c32used

I have a Memoscan u581 and I was looking at live data and took 2 pictures with hope someone can identify what these may point to...

picture 9394 I presume means secondary air pump but wondering if it means pump itself bad or what it feeds has fault

picture 9395 fuel sys1/2 OL,Fault means what to the C32? I heard those usually applies to Diesel engines which then I understand why a fault

this shows up when I first start car and engine is cold and I let idle while secondary air pump is on engine revs fine but very shortly after secondary air pump turns off my engine runs rough and p0303 shows up...I can clear code but til engine gets warm like 60 degrees the code returns and engine revs rough but if I clear code and engine is 60 degrees and start car again engine revs fine and no code at all. I don't think it has nothing to do with plugs changed last summer and issue there before If I recall right nor wires or coil packs because swapped many times. Compression is at 150 psi on cylinders 1-4 so didn't bother checking 5/6. Fuel rail pressure sits on 60 psi and new fuel filter thus new fuel regulator. CPS new like 2 summers. Cleaned fuel injectors thru fuel injector cleaner added to fuel. Last summer my friend changed my alternator prior to new plugs thus removed secondary air pump and after all was put back a weird grinding like sound was on while secondary air pump on..car stored in my garage so I didn't turn car on til next day or so...the noise was again so I looked further into it. I saw that picture 9400 and 9401 the metal tubing fed by secondary air pump wasn't fully inserted in the rubber hose connected to EGR on passenger side if I recall right but after I pushed it in rest of way that weird grinding like noise was gone and never returned so my conclusion is the pump is fine. Opinions??

c32used

I just put scanner on it waiting for fault to start the fuel sys 1/2 shows OL,driCL,using HO2S but once fault appears it goes to OL,fault. So I guess it has to mean something.

c32used

CL=CLOSED LOOP
OL=OPEN LOOP

I was told o2 not monitored in closed loop that it could be injector

MarcusF

Whoever told you that oxygen sensors are not monitored in closed loop mode is wrong. ECU's are typically in one of three modes: warm-up, open loop, and closed loop. Primary oxygen sensors are only used by the ECU while in closed loop mode. ECUs go into closed loop mode when the coolant temperature sensor indicates the engine is warmed up, AND when the engine is either at idle or at cruise.

c32used

Are you thinking it is an o2 sensor? This is only happening at very first start of day and if I let car idle to after secondary air pump finishes. This shows while engine warms up but once at 60+ degrees car is normal...any particular reason why code shows up mostly p0303?

MarcusF

You posted

Closed loop and open loop are modes that an ECU can be in. O2 is oxygen. It’s actually a diatomic oxygen molecule, but everyone knows it as oxygen. The ECU monitors the oxygen content of the exhaust with oxygen sensors. The ECU only does this when it is in closed loop mode. The ECU will only go into closed loop mode when (1) the engine warmed up and (2) the engine is idling or it is as a steady speed – IE cruise. Therefore, whoever told you that o2 (oxygen )is not monitored (by the ECU) in closed loop (an ECU mode) is incorrect.

I am not diagnosing a problem with your car. I am stating when O2 sensors are monitored with the hope that knowledge assists you in diagnosing the car.

c32used

Maybe I understood it wrong...I'm only looking for best advice that gets me closer to a solution...if I were to drop it off at any mechanic no matter what I've done they are going to do it again simply because it makes absolute sense to incase I missed something...If I had all the extra to spend I'd do it gladly...I been dealing with this for quite a while now and whatever it is doesn't keep me from driving car but eventually I'm going to sell it and my integrity makes me incapable of even thinking of potentially passing problem on. I know it's not plugs they are new and checked and swapped it many times, I swapped coil packs from 1 to 3 then 2 to 3 then 3 to 6 and p0303 comes on like issue is cylinder 3...I monitored alot the fuel rail pressure and runs constantly 60 psi. New fuel filter because regulator in it. Wires swapped also more times then coil packs. Recently did compression test and 150 psi. But no matter what I do same code is fault if I let car idle til after secondary air pump turns off...but if I drive car prior pump shutting off the car is 100% fine no matter how I drive even at WOT...to me I'm leaning on its electrical like a sensor of some kind...which I'm glad it's not engine or worse...whatever it is I've noticed that when engine is dead cold that situation of misfire happens til engine warms up to 60 degrees plus thus no fault occurs. Hard to say it's injector because an injector works or it don't or it's leaking and I've yet to find anything about injectors having intermittent problems that are affected by engine temp. This live data means something but I'm not a mechanic by trade thus have no idea and could only hope someone here knows so I can spend money wisely that's all.

c32used

I think to eliminate o2 sensor as possible fault going to swap front ones aka primary 02 sensors. Are the primary o2 sensors the same thus I can swap them to see if fault code follows? Or do you think swap the rear aka secondary o2 sensors? My C32 has 100k miles on it now and maybe an o2 sensor just going bad...but a swap should identify that.

MarcusF

O2 sensors are normal wear parts. If your's are original, after 14 years and 100K miles, there is a good chance they're done. Having changed my O2 sensors, I think you’ll find that you can’t simply swap them. Each O2 sensor has a unique electrical plug. Those plugs go into a position specific gang plug. So you can’t plug a secondary O2 sensor into the primary O2 sensor position on the gang plug. Can't swap it with the other secondary either. Each sensor will only plug into one spot – it’s own. I suppose you could if you take a dremel to the connector and remove enough plastic to make it fit. Even then, the cables are all different lengths – the wiring may not be long enough to swap positions. If you don’t dremel the connector, leave them plugged in where they are, and somehow can swap the O2 sensors, the ECU may have an issue with that. You see, the ECU compares the oxygen content reported by the primary and secondary sensors on each bank. It checks the before/after oxygen content to determine how well the cat is performing. See the problem? Also, if the primary and the secondary are swapped, and the ECU has no way of knowing they are, the idle may be “interesting”. The ECU looks at the primary O2 sensor reading to determine how rich the car should be at idle and at cruise. I have a feeling that the O2 level is a bit different in the secondary position. Yeah I know, I'm full of good news.

I changed my O2 sensors because I thought they were due. This webpage explains what happens when dead/dying O2 sensors are allowed to give their low voltage readings to the ECU. The short answer is, the car runs rich. Catalytic converter killing rich.

Here some good news, your primary O2 sensors are only about $200. I changed all 4, but unless your secondaries trigger the CE, you can leave them alone.

Lenin

You should swap the two primary sensors first. If the problem is still present, swap the two secondary sensors. Given all the other swapping you have done, you are basically left with the O2 sensors (unlikely but possible), the cats (once the right one warms up, the problem for the very last cyl on the right side goes away) or the injector.

c32used

Thanks for article.....I did notice all plugs I pulled out looked wet signifying rich right? Since I don't have a cell for o2 sensor maybe swap them first and see.

c32used

I'm going to swap first then see if problem persist then injector is next. Would any of you know if a thread exist that shows best way to change or swap them?

c32used

I have a question...when I lookup o2 sensors for Bosch which I believe are OEM I notice they have part number for both front primary o2 sensors

16167 Front(upstream) right
16318 Front(upstream) left

that being so doesn't it mean wiring or something different thus can't swap?

only rear(downstream) shows as 1 part meaning rear can be swapped.

16183 Rear(downstream) either side same

Lenin

You are correct. The primary O2s are different. I did not mean to imply that you should swap and leave it like that. Just see if there is a difference related to the misfire. Just another data point.

Lenin

BTW, if you are going to swap injectors, PM me know and I will send you one. This way if it is a bad injector, you will on be taking the intake and the fuel rail once.

c32used

thanks PM sent