2001 Z3 roadster

[Matthew0418]

Hello, I'm new to this site so hopefully I'm posting in the right place, if not let me know. I bought a 2001 Z3 roadster maybe a week ago with 130k miles on it. I'm fairly mechanically inclined except for troubleshooting issues and a little nervous to start taking things apart. I am pulling a list of codes that consists of (p0171) secondary dtc (p0300)(p1342)(p1346)(p1349)(p1353)(p1351)(p0505)( p0174) Iv been reading these forms the last few days of the individual codes I'm pulling and wondering if someone might have had the same batch of codes I do. From what iv been reading there is either to much air entering the system by a vacuum leak or a lack of fuel either by a clogged filter or weak pump both of witch can cause misfires. Iv visibly inspected all the weak points of a vacuum leak that u can check without taking to much apart and next step would be to have a smoke test done if I'm not mistaking. Next would be to check the fuel pressure once I get the kit for it. If the fuel pressure checks out an I believe it should be 50 with engine off or 70 while on. From my individual search of code (p0505) idle air control system can cause to much air to enter the system an cause misfires, witch seems to me might be the issue as I'm having most these problems while I'm idling/ sitting at stop lights etc.. so I suppose my question is if I'm on the right path or not and continue with these steps or if the car with think it's a p0505 code if I have a vacuum leak

[harveyottotech]

Yeah, definitely smoke check for vac leaks. It's a pretty common problem. The idle control valve has been known cause this issue. Clear codes and adaptations and try again

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[dworthy]

+1

Welcome to the Forum!

What would also help is if you can ID the motor that's in the car too, but yes I would start there and report back if you have any other issues.

[bmwdirtracer]

Hi Matthew, and welcome to the forum. You've receive great advice above -- you need to get a smoke test of the intake / ccv system done with a professional smoke machine. Taking stuff apart looking for a leak is counterproductive, because it's likely you'll cause more leaks, just moving the old hoses, and you'll convince yourself there are no leaks, when indeed there are. Only a smoke test will prove it, either way.

Also, you should get yourself a diagnostic scan tool which reads BMW codes, as P-codes are just emissions codes, and are generally terrible for diagnosing BMWs.

[Matthew0418]

Looks like I accidentally deleted my post lol. I really appreciate the advice and quick responses. I ordered a scan tool for bmw (autophix 7910) I ran a home diy smoke test and found a vacuum leak come from next to 1 of the spark plugs/coils so I'm assuming there's a gasket there somewhere that I'm looking at some videos to find the name for it. I'd post a pic but don't know how to

[328 Power 04]

Videos are a really poor way to identify parts and often really bad at fixing cars.

Use this: https://www.realoem.com/bmw/enUS/select

Type the last 7 of your vin in the serial number box.

[Matthew0418]

It's the valve cover gasket just wasn't sure if the gasket that goes around the spark plug hole was part of that set up or not but looks to be all apart of the valve cover gasket. I'll be picking 1 up today and replacing it. I'll run another smoke test and keep my fingers crossed that was the only issue, it was a pretty bad leak. Scanner will be arriving Saturday

[harveyottotech]

I just rebuilt the engine in mine and I now have a vacuum leak from the front half-moons under the valve cover. Turns out, the cover is warped and I need a new one. Gaskets are cheap so it's not really a big deal, but check the gap at the front when you are reassembling and make sure the squared section at the front on the half-moons comes all the way down into the bottom of the indent on the gasket. If it doesn't, you may need to replace the cover.

Sent from my KB2007 using Tapatalk

[bmwdirtracer]

The most common intake leaks I see from M54's are the accordion tube of the second intake elbow and the oil return hose to the dipstick tube. Nothing but a real smoke machine will find the second one.

[Matthew0418]

Update to current issue. Valve cover gasket and bolt grommets have been replaced, during replacement I noticed 1 of the bolts were the leak was coming from was missing a washer. Idk if it was like that or I somehow lost it myself, of course it was the last bolt to finishing so I took it all apart again to ease my mind that I didn't drop it in the engine. Valve cover no longer leaks and the old 1 looked fairly new as do most of the parts iv looked at. From more reading that iv done you kinda need to run a proper smoke test for 10m to reach certain areas. My smoke test was done by putting a glove over we're the maf sensor should be and blowing my vap pen smoke into it, the glove blows up like a balloon and take awhile to deflate, normal or possible vac leak still idk but it's 100x better then it was. Took off the disa unite and o-ring could probably be replaced as it's not really a secure fit to me. Took off the idle air control and seems to be fine, move freely but doesn't mean it's not bad. Change the spark plugs from single pin to ones recommend on the forms iv read to nkg 4 prongs. The coils seem to fit pretty loosely in my opinion, idk if that's normal or not as 1 of them looks like it's been replaced and has a good pop noise when I take it off that the others do not. So after doing all this I no longer get codes for lean banks 1,2 or idle air control system. So possibly I have fixed 3 of the 10 original codes. The 7 codes I'm still pulling are
Ca fuel trim bank 1 control limit
Cb fuel trine bank 2 control limit
E3 fuel trim bank 1 permissible range exceeded
E4 fuel trim bank 2 permissible range exceeded
F2 misfire, cylinder 5
F0 misfire, cylinder 3
F3 misfire, cylinder 6

So after more reading froms it sounds like I could still have a problem, the car needs time to adjust, the computer needs reset so I'm kinda at a stand still right now. I still have yet to test the fuel pressure witch I might do today and I will take a look into what the trims are reading, what the maf is doing or if theres some sort of cheat sheet of what a normal running car would look like on the data stream. Car idle runs a bit rough tell it's warmed up but I suppose to be expected if my fuel trims are outta wack

[harveyottotech]

3-5 g/s is the normal flow rate of the MAF. It may be displayed in kg/hr, but there are online converters that will tell you the g/s value. Rule of thumb is that the g/s reading should be done at idle, no AC, no extra loads on and it should be about the engine displacement in Ltrs on the g/s scale. There are still plenty of places for air to leak, so a real smoke test is in order.
If you look on you A/F ratio screen the normal values should be 0. If it above 0, it means the engine module is adding fuel to go with the extra fuel it's reading from the O2 sensors. If it's less than 0, -.9 to -20, its rich and it's taking away that percentage of fuel.
The easiest way to reset the adaptations is to use the scan tool. If you can't do that, do a hard battery reset. That involves taking BOTH battery terminals loose and touching the terminals together for 30 seconds.
PLEASE NOTE! YOU SHOULD NOT BE CONNECTING THE POSTS OF THE BATTERY TOGETHER. THIS WILL SHORT IT AND POTENTIALLY CAUSE AN EXPLOSION.
That said, if you take the terminal ends loose and touch them together, it clears the memory that's stored in the computer. This will bring the adaptations back to 0.
Give that a shot and see what happens.

Sent from my KB2007 using Tapatalk

[328 Power 04]

3-5 g/s is the normal flow rate of the MAF. It may be displayed in kg/hr, but there are online converters that will tell you the g/s value. Rule of thumb is that the g/s reading should be done at idle, no AC, no extra loads on and it should be about the engine displacement in Ltrs on the g/s scale. There are still plenty of places for air to leak, so a real smoke test is in order.
If you look on you A/F ratio screen the normal values should be 0. If it above 0, it means the engine module is adding fuel to go with the extra fuel it's reading from the O2 sensors. If it's less than 0, -.9 to -20, its rich and it's taking away that percentage of fuel.
The easiest way to reset the adaptations is to use the scan tool. If you can't do that, do a hard battery reset. That involves taking BOTH battery terminals loose and touching the terminals together for 30 seconds.
PLEASE NOTE! YOU SHOULD NOT BE CONNECTING THE POSTS OF THE BATTERY TOGETHER. THIS WILL SHORT IT AND POTENTIALLY CAUSE AN EXPLOSION.
That said, if you take the terminal ends loose and touch them together, it clears the memory that's stored in the computer. This will bring the adaptations back to 0.
Give that a shot and see what happens.

Sent from my KB2007 using Tapatalk

This is completely incorrect information for most modern BMWs after 90s, regarding "hard reset" of adaptations.

The M54 engine uses the Siemens MS43 dme which holds adaptations in the flash memory. It doesn't erase with any kinds of power manipulations. I can take a dme that was sitting for 20 years and read the adaptations from it from 20+ years ago.

Only the adaptation reset command via scan tool will clear it.

[Matthew0418]

Seems like when I go to edit my post it just deletes it, pff. So did a little drive, long term trims are set to zero, short trim running at +27 with little to no change from idle to throttle. Maf runs 3.5g/s at idle with fluctuations pending on throttle so seems to be running right, not sure if there's a minimum max threshold according to acceleration. Just ran a fuel pressure test with key jumped to 45psi and slowly dropped to 40 pis with key still in the start position and then waited 10 min with key out and creeping down to 35psi. I get conflicting information of what the psi should be from reading forms but what I do know is that it shouldn't depressurize. Posable reasons, fuel pressure regulator, fuel pump, anything else that could cause this issue?

[bmwdirtracer]

Well, officially, you should have 51 psi. Still, there's a matter of whether your gauge is accurate, and there's a matter of whether you had the vacuum line to the fuel filter connected.

All that said, a 45 psi reading isn't going to be your issue. Nor is dropping to 35 psi in ten minutes.

However: Your fuel trim is at the maximum limit -- there is something wrong. The DME (engine computer) is trying to dump full fuel in at low rpms, because it believes the mixture is extremely lean.

First step is still a smoke test.....using a real smoke machine.

[Matthew0418]

Ok, 1 real smoke test it is then to eliminate any leaks. So even with the fuel psi dropping to 10 psi in matter of 20-30 min is normal? And not holding psi when I have the key in.. I'll probably just replace the filter and regulator just for giggles tomorrow as I do not know when it was done before I bought it or if it was done right.

- - - Updated - - -

I appreciate your guys taking your time with this backyard mechanic

[dworthy]

It's normal for the fuel pressure to bleed off over time, so don't get wrapped up on it. The regulators just it to hold it at 51 PSI =/- 10% so seeing at 45PSI isn't much of a concern in my book.

Like noted by Chris, when you STFT are maxed out, there is a vacuum leak on the system, or it can even point to clogged cats.

[Matthew0418]

So after changing my fuel filter an stuff, went for a drive to watch trims and noticed when I'm driving and fuel systems in OP is when the fuel trims spike, when I'm sitting in idle and it switches to OL_FAULT and fuel trims go to 0%???

[Matthew0418]

Hmm weird, after sitting for a few minutes it went into ol fault and drove home that way with fuel trims normal

- - - Updated - - -

Is there's something in the date stream like cat load I can watch to see if it's running normal?

[harveyottotech]

When your car runs in open loop it's running off of an expected value and a few direct inputs like MAF, ECT, and Throttle position. In closed loop, it's self correcting by watching the O2 sensors. When it sits too long with a fuel fault it will stay in open loop just to get you back home. The reason the trim readings go to 0 is that the DME is now ignoring those inputs and running in a default mode.
None of this is really important to your issue though. It's just where this problem eventually leads. An open loop fault is the safety net at the end of the fueling strategy.
Great idea to change the fuel filter, I've seen several cause lean conditions. Usually, if a filter is bad enough to cause that, the fuel pump won't last much longer. If you haven't replaced the fuel pump in the last few years, I'd probably go ahead and change it. Not because it will fix your leans codes, but so you don't have to get towed home.
And, it may fix your lean codes too. It will also help to retain residual fuel pressure.
The fact that the fuel pressure drops while sitting isn't a huge deal. Most will loose some, and that's ok as long as it doesn't empty the fuel lines or rail. Even so, it's mostly a convenience thing as it takes longer to prime if the lines are empty.

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[Matthew0418]

I bought the car a few weeks ago for a good price as it needed work and have replaced the things I have since I don't know the history while I wait for an opening next Wednesday for the vacuum test. The guy at the shop doesn't do smoke test but a pressure test. Seems like both have there benefits. I was just hoping that maybe the fuel info would point to a specific thing I can fix an be done with it. My confusion is if there was a vac leak or fuel issue why would it run normal in ol fault. 1 video about gm motors talked about cams causing this type of issue causing vibration an also setting off misfire codes that was corrected by changing the computers interface. So if it runs normal in ol fault would that mean there's no vac/fuel problem and more a sensor or computer issue? Some have stated as the car gets older that the fuel MAP delivery if I'm not mistaking needs an update to match the cars age and wear and tear?

[bmwdirtracer]

You're getting a whole bunch of bad information. Pressure tests are for cooling systems, not intake/ccv systems. You have several BMW pro techs right here, and all of us are telling you to start with a smoke test. If the shop doesn't have a smoke machine, you need a better shop.

Forget the GM motors videos.

As Andrew has tried to explain above, CLOSED LOOP is the condition your car should be running in, any time it's warmed up (~90 seconds after cold start). OPEN LOOP is a "failsafe", where the computer ignores the faulty fuel/air data, and delivers "grossly correct" fuel to suit the rpms. The engine will always run "okay" in this state, but you're actually polluting your catalytic convertor, washing your piston rings with excess fuel, etc. (It's bad). It is an emergency "limp home" condition.

You absolutely have a fuel/air mixture fault. It is unlikely to be a fuel pressure fault, because the computer going into open loop will not make a fuel pressure fault better. It WILL make an intake/ccv system leak feel better though. It will also make a bad MAF fault feel better, because it's ignoring the MAF data. In fact, unplugging the MAF is one way of confirming a mixture-caused misfire, because it throws the computer into open loop.

[Matthew0418]

Yea I just been picking away at a few thing
I felt needed to be done anyways an trying to learn and understand a few new things along the way while I been waiting for the shop appointment witch was recommended by a couple of ppl so I just went along with what they had available, who knows maybe the guy I spoke with didn't know what he was talking about. A smoke test makes more sense to me I'll see what else is around. There next appointment was over a week out so that's why it hasn't been done yet

[dauberman1]

Replace the rubber gasket around the DISA Valve on side of intake. They dry and suck air and give offf multiple misfires. I had same codes in my 2001 z3 Roadster 3.0i