and it wasnt the injectors.

Even though I labored over changing my original injectors out for '99 M3 pink injectors( link to my DIY (http://forums.bimmerforums.com/forum/showthread.php?t=924903) ).. that didnt change the rough idle.. but did seem to make the throttle more crisp.

So today I tackled the O2 Sensor. Got underneath to find out the 3 prong plug had been damaged by a PO by draggin it on the pavement (O2 side of plug).

Just to check, I completely unplugged it and started it up.. it had the same rough idle. No change at all. I dont think the O2 sensor had a good connection this entire time. :banghead:

It was in the exhaust TIGHT. To get it off I first soaked it with wd40, then ran the car long enough to smell burning wd40. Shut the car off, jacked it up and put a 22mm wrench on the sensor with a slight angle for the UNSCREW side.. then lowered the car down onto the wrench with the floor jack.. the weight of the car did most the work.. had to do that about six times before it became loose enough for me to crank it out by hand.

So I went to NAPA and bought a 1986 Ford E150 O2 Sensor for the 5.0 engine for $40.. it's a Bosch 3-wire.. took it home and managed to temp. repair the donor O2 sensors plug (I need to find a better plug and swap out the bad one), transfer the plug and wires over to the new O2 sensor and put it back in..

Well, at first it seemed kinda choppy. So I decided to take it out for a spin for the first time since I changed over to newer injectors. Went a cpl miles up the road to get some fresh gas in, hit the highway for about 6 miles and by the time I got it home, it would just sit there and purr smoothly.. eleventybillion times better!


And as far as performance, well.. all I can say is man.. this car can get you a hefty ticket quick! Not only how fast it can get on the open highway.. but also all the shenanigans it's capable of on sidestreets.
And this is a friggin AUTO! I'm very excited to see how it performs with a 5-speed in it.

Awesome! Glad to hear that was the fix for the idle problem.

Isnt great how well they take off from a roll?

-Jeff

Isnt great how well they take off from a roll?

-Jeff


Actually, it can catch you off guard.. it's like at first.. meh.. then it spools past 3k and you better be ready to do some countersteering cuz the rear tires just broke loose and the ass end is kicking out!

I was literally going up a hill diagonally this evening!

Awesome...thats how i hope to be tomorrow when i get Wolfie up and running!!! Although i'll only be one wheel peeling...

not for long though haha

-Jeff

Yeah, congrats on that. It's always satisfying when you do something to your car and it makes a real difference (versus the "I wonder if I'm imagining this?" thing). A new O2 sensor helped my car a lot too. It was very underpowered except at WOT and had irritating little misses when cruising at constant speed. The new O2 fixed that right up. I wonder if yours was so hard to get out because it was installed without the anti-seize compound?

I was lucky when i did my new O2 sensor as i had a new cat to put in as well. I dont think i wouldve been able to pull the old one off of mine. The cat was original, and i have a feeling so was the O2 sensor...EW!!!

-Jeff

I wonder if yours was so hard to get out because it was installed without the anti-seize compound?


-or might be because the original exhaust has been replaced by a shop fabbed replacement.

They cut the original out near the exhaust manifolds.. where the turn down goes horizontal below the car about 8" and whacked off there.
Then dual pipes slipped on.. no resonator, a cross pipe between the two with a threadded washerlike nut welded to the middle of the crossover... this is where the oxygen sensor was installed..
Then it continues on a little and goes to a 2 in 1 out Catalytic.. the out is a slightly larger diam. pipe than one of the duals.
It goes on to a single in muffler with a 4" tail that turns sideways.

It's a sad exhaust, really. But it's fairly fresh parts.
Needs duals all the way back... dunno about puttin' resonators back in though.



Yea.. the O2 sensor actually hooked up made a ton of difference.. the moment of clarity hit when I found that messed up connector.

I'm pretty sure my cat's original and I've been thinking about replacing it once I get my rich mixture thing figured out. Was yours bad and how was the improvement with the new one? I've also been considering a set of headers because I've read the factory manifold is restrictive.

How does it sound without the resonators? And what the heck are resonators for exactly? Are they strictly for making the exhaust quieter?

I'm pretty sure my cat's original and I've been thinking about replacing it once I get my rich mixture thing figured out. Was yours bad and how was the improvement with the new one? I've also been considering a set of headers because I've read the factory manifold is restrictive.

PO had the exhaust changed.. so I dont know any difference about the cat.
But I think the cat is mismatched.. and perhaps dependent on resonators prior.. I think when it get's hot, it POP's and cracks the ceramic inside it.. I had a previous thread (http://forums.bimmerforums.com/forum/showthread.php?t=920262) about that noise..
then again, it didnt POP tonight like it usually did on the highway durring prior runs.. perhaps a leaner mix prevented fuel from coming in contact with the cat and thus no detonation.

The O2 sensor I had in it simply wasnt making connection.
I replaced with a new sensor and repaired the connection to fix my rich mixture problem.. plus it just flat out NEEDS that O2 sensor hooked up!
Imagine it was running in LIMP mode.. thing is, I never seen any CE Light.
Does the 86's have CEL's?

How does it sound without the resonators? And what the heck are resonators for exactly? Are they strictly for making the exhaust quieter?

The lower end just sounds blah. WOT it gets better of course. Has a bit of a growl, but not much. When it rough idled.. it sounded like it was cammed out.
AFAIK, resonators are for reducing noise.
I'd just like to get it to growl like my e36's old orig. exhaust sounds.
I know these have GOT to sound alot better than what I'm gettin outta it rite now.

Nice. I love finally finding a head scratcher.

That must be what's causing my rough idle. Sensor hasn't been replaced by me. It seems that a substitute 3 wire sensor on my Volvo, could use a Mustang 5.0 sensor. I think it was around $30 vs what a direct fit would cost.

That must be what's causing my rough idle. Sensor hasn't been replaced by me. It seems that a substitute 3 wire sensor on my Volvo, could use a Mustang 5.0 sensor. I think it was around $30 vs what a direct fit would cost.


They wanted $107 at Napa for a direct fit Bosch sensor.
I think saving $67 is worth the 5 minute rewire work.

You could also just have a bad connection.


To update. I still have something going on... even though it runs way better, it still will get cranky and flutter a bit, it'll have a chop here and there..
I'll have it sitting on the driveway running, and all a sudden it'll flutter for a few seconds, then go back to smoothe again.

It could be the damaged connector not holding up a good connection

Check the plugs for the Coolant Temperature Sensor (on the T-stat housing, closest to the valve cover) and the Ref/speed sensors on the rear intake manifold brace. They can get brittle and crack around the wire locking bail leaving them loose.

I had an intermittent shudder in traffic and found the Coolant temperature sensor plug was cracked , a wrap of black electrical tape secured it until I get a replacement plug. It is the same as the injector plugs and they sell a plug repair kit ($7) for them. You might want to check the injector plugs also now that I think of it.

try autohaus az they have the bosch with plug for I think it is $74 plus shipping

They wanted $107 at Napa for a direct fit Bosch sensor.
I think saving $67 is worth the 5 minute rewire work.

You could also just have a bad connection.


To update. I still have something going on... even though it runs way better, it still will get cranky and flutter a bit, it'll have a chop here and there..
I'll have it sitting on the driveway running, and all a sudden it'll flutter for a few seconds, then go back to smoothe again.

It could be the damaged connector not holding up a good connection


If you're handy with a soldering iron, there's a large circular transistor inside the ECU. It developes cold solder joints and reflowing the solder will make a good connection again. I would try another ECU first and see if the problem goes away, before opening up yours. There's a write-up in the archives on roadfly. You're looking for cold solder joints and you can see it with a good magnifying glass. My 6 started running terribly and then went to no power. It would hold a rough idle, but when putting a load on (as in driving) , it would start bucking and back-firing. I put all my spare parts on before getting a hold of another ECU for a test.

That must be what's causing my rough idle. Sensor hasn't been replaced by me. It seems that a substitute 3 wire sensor on my Volvo, could use a Mustang 5.0 sensor. I think it was around $30 vs what a direct fit would cost.

so the mustang version of the sensor is exactly the same (threads and all), and all i'd have to do is cut the ford connector off and put the old BMW one on? so they're basically charging $80 for that connector?! crazy....

Check the plugs for the Coolant Temperature Sensor (on the T-stat housing, closest to the valve cover) and the Ref/speed sensors on the rear intake manifold brace. They can get brittle and crack around the wire locking bail leaving them loose.

I had an intermittent shudder in traffic and found the Coolant temperature sensor plug was cracked , a wrap of black electrical tape secured it until I get a replacement plug. It is the same as the injector plugs and they sell a plug repair kit ($7) for them. You might want to check the injector plugs also now that I think of it.


hmm.. well I had ALL those connectors off/inspected when I swapped in the '99 M3 Injectors. Didnt notice any issues.
Hell, I even replaced 7 vac hoses in the immediate area of the intake... about 7ft of hose total.


If you're handy with a soldering iron, there's a large circular transistor inside the ECU. It developes cold solder joints and reflowing the solder will make a good connection again. I would try another ECU first and see if the problem goes away, before opening up yours. There's a write-up in the archives on roadfly. You're looking for cold solder joints and you can see it with a good magnifying glass. My 6 started running terribly and then went to no power. It would hold a rough idle, but when putting a load on (as in driving) , it would start bucking and back-firing. I put all my spare parts on before getting a hold of another ECU for a test.



Ahh.. I'm all too familiar with cold solder joints..
I need to pull my ECU anyway to see if it's been chipped or not yet. And if not, it should get one.



so the mustang version of the sensor is exactly the same (threads and all), and all i'd have to do is cut the ford connector off and put the old BMW one on? so they're basically charging $80 for that connector?! crazy....


yup, $80 for a cheapo connector. :shifty
Just make sure you get a BOSCH sensor and not some cheapo knockoff universal. Both will work, but personally I'm willing to spend the extra $18 for the real deal/Bosch.

oh yeah, i'd definately go with Bosch.

I fixed my rough idle as well. It was the injectors. Actually one of them. It was completely clogged. Took an air hammer to the side of it, works perfectly now. Though I need a rebuild kit for all of them because the plasic crap has become brittle and the o-rings are a little dried out.

You do definitely want to go with a Bosch unit. Correct me if I'm wrong, but go in and ask for the cheapest 3 wire sensor. You may even be able to go with a single wire, since the other 2 wires are for the sensor heater. The heater just brings the sensor up to temp quicker.

You do definitely want to go with a Bosch unit. Correct me if I'm wrong, but go in and ask for the cheapest 3 wire sensor. You may even be able to go with a single wire, since the other 2 wires are for the sensor heater. The heater just brings the sensor up to temp quicker.



I could be wrong, but some systems will have a bad reaction if it senses that it cant heat up the sensor... think checking the heating element is part of the diagnostic for cars equipped with 3wire.