P0300-P0306

drocket77 · Post by **drocket77** » Mon Sep 21, 2020 7:10 am

2004 Z4 M54B30 (Oct03 Build)

As the title states I am getting those codes, except for P0301. #1 will have a misfire maybe 1 out of 10 times, with the exception of removing the intake pipe while running. Here is the things I have done so far.

1. Replaced spark plugs.
2. Switched the coil packs around, and all will eventually have a misfire except #1.
3. Made a smoke machine and have checked while warm, and cold, no leaks.
4. Dangerously sprayed starting fluid around vacuum tubing, and no change in rpm digital bi scanner was hooked up, and idle stayed at 745-765.
5.New oil cap(holds pressure when I did smoke test, and rpm will change if I take it off while car is running.)

I have reset then went on a drive from a cold start and it throws the code exactly 3 miles into drive. Tried it after it warmed up, and exactly 3 miles into drive. It doesn't matter if I was stopped at a light, did 70mph on the longer stretch or 35 mph.... 3 miles in it ALWAYS throws the first code.

I have also reset adaptations about 200 miles ago, and wondering if it is still in a learning state. And the reason I reset adaptations is that I got new exhaust, new IAC, and new MAF sensor(previous owner didn't even have one).
Here is what is replaced, and checked that it is working.

1.MAF sensor
2. IAC valve
3.New Intake boot
4. Plugs and coils.
5.Injectors

3 Days ago I did a little experiment by unplugging the MAF sensors. Wouldn't you know it didn't throw any codes other the the 2 for the maf sensor. Which brings me to something with AF ratio. I try and get into the EKPS module, but it has no comms... weird..after searching 2 days for the actual module, and reading another post here, I think it is controlled through a relay and the ECU. Now that brings me to why it does not throw a code while the MAF is unplugged, as it is running in fail safe and the pump will run at 100% since it cant tell how much air is coming in. I am gonna attempt to get the relay out, and see if I can find one online somewhere and test that. Or does anyone know if the EKPS is on this vehicle, and before you suggest the boot/trunk, it is not there. I destroyed sub amp by not unhooking the power before i took my trunk apart.... so I down $300 for that now....and no bass for the time being. I don't think its the fuel pump, as it works fine without the MAF, but it also could be "going" bad and the when it thinks its 100%, it may actually only be say 80% which may be enough for it to run fine. I would rather it be a simple relay, and not the pump, but hey my luck its both.

ph001 · Post by **ph001** » Mon Sep 21, 2020 12:17 pm

When you disconnect the MAF the ECU determines fuelling from the MAP and pre-cat o2 sensor readings - the fuel pump doesn't play a critical role at all.

The primary way the ECU detects a misfire on the cylinders is crankshaft speed variations between between the firing of cylinders. Of course, this in turn causes unburned fuel to pass the o2 sensor, but the ECU needs to MAF signal to correlate that. No MAF signal = no misfire codes.

When you changed your coil packs and plugs, what did you put in there? I'd definitely be changing them for OEM quality if they were Ebay specials.

drocket77 · Post by **drocket77** » Mon Sep 21, 2020 2:58 pm

I replaced the crank sensor also. But yes, they are ebay special.. but it is doing the same as OEM ones. I am getting the same resistance on all 12 of the coil packs. I have also tested with spark light, and old school plug to ground, all look exactly the same, and looks just like my Dodge Rams spark. And I have read that if there are any faults on the EKPS or in the system, the pump will run at 100%. If the pump itself is going bad, 100% may actually as low as 60%. I am still gonna go forward with the relay, then pump.

ph001 · Post by **ph001** » Mon Sep 21, 2020 3:54 pm

It’s your money I guess but pump failures are rare indeed on the M54. If the pump wasn’t able to supply enough fuel you would get lean codes and fuel trims would increase dramatically. Anyway, simply monitoring your fuel pressure would tell you for sure.

drocket77 · Post by **drocket77** » Mon Sep 21, 2020 5:18 pm

Thats the thing. The previous owners kid used the car for 2+ years and never had the MAF sensor connected or any O2's. This would mean for however many miles they drove the thing, the pump was running at max. I did a leak down test and was getting at Fuel rail after starting the car for 10 seconds was 52psi. Shut the car off and I waited 10 minutes and checked again, and it dropped to 46. After about 3 hours it was at 0. And just because somethings rare, doesn't mean it won't happen. If there was any indication on what the previous owner did to this car, like the lack of MAF,O2, and a Wish muffler with no cats...... I would assume he was putting the cheapest gas/petrol in as he could. Since I have owned it I try to alternate between 90 and 93 octane from either Shell or BP. I think I may have filled up at an off brand gas 2x and got 93 both times. This car has had a rough life, and I am just trying to get it as correct as I can.

Jfgoldfish · Post by **Jfgoldfish** » Mon Sep 21, 2020 5:40 pm

drocket77 wrote: ↑Mon Sep 21, 2020 2:58 pm I replaced the crank sensor also. But yes, they are ebay special..

drocket77 wrote: ↑Mon Sep 21, 2020 5:18 pm I am just trying to get it as correct as I can.

These statements just don't go hand in hand.
I am not trying to disrespect the work you are doing to get your car back to its former glory. Just be aware that many people have been bitten by the quality (or lack thereof) of some ebay parts.

The best way to properly fix these relatively modern cars is to spend your money on the best diagnostics software or code reader you can. A basic oscilloscope and a multimeter can come in handy if you are chasing sensor or wiring faults. Learning to use these tools can save a lot of money; money that I would recommend spending on quality replacement parts once you have confirmed a part is at fault.

ph001 · Post by **ph001** » Mon Sep 21, 2020 8:35 pm

drocket77 wrote: ↑Mon Sep 21, 2020 2:58 pm The previous owners kid used the car for 2+ years and never had the MAF sensor connected or any O2's. This would mean for however many miles they drove the thing, the pump was running at max.

It’s not the pump that controls the mixture, it’s the injector duty cycle. The pump’s job (with the aid of the fuel pressure regulator) is to maintain the correct fuel pressure in the fuel rail (which generally speaking is kept constant apart from at idle). The fuel rail pressure is not really influenced by the MAF signal or the o2 sensor at all.

drocket77 · Post by **drocket77** » Tue Sep 22, 2020 5:46 pm

And the only thing that I have purchased for this car that was of questionable quality was the coils. So if you feel like belittling someone who is genuinely trying their best with what knowledge and funds that are available, then I will just stop asking, and move on to somewhere that will help. When I said "yes, Ebay special" that was referring to the coils, everything else has been of good quality.

1.unpainted front bumper $450.00
2.Unpainted side Fender $250.00
3.MAF sensor $130
4.Intake Boot $45.00
5.Injectors $110.00
6.Plugs $94.00
7. 1qt of Paint $165.00
8. Head Lights $490.00
9. Wiring connector for Cam Pos..$45.00 (dealer)
10.rotors,brakes $350.00
11.New custom exhaust $800.00
Many other small odds and ends, oil changes, fluids....ect.

Oh, and a bi-directional scanner. $900.00(not just for this car, but was a big reason I bought it)
So, do I buy the most expensive things for the car, no, do I buy the cheapest, no. I am trying to be as economical as possible,yes.

Jfgoldfish · Post by **Jfgoldfish** » Tue Sep 22, 2020 6:33 pm

Wow, that's quite a sharp reaction. I wasn't trying to belittle you, what gives you that impression?
Nobody is telling you the parts you purchased are of questionable quality but as I stated above, be wary of bits purchased from eBay.

You can only provide limited information in a post and you provided no information that suggested you had purchased a 900 dollar scanner (I hope it fixes the car for you at that price

), and some of the information you did provide gave the impression that money was being thrown at the car without good reason.

drocket77 · Post by **drocket77** » Tue Sep 22, 2020 8:46 pm

Money wasn't being thrown without reason. The only thing I have thrown on without "good" reasoning was the coils, and they were original. All other stuff it needed.
And the scanner was on the cheap end for a BI-Directional scanner. It could have a few more options, but overall it is good. I can do a lot more with this other than a $100 reader. I also have just installed ISTA/P and ISTA+. I haven't had the opportunity to use it yet, as I need to solder wires 7 and 8 on my OBDII usb wire. Or buy one that has a 3 way selector, better idea.

As of now, I think I am going to buy the VDO MAF, though I am not optimistic, I can always return if that doesn't work. I also looked at smooth running values, and cylinders 2 and 5 will go as low as -4, but that is still within spec, as -6% is out of spec. The rest are always at 0. I have attempted a leakdown test on all cylinders, but every time i put air to them, they move, and I do not have a reliable way to keep the crank shaft from turning, unless I buy a long breaker bar and can wedge it to the asphalt when i am at TDC. I had a decent sized Craftsman one, that I broke on my Ram while trying to take off the hub nut.

Jfgoldfish · Post by **Jfgoldfish** » Tue Sep 22, 2020 9:21 pm

drocket77 wrote: ↑Tue Sep 22, 2020 8:46 pm every time i put air to them, they move

I have managed to lock an engine for leak down by holding the brake whilst in a high gear. It's a pain though because often the engine will nudge past tdc enough to open a valve and spoil the test.
Is yours a manual or auto?

Have you taken compression for each cylinder? I much prefer it as a good indicator of engine health.

drocket77 · Post by **drocket77** » Wed Sep 23, 2020 2:02 am

Manual, I may be able to put it into 5th after i get it into TDC. I can try that. Each cylinder moved every time, so I have not been able to do a good test. I also lent my normal compression tester to a friend last year..... thats why I was just going to do a leak down and just skip the compression test. I can pick one up from Pepboys or Autozone... And when I do, next week my friend will return mine...

qhrjsdl · Post by **qhrjsdl** » Fri Apr 19, 2024 4:59 am

drocket77 wrote: ↑Wed Sep 23, 2020 2:02 am Manual, I may be able to put it into 5th after i get it into TDC. I can try that. Each cylinder moved every time, so I have not been able to do a good test. I also lent my normal compression tester to a friend last year..... thats why I was just going to do a leak down and just skip the compression test. I can pick one up from Pepboys or Autozone... And when I do, next week my friend will return mine...

Any update after?

I'm getting P0300 / P0303~6 lol

Z4-forum.com

Z4-forum.com

P0300-P0306

P0300-P0306

P0300-P0306

P0300-P0306

P0300-P0306

P0300-P0306

P0300-P0306

P0300-P0306

P0300-P0306

P0300-P0306

P0300-P0306

P0300-P0306

P0300-P0306

P0300-P0306