Clear all codes, and see what comes back. If you need to, disconnect only the negative battery cable, insulate from the terminal and short to positive for 30 seconds, then reconnect, idle up to operating temp and take for a 10 minute drive to relearn TB, idle, fuel and driving adaptations.

Post fuel trims at idle and at 2500 RPM.

The glove over the boot... I’m assuming this is when the engine off? If so, a non running engine isn’t supposed to hold vacuum, especially upstream of the throttle plate. Do not confuse vacuum with suction; vacuum and RPM have an indirect relationship.

As it was never mentioned, I have to assume you didn’t check the head for trueness or warpage. If that is the case, compression check all cylinders, paying close attention to #3 and 4 compared to # 1 and 6.

Head gaskets come in varying thicknesses in order to account for head milling. As it wasn’t mentioned that your head was milled, make sure that the head gasket you installed has the same compressed thickness as stock, or you’ve lowered your compression ratio and idle vacuum.

If you have an android phone, the $5 Torquepro app and a BT single can give you all the run time info you’ll need more conveniently than INPA or ISTA.


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Thanks for the response I suppose i could've stood to be more clear. When i smoke tested for leaks i pumped in air through the brake booster hose but in order to seal the system i pulled the air box and MAF and put a glove over that boot. whenever i pumped in the smoke the glove would inflate real big then slowly deflate. When the valve cover was leaking there wasn't a TON of smoke but definitely enough to notice so its possible there is a small leak deep down but i dont hear any vacuum leak sounds when running.

As for compression i checked all cylinders and they're all at 150. The furthest cylinder back from the grill (6th?) is reading a little higher but no more than 160. I can check again it was just something i noticed. The head ended up being flat so it must not have overheated too bad. I also replaced all plugs with NGK platinum whatever as the old ones looked pretty bad.

Also, Is fuel trims something i might be able to see on a code reader? I have just a basic fox well reader but it does show some live data. I know INPA shows alot more than any universal code reader would and unfortunately i have an iPhone

 

My code reader was able to get fuel trim readings!! Full warning im not sure how accurate it was because the "live data" had a pretty slow refresh rate (almost 1 a second). I have a few snapshots below although i gotta be honest i have no idea what it means but if it helps you help me thats all i need.

SFT=short fuel trim
LFT= long fuel trim

SFT1(%)-27.3
LFT1(%)-5.5
SFT2(%)-0
LFT2(%)-7.0
RPM-2445

SFT1(%)-20.3
LFT1(%)-5.5
SFT2(%)-0.0
LFT2(%)-5.5
RPM-2428

SFT1(%)-0.0
LFT1(%)-6.3
SFT2(%)-0.0
LFT2(%)-7.8
RPM-556

SFT1(%)-0.0
LFT1(%)-6.3
SFT2(%)-0.0
LFT2(%)-7.0
RPM-18.21

SFT1(%)-0.0
LFT1(%)-7.0
SFT2(%)-0.0
LFT2(%)-7.0
RPM-1477

Today i also removed the battery terminals and shorted for about 10 seconds and then puttered the car around the yard. I didnt feel comfortable taking it out on the road because it stalled pretty regularly when idling. It ran great when i gave it some gas however. After all that i got a new code. P0155 - 02 sensor heater circuit bank 2 sensor 1.

I have a confession to make. I ordered two bosch o2 sensors awhile ago. I'm pretty sure they were tested to be working but they were used on ebay. The plugs were damaged but i couldnt afford new sensors so i did a little cutting and soldering (i know i know, but desperate times...) I did this for both upstream sensors and obviously one isnt responding well. They were both done in the exact same manner, i just checked my solder joints and theyre all solid, so it may be a faulty sensor. Is it possible they arent wired the same?? I kinda made more of a mess for myself but i guess i just need to figure where to go from here.

The first video i didnt touch the accel pedal at all. The second video i revved it up pretty high. I also really appreciate all the help so far. This being my first bmw it really helps to have some experts share their wisdom

https://drive.google.com/file/d/1eIw18u_FS9iA62FzMpdDTVFcaB6zMf98/view?usp=sharing
https://drive.google.com/file/d/1WV3zLVjtmjEH8s7QqkcmrE0Ahk98cgjX/view?usp=sharing

 

OP: IDK if the O2 / "Lamda" sensors are the same for the M54 as the N52, but I know where you can find some used but were-working ones for the N52. (see far below)

Yes, all the smoke-leaks must be fixed, even the small ones. One of my weird leaks was in the hose to the exhaust damper -- under the dash, the brake pedal had worn a hole in the little rubber tube.

 

Yup with probable vacuum leaks and probably errant sensors, you have some things to trouble shoot. You'll need to monitor some more items on the scan tool. While you have a code for B2 lambda (O2) pre-cat sensor, your STFT points to a problem in cyl 1-3. You should be able to read O2 sensor action with your tool.

Here's a great primer:

https://www.autoserviceprofessional.com/2858/fuel-trim-how-it-works-and-how-to-make-it-work-for-you

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What 02 action specifically am I looking for with the tool? also how were you able to find the leak under the dash? i guess i could just sit and pump smoke into the system until i see something. Also, should i replace both sensors or just the one sending codes. Last question, what are the odds my problem is more than sensors and leaks?

 

Another good read:

https://www.hella.com/techworld/us/Technical/Sensors-and-actuators/Test-lambda-sensor-4379/#

Your scanner can show you the in time voltages as well. You'll want to watch fuel trims and O2 sensor voltages graphically. At the most basic level, play a little game of "one of these things is not like the other" I.e. looking for signal abnormalities. We know your B2S1 will be errant, but we want to try and get a glimpse of B1.

The odds are highly likely that you have more issues than sensors and leaks. A $2500 BMW is an obnoxious $6000 car. Definitely more than anyone with a tight budget should attempt to deal with, but that genie is out of the bottle. I'm not implying you screwed up the job, but because the head was replaced, anything is up for grabs now (gaskets, VANOS, timing, etc.) but some of that will code.

FYI you mentioned unhooking the battery cableS... if you did both, you didn't do anything. To wipe adaptations and codes, disconnect ONLY the negative and short against the positive, being sure to insulate the terminal.

In addition to smoke, you can use an unlit but open propane torch around all areas with the engine running and graphically watching fuel trims and O2 sensor voltages. When you get the curves to suddenly spike, you've found your vacuum leak.

Misfiring cylinders will also drive fuel trims way positive, so get brand new NGK plugs in it. These will misfire long before throwing a code for it, but positive fuel trims under load help confirm the misfire.

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I blew $60 on new NGKs last week and put them in. Im realizing what im in for as im nearing $4,000 and not a whole lot to show for. Theres a guy with an e46 parts car about 20 minutes away who has pretty fair pricing so i'll see about getting some o2 sensors off him. Thanks for pointing out the battery thing, i definitely did it wrong and i'm gonna go smoke test right now then try the propane trick and come back with my findings. I'll try and get some o2 sensor data but i was also curious about how much my TP% is supposed to change. It rests at 16 and doesnt get much above 20 from the short time i watched/pushed the pedal. Is that normal?

 

Ok good on the plugs.

Not sure on the throttle position. Throttle plate is probably restricted in movement in park anyway.

Oh, and make sure the propane isn't lit. [emoji6]

My first several cars were all carbed. If they acted up I could fix them with a screwdriver in the 7-11 parking lot (like I did a starter). [emoji6][emoji106]

O2 sensors are different between manual and auto M54 cars. I'd bet they're different between M54 and N52 but don't remember for sure, look up and check part numbers on REALOEM.com. Also make sure to check than E46 and E83 sensors are compatible. If they differ only in wire length go for it.

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Great news! Turns out I accidentally pulled the boot off the IACV when replacing the DISA. I fixed that and now I cant find any smoke during a smoke test (i checked under the dash near the pedals too) and it idles and drives smooth. It seems like it takes a second to reach a smooth idle and the RPMs will bounce around a bit before settling. One thing i noticed is a weird delay in shifting, like it seemed like it revved too high before shifting. I may have been overthinking it im not sure but I'll look into that once i get it all squared away under the hood. Unfortunately 1 mile into the test drive the temp needle started to rise so i pulled over immediately before going home. When i got into the driveway i realized i had a trail of coolant behind me which is strange because i topped it off and monitered the coolant level daily for two weeks and showed no leaking. I rented a pressure tester a few weeks ago from oreilly but it didnt fit my style radiator cap so i could never pressure test it. I did a visual inspection once i got home and coolant appeared to have sprayed on top of the air filter housing and intake plenum and a trail of coolant down to the ground meaning it had to have come from the cap or bleed valve. They both seemed tight and i loosened the cap while the car was still warmish (maybe 1o min. after turning the car off) and it hissed (obviosly) but when i re-tightened the lid i didnt hear any obvious hissing. Is this a common problem? The PO said he recently replaced radiator and expansion tank and it didnt appear that any coolant was coming from the sides of the tank (there was actually coolant sitting on top of the tank but it didnt seem like it had seeped out any seams)

Later tonight i'll go fetch the new re-learned fuel trims and 02 data. Aside from the knock sensor code i'm only getting 3 different 02 sensor codes so i'll post those later as well. From what i recall it was something to do with "stuck lean"? bank 1 and 2 sensor 1 and then the P0050.

Thanks!

 

Current codes:
P0050
-HO2S heater control circuit bank 2 sensor 1

P0328
-Knock sensor circuit high

P2197
-O2 Sensor Signal Biased/Stuck Lean Bank 2 Sensor 1

P2195
-O2 Sensor Signal Biased/Stuck Lean Bank 1 Sensor 1

Some data snapshots that seems applicable:

RPM- 738
STFT1- 27.3
LTFT1- 7.0
STFT2- 0.0
LTFT2- 7.0
MAF(lb/s)- 0.00
O2SLOC- B1S12--B2S12--
O2B1S2(V)- 0.715
SHRTFTB1S2(%)- N/A (a wire came loose and I meant to fix but its post cat so lower priority)
O2B2S2(V)- 0.830
SHRTFTB2S2(%)- 99.2
EQ_RAT11- 1.450
O2S11(mA)- 0.750
EQ_RAT21- 1.003
O2S21(mA)- 0.008


RPM- 2604
STFT1- 27.3
LTFT1- 4.7
STFT2-0.0
LTFT2- 5.5
MAF(lb/s)- 0.00
O2SLOC- " "
O2B1S2(V)- 0.870
SHRTFTB1S2(%)- N/A
O2B2S2(V)- 0.930
SHRTFTB2S2(%)- 99.2
EQ_RAT11- 1.998
O2S11(mA)- 2.391
EQ_RAT21- 1.002
O2S21(mA)- 0.008


RPM- 672
STFT1- 0.0
LTFT1- 12.5
STFT2- 0.0
LTFT2- 10.9
MAF(lb/s)- 0.00
O2SLOC- " "
O2B1S2(V)- 0.975
SHRTFTB1S2(%)- N/A
O2B2S2(V)- 0.950
SHRTFTB2S2(%)- 99.2
EQ_RAT11- 1.998
O2S11(mA)- 1.832
EQ_RAT21- 1.003
O2S21(mA)- 0.004

I know some of this isn't useful but i figured i'd throw in anything with "O2". I'll learn to read this stuff someday but i think a trained eye looking over would be much more reliable.

 

Also something to mention, when the car is in P at idle and i give it gas it wants to die unless i depress it very slowly. I know flooring it really quickly will do that but moving the pedal just an inch in under a second causes it to wanna die.

 

Post cat O2 sensors on these cars aren’t low priority, they’re actually quite high priority. Your stupendously high fuel trim on that bank is, at least in part, due to that. The post cat sensors do more than monitor cat efficiency, they do affect trims on these.


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It's running really great now all thanks to all the advice everyone has shared.
I just messaged the guy about his O2 sensors so I should be getting those soon. Since The car overheated during the test drive, I let it idle in the garage for about 20 min to watch what was happening. The lower radiator hose seems to be leaking, but not from the temperature sensor. I noticed during the rebuild that the connection on the radiator was very very tight and was a a pain to get the metal clip to snap over the connection. I know the PO replaced the radiator and possibly the hoses and i'm not sure if either/both of those parts were aftermarket. I'll probably see if the guy on craigslist with a parts car has that hose and see how his OEM one fits on the radiator. After leaking for about ten minutes, the coolant cap pressure relief goes off and sprays coolant EVERYWHERE and ended up all over the garage. So aside from getting that sorted out and putting my shiny refinished headlights on, i think she'll be roadworthy.

Thanks again everyone!

 

- At this mileage, I'd recommend a full cooling system overhaul.
Tons of info in E39 forum (I wrote quite a few DIYs there) on brand-name for WP, belts and pricing.

- Also, I'd clean the ICV valve. My 2004 X3 2.5i with 100K miles would stall randomly during idle. After removing the ICV, it was clear why: quite a bit of gunk.
Cleaned the ICV, no issues since then.

- I have a spare rubber boot for the 2004 X3 2.5i (still in great condition), too bad you are not near here, otherwise, I can give it to you for free.

 

The PO replaced everything but the water pump and i've replaced the hard hoses under the intake so I'll probably replace the pump. I'll check the part manufacturers and figure out which one is aftermarket causing the ill fitment on the radiator but I was thinking I could take an e46 lower radiator hose, cut off the clip that holds on the plastic fitting, and put the proper end onto my existing hoes with a hose clamp. Sure it may be sacrilege to some but its easy, cheaper, and i've seen it done before. The biggest thing is I wanted to make sure that the fitting on the radiator is the same size between my e83 and the e46 parts car.

Also i'm gettin a P0300, P0301, P0302, and P0303 (all misfire codes) but the car is running better than ever so i'm not sure why those codes showed up.

 

Tanner, this thread is all over the place.
OVerheating. O2 sensors.
Is the car still overheating?

Can you post a summary update of each problem and resolution?

 

Ive been busy but it seems due time for an update.

-engine runs, SES light is still on for O2 sensor codes and im looking to buy new ones
- Coolant was leaking from the lower radiator hose causing the overheat but i replaced the o-rings and now there's no more leak
- I've bled the system a bunch and it still overheats after like 5 minutes. No leaks I'm really not sure what the issue is now
- I'm gonna check the t-stat tomorrow. The upper radiator hose gets really hot but the lower hose stays cool even once the needlle gets in the red. Is that normal?
- An oil leak has developed near the exhaust side CV axle boot area. It is definitely motor oil and it's not coming from above the VCG is new and verified non leaking so if you have any ideas...

if anyone has good prices on the 6 wire upstream kind please let me know. i've already spent $150 on some that are apparently defective. I figured i was better off buying used OEM was better than aftermaket... my mistake.

 

Ok I cleaned the underside thoroughly and found the leak is right under the crank pully. The harmonic balancer is too big to tell if its the front main seal or the lower timing cover gasket but its definitely one of the two. I replaced the chain tensioner when i had the head of and i'm currently kicking myself for not putting a dab of rtv silicone on the LTCG. I will say that ive had oil in the car for about a month with no leaking problems but one of the days i pulled it into the shop it formed a decent puddle after only 30 minutes so its coming out pretty darn fast. I wanted to ask if the profuse leaking could indicate LTCG/Front main seal? I'm really hoping it's the front main because i really dont wanna take the damn head off again but maybe i should just bite the bullet.

I've been bleeding the coolant system a bunch because the car keeps overheating and it seems like there's a whole bunch of big air pockets because the bobber will drop when i start up every once in awhile so its just kinda taking awhile. I think it's do to the fact that I yanked the lower radiator hose off to replace the o-ring while the system was gull and then just dumped more coolant in so it probably just trapped a bunch of air pockets. I've dont the whole bleed screw/Heater full blast dealio about 5 times now and 3 of those times the level would drop so i'll just be patient.

As for the O2 sensors, its idles perfectly fine enough for all the testin i need right now so i'll wait until its in ship shape to drop the big bucks on those

 

... to drop the big bucks on those

As another member says wisely, "there's nothing more expensive than a cheap/used BMW." If money is likely to stay tight, maybe reconsider owning a BMW. Unfortunate truth that has been learned the hard way by thousands before.

 

It’s tough love but there is rarely a path to an economical daily driver starting with a sub 5000 usd BMW

Plan on 10-30 cpm maintenance cost until you get all the deferred items discovered and fixed

 

I'm well aware. Seemed fun to fix up an old cheap car and drive it around for a bit but my plan was always to resell it. Even if i only break even it'll still have been more fun and cheaper than a rental car. The next fixer upper probably wont be a BMW but i really wanna circle back around and get an E21 when i'm older and have more $$$. Working 20 hours at a barbeque joint just isn't cutting it :rofl:

I'm gonna look into a vacuum bleeder to properly bleed the system before looking into other possible causes, a cooling overhaul was done pretty recently so hopefully nothng needs to be replaced but we'll see. I'm gonna pull the harmonic balncer and see if i can tell where the leak is. I'm really hoping its the front main but i have a feeling its not because the LTCG seems like a much more likely culprit. I know i'll have to remove the vanos to get the timing cover off but is there any way to pull it off without pulling the head. From what i understand its pinched in there goo and tight but can I loosen some of the oil pan bolts or something? I'll do what I have to do but if anyone knows an easier way id love to hear.

Thanks!

 

I’m developing an intense respect for the E21, follow my build thread. I’m experiencing first hand how robust the M10 is.

I wouldn’t recommend getting into one unless you own a welder!

I’m not home to look in the book, but I’m pretty sure the timing cover can be removed without pulling the head. On the M54 the front seal can be removed with a good old seal puller, not like the N52.


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Your thread is actually what peaked my interest. The shark nose always seemed cool to me anyway so thats not much of a suprise. Ive been welding since eighth grade on a crappy harbor freight welder but that's not saying much since i'm only a senior now. I'm no certified welder but i can lay down a pretty good bead if i do say so myself. I'm certain your build thread will be an excellent resource so i'll go ahead and thank you in advance.

also, I'm about to go outside and attempt to remove the Jesus bolt wish me luck...

I got a tip from a local guy with an e46 that the oil leak im experiencing might be my oil filter housing gasket leaking down behind the front pulley, so i went ahead and ordered the gasket to o'reilly since its a pretty easy fix and probably long overdue at 180k anyway. Once i replace that and refill the engine with oil i'll watch to see if i have any more leaks. After that I'll go ahead and refill coolant and by that time i should have my new O2 sensors and we should be set... for now.

I wanted to make an odd request to anyone who already had their engine covers off. I need a picture of the wires on the upstream O2 sensors (M54) on each side of the plug so i can be %100 certain i get the new ones wired up. I'm fairly certain i have my current ones hooked up right but id rather be safe when i'm dealing with $200 parts (my second set mind you). f anyone could snap a quick pic it would help tremendously. If anyone, by some odd chance, had a spare wiring harness laying around and wanted to snip off the plugs and throw them in the mailbox for me i cant say i'd mind that too much either.

 

You’re welcome in advance. I’ll be replacing chain and guides soon, and plan to start cutting and welding the body/floor to deal with rust. I’ll be sure to post any tips I find. I learned to weld on aluminum before steel (reverse of the norm) with a $5k Miller machine, and prefer Al to steel anyday. My little Lincoln FCAW unit can put down a decent weld though; once I require the barn with 220 I plan to get a TIG machine.

I digress... OFHG is certainly long overdue. FCP and ECS sell Liquimoly oil with fluorescent die built in, so you can track the oil leak.

I’m nearly 100% positive you can replace the front seal without pulling the head. I’d be a full 100% except that I’ve never done it on an M54 but have on many other engines including N52.


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If you cross up,the OXS wiring you will get a nice error code telling you that. You won’t damage them