Misfire AGAIN P0300 and P0430

[nimrod.sixty9]

I thought that's what I did. If not, how do I do it?

No arching.

---------- Post added at 07:54 PM ---------- Previous post was at 07:08 PM ----------

Okay, well I officially no longer trust this app. Shows current misfires all over the place. Often they match each other in numbers, yeah right. Shows RPM going from 9000 to 600 to 3500 and I'm just cruising. Total BS.

 

[SunlitComet]

does the vehicle dash tachometer and vehicle speed remain constant when the pcm has really wild numbers?

 

[nimrod.sixty9]

does the vehicle dash tachometer and vehicle speed remain constant when the pcm has really wild numbers?

Maybe I should explain more how it feels; most of the time it feels fine with just a slight miss here and there. But sometimes, it's crazy missing and hesitation with massive loss of power. If I floor it, it can get up to speed pretty well. Slower seems worse as well as going up bridges (my hills).

RPM does not match the PCM numbers at all. Every frame refresh shoes it's all over the place.

 

[SunlitComet]

The rpm that the pcm puts out is based on the crankshaft sensor. That sensor is required for starting and running. Ignition and fuel timing is based off it as well as misfire monitoring. So again say you are cruising down the road in the consistent 60's and say your tachometer(see's it signal from actual ignition wiring so very separate sources.) says 1800 rpm while in lockup overdrive. Your pcm should be saying saying about the 1800 rpm too. If it at all says 9000 (Should never see that kind of number) rpm or some numbers that does not match the tach something is very wrong.

Possibilities include:
1. a screwy diag program, head to a local store and use there scanner and verify say with the throttle open part way.

2. Defective crankshaft sensor.

3. Defective sensor wiring.

4. Damaged reluctor inside the timing chain cover(highly doubtful tho.).

5. A defective pcm.

If you have to change the pcm or crankshaft sensor you will need to perform the relearn procedure. It is used to learn the variances in the sensor so it gives proper misfire data detection to the pcm. Will need a high end scanner for the procedure that can initiate the function. Put it in park and set the parking brake. Start the function on the scanner. Once the scanner says accelerate, scream for your life real loud and floor it WOT your engine will head for the redlining. On it way to blowing up in a ball of fury it will sudden start dropping a few cylinders. Immediately release the pedal to avoid redlining it and consider the test done unless the scanner says you failed in a crash. If all goes well you will be done 2-3 seconds after you mash the throttle open.

 

[nimrod.sixty9]

Just checked it with Tourqe Pro on my cell and the RPM reading is spot on. Like I said, the app. So now what?

 

[SunlitComet]

If you are sure the program is wrong then tell the maker of it so they can solve the issue that way you can get some accurate data to help diagnosis. Read those plugs yet. remove them, label and take multiple pics to post.

 

[nimrod.sixty9]

If you are sure the program is wrong then tell the maker of it so they can solve the issue that way you can get some accurate data to help diagnosis. Read those plugs yet. remove them, label and take multiple pics to post.

Thanks Sun. Ill get the plugs changed out and posted as soon as I can.

Im going to reinstall the app and see if I can get some trustworthy readings.

Hopefully soon I can find my fuel pressure gauge. Im thinking maybe weakening fuel pump. We will see.

 

[SunlitComet]

Don't really need to change them out just inspect them for now. Platinums can cost about $5 each you know.

 

[nimrod.sixty9]

Just as I was about to go out and pull the plugs, it occured to me that I do not trust what ScanXL is showing for all the misfires. Why would I trust it for the codes?

Sure enough, codes did not match.

It was one again cyl 3! Changed just that plug and once again runs like a dream...

Im suspecting it was fouled up from last time it had a misfire from what I assume to be the cap (what I replaced 4ish months ago) and steadily got worse from there. What say you?

 

[SunlitComet]

I say if it happens again let me know. Still does not solve the bad data issue in the diag software.