E36 - Crappy Acceleration, Rough Idle, "Putting" Engine, and a seriously loud pop

[abomb93]

Alright...
I bought myself a 1993 325i a couple months ago. It ran perfectly until about a week and a half ago. It died on me at a stoplight. Turns out, the fuel filter AND fuel pump were original. I took the car to the shop and had them replaced. It ran just like new again after that. However, yesterday, while I was driving at about 50mph, the car made an explosive-sounding pop from the right rear. I pulled over to see if I hit something, but there was nothing. The car ran fine and there were no dents or scratches or any debris in the road. I was a little nervous thereafter. I drove about 5 more miles and I noticed the car was "putting" along. I had poor acceleration and the car sounded terrible. This morning, the car almost died on me just backing out of the driveway. It idled terribly in the garage as well. It's been driving this way all day long. Everywhere I've looked has told me to change the fuel filter or the fuel pump, but I just did that. The OBC isn't producing any codes, the check engine light isn't on, and I only use premium gas. Also, I'm a very conservative driver, so anything related to outrageous driving is ruled out. I need some help because I'm a total newb. Thanks to all in advance :(

[projectXe36]

Try disconnecting your battery for a few minutes and see what happens. Also try cleaning and checking your MAF

[flyfishvt]

Your OBC has absolutely nothing to do with the engine. Personally I think you're crazy to drive that car anther foot until you find out what's wrong. Explosive noises like you heard are obviously not normal and then to have it run bad and continue to drive it is just plain crazy.

You need to start by pulling the plugs and looking at those then have a compression test done. Look over every inch of the engine for loose or broken hoses. Start with the basics

[abomb93]

Your OBC has absolutely nothing to do with the engine. Personally I think you're crazy to drive that car anther foot until you find out what's wrong. Explosive noises like you heard are obviously not normal and then to have it run bad and continue to drive it is just plain crazy.

You need to start by pulling the plugs and looking at those then have a compression test done. Look over every inch of the engine for loose or broken hoses. Start with the basics


I have to agree. I'm crazy. I was beyond terrified to drive the car, but I don't exactly have options. It still drives, but it drives like my old ass Alfa Romeo...that car had 2 bad injectors. My E36 was marvelous 2 days ago, but it feels like an old beater now.


Try disconnecting your battery for a few minutes and see what happens. Also try cleaning and checking your MAF

I did this exactly. I disconnected my battery for about 10 minutes and reconnected it. I picked up some MAF cleaner and cleaned the sensor. The car drives much better now. The rough idle is gone and the crappy acceleration is MOSTLY gone. Now there's this rumbling sound coming from the right rear side of the car. It sounds like the thunderous roaring sound when you hit 6000 rpm, but a little punchier. I'm pretty sure it shouldn't sound this way. It's definitely better than how it was 2 hours ago.

[Kody]

Why would you be at 6000rpm if the car is running so badly?

[abomb93]

Why would you be at 6000rpm if the car is running so badly?

I'm not taking it to 6000 rpm. I'm trying to make a comparison that people will understand.

[chadb08]

check vac hoses. it fixed my idle. you may have a few of them lose or even off if its idling that bad. as for the pop noises, i aint gotta clue. im still new to beamers my self

[abomb93]

check vac hoses. it fixed my idle. you may have a few of them lose or even off if its idling that bad. as for the pop noises, i aint gotta clue. im still new to beamers my self

I cleaned my Mass Air Flow sensor and it fixed the rough idle.

[e36msp]

What cleaner did you use for the MAF?

[abomb93]

What cleaner did you use for the MAF?

I used specialized MAF cleaner from AutoZone. I picked it up for about 7 bucks

[epmedia]

Maybe one of your O2 sensors popped out :eek:

[dantheman67]

Maybe one of your O2 sensors popped out :eek:

X2; I would get it on a lift and check. On my M60 the O2 sensors are accessible without removing anything, they're mounted in the exhaust just aft of the cats, 45 degrees below the horizontal. Hope this helps.

Edit: missing o2 sensor would fit OP's description of the deep rumble only on one side of the car.

[DrinkCoffee]

I was thinking o2 also. This would definitely throw a check engine light, though. Are there any CELs on, OP?

If one were to pop out, why would it do so? Clogged cats? Corroded?

[abomb93]

I was thinking o2 also. This would definitely throw a check engine light, though. Are there any CELs on, OP?

If one were to pop out, why would it do so? Clogged cats? Corroded?

No. There haven't been any CELs. I'm going to ghetto stethoscope my plugs today to see if that's affecting anything

[joey79]

His car is obd1, so it only has one o2 sensor. If the o2 sensor did pop out for whatever reason, there would definitely be a CEL.

[dantheman67]

His car is obd1, so it only has one o2 sensor. If the o2 sensor did pop out for whatever reason, there would definitely be a CEL.

Not necessarily? My understanding is that the O2 sensor code is thrown if the voltage reading from the sensor is out of range, ie the sensor is faulty. Iirc the range is .2V to 1.0V. Its possible the sensor is still plugged in, still working within spec, but not in the exhaust. Then it should be give an incorrect, although in-range voltage reading within spec, NOT triggering the CEL.

It could've come out for a number of reasons. Over-tightened and stripped the threads/previous owner duct taped it in, or maybe under tightened and the vibration from the engine shook it loose? People do pretty stupid stuff to cars. Spoilers on Civics, cold air intakes that take in hotter air than the factory setup, lol. You get the idea. My favorite, the PO of my 540i cut the wiring harness to my original BMW radio so he didn't have to buy the $20 wiring harness for the chintzy Kenwood deck I found the car with.. ugh..

[GL0D]

... I had the same problem until today.. Now fixed! (very cheap)

Firslty, I'm not sure the popping noise is related to the same problem. My car devoloped that popping noise a while ago from the exhaust when started from cold. It then gradually goes away. (kinda like it though)
Secondly, Noticed the engine problem when sitting at traffic lights, suddenly engine cut out. Run normally after restart. Later developed loss of power when accelerating, and 'lumpy' misfire occasionally. Got to a point where the engine was struggling to run smoothly at all.

FIX;
- Removed air filter.
- Checked main rubber air-intake hose hose before the throttle body to discover a large split underneath.
- Removed the main hose.
- Checked for further splits
- Wrapped with duct tape to seal the splits, then further wrapped with rubber tape.
- Reassembled back to car, replaced air filter and started engine.
- Checked for further leaks.
- Engine now sounds and runs perfect again.

This is only a temporary fix for me, I intend to get a new hose soon.
Your problem may not be as technical as you think.
This fixed mine, hope it helps.

[flyfishvt]

Only one teensy weeny problem with this....the o2 sensor in his car is almost directly under the center arm rest. His noise came from the front passenger side.

[dantheman67]

Only one teensy weeny problem with this....the o2 sensor in his car is almost directly under the center arm rest. His noise came from the front passenger side.

Original post said passenger-rear. I'm not sure how hard it is to check the O2 sensor on the i6 but I would still do it. Loud pop outside of engine bay, car idles badly.. says O2 to me

[abomb93]

You need to start by pulling the plugs


Good call, sir. Turns out my spark plugs were in absolutely TERRIBLE condition. Half of them had outrageous gaps and the others barely worked. It's a miracle the car even ran. I replaced all six. Problem solved :)

[dantheman67]

Glad you got the problem solved.

[epmedia]

Good call, sir. Turns out my spark plugs were in absolutely TERRIBLE condition. Half of them had outrageous gaps and the others barely worked. It's a miracle the car even ran. I replaced all six. Problem solved :)

:buttrock nothing beats a little tlc
I'm glad it was not a sparkplug that popped out :eek: