New neglected Z4 owner

[Zet941]

Hello all, this is my first BMW and I’m in for some work. Car has been sitting most of its life, lots of sun, and has been left outside; with the top down over several months to my knowledge!! I’ve been reading and watching videos quite a bit to try to figure out the best approach. It only has 54K miles, no oil or gas leaks anywhere. Top is inoperable, far too deteriorated parts to worry about at this time. The pump and motor literally went “poof” when taken out of the plastic container in the back. Hydraulic lines are in horrible shape and possibly a leak on the driver’s side hinge.
Soon after I got it, and within a few miles of running it, I noticed a rough idle, and then the limp mode. Dashboard looked like a Christmas tree. I replaced the YAW sensor, since many things pointed to it, and it was probably under water from the rain. had to replace both seat rails (corroded), and various other things.
Scanning come up with cylinder 1,4 misfire. Same cylinders repeatedly. New spark plugs, swapped the coils to test and misfires did not follow.
Found and replaced known vacuum leaks, and decided to peak under the intake manifold hoping to find an obvious culprit. Did not. CCV valve looked pretty messy, new one on the way. I wanted to save some money and clean the injectors but now thinking either send them out for professional cleaning/test or buy a refurbished set. Any thoughts?
Purge valve good, DISA tested and works, also holds closed when tested manually. Cleaned the manifold, throttle body.
One thing I regret is draining/ replacing the fuel initially. Next on the list of things to do.
Hoping to put this together and see some improvements. I just wanted to see if anyone has any suggestions for me at this stage with the manifold off?

[Our03z4]

Originally Posted by Zet941

Hello all, this is my first BMW and I’m in for some work. Car has been sitting most of its life, lots of sun, and has been left outside; with the top down over several months to my knowledge!! I’ve been reading and watching videos quite a bit to try to figure out the best approach. It only has 54K miles, no oil or gas leaks anywhere. Top is inoperable, far too deteriorated parts to worry about at this time. The pump and motor literally went “poof” when taken out of the plastic container in the back. Hydraulic lines are in horrible shape and possibly a leak on the driver’s side hinge.
Soon after I got it, and within a few miles of running it, I noticed a rough idle, and then the limp mode. Dashboard looked like a Christmas tree. I replaced the YAW sensor, since many things pointed to it, and it was probably under water from the rain. had to replace both seat rails (corroded), and various other things.
Scanning come up with cylinder 1,4 misfire. Same cylinders repeatedly. New spark plugs, swapped the coils to test and misfires did not follow.
Found and replaced known vacuum leaks, and decided to peak under the intake manifold hoping to find an obvious culprit. Did not. CCV valve looked pretty messy, new one on the way. I wanted to save some money and clean the injectors but now thinking either send them out for professional cleaning/test or buy a refurbished set. Any thoughts?
Purge valve good, DISA tested and works, also holds closed when tested manually. Cleaned the manifold, throttle body.
One thing I regret is draining/ replacing the fuel initially. Next on the list of things to do.
Hoping to put this together and see some improvements. I just wanted to see if anyone has any suggestions for me at this stage with the manifold off?

Is the battery under water? Guessing you put a new one in? Bad batteries cause tons of problems in these cars. There really isn't too much to the 2.5i, pretty simple engines. Do you know the reason why it was parked? Have you checked all your grounds? Make sure to check the intake boot for cracks. If you have that extra room right now go ahead and change the oil filter housing gasket, if it isn't leaking it will be soon. Are you sure you don't have a blown head gasket?

[grannyknot]

Welcome, you came to the right place, some very knowledgeable guys here.
Sounds like basically you are going to have to go through each system and do some cleaning and refreshing. Having the injectors refurbed is always a good bet if only to eliminate a possible culprit.
You say you regret draining the fuel tank, why is that?

[Zet941]

Originally Posted by grannyknot

Welcome, you came to the right place, some very knowledgeable guys here.
Sounds like basically you are going to have to go through each system and do some cleaning and refreshing. Having the injectors refurbed is always a good bet if only to eliminate a possible culprit.
You say you regret draining the fuel tank, why is that?

Thanks,
Because I may have introduced dirty or bad fuel into the system I guess. It’s only been ran a total of 15-20 minutes or a couple of miles of going up and down the street but if I did this initially I would have eliminated the chance of making things worse maybe?
I installed a new battery, took out the O2 sensors up front to see if it made a difference with back pressure from the cat and ended up installing new ones for good measure. Found a leak in the intake boot as the other user suggested and will look into the oil filter gasket as well
Thanks for your input

[Zet941]

Originally Posted by Our03z4

Is the battery under water? Guessing you put a new one in? Bad batteries cause tons of problems in these cars. There really isn't too much to the 2.5i, pretty simple engines. Do you know the reason why it was parked? Have you checked all your grounds? Make sure to check the intake boot for cracks. If you have that extra room right now go ahead and change the oil filter housing gasket, if it isn't leaking it will be soon. Are you sure you don't have a blown head gasket?

Thanks,
I did find a broken intake boot that was replaced. New battery yes. Will look for suspect ground connections as well as a test of the coolant for presence of exhaust gasses. I don’t see any smoke from the tailpipe and car has not been driven enough to tell if I’m losing any fluids. No leaks visible

[wdb]

Get the fuel system straightened out. If you ran old gas through it could be causing all kinds of woes.

Get an OBD code reader.

[Coi]

You might be best off getting a known working whole roof and motor from a crashed car at a wrecker. Just buy the frame, lines, and everything with the top to save trouble.

As well as throttle body, also clean the MAF. Use dedicated MAF cleaner though because other products can damage it. I'm guessing you replaced the intake air filter or at least made sure it wasn't clogged. Might as well do cabin air filter too while you're at it.

Do you have a borescope camera you could stick into those cylinders. Could help diagnose what's going on.

There's no reason to expect an issue with compression to be causing your misfires, but it's often free to rent a compression tester or even leak down tester from an auto parts store. It's probably injectors though.

Should also do an oil change, power steering fluid change, transmission fluid change, diff fluid change, and bleed the brakes; especially if you think the car might have spent some time in water.

[Zet941]

Thanks for the advice. Brakes are a must once this thing is put together and running; I will hold off on any roof repairs but never thought of getting the complete assembly, thank you for that.

[Zet941]

So I put the car back together, and was very disappointed to find out that all of what I did had apparently very little effect. With the intake cleaned, throttle body cleaned, ccv replaced, two O2 sensors replaced and no leaks found, fuel replaced with high octane etc, fuel injectors cleaned and working. no improvement. Honestly more codes came up that were not present before, makes me start to think about the ECU? Only positive is that the car does not smell rich from the exhaust as it did before.
2747 Misfire, cylinder 4
2742 Misfire, cylinder 1
2783 Hot-film air-mass flow sensor (new code)
278c Intake-air temperature sensor (new code)
271D Oxygen-sensor before cat. Conv bank 1 activation (new code)
2715 Osygen-sensor heater before cat conv banik 2 activation (new code)
27B5 Inlet camshaft: activation (new code)
281E Variable intake system: activation (new code)
2745 Misfire, cylinder 6 (new code)
28A2 Air path: monitoring
And that’s it…. Could write a novel.
I’ll look around the wiring again but an awful lot of codes

[wdb]

Have you tried clearing the codes to see if they return?

I've heard of substandard O2 sensors in the Porsche community -- they strongly recommend buying Porsche-brand sensors because of the high frequency of getting bad ones from the aftermarket.

[Steeler]

Sorry if this sounds obvious.
Was the battery disconnected when you were unplugging all the components you cleaned/worked on?

I agree with WDB, clear all codes again and see what comes back.
Hard to believe the ECU is bad.

Misfires quite often are MAF/lean conditions. You repaired the torn intake boot so it could be a faulty MAF. The IAT is incorporated into the MAF.

Again, clear the codes and see what returns.

[Zet941]

Originally Posted by Steeler

Sorry if this sounds obvious.
Was the battery disconnected when you were unplugging all the components you cleaned/worked on?

I agree with WDB, clear all codes again and see what comes back.
Hard to believe the ECU is bad.

Misfires quite often are MAF/lean conditions. You repaired the torn intake boot so it could be a faulty MAF. The IAT is incorporated into the MAF.

Again, clear the codes and see what returns.

No, I did not clear them, I will try that thanks. Batter was disconnected, O2 sensors OEM. I ordered a cheapo MAF just to see if it makes a difference before shelling out 300 bucks.

[Zet941]

Originally Posted by Steeler

Sorry if this sounds obvious.
Was the battery disconnected when you were unplugging all the components you cleaned/worked on?

I agree with WDB, clear all codes again and see what comes back.
Hard to believe the ECU is bad.

Misfires quite often are MAF/lean conditions. You repaired the torn intake boot so it could be a faulty MAF. The IAT is incorporated into the MAF.

Again, clear the codes and see what returns.

Will do. I have a small valve cover gasket leak that I haven’t repaired yet. I know it could cause misfires but hard to believe such a small one would? I’m curious if any of you all have had that happen. Thanks again for everyone’s input. Highly appreciated.

[Zet941]

MAF replaced, car behaves the same way. Still has cyl 1 misfire. I’d like to test fuel pressure but have seen 35 and 75, can anyone confirm which pressure is correct on a 2.5 2003 please?

[Steeler]

Move the #1 coil to a different cylinder and see if the misfire follows it

[Our03z4]

Originally Posted by Zet941

MAF replaced, car behaves the same way. Still has cyl 1 misfire. I’d like to test fuel pressure but have seen 35 and 75, can anyone confirm which pressure is correct on a 2.5 2003 please?

I'm betting blown head gasket, there is a reason it was parked. Harbor Freight sells a pump type test kit that uses fluid to check for gases in the coolant. It's cheap and you may want to do that to be sure. These cars are very touchy if they over heat.