1991 325i m20 help, madison
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If disconnecting the 02 sensor made no difference in the surging then perhaps there is a problem with the O2 sensor. An O2 sensor on its way out would cause idle problems once the engine is warm.
I don't remember reading in the thread but are you throwing any CELs?
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i have above a 1/4 tank left. i had to fill it up on my way back from IL when i bought it end of Nov. I did start it throughout the winter and i did just yesterday throw some fuel injector cleaner in. Unfortunately it won't make it to a gas station to top her off:( Did the stomp test and didn't get any codes.
So, you think o2 is the next cheapest thing to try? no other way of testing that I assume?
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Cheap: Since the car won't make it to the gas station go to Wally world or where ever and pick up a 5 gallon plastic gas container and a bottle of HEET gas line dryer. The injector cleaner you added needs to get mixed in with the gas, so maybe adding some will help.
Cheap: 1/4 tank maybe your fuel pump pickup is clogged (rust flakes etc)? Pump is under the rear seat passenger side. Pull the pump and see if the screen/sock is clogged.
Cheap: metal elbows on the throttle body. Are these tight?
O2 sensor: not so cheap. There are ways to test (folks will weigh in here, or if you have an Bentley handy; maybe this http://www.verrill.com/car/idle/e30_o2test.shtml), but I replaced mine on both e30s since very high mileage and I had no idea when it was done last. Just a heads up that they were a pain to remove. A fouled O2 sensor could be the issue and would not necessarily show up in the stomp test/code read.
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thanks Boris3. I might just do the o2 sensor. Car has 100k on it and i dont know when it was ever done. I'd be surprised if the filter gets clogged as it take the car running for about 5 mins of running before it starts to bogg down. If it got clogged do you think that would happen quicker? I'll check it eitherway though. Cant hurt!
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You haven't put gas in since last November? Get some fresh stuff asap. Try to find it without ethanol, ethanol deteriorates quickly and is not friendly to older cars. If the cat was plugged the vacuum would drop as you revved the engine higher. And typically idle will be ok but power will be poor to terrible when trying to drive.
Sent from my potato phone
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yes same tank, car has been in and out of storage for the winter. it does fire right up and drives fine for a bit, so it doesn't seem like the gas is bad? Does smell like she's running a bit rich though. But yes, some fresh gas is on the list. Was going to try to get some today but didn't make it out of the subdivision.
Here's what she looks like today. Figured I'd give you all some eye candy so you can see the cause you're working on
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Hi again all. Looks like i'm stuck. Added fresh gas, checked the gas pump filter and that was clean, changed o2 sensor. Still having the same problem. No idea and its not driveable. Bad DME?
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Ok time to go back to the beginning. Car was running better before you did all the tune up things, correct? Was it sputtering at all before you did anything to it?
So it's something you did.
Basics:
-the plug wires are connected correctly to the proper holes on the distributor cap and to the proper cylinders.
-you replaced the rotor ; rotor was ok
-you removed the metal screw on pieces on the ends of the spark plugs
-You made sure timing was correct (nothing jumped a tooth when you were installing the belt, tensioner was changed)
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Basics cont:
-any hoses removed, reattached improperly when removing the valve cover, or opening the air box to replace the filter (the wire plug to the air box unconnected/ reconnected), metal elbows still tight on the throttle body after working on the air box,
-main accordion air hose to throttle body not cracked in the accordion seams (old hose could crack when opening the air box to replace the filter)
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Thanks Boris,
I'll double check everything again, i think you're right i'll just have to take things apart again. I got the Bavauto performance wires. I was told not to remove caps from the plugs for those wires. The wires click onto the plugs so I think they're on there correct. I have also tried it with the caps off and it didn't make a difference.
Snap - that would be great, i'd love a second set of eyes. I'm sure once I figure it out it'll be something stupid. The car isn't my daily driver so it's just sitting in the garage right now until i can figure it out. I can come home over lunch or am generally free after about 5:30pm.
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Update - Ran a homemade smoke test with a compressor and paint can trick. Worked like charm. One very small vaccuum leak on the bottom of the hose that attaches to the valve cover. Took it off and it basically snapped apart it was so brittle. Ordered a new one.
While waiting for that to come in I popped the valve cover and adjusted the valves. There wasn't 1 that I could get the feeler under, so they were pretty tight. I adjusted those to the best of my ability. Definitely a finky job. I don't feel like I did as good as I could have, anyway...
Hose came in today and put it back on over lunch. Fired it up. Seemed to still do the same thing initially but settled down after a little bit. DME adjusting itself?? I let it idle for 5 mins before working up the courage to take it out. Drove it for 10 mins around the subdivision and a road up to 45 mph. Knock on wood it performed well. Going to put it through some more rigorous driving tonight.
I did notice my idle dropped to the 800 ish rpm range, where before it was about 1100 rpm. So, I think that's a good thing too. Valves still seem to tick a bit, there's probably one or two that aren't quite right.
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I am not sure if the version of Motronic you have adapts like the ECU in the e36 but you should reset it by disconnecting the battery and touching the cables together to clear the ECU and force it to relearn the engine. On the e36 you have to do this anytime you make a modification and/or fix a problem like that. I installed a lightweight flywheel in a 328 and it would hardly idle until the ecu was reset, then it relearned and smoothed right out.
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Drove it more last night. Still has some sputtering issues, but not NEARLY as bad. I at least feel like I can drive it to places. It smooths out more after its warmed up. Still might have to take up a couple of your offers to look things over to see if I'm missing anything if you're still willing.
Looking online it doesn't look like my ECU resets like the e36. I unplugged the battery last night and am letting it sit all day today. Will try again tonight.
As for the smoke test I just modeled it after these two posts. I put a hole in a soda can and the can fits nicely into the intake hose. Just tape it and seal it off good before putting smoke into the system. Dont forget to open the throttle.
http://www.r3vlimited.com/board/showthread.php?t=292791&page=2&highlight=smoke
http://www.r3vlimited.com/board/showthread.php?t=274418&highlight=smoke
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hooked the battery up again and turned on. Still sputters like before. Still bad enough that its definitely not right. I have no idea. Ugh.
I'm thinking this still might go back to those Bavauto performance wires and plugs. I did find one buried topic online of a person having issues with those wires.
Is there anyone I could meet up with that has an m20 engine that would be willing to let me try their plugs / wires to rule that out?
Thanks again for every ones help here. Oh, I did also hook the vacuum test back up and I got 16-17 psi, so that was much improved from before and where it should be.
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