice (I hoped you'd weigh in). BTW I changed out the fuel filter right off the bat along with the other 'obvious' things like trying a different MAF, blocking off the CAI and bypassing the PCV weeks ago. Once I'm warmed up I'll try unplugging the MAF to force OL (thanks Mr Dude) to test the possible bad MAF versus potential intake leak theory. I am going to try swapping out my O2s as 99TALS16SPD mentioned. I'm guessing that showing good voltages doesn't necessarily mean they are switching correctly. And I am in full agreement with CalEditor that it still could be a sneaky manifold leak. Carb cleaner didn't reveal it, but the back end is tough to get at in an Fbody. A friend says the propane wand will get back there, so I may drive her out to his shop to have a pro double-check my leak diagnosis.
This is not my first rodeo guys, just first problem with an LS ever. My C6 runs like a dream and so did this one until recently, just a bit underpowered was all. Either way, I've got lots a muscle car builds under my belt the last twenty years, so the real obvious 'ya left something unplugged' or 'what kinda dumbass are you portin yer MAF' stuff isn't helping me much lol. Thanks anyway though.
I'm gonna get this figured out and I'm sure all the guidance from you guys will get me there faster. Thanks for the constructive ideas, I hope (most of) you can drop back to brainstorm once I run through this first batch of things you've given me to test tomorrow and Friday.
06-09-2011, 01:45 PM
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You should still check fuel pressure, there are other ways
for it to degrade (pump electrical, line kinks etc.).
It's hard to detect a vacuum leak with spraying if you
have the IAC hooked up, it will fight any rise / drop
faster than you can pick up the change by ear. You
can use the real time controls to lock IAC position
though.
for it to degrade (pump electrical, line kinks etc.).
It's hard to detect a vacuum leak with spraying if you
have the IAC hooked up, it will fight any rise / drop
faster than you can pick up the change by ear. You
can use the real time controls to lock IAC position
though.
06-09-2011, 02:08 PM
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You should still check fuel pressure, there are other ways
for it to degrade (pump electrical, line kinks etc.).
It's hard to detect a vacuum leak with spraying if you
have the IAC hooked up, it will fight any rise / drop
faster than you can pick up the change by ear. You
can use the real time controls to lock IAC position
though.
for it to degrade (pump electrical, line kinks etc.).
It's hard to detect a vacuum leak with spraying if you
have the IAC hooked up, it will fight any rise / drop
faster than you can pick up the change by ear. You
can use the real time controls to lock IAC position
though.
The flexible fuel line in the tank unit had rubbed on the tank unit and it had a small hole in the plastic flex line. Just another stange problem
