M42club.com - Home of the BMW E30/E36 318i/iS
DISCUSSION => Engine + Driveline => Topic started by: sqlpython on April 30, 2011, 11:58:46 PM
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93 E36 m42 4cyl 318i sedan.
The title speaks the problem....
I can install another Oxygen Sensor but why did it fail again so quickly.?
The check engine light came on and the RPMs began to fluctuating between 1200 and 400 rpms...
Back to the shop place it on the diagnostic computer which confirmed the New Oxygen Sensor did not completely fail but was behaving erratically.
Just before it failed I was removing the Radio to upgrade it. I unscrewed the Torcs that were holding the radio in the dash but never disconnected the Radio from the system... This should have nothing to do with the situation just thinking (really reaching here) that the computer shocked during the process ??
Any help?
I don't want to install Oxygen Sensor #3
Thanks
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Ok, While everyone has their thinking caps on..
I did some more on line research plus spoke to a Tech and the Parts manager.
Seems of all the after market 318i parts that either had used the O2 sensor just is a happier marriage with fewer failures if you use a BOSCH O2 sensor..........
In fact the parts manager said.. "I get a better mark up on the After Market O2 but recommend that you buy the BOSCH in this instance."
Any opinions or thoughts?
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They're all the same part with different plugs. As long as the universal you installed was a pre-cat model it should have worked. In fact, most of the later BMW sensors are a direct exchange, only with different length pigtails. If you want to get a genuine Bosch that works, any '90s Ford V8 four-wire pre-cat sensor is the exact same part with a different connector. They're usually about $50 instead of the $120 that BMW wants.
The parts guy is trying to help by telling you what works most of the time. He's right, often older FI cars are just an O2 sensor failure. Our M42s have a more elaborate idle control, so you often have to do a bit more digging. Code scanners aren't a great way to diagnose older cars, the codes in our OBDI are very limited compared to OBDII.
Rough idle and O2 code failures can also be a result of vac leaks, bad ICV, miscalibrated AFM, bad temp sensors, plugged fuel injectors, bad FPR, the list goes on and on.
Also, long shot here, but do you have any silicone sealant on the intake or exhaust manifolds? Unless it's marked 'sensor safe' it will kill O2 sensors.
The radio had nothing to do with it.
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BTW I edited post one as it was ignorant of me not to post the The Yr Make Model..
Thanks Dave...
That is what I needed to hear and gives me lots to look at...
This input puts a face on what not to look at. I wanted to close a few doors before pursuing a solution.
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unrelated to the O2 sensor issues that you are talking about but your running problem could also be the cat.
I had a 1999 E36 compact M44 that died. The stealer changed a whole bag load of stuff including the O2 sensor -twice- and eventually the ECU.
After that they still couldn't get it right so disconnected the exhaust before the cat and it ran fine again. I got the cat changed with a non-BMW part but the dealer never admitted that the ECU wasn't at fault. Even the dealer principle stuck by the service dept line, and they never proved the ECU was at fault.
I put the old ECU back in but they had recoded the EWS system and the car wouldn't do anything with the old ECU in it.
My advice? Don't forget to check the cat. Mine had blocked and collapsed. The car would start and then slowly die. I believe it was because the cat would heat up and completely block when the car was running but then when it cooled during more fault finding it allowed flow through until it got hot again..
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A stuck injector will fail an O2 in a few minutes, the bright side is if its an injector, once you fit a new one it will usually burn clean.
I found that several of my local auto parts stores carry the O2 for less than 100 and no matter what box its in its got a Bosche stamp on it... Even the correct connector.
Dave
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My advice? Don't forget to check the cat
Thank You.. The Garage/Seller would be responsible in this case as he gave me 30 days of drive train failure to include the cat as it is an emission item.
A stuck injector will fail an O2 in a few minutes, the bright side is if its an injector, once you fit a new one it will usually burn clean.
Again part of my 30 day warranty..
I will bring all this to the seller's attention..
A Cat is expensive.. with Y pipe $395 just the part..
THANK YOU!
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Universal catalytic converters are an excellent solution. I believe the exhaust is 2.25", easy to find a three-way replacement. OEM is best, of course, but improved units are on the market and are less than $100. There's a thread about it here somewhere.
Getting a shop to weld it in would only be another $40 'round these parts.
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Good Tip! I will keep that in mind Dave.
I am always mindful of how intolerant small engines can be and opt for the OEM whenever it works for my wallet and availability.
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When replacing O2 sensor you must clean thread with tap and do not tighten it too much otherwise you will crack ceramic inside O2 sensor.
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OK.. O2 is back again as an Error Code..
So looking at the System problem as a possible Open Vacuum issue..albeit a small one.
The engine idles Rock Solid and even at 106K miles on the odo.. Revs easily to 6500 rpm without a hiccup...probably higher never tried.
I ordered an OEM Gas Cap.. I know from other experiences that a poor Gas Cap can kick on on the Check Engine Light.
Any thoughts?
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OK.. O2 is back again as an Error Code..
So looking at the System problem as a possible Open Vacuum issue..albeit a small one.
The engine idles Rock Solid and even at 106K miles on the odo.. Revs easily to 6500 rpm without a hiccup...probably higher never tried.
I ordered an OEM Gas Cap.. I know from other experiences that a poor Gas Cap can kick on on the Check Engine Light.
Any thoughts?
Connect it to diagnostic equipment to see is there any wrong indications from sensors. It worth to buy cable and INPA software for that...
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Try a stomp test as well. It's not incredibly helpful, but it'll get you the same codes as the dealer does.
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Any leak in the intake behind the air meter will toss a O2 code.
I'm betting vacume leak or bad injector.. Lean = vacume leak, rich usually a bad injector.
My 1995 had a TINY cracks in the air boot to the throttle body from the air cleaner. Caused everything from a O2 code to accelerated global warming according to the codes it was throwing...
Dave
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I'm betting vacume leak or bad injector.. Lean = vacuum leak, rich usually a bad injector.
I am beginning to think you are Dead on.. I am starting to get Stall type cut outs and hesitations in throttle... this happened with the first O2 sensor but then went away for 300 miles.....
Somehow I am getting a bad Fuel Air mixture..
Perhaps I should look at Gas Filters and Fuel Pump first to make sure the fuel delivery system is OK before the Injectors and Manifold are looked at ??..
Any suggestions or thoughts..
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I'm betting vacume leak or bad injector.. Lean = vacume leak, rich usually a bad injector.
I am thinking along those lines as................................
The Check Engine light finally went Out while Driving..
Now that is replaced with Intermittent surges during acceleration and rough idle.
This symptom will sometimes stop but only to return during the same drive.......
... Threw in some Injector cleaner but I doubt that will have any effect.
One of the main reasons I purchased this car last month was how impressive and responsive the Engine / Drivetrain was... very Disappointing..
.......Any input on similar experiences?
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My posts on this thread are being Held for Review...Don't know Why?
Anyway, I am attempting to post a solution again.
I the leak theory air/vacuum has a lot of merit.
On a whim, I replaced the Old Gas Cap with a New OEM.
Currently, Check Engine Light Out.... and Vehicle runs smoothly.
Matter of fact I thought it ran great before but Now, maybe perception it seems to run better.
Time will tell... Will post in 48 hrs
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I approved the posts, you can edit/delete/merge as you see fit.
Gas cap?!?! Well, it is a critical part of the emissions control system and a frequent CEL cause. There is a good length of vac lines and a purge valve that are also part of that system, but they've been very reliable in my experience.
I'm thinking that alcohol fuels might have something to do with it...but that's just a hazy guesstimahunch. I have absolutely no evidence to back it up.
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Well, Times up! and the Gas cap while it has definitely altered the symptoms the Check engine light is back.
The situation is that now it will go out more frequently but when it does the on board CPU will make Fuel adjustments and the Car will run horrible.. Once the the Check engine light resumes and lights up then the CPU backs away and the car runs very good.
The mechanic that sold me the car is taking it back this week to try a replacement Onboard CPU to see if that is part of the issue.
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Conclusion:
Changing the OBC (On Board Computer) cured all ills.......
Not only does the E36 now run correctly but better then ever
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That's great news. I was going to start encouraging you to take a look at the coil box next, but I'm glad you avoided all that.
The OBC or the DME? The OBC is the little display unit in the center console for date, time, instant MPG, etc. The ECU is the one that runs the motor...Bosch calls their fuel injection computers a "DME" (short for Digital Motor Electronics) or Motronic.
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The ECU is the one that runs the motor...Bosch calls their fuel injection computers a "DME" (short for Digital Motor Electronics) or Motronic.
The ECU........
Now it is on to the Front struts which I ordered at $115 apiece..
And they rear Window defroster which lights at the switch but does not heat the rear Window... Got a 2nd had Heater Control unit to try for that one
So.. I will post these in other threads when/If I have issues....
Thanks to All who lent their experience and expertise to help solve the Oxygen sensor mystery...because it was a mystery to me.. :)