Random Misfires and O2 Codes

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Topic: Random Misfires and O2 Codes (Read 3582 times)

Poody

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	Random Misfires and O2 Codes « on: June 14, 2019, 01:25:51 AM »

So I recently purchased a 2000 s4. Since I purchased the car 3 months ago, I have replaced the following

-Spark plugs with NGK BKR7E @ .028
-2.0T coils with soldered plugs and grounded to the valve covers
-Coolant temp sensor
-Motor and trans mounts
-Fuel and air filters
-Timing belt, water pump, serpentine belt, tstat etc
-All fluids minus the trans and diff
-Cleaned MAF

The car already had unknown brand of upgraded side mount ICs, APR bipipe, Miltek catback, 2 shiny DVs of unknown brand, and a tune of some sort (it is read protected so likely an OTS tune from APR or Unitronic etc.) It reads as an M-box in VCDS.

Now, its been giving me hell with misfire codes for the past 2 weeks. I can't feel any misfires ever, and the codes come back whether I drive normally or if I'm driving somewhat aggressively. I went to read the codes tonight immediately prior to taking my first datalog and noticed codes for both primary o2 sensors. Not all the standard variables are logged, I just picked a few familiar variables in the ecu file and went for it.

Here are the codes as of tonight prior to clearing:

VCDS-Lite Version: Release 1.2
Thursday, 13 June 2019, 23:49:36.
Control Module Part Number: 8D0 907 551 M
  Component and/or Version: 2.7l V6/5VT G 0002
   Software Coding: 06611
   Work Shop Code: WSC 40821
   VCID: 341B9FD31723
8 Faults Found:
16684 - Random/Multiple Cylinder Misfire Detected
   P0300 - 35-00 - -
16687 - Shareware Version. To Decode all DTCs
   P0303 - 35-00 - Please Register/Activate
16686 - Shareware Version. To Decode all DTCs
   P0302 - 35-00 - Please Register/Activate
16514 - Oxygen (Lambda) Sensor B1 S1: Malfunction in Circuit
   P0130 - 35-10 - - - Intermittent
16534 - Shareware Version. To Decode all DTCs
   P0150 - 35-10 - Please Register/Activate - Intermittent
16685 - Shareware Version. To Decode all DTCs
   P0301 - 35-00 - Please Register/Activate
16688 - Cylinder 4: Misfire Detected
   P0304 - 35-00 - -
17977 - Shareware Version. To Decode all DTCs
   P1569 - 35-10 - Please Register/Activate - Intermittent

Three questions:
1. I've moved coils and injectors, but the misfire codes seem to set on random cylinders each time. It always starts with p0300 and then over the course of a week, individual cylinder misfire codes will pop up. I'm new to the platform, am I overlooking something simple? Misfire codes need to go.

2. Do I need to be worried about writing over the current flash? I would really like to start from a stock file and do a mild "stage 1" tune after seeing how shit this current flash runs under WOT. Look at msdk vs mshfm and timing correction on all cylinders.

3. I'm used to ME7.5 and wideband o2 control. I know its not worth trying to retrofit wideband control into ME7.1, but has anybody here had experience with a wideband gauge and narrowband simulation to the factory harness? If I'm going to be replacing the sensors, I would prefer to do this, on the condition that it wont cause issues.


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_nameless

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	Re: Random Misfires and O2 Codes « Reply #1 on: June 14, 2019, 04:16:10 AM »

First and foremost replace your primary sensors. Log more values or at least useful ones. With that being said your ignition correction is crazy high pulling 10° of ignition correction. Don't waste your time trying to convert it to wideband the ecu doesn't have the logic or hardware for it and unless you're a programmer / developer youre wasting your time. Run the wbo2 into bank 2 downstream o2 and log wideband like everyone else. In my opinion best off flashing it back to stock, get your hardware situations figured out first. Oh and pm me if you want the full version of lite


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_nameless

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	Re: Random Misfires and O2 Codes « Reply #2 on: June 14, 2019, 04:17:12 AM »

See


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Poody

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	Re: Random Misfires and O2 Codes « Reply #3 on: June 14, 2019, 11:10:44 AM »

Quote from: Marty on June 14, 2019, 04:17:12 AM

See

And that's is the correction I was mentioning above. I have no problem flashing it with a stock bin and starting from scratch, but I'm not sure if APR and other companies bins can be directly flashed over or if I'm going to brick the ECU trying.

As for widebands, I'm not looking for wideband control, I'm just curious if I can run a wideband sensor in the stock location and have a controller simulate narrowband output for the ECU. That way the ECU stays happy with a narrowband signal, I can log WBO2 to tune, and I don't have to waste money on narrowband sensors. Anyone have experience with this or am I better off buying 2 narrowband sensors and then a separate wideband for tuning/logging? Like I said, new to the platform. My last car was a BT 1.8T making around 500hp which I tuned myself, just not familiar with how people go about it on the s4s without native wideband control.

EDIT: Ran a fuel pressure test today and with the vacuum line on the regulator, I'm only seeing 20psi. I know this is low, but it seems too low for the engine to even run properly as spec is 51psi. Also immediately bleeds down to zero when engine is shut off. Ordered a new FPR and if that doesn't solve my issue I will be installing a Walbro 450.


« Last Edit: June 15, 2019, 11:41:53 PM by Poody »	Logged

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