Inconsistent performance - 1985 BMW 318i

Discussion in 'The Garage' started by crazydrummerdude, Dec 27, 2011.

  1. crazydrummerdude

    crazydrummerdude Wacky Bongo Boy

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    Trading vehicles with friends and random people on craigslist means I ended up with an '85 BMW 318i, 5-speed manual, 1.8L engine. For free.

    The guy I got it from said that it's often hard to start, and that all I'll have to do is move the wheel in the mass air flow sensor over a couple clicks. I noticed the rubber boot between the sensor and the intake had a few substantial cracks in it. So, $20 and a new boot later, the car started up and drove just fine. I insured it and did many test drives to shake out any other problems in preparation to make it a daily driver. I might have done a few donuts in my field, too. (Hey, it's a free car.) Fast forward a couple weeks, and it's hard to start again and losing power. Some more fiddling with the mass air flow meter and the mixture, and it would sometimes be just fine and sometimes not be able to drive up the slightest incline. At this point, every time I start it up, I fiddle with the air flow meter. I honestly don't know if I'm doing anything or if it's just "luck." Sometimes, it's a regular car. Sometimes, it's a turd.

    Right now, it's in the poor-performance stage. It's hard to start, and any amount of throttle will bog it down. If I let it warm up and kill it, it won't be any easier to start up.

    Before I dump $185 on a reman. MAF sensor, I asked around. A friend suggested that my O2 sensor may be bad. That's $110. Hell, it also sounds like dirty injectors. (Those are $181 each on pelicanparts.com?!)

    Any tips? I'd rather not just throw money at the problem.

    (....and no, I'm not just asking for advice so I can flip the car. I want to drive it.)
    #1
  2. Tweaker

    Tweaker ...

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    Oddometer:
    9,677
    I know nothing about this car but sometimes a bad or plugged catalytic converter will do some strange things just like you say. You could try disconnecting for a test.
    #2
  3. tytek

    tytek Adventurer

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    I think that I have a few service manuals for the e-30. Let me know if you are interested and if you pay shipping, you can have them.
    #3
  4. P B G

    P B G Long timer

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    Oddometer:
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    Location:
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    O2 sensor, I believe the cheap way to go is to buy a Ford Mustang 02 sensor and swap the plugs around, believe this to be the case for an 1985.

    On my 91 318i, there are a lot of other vacuum hoses, and an Idle Control Valve. All of those hoses can lead to vacuum leaks which will cause weird running issues.

    If there is an ICV those are usually something that can be cleaned out, and I believe you can test them like a solenoid, with some jumper leads it should open/close when you swap power. Should have instructions online for this.

    I bought 4 injectors for my 91 318i off ebay, I got the interchange numbers for more modern ones out of a volvo I believe, depending, I uprated my flow slightly, and also the new ones have 4 pintle holes instead of 1, so it atomizes the fuel better.

    Some of the older BMW fuel injection systems have a way to pull fault codes, in my car for instance you turn the key to "on" and push the gas to the floor 4 times.

    After this the check engine light blinks, its sort of like a code for instance.

    http://www.pelicanparts.com/bmw/techarticles/Mult-Code_Reading/Mult-Code_Reading.htm

    If it does anything other than 1444 (one flash pause, 4 flashes, pause, 4 flashes, pause, 4 flashes pause) then you have a problem. And O2 sensors should show up on that.

    Enjoy.


    1211 DME Control Unit
    1215 Air Mass Sensor
    <?XML:NAMESPACE PREFIX = O /><O:p>
    </O:p>1216 Throttle Potentiometer
    <O:p>
    </O:p>1218 Output Stage, Group 1
    <O:p>
    </O:p>1219 Output Stage, Group 2
    <O:p>
    </O:p>1221 Oxygen Sensor 1
    <O:p>
    </O:p>1212 Oxygen Sensor 2
    1222 Lambda Control 1
    <O:p>
    </O:p>1213 Lambda Control 2
    <O:p>
    </O:p>1223 Coolant Temperature Sensor
    <O:p>
    </O:p>1224 Intake Air Temperature Sensor
    <O:p>
    </O:p>1225 Knock Sensor 1
    <O:p>
    </O:p>1226 Knock Sensor 2
    <O:p>
    </O:p>1227 Knock Sensor 3
    <O:p>
    </O:p>1228 Knock Sensor 4
    <O:p>
    </O:p>1231 Battery Voltage/DME Main Relay
    <O:p>
    </O:p>1232 Throttle Idle Switch
    <O:p>
    </O:p>1233 Throttle Wide Open Throttle Switch
    <O:p>
    </O:p>1234 Speedometer A Signal
    <O:p>
    </O:p>1237 A/C Compressor Cut Off
    <O:p>
    </O:p>1242 A/C Compressor
    <O:p>
    </O:p>1243 Crankshaft Pulse Sensor
    <O:p>
    </O:p>1244 Camshaft Sensor
    <O:p>
    </O:p>1245 Intervention AEGS
    <O:p>
    </O:p>1247 Ignition Secondary Monitor
    <O:p>
    </O:p>1251 Fuel Injector 1 (or group 1)
    <O:p>
    </O:p>1252 Fuel Injector 2 (or group 2)
    <O:p>
    </O:p>1253 Fuel Injector 3
    <O:p>
    </O:p>1254 Fuel Injector 4
    <O:p>
    </O:p>1255 Fuel Injector 5
    1256 Fuel Injector 6
    <O:p>
    </O:p>1257 Fuel Injector 7
    <O:p>
    </O:p>1258 Fuel Injector 8
    <O:p>
    </O:p>1261 Fuel Pump Relay Control
    <O:p>
    </O:p>1262 Idle Speed Actuator
    <O:p>
    </O:p>1263 Purge Valve
    <O:p>
    </O:p>1264 EGO Heater
    <O:p>
    </O:p>1265 Fault Lamp (check engine light)
    <O:p>
    </O:p>1266 VANOS
    <O:p>
    </O:p>1267 Air Pump Relay Control
    1271 Ignition Coil 1
    <O:p>
    </O:p>1272 Ignition Coil 2
    <O:p>
    </O:p>1273 Ignition Coil 3
    <O:p>
    </O:p>1274 Ignition Coil 4
    1275 Ignition Coil 5
    <O:p>
    </O:p>1276 Ignition Coil 6
    <O:p>
    </O:p>1277 Ignition Coil 7
    <O:p>
    </O:p>1278 Ignition Coil 8
    <O:p>
    </O:p>1281 Control Unit Memory Supply
    <O:p>
    </O:p>1282 Fault Code Memory
    <O:p>
    </O:p>1283 Fuel Injector Output Stage
    <O:p>
    </O:p>1286 Knock Control Test Pulse
    <O:p>
    </O:p>1444 No Fault Codes<O:p> </O:p>
    #4
  5. crazydrummerdude

    crazydrummerdude Wacky Bongo Boy

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    I have the Haynes, but I'll send you a PM. Thanks!

    Thanks!
    #5
  6. Alijonny

    Alijonny ADVENTURERERERERERER

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    I might recommend you check out R3vlimited.com. They are one of the larger e30 forums around. You will have to weed throught he noobs and such, but by searching, you might find what you need withoug making a post. GOOD LUCK!
    #6
  7. LuciferMutt

    LuciferMutt Rides slow bike slow

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    OBD1 EFI system. Look up on the interwebz how to read the codes directly from the car -- usually you jumper a wire in a terminal box somewhere, turn the key to on and count the flash sequences of the check engine light.

    BTW....you fiddle with the MAF and the car runs well, then doesn't, you fiddle with the MAF again and it runs well...sounds like you miiiight need a new MAF :deal But get a code anyway.
    #7
  8. P B G

    P B G Long timer

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    These are Pre-OBD cars, that would be more like 1991, and BMW used their own plugs up until OBD-II I believe implementing that around ~95 or 96.

    These cars are Bosch Motronic fuel injection, there are a few varieties and I am not well versed on which versions came with which cars in which years in which countries.

    I know that for a good portion of the 80's and early 90's the codes I posted work.

    Before a certain year, I am not certain, 1985 is the year of my birth, so anything of this vintage I have had to learn much after the fact, maybe someone on here worked as a BMW tech in the 80's and would know more.
    #8
  9. trailsaw

    trailsaw remember tomorrow

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    This 318 is non motronic-known as simply "l-jet".

    Check the circuit board in the airflow meter for cracks-must remove black cover where "wheel" is. By loosening that clock spring in there, you make it richer.
    o2 sensor will not cause this-in fact-unplug it for a 50/50 value.

    Pull back black boot on afm and check pins-might be corroded.
    Check connector @ control unit in top of glove box for corrosion etc.

    **Check and clean all grounds for motor/harness etc.** check running voltage!
    Pull dist cap and look for arcing etc inside from rotor as well.
    Pull plug off side of dist and inspect connectors.

    Experiment with filling the gas tank-see if it goes away(split in pick up tube)

    PM if you need any more help.
    #9
  10. crazydrummerdude

    crazydrummerdude Wacky Bongo Boy

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    Eh, the process seemed to work before, but at this point fiddling with it doesn't make a definite difference. It seems random. Fiddling with the MAF might just be a placebo.

    Thanks!
    #10
  11. crazydrummerdude

    crazydrummerdude Wacky Bongo Boy

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    Update:

    So, I've got a lot of projects going on at once (like usual). I haven't done the code checks yet, but the physical condition of my AFM was obvious that I needed a new one. Er, a rebuilt one.

    With the wiring harness to the AFM unplugged, the car idles/runs rough but continuously, with a slowly surging RPM. If I plug it in while the engine is running, the RPM will raise slightly, the idle will smooth out, then it'll cut out, as if I turned off the ignition. In summary: The rebuilt AFM makes the car run well for about 3 seconds, then kills it. (..and yes, this is an AFM, not a MAF.)

    I've been fixing on some other parts of the car - clutch/brake system, electrical oddities, etc. The last issue is getting the fuel/air system working properly. I'll continue on it this week.
    #11
  12. chammyman

    chammyman Been here awhile

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    I'd be checking the coolant temp sensor, they are generally corroded a lot sooner than nearly 30 years
    #12
  13. willis 2000

    willis 2000 neo-quixote

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    l-jet is simple to work on, and most of the problems are easy to find. You have the barn-door airflow meter, and it was a good idea to replace it. Be absolutely certain you don't have vacuum leaks. Brake booster? Yes, check for corroded electrical connections. I had these on Lancias and Fiats. The various sensors, including O2, didn't seem to have much to do with the vehicle running well. Do you have enough vacuum at idle? A lot of blow-by can make these things run poorly. I had to rig up an external crankcase vent on one. They require a lot of fuel pressure for the injectors to perform properly. Maybe a restricted fuel filter, but the fuel pumps fail, too. On the fuel injector pipe, there is a fitting to attach a pressure gauge. Your manual should show this. Block the barn-door flap open with a large screwdriver, this allows the fuel pump to run, and you can check the fuel pump without starting the engine, only turn the key to on. If you crack open the fitting, and get air, it's likely the fuel pump is bad.Be careful, there's a lot of pressure there.
    #13
  14. BFG

    BFG Adventurer

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    As said check all the small vac pipes they are all over the place and get brittle where they connect, but also a look at the mass air flow meter. If memory serves it is a &#8220;hot wire&#8221; type. If the original hose was cracked it will have been drawing in unfiltered/dirty air this contaminates the wire and gives a false flow reading to the control unit, if it&#8217;s really crappy it will show very low air flow so little fuel for a lot of air! Try taking the sensor out and clean with some spray carb/injector cleaner. Or with the engine off take of the large intake pipe and give it a good spray around the intake body, you will be surprised how much junk there is in there. Let the cleaner evaporate before re starting.
    If you can get the engine diag done and clear all the stored fault codes, there will probably be loads, then try again and see what shows up. Good luck.
    #14
  15. willis 2000

    willis 2000 neo-quixote

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    I remembered my last Lancia and the fuel pump. I replaced it with new, and it lasted two weeks. The subsequent owners did, too. I wonder if the age of the car and the changes to gasoline didn't condemn this vintage of car to the scrap heap. Does anyone on here still drive a car equipped with l-jetronic? Yeah, you might have a hot-wire airflow meter, the Germans got Bosch upgrades (experiments?) before the other Euros.
    #15
  16. Minnesota

    Minnesota Conform or be cast out

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    I have the 1984 version of your car. 111000 miles. I went through something similar last fall. The car is usually pretty snappy but it went through a phase where it was an absolute dog. I had just put a thread up on bimmerfest.com about this and the car snapped out of it. I drive it all winter long and it sits most of the summer.

    I have no idea what the cause was or what happened that fixed it. I just drive it to work and back every day.

    One thing to check is the connection at the computer, which is inside the glovebox. I have solved some poor performance issues by simply wiggling the plug on the computer, or tapping lightly on the computer housing.
    #16
  17. P B G

    P B G Long timer

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    Mine has up and died a few times in the past few months. When I head to down shift clutch goes in and engine just isnt' on anymore.
    #17
  18. trailsaw

    trailsaw remember tomorrow

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    Check/clean idle valve?
    #18
  19. crazydrummerdude

    crazydrummerdude Wacky Bongo Boy

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    I was trying this today, as per the pelicanparts link, and... nothing. Hell, I don't even know where the check engine light is on this thing.
    #19
  20. trailsaw

    trailsaw remember tomorrow

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    '85 318i does not have a check engine light....
    #20