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Looked at his data log and his MAF was WAY "over reporting" at idle !!...his was almost 13-14 grams/second...normal 6-7 at idle...I was thinking wiring issue...ok, good 12volt feed...good 5 volt ref. but NO GROUND !!...figuring G106 since he was working in that area...I think he said he found bad wiring near the R/H exhaust manifold maybe ??...I can't remember MAF voltages at idle and WOT (my girlfriend says I'm like "Rainman" but without the math skills...so maybe the PCM thinks he's at WOT...and maybe because the PCM thinks he's at WOT he was always in "open loop" like it would be...I believe he said the car would not go into closed loop...he couldn't even run the engine too long cause the cats were cherry red !!...I asked him to call a few engine rebuilders in his area to ask about the CKP sensor issue...they said the brand he was using was junk...can't remember what brand...not Dorman... I told him to go right to the Chevy dealer an get an OEM sensor and after that it was purring like a kitten...motto of the story...ONLY USE OEM SENSORS ON YOUR C5...PERIOD !!...maybe I'll de-pin my MAF ground and see what happens !!
Yeah all 8 injectors dropped to 0 psi once the injector energized. I’ll take some more pictures of the MAF specs tonight and I didn’t have an extra person to look at the scanner while I was spraying the propane. I was listening for the change in idle.
Really should check those injectors...there are injector "pulsers" on Amazon for $35.00 !!
Mine had a misfire problem too after trying and testing just about everything I could think of I started to take the intake manifold off to change the gasket on it to see if it changed anything I came across the pcv line which had dry rotted in the back I would of never seen it since it was hidden I changed it and know it drives great
Mine had a misfire problem too after trying and testing just about everything I could think of I started to take the intake manifold off to change the gasket on it to see if it changed anything I came across the pcv line which had dry rotted in the back I would of never seen it since it was hidden I changed it and know it drives great
That’s ls1 pcv routing. The ls6 doesn’t have the routing that ties in both valve covers. I know because I used to have a ls1 camaro
The 01-04 ZO6 (LS6 engine) does not have that PCV Pluming. The C5 97-2000 LS-1 engine does use that same PCV Pluming and YES,, it does rot/crack and fail. Very likely source for a LS1 vacuum leak if you are have one on the early cars.
HOWEVER,, The 01-04 cars can also have a serious PCV leak on the very short piece of vacuum line that connects the valve to the TB. Seen it tooo many times to count. That short piece of runner line can rot and crack too. That PCV assy is on the passengers side of the intake manifold at the front just aft of the throttle body and it connects to a fitting on the valve valley cover.
MMM ??...I think you said you cleaned your MAF but it may be a MAF sensor..,the Solus should be able to show MAF grams/second and frequency...here is a snap shot of my 01 at idle...compare them to yours !!
The bark and map sensor don’t seem to match up with yours. Could this be the problem?
The 01-04 ZO6 (LS6 engine) does not have that PCV Pluming. The C5 97-2000 LS-1 engine does use that same PCV Pluming and YES,, it does rot/crack and fail. Very likely source for a LS1 vacuum leak if you are have one on the early cars.
HOWEVER,, The 01-04 cars can also have a serious PCV leak on the very short piece of vacuum line that connects the valve to the TB. Seen it tooo many times to count. That short piece of runner line can rot and crack too. That PCV assy is on the passengers side of the intake manifold at the front just aft of the throttle body and it connects to a fitting on the valve valley cover.
Have pictures of it if you need it.
Bill
So I spent some time yesterday with a buddy going over the car and he noticed that the O2 on bank 2, rear sensor is stuck at 500ish and does not fluctuate like the other 3 O2 sensors do. I thought that would throw a check engine light? But anyhow I’m thinking that’s my problem.
Sensor 1 in bank 1 and 2 should fluctuate between approx. 0,1-0.9 volt in idle .
Sensor 2 in bank 1 and 2 should not fluctuate when the cats are Ok .
When the rear sensors get similar activity to the post catalyst it indicate that the catalsyts efficiency is degraded
Oelarse is 100% correct. With the cats hot and at higher rpm the downstream is fixed...if it switches like the upstream you may have a bad cat..,it is not storing oxygen ...Now you said the bank 2 downstream remains near 500mv...a good O2 downstream sensor waveform will usually be a little on the “rich” side and read somewhere between 600-700mv...my downstreams with my cats hot at around 2000 RPM reads around 725-750 Mv !!...the 500 Mv reading you are seeing may be reading your “bias voltage” which is around 450mv...you might have an open in the signal wire or a bad O2 sensor...if at idle if you snap the throttle both upstream and downstream should momentarily go rich...see if yours remains at 500mv and remains fixed...,to test disconnect the O2 sensor and with the scan tool connected take a 12 volt test light connected to ground..,touch the tip of the test light to the signal wire...if the sensor shows 0mv on the scan tool the signal wire is good and you have a bad O2 sensor...if test light does not pull the signal to ground you have an open in the signal wire...you said the car ran better with your MAF disconnected...if your long terms are high and you run the engine at 3000 rpm and the long terms decrease over a few minutes ( the short terms will quickly go negative ) YOU HAVE A VACUUM LEAK..,if the long terms and short terms stay high you have a bad MAF or fuel delivery issue...using a scan tool is of NO help if you don’t understand the data you are looking at !!...does the scan tool show any misfires...if no misfires showing in OEM (enhanced OBD2) go into generic OBD2 and see if any misfires there !!
Oelarse is 100% correct. With the cats hot and at higher rpm the downstream is fixed...if it switches like the upstream you may have a bad cat..,it is not storing oxygen ...Now you said the bank 2 downstream remains near 500mv...a good O2 downstream sensor waveform will usually be a little on the “rich” side and read somewhere between 600-700mv...my downstreams with my cats hot at around 2000 RPM reads around 725-750 Mv !!...the 500 Mv reading you are seeing may be reading your “bias voltage” which is around 450mv...you might have an open in the signal wire or a bad O2 sensor...if at idle if you snap the throttle both upstream and downstream should momentarily go rich...see if yours remains at 500mv and remains fixed...,to test disconnect the O2 sensor and with the scan tool connected take a 12 volt test light connected to ground..,touch the tip of the test light to the signal wire...if the sensor shows 0mv on the scan tool the signal wire is good and you have a bad O2 sensor...if test light does not pull the signal to ground you have an open in the signal wire...you said the car ran better with your MAF disconnected...if your long terms are high and you run the engine at 3000 rpm and the long terms decrease over a few minutes ( the short terms will quickly go negative ) YOU HAVE A VACUUM LEAK..,if the long terms and short terms stay high you have a bad MAF or fuel delivery issue...using a scan tool is of NO help if you don’t understand the data you are looking at !!...does the scan tool show any misfires...if no misfires showing in OEM (enhanced OBD2) go into generic OBD2 and see if any misfires there !!
My question is would a bad down stream O2 sensor cause the car to idle bad? And car only ran slightly better with the MAF unplugged i could still feel it shaking. With the scan tool I can see the rpm dropping by about 50 rpm when it shakes and then it tries to correct and picks back up. It’s also a consistent pattern of when it happens. Yesterday I changed out the pcv hose and spent about 10 minutes spraying around with a propane bottle looking for a vacuum leak and found nothing. The O2 sensor is the only real thing I’ve found so far that seems to be out of spec. The scan tool also shows no misfires like I said before.
A bad downstream O2 sensor WILL NOT cause the engine to idle badly...it is there to monitor the cats...in plain English it monitors the pollutants coming out of the tailpipe. Like I had mentioned a few times in this thread you have to look at fuel trims at idle and at high RPM to diagnose a vacuum leak vs MAF/ fuel delivery...if the car runs fine at high RPM this is the sign of a vacuum leak...like I said before here look at your short term fuel trims when you spray the Brake Kleen or propane...when the Propane gets drawn into the engine short terms will quickly go NEGATIVE. I’m lucky enough to have a smoke machine and that is the “Gold Standard” to find vacuum leaks. I don’t want to waste time with the vacuum leak diagnosis. I would also clean your Throttle Body if you haven’t done this yet...this can cause idle issues. You have already changed all your ignition components so I’d move away from that...have you looked at your injectors yet ??...you can check each pink wire at each injector with key ON and make sure you have 12 volts there...you can check the “control side” of each injector with a 12 volt test light connected to battery POSITIVE...disconnect each injector with engine running and touch the tip of the test light to the other injector wire...the test light will blink very dimly if the PCM is grounding the injector. If all good I would OHM out each injector with the engine cold...If I can remember 11-13 ohms is good...to test if the injector is not clogged you would need that pulser to check for pressure drop in each injector. That’s all I got for you... might be best to take the car to a good diagnostic guy with all the equipment...for the DIY’er you’ll only be guessing !!..,good luck Bro !!
p.s. an old timer trick to see if you have a misfire is to hold up a small piece of paper to your exhaust with the engine running..,if the paper gets drawn into the exhaust you have a misfire !!!
