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N62 Z3 Part 9: More Start Attempts & Successful First Start

So, further diagnostics of the no-start condition

You ever look at your hands and you are like wow, those wrinkly hands aren't my hands. But they are. I bet I'm gonna be so wrinkly when I'm older


This is a bad signal. So I need a crankshaft sensor... which is in the mail to me now

But, me, being impatient, I went ahead and bought one locally

The crankshaft sensor came with a 4.8is attached... this was it as I first saw it

It was cheap, but has a plentiful amount of issues. This N62's valve stem seals are shot... it was quite smokey. The sunroof doesn't work, well it works - but the inner shade doesn't fully work - so it doesn't allow full functionality. The front tires are pretty worn. Power steering pump is bad, as are the control arms

Most notably though, the air suspension is totally shot. Like, zero air pressure at all. It bounced very violently the entire two hour drive home. Finally, at my shop

I really love this color, Le Mans Blue. It had been stored out side for a year or so, so it's filthy but just look through the dirt to the beautiful paint underneath

It's currently parked in the overflow lot and I need to move it tomorrow so couldn't take the crank sensor off today

Not entirely sure what the plan is for this X5, but I think most likely, it will become a parts car...

It does come with the crankshaft sensor I need. And of course the 4.8L N62. And a known good IVM. And a known good DME (would need to be coded to the Z3 though, of course). So I want to focus on getting the Z3 started and if I get it running... I will likely throw this 4.8L lump in

Once I got the new sensor in, aligned the DME-EWS, still no cranking. Still no crank signal either. Little disappointing. Going to take a few days off and come back to it next week

In the meantime, here are some photos of the Rosy-faced lovebirds that live in my backyard

Back to work on the swap and immediately seems I have another faulty crank sensor so I might already be back to waiting a few days until I can go to the junkyard...

Many months pass...

After my last update I've been very busy between my shop and the fabric stuff. I had to move the N62 swap off the lift to make room for some customer work. Then around the Holidays when it was a little slower I took some time to work on my personal cars which had seem some deferred maintenance that had piled up. Was great to catch up on all that. Oh and Merry Christmas, Happy New Year, all that...

One of those jobs some of you might find entertaining. My Z3 coupe has had a small rattle since I bought it 6 years ago. Yesterday while stripping the hatch to do RSM's and a bunch of other stuff, I found the cause of the problem

On the top side was sheet metal... just a thin access hole I could shove a thin flathead into and hammer the nickel out of the hole in the above image

Nickel was from 1986 which raises more questions than answers. Are any of the Spartanburg factory line workers missing a nickel? If so I may know where it is located...

I also spent a few days doing a deep clean of the shop. I've been at this shop over 2 years now and the last year especially it has just gotten so cluttered. I moved into a new house Feb of 2020 and the garage/storage space was much smaller in the new home, so a lot of stuff just got dumped off at the shop... it's been very satisfying going through and really cleaning all the junk and decluttering. I still have the outside area (and the roof of my office) to go through, but the functional/workable space is now clean and more importantly, organized

Now that's all done... or at least, done enough to move on for now. So I got the Z3 back in front where I can work on it and that is where I left off last time I was at the shop

So this is where I am today, now January 14th. Also less than a week until my 30th birthday. Not looking forward to that! But am looking forward to making more progress on this

On that note, I am going back into this with a battle plan

  • I have a crank sensor and fresh DME in hand

  • Then I will test the crank sensor in the parts car X5 I have

  • If it tests good, I'll double check the wiring from the crank sensor to DME/IVM

  • If that looks good, I'll install the new CPS/DME/IVM, align EWS and try again

It doesn't sound like a lot, but if it doesn't work from there... I'm sort of out of ideas! Maybe that's why I've been dragging my feet on it a bit too, I was hoping to think of other possible solutions but couldn't come up with anything

I did get a chance to work on the car a bit today. The first thing I did was pull the parts car X5 in behind it so it was easier to get out to the X5

Not a proper alternative for jackstands, do not attempt this at home...

First thing to do was get underneath and remove the under panel so I could access the crankshaft sensor easily. On the E65 and E60 the belly pan ends far enough forward that that the crankshaft sensor is easily accessed. On the E53's however, the belly pan obstructs it just enough to make it virtually inaccessible. Normally it's not a big deal, it's just a belly pan right, just unbolt it... but there is something reaaally annoying about these... they have nuts on the top side that need to be counter-held. Oil, ATF and other various fluids tend to pool on the top surface around those nuts, which combines with dust/rocks from the road and in some cases (notably, in this case) there is so much crap that you have to wipe off piles of rock/oil sediment to be able to even get the wrench on to counter-hold it. This is the first step towards any sort of maintenance underneath the car. No wonder these cars have a bad reputation among mechanics...

I had limited time to work on my cars today and this alone took me about 30 minutes just to get that thing off but once it was finally off (and once I was sufficiently filthy) I was able to access the crankshaft sensor. And it did yield some diagnostically interesting information. But first, the disgusting belly pan

First I removed the sensor in the X5 - labelled it as good and set it aside

I then plugged in the "fresh" one I had just bought. X5 fired right up. Labelled it as good and set it aside with the other one

Went to check one of the old sensors that was giving that weird reading. With that sensor installed it cranked about 5 seconds and didn't start, tried a few times but same results

So... that at least does confirm the sensor was faulty

I don't want to rush things, I feel like that was part of my problem before - I got too excited and didn't double check everything at every step. Especially since I know the crankshaft sensor is bad now, it feels like there is something to go off of. I'm going to follow my guide list from before. Now I have an IVM in hand and have tested the crank sensor so the next step is to double check the wiring

If the wiring checks out and looks good (paying special attention to the crankshaft sensor wiring) then I will install one of the known good crank sensors, the good IVM from the X5 and the "fresh" DME and try again I did find time to swap my S54's thermostat before going home for the day though... it's my daily and wasn't getting up to operating temp for a little bit now

Then I thought I should test the IVM currently installed in the Z3, to determine if the IVM was also fried during this process. With the Z3 IVM installed, the X5 started up. Great - I have at least two good IVM's in that case

That's the X5 DME/IVM cubby above...

Next was to check the Z3 wiring

Everything looked good... so I installed a battery, good DME, IVM and sensor then aligned this DME and the EWS

Went to crank and... it fired! For one brief glorious second, there was combustion! It died almost immediately afterwards, triggering a whole bunch of codes in the aftermath, the most relevant of which I thought was this for fuel pump activation

Was very happy to get it to fire, even if only for a second. It would occasionally sound like it was going to catch and start running but never quite got there

But look at that - finally a crank signal!

I like that. That's really nice to see

More diagnosing to do. But very happy I seemed to have gotten past this little crankshaft sensor hurdle

Next time I went to work on the car I was planning on doing more but got a frantic call from a customer... But first I did have time to swap the fuel relay, with a fresh one from my pile

They made these very inaccessible for some reason

So fresh relay in, about to test it, customer calls me - a car he was getting towed to my shop had it's wheel fall off? What?? Asked him to send me pics...

So I had to help sort this out and get it to my shop (parked in front of my other silver E39 parts car, lol)

Tow truck driver claimed the brakes locked. If I had to wager a guess - they didn't ensure the wheels were secured to the hub properly before towing it away. Either way, this car is totaled

Bummer too - the owner just dropped some coin manual swapping it and was bringing it to my shop so I could finish the coding and some other odds and ends. Owner never even got to drive it as a manual transmission

Back to work on the Z3 though... Testing the fuses, this one was supposed to see 12v at all times - good

This one should be hot only when key is in

Key out

And key in... values may be a little low

Next step for me was to check the voltage at the fuel pump but my passenger seat was stuck. I had my drill at home for some home projects so that was a lame reason to get stopped for the day but it is what it is

I'm trying not to make this a personal blog, but I worked on this customer car later in the day... crazy!

Safe to say I have diagnosed where the vibration is coming from...

The next day I got back to work on the Z3 getting the seat out using the ol' drill method

This is what greeted me under the seat...

One shopvac later...

Then I had access to the fuel filler area - it was the first time on this car it had been accessed as the carpet was not cut

The fuel pump did not receive voltage with the key in, so that seems to be confirmation the issue is fuel supply related and in particular with the voltage to the pump. That will require some further diagnosing, but on the right path!

I also did figure out what happened to that transmission from the previous photos...

Two of the three plates holding the pressure plate assembly together were completely missing. The rivet holding them in must have failed, allowing them to gouge the inside of the transmission as it spun - then it looks like they eventually got caught on something, probably the hole they gouged and it violently ripped off. There was no evidence of them anywhere inside the bellhousing

With the "plate" intact

And missing...

Where it looks like they got "caught" on the hole they made and got violently ripped off

One remaining plate barely keeping it together!

The pilot bearing is also loose now which is not good Anyways, back to The Dunklenator Next steps for once are fairly straightforward

Align DME/EWS again just to make sure it is good

Try to test start it again when powering the fuel pump directly with 12v

So... here we go...

DME/EWS aligned

Fuel pump provided with 12v connection

Aaaaand yup, it's running!

It was just a fuel pump relay issue, after some research it was determined that the N62 X5 powers the fuel pump relay from the IVM, on the Z3 it powers it from a wire on the engine harness. So the next step is to simply re-route the IVM fuel pump output to the correct terminal on the fuel pump relay and it should be good to go!

I was also cleaning my desk area the other day and just thought you guys might be amused at seeing how many various wiring diagrams were printed out and fastidiously looked over to get here

Crazy thing is that's not even all of them, a good 90% though certainly

Well now that we FINALLY have a successful first start... we can finally move onto Part 10



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