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-   -   Z4 Roadster (E85) 03 Z4, couple of problems. (

ligfyr 07-25-2012 01:26 PM

03 Z4, couple of problems.

My Z4's been giving me a couple of issues as of late, and I was hoping some if you had some insight into the matters.

Firstly, my car has been having some performance issues. I only really notice this one when I downshift into 2nd (no other gear has done it) and accelerate. The car bogs for a slight moment before it begins reving up. It's only a couple fractions of a second, but it happens pretty frequently. Checked the spark plugs and coils, and all visually checked out. One thing of note is that the Coil in cylinder 2 is not the original, like the other 5, and a check engine light a bit ago noted a misfire in cylinder 2.

I tested the problem about a week ago and upon returning I noticed that my intake boot had a gaping hole in it. We replaced the part, and it ran significantly better, but the problem still remains, it's just not as bad.

I haven't ran it hard since replacing the intake boot, but before the car would seem to critically misfire in cylinder 2 with fuel cut off and go into limp mode.

Secondly, and this might be related to the first issue, but running the car around 75mph on the Highway, the car feels like the brakes are sticking on a bit for about 15 seconds, and then when I slow down the whole car starts shaking, I won't say uncontrollably, but rather violently, as if I had a flat tire without any pull to one side. Both times it's happened, I've pulled off the highway immediately, and when I get into the gas station, turn the car off to check things out to find nothing visually wrong, and turn the car back on again, the problem goes away.

I did recently get a new set of tires on the car, and I don't really trust the guys who did it (bunch of crack heads at a local tire shop. They even chipped my wheel and I made them buy me a new one.) so that may be related, but turning the car off and on shouldn't fix the problem if it was tire related.

Lastly, and this one just started about 30 minutes before writing this, my fan would turn itself on when I turned the car off. It wasn't on when I had the car on before, and it turned off when I turned the car back on. However turning the car off turned it back on again, so this leads me to believe it isn't a stuck relay or anything of that nature. It's only done it twice, and leaving the car running for a minute or two made the problem go away, at least for now.

My car's been relatively reliable for a foreign sports car (aside from a rain water leak that my incompetent dealer spent about 5 months messing around with), but this seems to have all hit at once.

The car has around 73k miles on it, and I don't really drive it that hard. Any insight would be much appreciated!

Droptop85 07-25-2012 07:22 PM

First issue. Sounds like your vanos seals are bad
Second. After run fan. When you turn your car off your engine builds heat. The fan kicks on to cool it back down

Mikey48 07-26-2012 04:14 AM

I would install a fresh set of plugs. Then I would add a really good fuel system cleaner to the fuel system fill up with premium gas. Do this for the next 5 or so fill ups. Sounds to me like you got a lot of carbon build up in your engine. I had this problem with my 04 Z4 3.0i and it did the trick for me. My car now runs like new. It also sounds like your new tires are not balanced right. They will cause this problem if they are not balanced properly. These days they stick the balance leads on with double sided tape and they fall off most of the time. Mine did this also. Check your cooling system to make sure the water level is where it should be, it could be low. Good luck.

pokeybritches 07-26-2012 06:28 AM

I agree you should change the plugs and get a fuel system cleaner. A clogged fuel filter can cause strange behavior. After filling up at a gas station near Vegas, the car died at 75 mph on the interstate. I restarted it and it drove alright for a few minutes, and then suddenly pressing the gas felt like I was putting on the brakes. This cycle repeated itself 3 or 4 times until I hit the next exit. I added a couple bottles of fuel system cleaner and physically shook the car to get it evenly diluted. I fired it up and the problem was gone. My dad (chemistry major) explained how the cleaner can bond with particles and safely unclog the filter.

You need fuel, air, spark, and timing to create power. If a new spark plug and coil don't stop the misfiring in cylinder 2, you may need a new injector, or the current one is clogged. If the fuel system cleaner doesn't do the trick, you might try swapping injectors and see if the problem persists.

SC2003Z4 07-26-2012 07:41 PM


I did recently get a new set of tires on the car, and I don't really trust the guys who did it (bunch of crack heads at a local tire shop. They even chipped my wheel and I made them buy me a new one.) so that may be related, but turning the car off and on shouldn't fix the problem if it was tire related.
Dude, I'm just a restaurant manager......but please do take this word of advice: do not piss off a waiter/waitress who has yet to "serve you" before you pay and leave. Same goes for any kind of mechanic, tire guys included. Unless you are allowed to stand right there next to them overlooking what they are doing until they are finished. I hope non of these issues were caused by some complimentary work done at the tire shop.

By the way, Techron by Chevron is the can find it at any of the popular auto parts stores

dgomez89 11-18-2012 05:12 PM

How much of the fuel cleaner did you need to put i it, and how do you have to drive it once it is in? Cyl 2 in my 2003 2.5 z4 is misfiring. Its not the coils for sure.

shipkiller 11-19-2012 09:02 AM

As others have stated, I personally would replace the spark plugs and run a few tanks of fuel system cleaner through the engine if you are using the generic fuel cleaners.
The absolute BEST fuel system cleaner is something called BlueChem Fuel System Cleaner with number two being BG Products 44K. One treatment is usually sufficient to clean the entire fuel system. Then run a can of cleaner every 3000-5000 miles.

On your misfire, is the SES light steady or blinking? A steady light indicates a minor misfire and a blinking light indicates a major misfire. You are at the point, mileage wise, in your car that you can start to experience cascading coil failures. Replace one failing coil and another one goes out. The reason this happens is that when a misfire occurs, the DME attempts to compensate for the misfiring cylinder and any already weakened coils might fail. You might want to consider replacing all six at once. I did this on my wife’s roadster when the coil cascade failures started. If I remember, all six were about $150.00 from Bravarian Auto.

If coils do not fix the misfire issue, then either the wiring from the DME to the coil is at fault or the DME. It is a straight shot from the DME to the coil….

One other thing, I have seen coils operate properly in one cylinder but not another. So sometimes swapping coils for troubleshooting does not work…. Just be warned

As for the vanos O-rings being bad, yea they are. Is it catastrophic? No… just a minor performance lag issue. A vanos O-ring replacement is not really hard, just time consuming. I did this myself back in 2008 or 2009. Took about four hours.

dgomez89 11-19-2012 09:48 AM

I replaced all the spark plugs. And switched the two coils to check if it was the coil that was making the cylinder misfire, but it continued in the same cylinder. I'm hope that maybe the injectors need to be cleaned and not replaced. I have read a few instances where the fuel cleaner also cleaned out the injector

SC2003Z4 11-19-2012 10:10 AM

Dude, before spending any more time and money go buy the fuel system cleaner and fill up with the best gas you can buy (93)
...then go run that car down some back roads like you stole it.
Rev it up hard, have fun. And remember, fuel sys cleaner ain't gonna do the work in 5 mins.
It might take a good half a tank to clean up the gunk but you will notice the difference once the stuff is out of the system. I use Techron every few tanks of gas and love it.
I hope I am not messing anything up. If so, please someone tell me....I don't drive the car but once a week, sometimes less than that. 2003 2.5 with 75K.

dgomez89 11-19-2012 10:12 AM

How many bottles do you put in it? And is it normal for it to run ****ty while in the process

Mikey48 11-22-2012 06:47 AM

One bottle in an empty tank should do it. But, If the car is gummed up pretty bad I would add the cleaner to the next few fill ups.I add fuel system cleaner to my tank at every fill up. Add it to tank and then fill up with a top grade gas. If it is not the coil misfiring than I would look at installing a fresh set of plugs. I got my plugs from my BMW Dealership and installed them myself . It is an esy job. Good luck and Happy Holidays !

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