Getting random multiple misfires P0300

[simple_king]

So I been getting random multiple misfires on all 8 cylinders. I just purchased a vag cable a few days ago so I can trouble shoot myself. 2 months ago I had some EB works down pipes installed. The shop installed the downpipes and later told me he moved the location of the rear lower o2 sensors in front of the high flow cats. He felt they where in the wrong place. Originally the o2 sensors where suppose to be behind the cats. I purchased 4 aftermarket o2 sensors for the install and everything seemed fine. 1 day after pick it up I get a check engine light. I emailed him asking about the check engine light and he says its from the downpipes. He let me know that a tune will fix that. With no Vag cable available I went of his word.

Later I get a AMD HP supercharger kit installed from a different shop. This is where the fun begins. I tried to replace as much potential weak parts that could go wrong from this install like Hitachi fuel injectors, Fuel filter, PCV, engine mounts, and later a tensioner. After everything was installed the check engine light flashes with misfires on all 8 cylinders. Since new platinum plugs came with the kit the shop figured coil packs even tho they where replaced 25000 miles ago. New coil packs installed and its still misfiring. Holy Moly I thought to myself this doesn't sound good. Shop did a leak down test and all numbers where within good range. So pulling straws here I thought maybe the plugs where crap and told them to swap them for Iridium plugs. The misfires went from 7,000 rpm to 7599 rpm. The plugs where gapped to .022. This is odd...
Did logs and fuel trim was ok, fuel pressure seems ok, Maf is reading, and i swapped the MAF with a new one just to make sure. Still misfiring on all 8 cylinders. Carbon clean was also done right before install. I did a scan and no faults for sensors are coming up. Just misfires showing with everything else showing ok for no faults besides a rear parking assist sensor.

Questions in hand. Could the Hitachi fuel injectors be in question? It was suggested to swap them out with OEM injectors(still pending). The fuel HPFP where rebuilt with new internals. I purchased the injectors from a clearance sale for $30 dollars a piece. Not sure if they could of got damaged from it going missing for week from UPS and later delivered a week after with the box open. Also can the spray pattern be off? Not sure.

Is there something Im over looking here? All new parts and still misfiring on all 8 cylinders. Log shows random multiple misfires P0300 Intermittent- MIL ON

[JimmyBones]

This sounds like a nightmare. I will post something productive in a little bit.

[simple_king]

This sounds like a nightmare. I will post something productive in a little bit.

Thank you. Nightmare it is. Hoping to swap injectors out this week with some brisk spark plugs

[FWP!]

So you did end up getting a vac com cable? What do your short and long term fuel trims look like? (I think it's block 032 in Engine 1 and 2).

[JimmyBones]

Ok, on to being productive.

Thank you. Nightmare it is. Hoping to swap injectors out this week with some brisk spark plugs

I don't think that this is related to the injectors or plugs.

Lets back up and talk about the exhaust work because some things stand out to me.

1. Why did the guy move the rear oxygen sensors in front of the cats? That is stupid IMO. The whole reason to have the rear oxygen sensors behind the cats is so that it doesn't throw a set of codes for catalytic converter warm up efficiency. Do you have any pictures of the rear oxygen sensors to better illustrate the work done? I would have assumed that the guy was trying to screw me if I were in that situation. Just being honest.
2. Are you getting any codes for the oxygen sensors? I ask because it is very common to have the RS4 oxygen sensors installed and the connectors plugged into the wrong connectors so that the ECUs get confused. Especially since all four of the oxygen sensor connectors are on the passenger side of the transmission.

It is unlikely but I am wondering if the high flow cats are bad. I was going to type out how to run the catalytic converter basic settings tests but I remembered that the rear O2s are in front of the cats so that would not be helpful. If you can handle the noise then remove the downpipes and run the engine on a lift to see if the misfires go away. Warning it will be loud as hell!

[simple_king]

So you did end up getting a vac com cable? What do your short and long term fuel trims look like? (I think it's block 032 in Engine 1 and 2).

Yes I did. I sent the logs to AMD and they said it looks normal. I looked up that 032 and not sure if that's the right measuring block

[simple_king]

Ok, on to being productive.



I don't think that this is related to the injectors or plugs.

Lets back up and talk about the exhaust work because some things stand out to me.

1. Why did the guy move the rear oxygen sensors in front of the cats? That is stupid IMO. The whole reason to have the rear oxygen sensors behind the cats is so that it doesn't throw a set of codes for catalytic converter warm up efficiency. Do you have any pictures of the rear oxygen sensors to better illustrate the work done? I would have assumed that the guy was trying to screw me if I were in that situation. Just being honest.
2. Are you getting any codes for the oxygen sensors? I ask because it is very common to have the RS4 oxygen sensors installed and the connectors plugged into the wrong connectors so that the ECUs get confused. Especially since all four of the oxygen sensor connectors are on the passenger side of the transmission.

It is unlikely but I am wondering if the high flow cats are bad. I was going to type out how to run the catalytic converter basic settings tests but I remembered that the rear O2s are in front of the cats so that would not be helpful. If you can handle the noise then remove the downpipes and run the engine on a lift to see if the misfires go away. Warning it will be loud as hell!

I was thinking the same thing with the o2 sensors. I know o2 sensors can throw misfire codes and with them being moved I was worried. Again no cell or misfires before install. 1-2 days later I get a cell after install. Logs don't show any faults for o2 sensors but I'm thinking with the tune coded for no cats if something is screwing it up. I asked about that and was told many Audis have run with no cats and it takes a long time to get a cell if none sometimes. I never heard of that so I'm confused now about the way things work.

[Quattrors4]

the rear 02 sensors don't matter specialy when they are coded out,check your low pressure fuel pump and your high pressure pumps see if they follow the demand,you need to log ecu 1 and ecu 2,also .22 in spark plug gap is to small ,.28 is just fine on iridiums

[JimmyBones]

Usually on the stock NA tune Audis will throw O2 or warm up cat faults after a day or two. It needs to see the problem from running the basic settings test twice usually.

If you can then I would strongly recommend double checking that the O2s are plugged in correctly. As I said before it is a very common mistake with RS4s.

[Quattrors4]

if the front 02 will be connected in reverse his short term trims yould be -25 on bank 1 and +25 on bank 2 ,I've seen this many times

[JimmyBones]

if the front 02 will be connected in reverse his short term trims yould be -25 on bank 1 and +25 on bank 2 ,I've seen this many times

It is smart to start with the cheap and simple stuff first and then move forward from there.

Just like you learning how to drive your car instead of your jockey for trying to set records. Damn this is too easy.

[simple_king]

the rear 02 sensors don't matter specialy when they are coded out,check your low pressure fuel pump and your high pressure pumps see if they follow the demand,you need to log ecu 1 and ecu 2,also .22 in spark plug gap is to small ,.28 is just fine on iridiums

High pressure pumps are within 3%

[simple_king]

If the plugs where mixed up would they throw a code besides misfires?

[simple_king]

I purchased Bosch o2 sensors for down stream and walker for upstream

[Quattrors4]

If the plugs where mixed up would they throw a code besides misfires?

not right awy but yes it will throw a lean code one 1 bank and a rich code on the other bank
do me a fever re gap your plugs to .28,.22 is way to small for direct injection,your not getting enough spark energy at high rpm
quick fix man

[simple_king]

It starts with no hesitation. Runs normal till you floor it then the high rpm misfires occur. I will put the regular gap with the new brisk silver racing plugs.

[Quattrors4]

I purchased Bosch o2 sensors for down stream and walker for upstream

i would def stay with bosh o2 sensor specialy for upstream,but your afr are on spot then this is not an issue

[Quattrors4]

It starts with no hesitation. Runs normal till you floor it then the high rpm misfires occur. I will put the regular gap with the new brisk silver racing plugs.

it's when you floor it thats when you need more and more spark energy,.22 is way to small on direct injection

[Quattrors4]

it's when you floor it thats when you need more and more spark energy,.22 is way to small on direct injection

I've tested a lot of plugs for fi on rs4 the bkr8 eix at.28 are the best so far

[simple_king]

I've tested a lot of plugs for fi on rs4 the bkr8 eix at.28 are the best so far

I heard good things about Brisk silver plugs. I will keep the gap you recommend at see if any changes.

[simple_king]

It feels like spark blow out but nobody else with the kit from what I have heard are having problems like this. I wish it was easy as a fuel pump or such but almost everything has been replaced.

[Quattrors4]

It feels like spark blow out but nobody else with the kit from what I have heard are having problems like this. I wish it was easy as a fuel pump or such but almost everything has been replaced.

I'm sure they are not running .22 gap on there kit

[simple_king]

Looking at live data on idle. Knock sensor has zero volts on idle cylinders 5-8. Not sure if this means anything

[simple_king]

I'm sure they are not running .22 gap on there kit

True

[your daddy]

did you do a clutch recently?

[simple_king]

did you do a clutch recently?

Yes. Same time with the down pipes. Stage 3 clutch and flywheel

[simple_king]

I will also add that the flywheel that was given was a stock balanced flywheel. The engagement is rough and my tach doesn't shoot up fast how I see others. This can be from the flywheel. The power is felt tho.

[your daddy]

I would love to give it a shot if you cant figure it out. I'm in MA though.

[simple_king]

Sent you a private message

[JayTeeC]

Did you ever get this figured out? I'm having the same problem - P0300 and all the cylinders P0301 thru 0308... car runs and idles absolutely fine tho. Thanks!