MazB4000
New Member
- Joined
- Dec 5, 2012
- Messages
- 1
- Vehicle Year
- 1994
- Transmission
- Automatic
Hey guys, first time posting on here!
First off, sorry this post is so long! But I figured someone might learn from some of the things I have gone through here.. and I promise there IS a question at the end!!
Here's the scoop..
A few weeks ago I bought a 94 Mazda B4000 (auto trans) with 150,000mi to use as a daily driver/commuter vehicle.
When I test drove it, the CEL was on. It idled ok/rough/ok/rough -kind of going back and forth every 30sec or so. It shifted and drove pretty ok on the test drive but smelled very very rich and had little power (but figured it was just whimpy.. compared to my 5.7 Charger..). The truck would also hesitate and shudder when coming out of a complete stop, but would kick out of it when I gave more throttle. Engine oil was black not milky so I felt pretty confident that water wasn't anywhere it shouldn't be (however, it looked like the guy had put 6qts into the 5qt system
). Despite all of these issues, the price seemed too good to pass up since I was only planning on piling miles on it anyway, so I bought it.
When I got it home, I ran the KOEO/MEM/KOER tests using the jumper wire method. My results: KOEO:335 MEM:157,336,337 KOER:998,157
Changed plugs and wires (plugs were black/oily and one wire had a split in it). I checked vacuum lines (re-hooked one that had come undone, and took a hose clamp off one that connected intake man to EGR valve sol.). I found no other vac leaks after that. I cleaned the MAF and throttle body (butterfly valve was covered in nasty crap..). I ran half a can of Seafoam through it (slurped up through vac line), and it ran 10x's better after that! But still hesitated and shuddered accelerating out of a stop and still gassy smelling. I cleared all codes (that it would allow), and drove it about 20mins. CEL was on the whole time.
Re-checked codes with these results: KOEO:114,335 MEM:157,336,337 KOER: didn't check these..
I replaced the EGR sensor hoping to get rid of the 335 from KOEO. I cleared codes again and rechecked. Results: KOEO:114 MEM:157,336,337 KOER: didnt check these..
I read a bunch on the forums about 114, 998, & 157 codes and decided to try changing MAF sensor. After putting a re-man MAF in I cleared codes, drove around the block, and rechecked. Results: KOEO:111 MEM:111 KOER:111
YESSS!!! Fixed!! Or, so I thought...
The next day I drove to work and back (70mi round trip) and the CEL came on after about 15mins of driving. It would go on/off/on/off the whole way to work. It still ran good at 60mph but would idle rough at lights. The story was the same on the way home from work. Also, the CEL would not come on until the truck got up to normal operating temp. I got home and re-ran the codes. Results: KOEO:111 MEM:172,173 KOER:172,536 (I think the 536 is due to me being a dummy and not pressing the brake when I should have..)
So after looking up 172/173 codes it looks like it could be just a bad Bank 1 O2 sensor. Given that this is the first time these codes are showing up, I am wondering if there might be something more going on other than an O2 sensor..
Question:
Given all of the crap that I have replaced already, what else might be triggering this 172 code to pop up?
Thanks for hanging in there reading all of that!!!
First off, sorry this post is so long! But I figured someone might learn from some of the things I have gone through here.. and I promise there IS a question at the end!!
Here's the scoop..
A few weeks ago I bought a 94 Mazda B4000 (auto trans) with 150,000mi to use as a daily driver/commuter vehicle.
When I test drove it, the CEL was on. It idled ok/rough/ok/rough -kind of going back and forth every 30sec or so. It shifted and drove pretty ok on the test drive but smelled very very rich and had little power (but figured it was just whimpy.. compared to my 5.7 Charger..). The truck would also hesitate and shudder when coming out of a complete stop, but would kick out of it when I gave more throttle. Engine oil was black not milky so I felt pretty confident that water wasn't anywhere it shouldn't be (however, it looked like the guy had put 6qts into the 5qt system

When I got it home, I ran the KOEO/MEM/KOER tests using the jumper wire method. My results: KOEO:335 MEM:157,336,337 KOER:998,157
Changed plugs and wires (plugs were black/oily and one wire had a split in it). I checked vacuum lines (re-hooked one that had come undone, and took a hose clamp off one that connected intake man to EGR valve sol.). I found no other vac leaks after that. I cleaned the MAF and throttle body (butterfly valve was covered in nasty crap..). I ran half a can of Seafoam through it (slurped up through vac line), and it ran 10x's better after that! But still hesitated and shuddered accelerating out of a stop and still gassy smelling. I cleared all codes (that it would allow), and drove it about 20mins. CEL was on the whole time.
Re-checked codes with these results: KOEO:114,335 MEM:157,336,337 KOER: didn't check these..
I replaced the EGR sensor hoping to get rid of the 335 from KOEO. I cleared codes again and rechecked. Results: KOEO:114 MEM:157,336,337 KOER: didnt check these..
I read a bunch on the forums about 114, 998, & 157 codes and decided to try changing MAF sensor. After putting a re-man MAF in I cleared codes, drove around the block, and rechecked. Results: KOEO:111 MEM:111 KOER:111
YESSS!!! Fixed!! Or, so I thought...
The next day I drove to work and back (70mi round trip) and the CEL came on after about 15mins of driving. It would go on/off/on/off the whole way to work. It still ran good at 60mph but would idle rough at lights. The story was the same on the way home from work. Also, the CEL would not come on until the truck got up to normal operating temp. I got home and re-ran the codes. Results: KOEO:111 MEM:172,173 KOER:172,536 (I think the 536 is due to me being a dummy and not pressing the brake when I should have..)
So after looking up 172/173 codes it looks like it could be just a bad Bank 1 O2 sensor. Given that this is the first time these codes are showing up, I am wondering if there might be something more going on other than an O2 sensor..
Question:
Given all of the crap that I have replaced already, what else might be triggering this 172 code to pop up?
Thanks for hanging in there reading all of that!!!
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