Need help with Multiple Engine Codes and Failed Smog Inspection!!
Thread Starter
Newbie
Joined: Apr 2010
Posts: 9
Likes: 0
1999 ML 430 2001 BMW 330i
Need help with Multiple Engine Codes and Failed Smog Inspection!!
Girlfriends '99 ML430 failed smog. Smog tech gave her two codes PO130, PO150 for failed O2 sensors. I bought the two front O2 sensors but did not install them. When I hooked up my OBII scanner it also showed PO301 (cyl 1 misfire) PO304 (cyl 4 misfire) PO303 (cyl 3 misfire) PO300 (Random Mult misfire) PO135. Since the truck has 155k and I don't know the history, it is conceivable the O2 sensors are bad, but I figured with the other codes the problem was more likely electrical. My scanner also takes "live" readings so I could see the O2 sensors receiving info -- i just didnt know if the flows were where they were supposed to be. Anyway, I replaced all 16 plugs with Bosch IR-Fusion 4s, Replaced the plug wires, air cleaner, and cleaned the MAF. I cleared the codes, but a few days later they were back showing at first the misfires, then a week later the O2 sensor faults. Any ideas what else could be the problem? Coilpacks? Something else? The temp smog passes are costing money and she's freaking out.
Any help is appreciated
Any help is appreciated
MBWorld Fanatic!
Joined: Nov 2001
Posts: 4,260
Likes: 6
From: Philadelphia area
2010 ML550, 2010 E350 4M, 1966 Corvette Convt C2
The other faults you are showing are most likely not an electrical malfunction, they do most likely exist. Were the 02 sensors OEM?? If not that could be your issue. Do not think that the plugs you used are the correct ones called for by MB and that could be your issue. Another possibility is that the wires are bad or you could have damaged them during the plug change which is easy with 155K on the ML. Do your girlfriend a favor and take it to an MB shop, either indy or dealer and let them resolve the issue. Sounds like you do not have the knowledge or correct equipment to go any further than you have. Pick up the bill and she will be pleased.
Thread Starter
Newbie
Joined: Apr 2010
Posts: 9
Likes: 0
1999 ML 430 2001 BMW 330i
Thanks but no thanks Sosh. I think I'll wait for someone to reply with useful information. The plugs are in fact the high end of MB calls for. If you'd read my initial post you would also see that I replaced the wires with genuine, factory plug wires when I replaced the plugs. Since the codes are EXACTLY the same as before the work, logical deduction would show that there is something else going on. O2 sensor malfunction would not cause engine misfires. But spark/ignition problems WOULD cause O2 sensor faults. And since those faults showed up again a week following a code reset, it stands to reason the engine misfires are to blame.
As for "Sounds like you do not have the knowledge or correct equipment to go any further than you have"... is a waste of my time and yours. I've had over 25 years of rebuilding cars ( mechanical, electrical) foreign and domestic. I'm putting aside my BMW for a time being to fix my lady's MB. The great thing about about forums such as these, it's a fantastic resource for people that have experienced similar issues to share those experiences for the sake of others.
Now, anyone else out there that has had a similar issue or relevant useful ideas on what might be going on -- please feel free to drop a line
As for "Sounds like you do not have the knowledge or correct equipment to go any further than you have"... is a waste of my time and yours. I've had over 25 years of rebuilding cars ( mechanical, electrical) foreign and domestic. I'm putting aside my BMW for a time being to fix my lady's MB. The great thing about about forums such as these, it's a fantastic resource for people that have experienced similar issues to share those experiences for the sake of others.
Now, anyone else out there that has had a similar issue or relevant useful ideas on what might be going on -- please feel free to drop a line
MBWorld Fanatic!
Joined: Nov 2001
Posts: 4,260
Likes: 6
From: Philadelphia area
2010 ML550, 2010 E350 4M, 1966 Corvette Convt C2
Well if you have done all the stuff you said and you are certain the the 02 sensors are OK the next thing to look at is the coil packs. Try swapping with a good cylinder and see if the problem follows the pack.
MBWorld Fanatic!
Joined: Sep 2005
Posts: 6,189
Likes: 242
From: Albuquerque
'10 CL550, '12 GL550
It's ususally pretty foolish to take the messages at face value.
Most of the time the problem is the MAF sensor, which then results in improper exhaust mixture downstream that creates the O2 sensor message.
While you're at it, replace the plugs (again) with the correct ones--KMart Bosch don't work.
Most of the time the problem is the MAF sensor, which then results in improper exhaust mixture downstream that creates the O2 sensor message.
While you're at it, replace the plugs (again) with the correct ones--KMart Bosch don't work.
Thread Starter
Newbie
Joined: Apr 2010
Posts: 9
Likes: 0
1999 ML 430 2001 BMW 330i
Thanks for the info, but why all the flamming on the message board?? Bosch IR-4's are most definitely NOT Kmart Bosch, if there is such a thing. Should probably look something up before putting down. IR-4's are the top-of the-line Iridium plug for the ML430 -- they retail over $20 per. I got for about $7 each at the same place I get all my German parts, Autohaus
MBWorld Fanatic!
Joined: Nov 2001
Posts: 4,260
Likes: 6
From: Philadelphia area
2010 ML550, 2010 E350 4M, 1966 Corvette Convt C2
Thanks for the info, but why all the flamming on the message board?? Bosch IR-4's are most definitely NOT Kmart Bosch, if there is such a thing. Should probably look something up before putting down. IR-4's are the top-of the-line Iridium plug for the ML430 -- they retail over $20 per. I got for about $7 each at the same place I get all my German parts, Autohaus
Trending Topics
Super Member
Joined: Apr 2005
Posts: 666
Likes: 4
From: Boston, MA USA
03 E320 -wife's car now; 07 Porsche Boxster S - my toy
Girlfriends '99 ML430 failed smog. Smog tech gave her two codes PO130, PO150 for failed O2 sensors. I bought the two front O2 sensors but did not install them. When I hooked up my OBII scanner it also showed PO301 (cyl 1 misfire) PO304 (cyl 4 misfire) PO303 (cyl 3 misfire) PO300 (Random Mult misfire) PO135. Since the truck has 155k and I don't know the history, it is conceivable the O2 sensors are bad, but I figured with the other codes the problem was more likely electrical. My scanner also takes "live" readings so I could see the O2 sensors receiving info -- i just didnt know if the flows were where they were supposed to be. Anyway, I replaced all 16 plugs with Bosch IR-Fusion 4s, Replaced the plug wires, air cleaner, and cleaned the MAF. I cleared the codes, but a few days later they were back showing at first the misfires, then a week later the O2 sensor faults. Any ideas what else could be the problem? Coilpacks? Something else? The temp smog passes are costing money and she's freaking out.
Any help is appreciated
Any help is appreciated
With what you described, I tend to agree with lkchris' assessment. Try and back-probe the MAF and see how the voltage swings are. Also, don't manually reset the codes and let the PCM does its testing to clear the CEL. Good luck.
Regards,
paul...
Last edited by paulv; Apr 29, 2010 at 01:29 PM. Reason: added info
MB World Stories
The Best of Mercedes & AMG
Manual Mercedes? 6 Times Sindelfingen Let Drivers Have All The Fun
Verdad Gallardo
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Verdad Gallardo
8 Classic Boxy Mercedes Designs That Have Aged Like Fine Wine
Verdad Gallardo
Flawlessly Restored Mercedes 190E Evo II Heads to Auction
Verdad Gallardo
Electric Mercedes C-Class Unveiled: 11 Things You Need to Know
Verdad Gallardo
Mercedes EQS Gets A Major Update: Everything You Need to Know
Verdad Gallardo
5 Underrated Mercedes-Benz Models That Don't Get the Love They Deserve
Verdad Gallardo
Mercedes 300D Has Pushed Well Past 1 Million Miles and It Ain't Stopping
Verdad Gallardo
10 Most Reliable Mercedes-Benz Models You Can Buy Used
Verdad Gallardo
Thread Starter
Newbie
Joined: Apr 2010
Posts: 9
Likes: 0
1999 ML 430 2001 BMW 330i
Thanks paulv
Good info there. I checked the LTFT percentages in freeze-frame and the were within 10% - one was 6.10 and the other 10 i believe. So looking like MAF? I did use the CRC brand of MAF cleaner because everyone seemed to recommend. I had planned on swapping coil-packs between cylinders but thinking now should just replace MAF
MBWorld Fanatic!
Joined: Nov 2001
Posts: 4,260
Likes: 6
From: Philadelphia area
2010 ML550, 2010 E350 4M, 1966 Corvette Convt C2
Good info there. I checked the LTFT percentages in freeze-frame and the were within 10% - one was 6.10 and the other 10 i believe. So looking like MAF? I did use the CRC brand of MAF cleaner because everyone seemed to recommend. I had planned on swapping coil-packs between cylinders but thinking now should just replace MAF
Super Member
Joined: Apr 2005
Posts: 666
Likes: 4
From: Boston, MA USA
03 E320 -wife's car now; 07 Porsche Boxster S - my toy
Good LTFT numbers
Good info there. I checked the LTFT percentages in freeze-frame and the were within 10% - one was 6.10 and the other 10 i believe. So looking like MAF? I did use the CRC brand of MAF cleaner because everyone seemed to recommend. I had planned on swapping coil-packs between cylinders but thinking now should just replace MAF
A big problem is that if you don't have any OBD2 diags data for the car, you won't know what all the conditions are required before you test a component, and many of these components depend on another one (i.e., crankshaft position with camshaft position sensors). Good luck.
Regards,
paul...
