LS1 63,000 miles power loss
#1
LS1 63,000 miles power loss
Guys,
Need help on resolving power loss issues on a 1998 Z28. Currently 63000 miles on the car running slp lid, K&N air filter other than that all stock. It has had multiple codes from all 02 sensor lean, P0420 Catalyst System Efficiency Below Threshold bank 1.
This all comes and goes depending on how I drive the car. At 4500-5000rpm never fails sevice engine soon light pops up, but is now starting to come on more frequently and there is a hesitation throughout rpm. Also hard starts and GAS hog
Suggestions?? I would like to give detailed report back of my findings to help others...
Need help on resolving power loss issues on a 1998 Z28. Currently 63000 miles on the car running slp lid, K&N air filter other than that all stock. It has had multiple codes from all 02 sensor lean, P0420 Catalyst System Efficiency Below Threshold bank 1.
This all comes and goes depending on how I drive the car. At 4500-5000rpm never fails sevice engine soon light pops up, but is now starting to come on more frequently and there is a hesitation throughout rpm. Also hard starts and GAS hog
Suggestions?? I would like to give detailed report back of my findings to help others...
#2
TECH Senior Member
iTrader: (35)
1# Did this start suddenly, or has slowly gotten worse over time? If it started suddenly did you just start getting fuel from a different gas station?
2# Have you cleaned the MAFS yet with spray MAFS cleaner, if not start there.
3# Check the fuel pressure at the schrader valve outlet on the GM factory fuel rail, if your not getting right about 55psi or higher then replace the fuel filter. IF the fuel pressure is still low then it's very likely a bad fuel pump.
4# Check the condition of the spark plugs, and make note of their condition at all cylinders(for future reference), and if they're original sparkplugs, fouled,or damaged, replace them.
5# Now if you're still getting the same O2 sensor codes, replace the front O2 sensors.
IMO, these seem like the most possible cause/s for those issues, there could be others, just less common. The most likely to me seem like a dirty(k&n oil) or damaged MAFS, and/or fuel supply issue like a clogged fuel filter.
2# Have you cleaned the MAFS yet with spray MAFS cleaner, if not start there.
3# Check the fuel pressure at the schrader valve outlet on the GM factory fuel rail, if your not getting right about 55psi or higher then replace the fuel filter. IF the fuel pressure is still low then it's very likely a bad fuel pump.
4# Check the condition of the spark plugs, and make note of their condition at all cylinders(for future reference), and if they're original sparkplugs, fouled,or damaged, replace them.
5# Now if you're still getting the same O2 sensor codes, replace the front O2 sensors.
IMO, these seem like the most possible cause/s for those issues, there could be others, just less common. The most likely to me seem like a dirty(k&n oil) or damaged MAFS, and/or fuel supply issue like a clogged fuel filter.
#3
Save the manuals!
iTrader: (5)
Here's a problem and, as mentioned above, the place to start. That oiled air filter will get you every time....
The oil will shed off the filter and coat the MAF in goo so it can't tell how much air is going in to the engine in certain situations. When this happens, it throws off your emissions and performance.
The oil will shed off the filter and coat the MAF in goo so it can't tell how much air is going in to the engine in certain situations. When this happens, it throws off your emissions and performance.
#4
Thanks for the responses:
I bought the car 2 months ago... Sluggish at first a little c-foam threatment and the car come to life, ran strong but still felt like there was power loss and back to the opening thread. So this what I have done so far before the thead was started.
New fuel filter
cleaned MAF with electiCal cleaner
recharged the K&N dried 100 miles later recleaned the MAF
added SLP lid
No performance changes to the car still getting worse as noted .....
Today I will check
Fuel Presure- if good will move on
Plugs &wires
reclean MAF with MAF cleaner
Thanks,
I bought the car 2 months ago... Sluggish at first a little c-foam threatment and the car come to life, ran strong but still felt like there was power loss and back to the opening thread. So this what I have done so far before the thead was started.
New fuel filter
cleaned MAF with electiCal cleaner
recharged the K&N dried 100 miles later recleaned the MAF
added SLP lid
No performance changes to the car still getting worse as noted .....
Today I will check
Fuel Presure- if good will move on
Plugs &wires
reclean MAF with MAF cleaner
Thanks,
#5
TECH Resident
Do you have stock manifolds and cats? I had a 02 T/A years ago that I had to have the catalytic converter replaced on one side bc it was having these issues that you describe at only 57,000 miles
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#8
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P0420/P0430 doesn't indicate a clogged cat specifically, just one that has a reduced oxygen storage capacity (not reduced flow), hence increased emissions. You would get this same code if you removed the cats entirely and never tuned for it. Generally what happens with these, and the reason for the GM TSB/warranty extension (FYI...this was only for 2000+ F-body, with the redesigned manifolds and cats), is that coatings wear off the substrate and the cats are no longer able to "scrub" the exhaust. At that point the cat(s) then become just a pass-thru that serve no purpose and the car would fail a sniffer test. One of mine had this code for years and it never caused a single driveability issue, I didn't worry about it because I didn't have to take a sniffer.
Having said that, there are things that can happen to cause a clogged cat though, such as overheated/melted substrate (due to misfires, too much fuel, excessive oil burning, etc.) or physical damage to the cat (such as impact) that can break up portions of the substrate and cause it to become lodged in such a way that blocks flow.
I would not first suspect a clogged cat though, based on what is known so far. I would re-clean the MAF but not with the spray cleaner. If it's gumed up with K&N oil, it will never get fully clean with just the spray. I prefer using Q-tips and rubbing alcohol, just be careful to not apply any real pressure to the wires, as you don't want to bend/break them. I simply allow the Q-tip to glide along the surface of the wires with almost zero pressure. This works great and will NOT cause damage if done properly.
If the above doesn't help I would next check fuel pressure and fuel trims (on each bank - requires an OBD scanner) before any other diagnostics are done.
Having said that, there are things that can happen to cause a clogged cat though, such as overheated/melted substrate (due to misfires, too much fuel, excessive oil burning, etc.) or physical damage to the cat (such as impact) that can break up portions of the substrate and cause it to become lodged in such a way that blocks flow.
I would not first suspect a clogged cat though, based on what is known so far. I would re-clean the MAF but not with the spray cleaner. If it's gumed up with K&N oil, it will never get fully clean with just the spray. I prefer using Q-tips and rubbing alcohol, just be careful to not apply any real pressure to the wires, as you don't want to bend/break them. I simply allow the Q-tip to glide along the surface of the wires with almost zero pressure. This works great and will NOT cause damage if done properly.
If the above doesn't help I would next check fuel pressure and fuel trims (on each bank - requires an OBD scanner) before any other diagnostics are done.
#9
Save the manuals!
iTrader: (5)
We would be happy to welcome you back in to the paper air filter club!
Having said that, there are things that can happen to cause a clogged cat though, such as overheated/melted substrate (due to misfires, too much fuel, excessive oil burning, etc.) or physical damage to the cat (such as impact) that can break up portions of the substrate and cause it to become lodged in such a way that blocks flow.
I also herd about another thing with a gerbil wrapped up in duct tape, but that was probably on a different website... But I digress;
I would not first suspect a clogged cat though, based on what is known so far. I would re-clean the MAF but not with the spray cleaner. If it's gumed up with K&N oil, it will never get fully clean with just the spray. I prefer using Q-tips and rubbing alcohol, just be careful to not apply any real pressure to the wires, as you don't want to bend/break them. I simply allow the Q-tip to glide along the surface of the wires with almost zero pressure. This works great and will NOT cause damage if done properly.
http://www.adorama.com/images/300x300/pk1964.jpg
#10
Good news and then the BAD.....
Okay,
#1)Fuel pressure checked out ok right at 58 lbs with very little change..
#2)Cleaned the MAF with q-tips and acohol.. and WoW!!!!!!! The power plant was back..Drove it around for a little while and man it was pulling good no issues. Stopped by Orieliys and they removed all codes. Hesitation was gone car was pulling good..... 15 miles later and bam there it was service engine light back on. Car went back went back to struggling in the 3500 rpm and up during acceleration
Man I thought I was in the clear..
What do you guys think???? Defective MAF
#1)Fuel pressure checked out ok right at 58 lbs with very little change..
#2)Cleaned the MAF with q-tips and acohol.. and WoW!!!!!!! The power plant was back..Drove it around for a little while and man it was pulling good no issues. Stopped by Orieliys and they removed all codes. Hesitation was gone car was pulling good..... 15 miles later and bam there it was service engine light back on. Car went back went back to struggling in the 3500 rpm and up during acceleration
Man I thought I was in the clear..
What do you guys think???? Defective MAF
#11
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Okay,
#1)Fuel pressure checked out ok right at 58 lbs with very little change..
#2)Cleaned the MAF with q-tips and acohol.. and WoW!!!!!!! The power plant was back..Drove it around for a little while and man it was pulling good no issues. Stopped by Orieliys and they removed all codes. Hesitation was gone car was pulling good..... 15 miles later and bam there it was service engine light back on. Car went back went back to struggling in the 3500 rpm and up during acceleration
Man I thought I was in the clear..
What do you guys think???? Defective MAF
#1)Fuel pressure checked out ok right at 58 lbs with very little change..
#2)Cleaned the MAF with q-tips and acohol.. and WoW!!!!!!! The power plant was back..Drove it around for a little while and man it was pulling good no issues. Stopped by Orieliys and they removed all codes. Hesitation was gone car was pulling good..... 15 miles later and bam there it was service engine light back on. Car went back went back to struggling in the 3500 rpm and up during acceleration
Man I thought I was in the clear..
What do you guys think???? Defective MAF
If a proper MAF cleaning made that much of a difference for 15 miles, then you can definitely rule out an exhaust blockage.
I'd get a paper filter and then clean the MAF again with the Q-tips, see how that goes. If you already swapped to a paper filter before the last MAF cleaning, then you might want to try unplugging the MAF and driving it like that (would default to SD mode), see if the 3500rpm+ issues are made better before actually buying a new MAF.
#13
Is the K&N filter still in the air box? If it's over-oiled then it might simply be re-fouling the MAF shortly after every time you get it clean.
If a proper MAF cleaning made that much of a difference for 15 miles, then you can definitely rule out an exhaust blockage.
I'd get a paper filter and then clean the MAF again with the Q-tips, see how that goes. If you already swapped to a paper filter before the last MAF cleaning, then you might want to try unplugging the MAF and driving it like that (would default to SD mode), see if the 3500rpm+ issues are made better before actually buying a new MAF.
If a proper MAF cleaning made that much of a difference for 15 miles, then you can definitely rule out an exhaust blockage.
I'd get a paper filter and then clean the MAF again with the Q-tips, see how that goes. If you already swapped to a paper filter before the last MAF cleaning, then you might want to try unplugging the MAF and driving it like that (would default to SD mode), see if the 3500rpm+ issues are made better before actually buying a new MAF.
I will let you know what happens.. I believe we are on the right track.....
#15
hard starts
Okay,
#1)Fuel pressure checked out ok right at 58 lbs with very little change..
#2)Cleaned the MAF with q-tips and acohol.. and WoW!!!!!!! The power plant was back..Drove it around for a little while and man it was pulling good no issues. Stopped by Orieliys and they removed all codes. Hesitation was gone car was pulling good..... 15 miles later and bam there it was service engine light back on. Car went back went back to struggling in the 3500 rpm and up during acceleration
Man I thought I was in the clear..
What do you guys think???? Defective MAF
#1)Fuel pressure checked out ok right at 58 lbs with very little change..
#2)Cleaned the MAF with q-tips and acohol.. and WoW!!!!!!! The power plant was back..Drove it around for a little while and man it was pulling good no issues. Stopped by Orieliys and they removed all codes. Hesitation was gone car was pulling good..... 15 miles later and bam there it was service engine light back on. Car went back went back to struggling in the 3500 rpm and up during acceleration
Man I thought I was in the clear..
What do you guys think???? Defective MAF
#16
Is the K&N filter still in the air box? If it's over-oiled then it might simply be re-fouling the MAF shortly after every time you get it clean.
If a proper MAF cleaning made that much of a difference for 15 miles, then you can definitely rule out an exhaust blockage.
I'd get a paper filter and then clean the MAF again with the Q-tips, see how that goes. If you already swapped to a paper filter before the last MAF cleaning, then you might want to try unplugging the MAF and driving it like that (would default to SD mode), see if the 3500rpm+ issues are made better before actually buying a new MAF.
If a proper MAF cleaning made that much of a difference for 15 miles, then you can definitely rule out an exhaust blockage.
I'd get a paper filter and then clean the MAF again with the Q-tips, see how that goes. If you already swapped to a paper filter before the last MAF cleaning, then you might want to try unplugging the MAF and driving it like that (would default to SD mode), see if the 3500rpm+ issues are made better before actually buying a new MAF.
#17
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#18
P0131
P0151
Both front o2's
Just for kicks un-plugged the MAF the took it down the road, it is definitely working..
???????
What's next
plugs & wires
new front o2's
#20
OK cleaned MAF and went to paper filter---- No changes still running sluggish at high rpm. Had codes pulled and the rusults were
P0131
P0151
Both front o2's
Just for kicks un-plugged the MAF the took it down the road, it is definitely working..
???????
What's next
plugs & wires
new front o2's
P0131
P0151
Both front o2's
Just for kicks un-plugged the MAF the took it down the road, it is definitely working..
???????
What's next
plugs & wires
new front o2's
Acdelco plug wires and upstream o2's
Nkg tr55 plugs
I will try to install this afternoon. Remember stck manifolds any tips on install would be helpful