Graphs of O2 and MAF
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Pro Wrench
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From: SE PA
Graphs of O2 and MAF
Last night I drove through a torrential downpour for a good 1/2hr over about 10 miles. Some of the heaviest rain I've ever driven through for that length of time, it was relentless. Half of it was on the highway at 40-50mph so there was quite a bit of water thrashing about. I was glad to be in the Disco. Anyway, I parked the truck for about 3 hours and then headed for home in relatively dry weather. I went about 3 miles and filled the tank, then another 5 miles on the highway and everything was fine. I exited onto a country road and when climbing a pretty steep incline I felt the truck start to shudder as I neared the top. CEL started blinking and I couldn't tell if I was in limp mode or just misfiring, there was no power but the shuddering was really bad so this convinced me it was missing badly.
The Ultra Blue beeped a few times and said there were three codes. I nursed it a bit to a gas station but couldn't get the codes out of the Ultra Blue. I've never used it for anything other than a high temp alarm so am totally unfamiliar with its operation otherwise. I plugged in the Foxwell 510, which I'm also no pro at, it also said three codes but then it said the MIL was off and I couldn't find the codes there either. I may have been impatient ... however restarting the truck a few times did not help with the CEL (not that I thought it would). I contemplated calling AAA but decided to drive a little further, CEL did go solid though the truck drove pretty normally. The Ultra Blue beeped again and said 5 codes but not feeling anything wrong I drove on. Pretty quickly the power was back to normal and shuddering was completely gone. Another 10 miles to home and the truck drove as if nothing had ever happened.
When I got home I was able to get the codes out of the Ultra Blue, typical for a misfire situation, P0301, P0303 and P1300, but also P0103 (MAF) and P0003 (Fuel Volume Control ?? also MAF??). I cleared them last night and drove the truck twice today, about 12 miles total and it was completely normal. After reading other posts I plugged in my ELM and graphed my MAF (I think) and my O2 sensors; AFAIK they look pretty normal. I'm thinking (hoping) the missing was a fluke related to the heavy rain but thought I would post the graphs here for any input from those more familiar. It does seem odd that it would be so long after the rain event to throw codes.
First graph is Bank 1 Front and Rear O2. I have no idea of the mileage of these sensors but they look good to me.
Next is Bank 2 F / R O2 sensors, same condition
And finally a graph comparing the MAF AirFlow Rate to Engine torque (scaled to 10% for a better visual). I'm not sure if this is how you measure the MAF, I didn't see a voltage anywhere so I used lbs/min to see the correlation to engine's torque output. I think the value of this info is debatable since they're always going to be closely related but I couldn't see how to get any another MAF data out of the ELM. If nothing else it does show the MAF reading varying pretty well. Too much or too little air would rob torque so maybe this is more valuable than it seems on the surface. Any advice on how to better judge the health of the MAF would be appreciated. Finally, no need to be jealous over 380 ft/lbs of torque, the iPad wasn't mounted squarely so cornering forces were interpreted as acceleration in some instances. I wish I had that much power!!
I did check the footwell below the ECU and the carpet was perfectly dry, as was the engine bay when I got home. Any ideas of where to go next, beyond doing nothing and just driving it? I have a spare MAF in the boot but don't really want to swap it out without knowing more about the situation. Same for coil pack, wires, CPS and CKPS, but those aren't much fun to swap on the side of the road.
The Ultra Blue beeped a few times and said there were three codes. I nursed it a bit to a gas station but couldn't get the codes out of the Ultra Blue. I've never used it for anything other than a high temp alarm so am totally unfamiliar with its operation otherwise. I plugged in the Foxwell 510, which I'm also no pro at, it also said three codes but then it said the MIL was off and I couldn't find the codes there either. I may have been impatient ... however restarting the truck a few times did not help with the CEL (not that I thought it would). I contemplated calling AAA but decided to drive a little further, CEL did go solid though the truck drove pretty normally. The Ultra Blue beeped again and said 5 codes but not feeling anything wrong I drove on. Pretty quickly the power was back to normal and shuddering was completely gone. Another 10 miles to home and the truck drove as if nothing had ever happened.
When I got home I was able to get the codes out of the Ultra Blue, typical for a misfire situation, P0301, P0303 and P1300, but also P0103 (MAF) and P0003 (Fuel Volume Control ?? also MAF??). I cleared them last night and drove the truck twice today, about 12 miles total and it was completely normal. After reading other posts I plugged in my ELM and graphed my MAF (I think) and my O2 sensors; AFAIK they look pretty normal. I'm thinking (hoping) the missing was a fluke related to the heavy rain but thought I would post the graphs here for any input from those more familiar. It does seem odd that it would be so long after the rain event to throw codes.
First graph is Bank 1 Front and Rear O2. I have no idea of the mileage of these sensors but they look good to me.
Next is Bank 2 F / R O2 sensors, same condition
And finally a graph comparing the MAF AirFlow Rate to Engine torque (scaled to 10% for a better visual). I'm not sure if this is how you measure the MAF, I didn't see a voltage anywhere so I used lbs/min to see the correlation to engine's torque output. I think the value of this info is debatable since they're always going to be closely related but I couldn't see how to get any another MAF data out of the ELM. If nothing else it does show the MAF reading varying pretty well. Too much or too little air would rob torque so maybe this is more valuable than it seems on the surface. Any advice on how to better judge the health of the MAF would be appreciated. Finally, no need to be jealous over 380 ft/lbs of torque, the iPad wasn't mounted squarely so cornering forces were interpreted as acceleration in some instances. I wish I had that much power!!
I did check the footwell below the ECU and the carpet was perfectly dry, as was the engine bay when I got home. Any ideas of where to go next, beyond doing nothing and just driving it? I have a spare MAF in the boot but don't really want to swap it out without knowing more about the situation. Same for coil pack, wires, CPS and CKPS, but those aren't much fun to swap on the side of the road.
Maf's are affected by water. Seems like it is back to normal now. Everything looks normal as far as charts. I would recommend carrying a spare MAF, but in a pinch you can just disconnect it. The ECU reverts to RPM and TPS sensor when it has total MAF failure i.e. disconnected.
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