I need some advice on a project car

[R Shaffner]

A few more points to add:

1) If the rest of the car is in good shape, as you say it is, you got a deal. If at any point you find you can't or don't want to continue, you can sell it for a profit (with some patience). This would be a good place to try to sell it.

2) It is definitely worth investigating and putting some effort into, one step at a time. You might have gotten a steal. And if you discover bigger problems, at least you know what they are and you can tell others what they are. That might actually increase the resale value, if you have done some diagnosis and figured out what's good and what isn't.

3) As a general rule, you should always give the cheap/easy solutions a chance to work, first, with every issue. That's your motto for this car, unless it turns out to be a real gem. You might get lucky and the cheap/easy fix is all that's needed for any issue. And if you learn that a problem needs more, or a lot more, at least you haven't invested a lot of time and effort in it.

4) A common saying here is that "there's nothing more expensive than a cheap German luxury car." (The idea is that if it's cheap it has problems, and the problems can be expensive, especially if you pay someone else to fix them.)

5) If you get REAL lucky it might be an OK daily driver for a while. But heed the comments here that these cars are old and generally not great as daily drivers. Having said that, my brother still drives his 1992 525i daily and it has 280,000 miles on it. But he's 70 and real stubborn.

6) You've come to the right place. Many here know all there is to know about these cars, and they will be eager to help. Still, not all advice will be great, or even good, so you'll often have to discern for yourself what's good and what isn't. Feel free to ask follow-up questions.

Now, here's what I would do specifically:

Don't worry about the fuel filter. They hardly ever clog, and if it started to clog it would start to limit flow at full throttle and high rpm. Almost no chance that it's keeping the engine from starting, or keeping a few cylinders from firing.

Old gas is different. Putting new gas in would probably be enough, especially if some of the cylinders are firing. I like the suggestion of adding some gas treatment (fuel injection cleaner) too. I'd do that.

Look at the air filter to see how it looks. Look at the dirty side, where air comes in. Unless it looks filthy and blocked, leave it in and don't worry about it for now. No chance that it's not letting in enough air to idle.

The fact that you have some cylinders firing is good. Fuel pump must be working, and the gas can't be so old that it won't work. You might still have a fuel problem, like the fuel injectors in the cylinders that aren't firing. I think that's unlikely though.

Next step is to DISCONNECT the electrical lead to the MAF and see if/how the car runs. On some of the old cars, disconnecting the MAF tells the car to go "open loop" -- to ignore the O2 sensor and the missing MAF signal. If it doesn't help or run better, connect it back. If it does help, then you probably have MAF and/or O2 sensor issues.

I think your problems are most likely to be electrical (spark plugs and/or coil packs), or intake leaks. I agree with those who said to pull the coils and plugs, BEFORE you do, find out which cylinders are firing and which ones aren't. One way to tell is to disconnect the coil pack leads one at a time while the car is idling. When is slows or dies, then you know that cylinder was firing. Do that for all cylinders.

When you take the coil packs and plugs out, label and number them so you know which ones came from which cylinders. Look at them to see if any look damaged or different. Look for oil in the spark plug holes, surrounding the plugs, before you remove them. Now remove and look at the plugs and compare them to pictures online, for what different symptoms and normal plugs look like. Then do a compression test as described here and online. The best way to disable the fuel pump is usually to pull the fuse. Remember to put it back. If the compression test isn't great but still OK, the engine might still be worth saving. If one or more cylinders are shot, then the engine isn't worth saving and putting a lot of money into (though you still might be able to use it for a while -- you can drive it on 7 cylinders if you have to).

Buy new plugs for any that look real bad or too dirty to clean. You shouldn't need all 8 yet. Now, when you put the plugs and packs back, put them in different places, for different cylinders. Start the car and see what happens. If the same cylinders are firing and not firing, then you have issues other than the coil packs and plugs. If cylinders that used to fire are not firing now, then those coil packs are bad. (If you want to find out whether any coil packs are bad, keep swapping until all of them have been tried on previously firing cylinders. It can get confusing so keep track as you go.)


Do all that. Take good notes and report back. We'll have more to suggest then. Good luck!

[alang1990]

Those are great suggestions. Makes you want to just go.l out and get them done, right op? (Hint hint)
Like Shaffner said, you probably got a steal and whatever issues are there can likely be very easily solved - that happens often.

Just to clarify, I want him to do the compression test first because there is a known issue with the m60s block. If it's bad the engine needs to be replaced at least $1000 just for the engine.

Second at some point do change the fuel filter because most people one your side of the pond have a nasty habit of not doing so for 10-15 years. The engine runs ok but if you look up chrisfix fuel filter in YouTube you will think very differently - that guy perfectly analysed three filters of various mileage from running engines.

Anyway as mentioned earlier op for now don't change the fuel filter if you lift up the fuel rail - suspend with string- and most of them seem to fire normally. If some don't then it's an injector issue for those alone. If all don't fire properly or do so weakly it is the fuel filter. Then change immediately after you get home. But get it done somewhere down the line.

[R Shaffner]

Also:

That car has the OBDI software, with some limited diagnostics. Not great but better than nothing. Look online for how to do the "stomp test." Try it and read the codes. (They get cleared whenever the battery dies or gets disconnected, so the codes you have might be recent.)

Try the stomp test and see what you get. Clear the codes (by holding the pedal down 10 seconds or disconnecting/reconnecting the negative battery lead). Start the car, run it for a while or drive it if you can, and try the stomp test again. You might get different codes.

Of course, look up what those codes mean. Now comes the hard part. The most technologically dated part of that car is the computer. The rest of the car compares well with current cars, but in computer years that one is ancient. That means the codes might be right, or they might be just part of the problem, or merely a suggestion.

(For example, I recently worked on my brother's '92 525i. It gave me a code for a bad O2 sensor. I cleared it, drove it, and then got a code for a bad Throttle Position Sensor. I fixed both and still got a bad O2 sensor code. Then I read that code can mean the MAF is bad, instead of or in addition to the O2 sensor. I disconnected the MAF sensor and the car ran well, as opposed to stumbling horribly before. So the MAF was bad.)

These codes might help or might not, but reading them is in the free/easy category (as all this advice is so far).

And finally -- if all this sounds intriguing, then this might be a good car for you. If it's sounding tedious and like a hassle, you might want to consider selling it sooner instead of later. Getting into these details and processes is what owning/fixing an old Bimmer is all about.

[R Shaffner]

(Duplicate deleted)

[alang1990]

+1 on the stupid codes being not great. For the E34, they are to be treated as indicative, but not definitive. Anything they say needs to be independently tested out somehow. Anything they don't say but which might be likely in relation to a problem you have, still needs to be checked out.

But of course the codes are useful as they at least narrow the ballpark down most times.

[moroza]

I've seen perfectly-running E34s throw a CEL, and ones running like garbage fail to do so. The system is marginally useful at best.

Too many cooks at this point coming up with too much recipe. OP - do a compression test, report back, that's all for now.