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Hey folks. Got to go for a 16hr drive in my new to me c5 (took the old man to get his new to him c6)
Had a few codes come up and just want to see if people agree with my thought lol.
Po101. Po131 po151
So im thinking my maf is giving all the issues. Going to try cleaning it. I was also using regular instead of the usual premium on the highway. The car kinda has a flat spot from 2-2500 area. Other than that it ran like a top.
Car is all stock
Anything else I should check?
I will be getting the regular time up stuff soon as well (plugs wires)
Thanks for the confirmation bought the car has been in the family for 3 years now but I'm sure she needs a bit of love in this aspect.
Just wanted to make sure I was going in the right direction.
definetly dirty, pulled intake hose and cleaned all that, checked air filter and will be getting a new one soon as well, shook this out for now.
will post back in the next coming days after i get some more seat time in it
definetly alot better than it was, still abit flat around the 2200rpm mark, but also i noticed almost a stumble (very slight hiccup kind of feeling) so im wondering, can i unplug the maf and drive for a test run?
ive done this with my 5.3 mafs that gave issues.
just want to make sure i dont hurt anything lol
plugs and wires will be ordered as car has 95k miles on it and i know they havent been replaced in the last 3 years since my family owned the car
Yes, you can unplug the MAF and see how it runs !!...I’m almost thinking you TPS sensor may have a drop out in it at that RPM...you can use a multimeter to check the 2 signal wire voltages but a multimeter is really to slow to see if that voltage drops out !!...a scope would be the best...I think my scope samples MILLIONS of those voltages fluctuations every second... the littlest “blip” would be seen !!...clear the codes and see if they come back !!...I’ve includes a YouTube video I did on my 2001...we call it a TPS Sweep” !!
I'll check that out for sure. I was starting to think the same.
Codes aren't present I'm going by feel. These codes were totally new and happened on the long drive when I did a wide open pass. I'll try unplugging for drive home and see what that's like
unplugging the maf made the issue worse. so i plugged back in when i pulled over. i noticed when i hold it at the flat spot it will drop 100-200 rpm then pickup and go, im going to try to check the tps with my torque pro app on my phone, ill try spraying some brake clean around the intake but that doesnt seem like its the issue to me.
Can you read your Baro on that thing with key ON ??...see if it reads about 27.9 (94.5 Kpa)...sea level is 29.9...you are almost 2000 foot elevation you subtract 1 inch of mercury for every 1000 foot of elevation ...what does your MAF read in Grams/Second at idle and at 3000 RPM ??..also what do your long term and short term fuel trims at idle...they are probably pretty positive like 15-20 % maybe...with the 0131 and 0151 can you graph your sensor 1 O2's on both banks ??...it will set if the O2's are reading a lean condition...they may be well below 200 mv or so...they should oscillate between 200-800 mv give or take especially at 3000 RPM...they sometimes look "lazy" at idle...if they look lean at idle spray some Brake Kleen into a vacuum line....now see if the O2's go RICH.. above 900mv...that will tell you that the O2's are responding to a rich command !!
i can read the baro it looks like from the app, i got the long term 1&2 setup and short term, ill check o2s as well
will report back when i do that and check on the tps i can read throttle % and pedal position and all sorts of stuff on this thing lol.
Super !!!...see if you can "graph" TPS 1 and 2 with KOEO with that thing...if it reads the TPS voltages at around 12-13% throttle angle is about 2200 RPM...for me anyway !!
Mad idle 6.5
Mad 3k 24.6 roughly
Long term and short term both banks show 0 into -10 area at times
Banks 1&2 o2 @ idle fluctuate from 0-.8v
O2 @ 3000 jump around .0-.8 all over the place really.
Maybe my o2 are duds after all.
The codes haven't come back yet
I do get intermittent po420 which is just one of my rear o2 but haven't been worried about it
To check the TPS you would look at TPS VOLTAGE with Key on Engine off !!...scan tool isn't the best to find these dropouts...scan tool uses "voltage over frame"...scope uses "voltage over time"...you said MAD sensor...MAF looks good at idle but to really check it's function a volumetric efficiency test at WOT is best...at 3000 RPM the front O's are supposed to oscillate between those numbers so they look good...the rear O2's are more or less "flatline" ...around 600-700 Mv or so...if they oscillate like your front O2 at 3000 RPM after the CATS are hot that's not good...a P0420 is a Bank 1 (drivers side) CAT efficiency DTC and is either a bad CAT so you should worry or an exhaust leak aft of the forward O2 to before the rear O2...there is a test called an "oxygen storage test" that you would do with a scope and some Brake Kleen but I won't get into the details...what do the long and short terms look like at IDLE ??...what do they read ??...I concentrate on the long terms !!...what do they read when at 3000 RPM ??...below is my TPS1 voltage from idle to WOT and back to idle.
Sorry yes it's supposed to be maf. Phone autocorrected lol I'm pretty sure that rear o2 is failing but I will monitor it closer. Rear o2 on the drive I just went on were steady fronts were operating correctly. Very similar to the 05 I'm using as comparison.
When I get under the car again I'll have a look for leaks. It's been a month or so now since the last 420 code. Never got it once on the 16hr drive.
Side note I took maf off again gave it another cleaning and went for a drive and the car seemed to be better. Pulled all the way through checked long term trims at hwy speed and they were no more than 14%
Long term and short term at idle floated anywhere from 0 to -10 area.
I'm thinking I may have gotten it with this cleaning and new air filter. Will drive it for a bit see if the 420 comes back or any of the others. (Old air filter was worse than it looked)
Alrighty so po131 came back and only it. Didn't set a check engine light. Day before was the po420. All the same bank. So thoughts on cat being plugged? Car runs and drives well.
I am going to get cats cut out this month and ecm tune done at a local fellow as well.
2002 c5 few issues
