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· Popeye
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31 Posts
Discussion Starter · #1 ·
So I just bought his car today. Kind of an impulse buy, but from everyone I talked to it was a good deal. It's in amazing condition for being a 90' and having 150,000 miles. I paid $1800 for it, it has no mechanical issue and runs well and like I said is in amazing condition. Did I get a decent deal? Regardless, the car is mine. So I have a few questions. What kind of problems should I look out for? What things will I come to love? What kind of aftermarket parts are available and should I even bother with them? I know very little about BMW's but assume they don't need anything aftermarket to drive amazing. Thanks for any help, I'm extremely excited to own this car and can't wait to start workin on it and driving it.
 

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Your car has the M20B25 engine which I think is a fine engine but others say it is too underpowered.

Your particular engine is very easy to work on and will run a very long time with the proper maintenance.
First think this:
Has the timing belt been changed, any records?
How about the waterpump?
When was its last oil change?
When was the last cooling system service?
Anything unusual about the fluids?

Answer all of these questions, then take a look at this:
http://www.bmwe34.net/E34main/Trouble/What_will_break.htm

If you have any other questions please feel free to ask, all of us are here to help.
Welcome.
 

· Popeye
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31 Posts
Discussion Starter · #3 · (Edited)
Awesome, thanks for the reply that's exactly what I was looking for. I can understand the underpowered comment, I felt like it it would have more pick up to it but it doesn't bother me. As far as all the questions on maintanence I'm not sure. The first thing I'm doing this weekend is doing a complete tune up (iridium spark plugs, all filters, change oil ect.) then I'll go from there. I know the previous owner put a brand new radiator in it, an I want to say a new water pump as well. I'm guessing I should replace the timing belt as well when I do the tune up? Thanks again for the post really helps out.

Edit: also, just did a quick google search for aftermarket stuff for fun on my lunch break. I came across a chip (gfchips) that advertises 60hp ,30ft torque and 4-7 mpg increase. Only for $70. Sounds like bull****. Any opinions?
 

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Sounds great!

FYI: These older engines respond better to copper plugs, but its up to you. I would use copper.

AS far as chips, as long as they are brand name chips (WAR, TMS, etc.) you will be fine. You must use 91 octane fuel or higher wen you get a chip since all it does is re-map the fuel controls to work with higher octane gas as opposed to the stock chip which optimizes use for low octane fuel.
 

· Popeye
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31 Posts
Discussion Starter · #5 ·
Well cool, copper plugs are way cheaper haha so that works out great. Good advice on the chips, I was unaware so thank you. Without a chip I can use normal unleaded, not premium or the mid grade correct?
 

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Well cool, copper plugs are way cheaper haha so that works out great. Good advice on the chips, I was unaware so thank you. Without a chip I can use normal unleaded, not premium or the mid grade correct?
Yup, just like the 1989 owners manual says:


The stock ECU has a stock tuned chip from the factory. The stock chip works with 87 AKI.
The performance chips they sell out there (legitimate ones) are tuned to work with 91 AKI.

So, if you buy a performance chip, you are just replacing the old one.
 

· Popeye
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31 Posts
Discussion Starter · #7 ·
So just an update. My first impressions are great. Love the quality of the vehicle, am amazed at the features it has for a 1990 model, and only have a few things I need to fix. The latch for the glove compartment needs replacing. The paneldor the sunroof needs to be replaced( where the buttons are). It may have a fuel problem, as sometimes it won't start the first time I try. Perhaps fuel pump? Also, sometimes when I'm slowing down (braking or just coasting) I feel a very slight jerk. Makes me think downshifting isn't proper but that's a pure guess. Overall, very glad I bought it and can't wait to start fixing things and making it even better. I'll take some pictures and post them tomorrow.
 

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Great that you are getting familiar with it!

There are two screws for the glovebox latch once you get it open. It comes apart in two pieces, junkyard item.

The panel can also be found at a yard. If its only the clips that are broken you can make your own holding tabs. I made mine out of plumbers tape!

Perhaps its the fuel pump. Can't know for sure without running fuel pressure tests.
Check the Bentley manual for testing the Fuel pressure. The manual can be DL'ed here:
http://www.bimmerwerkz.com/forum/5-...ey-service-manual-e34-updated-10-a-42558.html

The jerk may be because of an improperly adjusted kickdown cable at the throttle body. Follow the instructions for adjusting it in this thread, you may need a feeler gauge:
http://www.r3vlimited.com/board/showthread.php?t=225936
 

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I have a 1993 521I touring, with the stock chip can I run 87 octane fuel, and would a performance chip give me increased hp and torque as advertised? Thanks
Mister, don't threadjack...

Your engine is an M50. What you need to find out is if it has VANOS or not. The M50TU has VANOS and the M50 does not.

If you have the M50 then Premium fuel is required for best performance, otherwise you will experience knocking.
IF you have the M50TU then Premium fuel is not required since the engine is equipped with knock sensors to compensate for lower grade fuel.

If you do buy a performance chip you MUST use Premium fuel since that is what the chip does. It re-maps the injection for use with Premium fuel only (91 AKI or higher). Otherwise you will not see an increase in HP or Torque.

Byork and I do not have to use Premium fuel with our stock chips because we have the M20 engine. It was made to be used with 87 as stated above.
 

· Popeye
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31 Posts
Discussion Starter · #11 ·
So I'm trying to learn more and more about my car and what I can do to maintain it. So far, I've heard a few things that if possible I would like clarification on. I was told the m20 doesn't need high octane fuel but responds better with it. Will I notice a difference if I use say 91 or 93 with the stock chip? Also, I was told that changing all the speed sensors is recommended. True or bull****? One last thing, I want to clean up the engine as best I can and from then on take great care of it. From what I can tell its been taken great care of so far but I would like to clean it out and get a fresh start so to speak. I was thinking of using motor flush, then changing the oil and putting in some engine treatment (zmax was recommended to me). Good idea or no? I'm not very car savvy but am a quick learner and am very interests in learning all I can about bmw's , mine specifically.
 

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You should focus on replacing ALL of the fluids before you start eating through petro products with an engine cleaner. Brakes, radiator, transmission, gas filter(if your model has one) Focus on that first. It'll give you a baseline for the car, and you'll insure its longevity.

After that read the error codes with a stomp test. Then fix whatever comes up. Then you can chip it since you know your transmission and radiator aren't trying to pump cow pies through a tube while you're flooring it. Good luck.
 

· Popeye
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31 Posts
Discussion Starter · #13 ·
Will do, that's good advice. How do I check the codes if my check engine light comes on? I read that I push the accelerator pedal down 5 times within 5 seconds with the key in the ignition but nothing happened.
 

· Popeye
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31 Posts
Discussion Starter · #15 ·
I tried that exactly and nothing happened. Ill give it another try and see if it works. My check engine light isnt always on, it usually on clicks on when im in idle or park for a small amount of time, then as soon as i give it gas it goes away.

Update:
Finally gave the car a wash. Was told it might have a small exhaust leak so i went to get it checked out and ended up putting a new cat converter and muffler on it. Just sold my truck today so this weekend is tune up and fluid change time. Pics will come as soon as it dries.
 

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I tried that exactly and nothing happened. Ill give it another try and see if it works. My check engine light isnt always on, it usually on clicks on when im in idle or park for a small amount of time, then as soon as i give it gas it goes away.

Update:
Finally gave the car a wash. Was told it might have a small exhaust leak so i went to get it checked out and ended up putting a new cat converter and muffler on it. Just sold my truck today so this weekend is tune up and fluid change time. Pics will come as soon as it dries.
That means that your TPS is not functioning properly since it is not reading your stomps.
It is also not telling the computer when the car is at idle so that is why it comes on and goes away.
 

· Old School
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4,146 Posts
If this is a long term buy get the manual. The EFI settings will need checking (throttle position etc) and the air flow resistor may need cleaning, O2 sensor change and the throttle by-pass unit cleaned and checked. I would not use 'flushing agents' just service at half the standard period. An injector clean (removed in a test rig type clean) may be a good idea.
 

· Popeye
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31 Posts
Discussion Starter · #18 ·
So random question. But whats a 1990 730i worth? It has 90,000 miles, motor is in great condition, so is exterior. The inrerior needs work though. My friend offered me his for $900 and im thinking of getting it, fixing the muffler and the interior with a $1-1500 and selling it for profit. Good idea?
 

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Just wanted to add a couple things here. Do your tune up and change ALL fluids.

However!

I don't remember if you have a auto or manual. If its auto I wouldn't mess with it or drain anything out of it. They are notorious for failing after a fluid change! If it's manual then definitely change fluid.

DO go to www.bmwe34.net
It's full of awesome info. Ask people on here when you get confused. And get yourself a E34 Bentley Repair Manual (amazon it). It E34 owner's bible.

If you want to clean everything in the inside of your engine I would suggest researching all you can do with SeaFoam. It's amazing stuff!

Also the front control arms are renoun for going bad. The car will shake terribly bad when you hit the brakes at 50-65ish mph. That's how you'll know when those are shot. In fact check all parts in the steering system.

And check shocks too. All you need to do is push down on one corner of the car at a time. It should feel very stiff and should have very little give. If you can push it down more than a fat inch or you can rock it, then you shocks are toast.
 

· Popeye
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31 Posts
Discussion Starter · #20 ·
That means that your TPS is not functioning properly since it is not reading your stomps.
It is also not telling the computer when the car is at idle so that is why it comes on and goes away.
Ahhh gotcha. Cool, they arent to expensive so ill switch that out and see if it fixes it. Thanks.

If this is a long term buy get the manual. The EFI settings will need checking (throttle position etc) and the air flow resistor may need cleaning, O2 sensor change and the throttle by-pass unit cleaned and checked. I would not use 'flushing agents' just service at half the standard period. An injector clean (removed in a test rig type clean) may be a good idea.
Thanks for info sir. I downloaded the bentley manual a couple days ago, and bought a haynes manual from my work as well. Ive been reading through them a little when i have the time. After i research how to do all the things you mentioned i will surely do them as well. Sounds like some sound advice.

Just wanted to add a couple things here. Do your tune up and change ALL fluids.

However!

I don't remember if you have a auto or manual. If its auto I wouldn't mess with it or drain anything out of it. They are notorious for failing after a fluid change! If it's manual then definitely change fluid.

DO go to www.bmwe34.net
It's full of awesome info. Ask people on here when you get confused. And get yourself a E34 Bentley Repair Manual (amazon it). It E34 owner's bible.

If you want to clean everything in the inside of your engine I would suggest researching all you can do with SeaFoam. It's amazing stuff!

Also the front control arms are renoun for going bad. The car will shake terribly bad when you hit the brakes at 50-65ish mph. That's how you'll know when those are shot. In fact check all parts in the steering system.

And check shocks too. All you need to do is push down on one corner of the car at a time. It should feel very stiff and should have very little give. If you can push it down more than a fat inch or you can rock it, then you shocks are toast.
Yes its an Auto. So i shouldnt change the fluid or filter? What about adding some? Thanks for the link, it looks awesome. Yea i was recommended sea foam and was going to give that a shot so im glad im hearing more good things about the product. The control arms look good, i checked both when i had the car lifted up. Ill check on the shocks tomorrow. Thanks again for the advice should be of great help.

Thanks everyone that has contributed with sounds advice. Im really learning a good amount of am excited to keep my BMW in top shape.
 
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