ExpressvanMan2000

Okay so after buying a maf sensor from carparts.com it threw the code po102. I did this because the van was originally throwing codes po101 and po 300 changed spark plugs and 300 code went away.

I have changed the fuel filter, fuel pump, maf sensor, and map sensor can still running as if it's bogged down,hesitating, stumbling randomly etc


Could the fact I didn't buy a OEM MAF sensor be the cause of all this? The only codes I get are related to MAF sensor I tested the connections of the MAF and the battery with a volt o meter(I think that's what it's called) and it checked out good....I guess if I OEM MAF DOESNT FIX this I have a manifold leak.

Triaged

Did you do all the things mountainmanjoe suggested in the last thread? Was the fuel pressure actually low on the old fuel pump? did it leak down? Do you have a code reader or a scan tool that can do freeze frame data? OBD2 adapters are cheap now and so is the Torque app. Post up the freeze frame data.

mountainmanjoe

For MAF sensors, I think it's a good idea to stick to OEM.

oilcanhenry

I agree.

And don't used oiled K&N filters. I made that mistake, but after I threw it away for a Wix air filter, and cleaned it up well, it's been working fine now.

chevyboy@22

• Black smoke exiting the tailpipe
  
• Worse fuel efficiency than usual
  
• Rough idling
  
• Check Engine Light
  

These issues can happen when the MAF sensor is damaged or when its wires are coated with dirt. It can't measure airflow accurately, therefore sending incorrect information to the PCM. When it overestimates the airflow, the PCM releases too much fuel. Most of the time, the problem can be fixed by cleaning the MAF sensor's wires.

MitchM

i add: DONT use non oem crankshaft position sensors. i spent $$ chasing a p0300 random misfire that still isn't fixd. non oem cCkPos sensor would not relearn. still throwing p0300. s.

ExpressvanMan2000

Its $270 for the MAF sensor..I'm scared to buy it lol. I hope it works. I'm I'm stumped and like I have said this is the one code that constantly shows up.

MitchM

we replaced the MAF on my 07 3500 express after cleaning it , didn't cure the p0300 code . (see my posts on this forum under p0300 express random misfire for a complete list of the expensive parts we have already replaced. without success. ) my understanding is that the p0300 random cylinder misfire can only b e diagnosed by a top of line OBDII unit like the snapon with GM capability , or a dealer's GM mode 06 OEM proprietary scanner . the scanner must be one which 1/ has the ' GM software' and 2/ can do data stream and freeze frame with engine running and be attached while the dtc code is showing to analyze what cylinder is msifiring. so scanner (w ocscillosscope) must be attached and van being driven, throwing the p0300 code on the road . WHILE the MIL check engine lite is on and p0300 code are showing up, w engine running. i found out 1/ lots of shops don't buy the vehicle- specific 'gm' $100 diagnostic pack (which is a vehicle-specific add on for ach manufacturer, or bmw or nissan . at 4100 apiece...) ) some shops won't pay the the manufactirer- specific software add charge on the cheaper scanner units and won't tell you they dont have it . ) 2/ a shop won't tell you what scanner they use and whether they have the GM specific diagnostic pack unless you ask. 3/ shops will take your van in cold then tell you for a $129 fee ' and say it wasn t showing a code,' so let's then start throwing $$$ parts at it . (chevy dealers included. ) p0300 is hard to diagnose. i finally found a independent mechanic with GM diagnostic capacbility on his $4000 snap on scanner, willing to let me bring the van in while it's running hot and throwing the P0300 dtc code. then they'll be scanning and freeze framing it 'hot w engine running while it's throwing the p0300 code . data stream and freeze frame the data might show what's up.

my list of suspects is :

1/ one bad injector -- though all were professionally cleaned . 2/ cam shaft position sensor -- but it's not throwing P0340, does not rough idle, fail to start, or hesitate on acceleration . 3/ bad ECU . putting excess fuel in and out (but fuel trims checked out fine. ) (NOTE I already replaced the crankshaft position sensor twice ( #1, 1 cheapchina, wouldn't relearn . then #2 oem . still no fix. earlier models of the ckcPos Sensor developed too much clearance and GM put out a TSB on it then changed the design of the CkKPos so the OLD design should NOT be used. see my previous posts for the TSB on shimming a worn cKposS , that is no longer recommended as a fix , just replace the thing . dont know if 'old' and ' new' part no s for ckCPos S remained the same but i do now the 'shim kit' reocmmended in the 06 TSB is NOT available. just go with NEW OEM cKPos S. ) Note a a crankshaft relucter wheel problem is still a suspect but i did not ever have and do not now have its symptoms of power falling off at high rpms or low compression which are suppposed to occur for crankcase position sensor and i did NOT have that code or its symptoms. ) . replacement of crankcase position sensor with an OEM should have fixed p0300 if that part was the problem...or 4/ stretched timing chain --to replace w newisa big 12 hour job, and $500 in parts . --and why should i need this on a on an engine w only 61,000 miles on it ?

for more than you ever wanted to know about random misfires see the you tube videos on LS and LQ engine misfires. and ssannerdanner's youtubes , on how problems can be caused by a bad cam sensor.

i ll have the freeze frame and data stream data by tomorrow.

ExpressvanMan2000

Yes I'm pretty much don't know what to do I believe it's not throwing code po300 anymore it's code 102 I think...maf sensor not reading in rage or something along those lines.

oilcanhenry

Code 102 could mean corroded wires or corrosion at the PCM.