2002 B3000 P0172 issue resolved
#1
10-02-2015, 08:31 AM
2002 B3000 P0172 issue resolved
Hello everyone,
I have seen threads on here about various issues these Vulcan engines can have. My issue started 3 years ago, when I noticed rough idle and a little hesitation when the engine was under load at low RPM. The engine would ping a lot, so I had to switch to 89 and 92 octane fuel. Sometimes, when it would idle rough, it would almost stall, but not quite, and the CEL would light up and throw P0172 (rich bank 1). I also got a general misfire code once in a while.
I replaced and cleaned all the usual things. I replaced an injector on cylinder 2 (it's been so long now I don't remember why I chose cyl 2). No good. I replaced the coil, replaced all plugs, and replaced all ignition wires. No good. I then cleaned the MAF sensor, and cleaned the IAC valve. Still no good. I took the wires back and got new ones. Still no good. I took the coil back and got a new one. Still no good. I bought a new MAF sensor, thinking that had to be it. No good. I bought a new IAC, thinking that had to be it. Still no good. I figured it had to be a bad O2 sensor telling the engine it was rich when it wasn't (since it was pinging). Still no good.
Finally, I borrowed a proper scan tool that gives real time data. Duh. The numbers were fairly normal except for long term fuel trim bank 1.
ABSLT TPS % 18.4
ENG SPEED RPM 701
MAF FLOW 4.09
COOLANT F 190
ST FTRM1 % -4.9
LT FTRM1 % -27.2
ST FTRM2 % .8
LT FTRM2 % -10.4
Obviously, the data above was at idle (RPM 701), so I drove it around. While driving, the LT FTRM1 would go down to about -18%, but still very high.
That ruled out coolant sensor being bad, since it read a nice 190 degrees. Good to know. That also ruled out the TPS, since it was consistently the same percentage at idle. Had to be an injector.
I read about how the Vulcan trims fuel in rich conditions. It can't limit fuel to a specific injector. Instead, it limits the open time of the entire bank of injectors, in this case cylinders 1,2 and 3. Ah ha! So, if there is an injector stuck open, it would overall cause a rich condition at the O2 sensor. The PCM would want to limit the open time of all that bank's injectors. That means one cylinder would be running on the rich side (stuck open injector), but the other two would be running LEAN (pinging!).
I pulled spark plugs, and sure enough, the plugs on cylinders 1 and 2 were white (lean), and cylinder 3 indicated rich.
I replaced cylinder 3 injector, and now it's fixed. No pinging. Relatively smooth idle for a Vulcan. Smooth under load at low RPM.
This story has a lot of "shoulda" moments, I know. I shoulda done this and shoulda done that. Moral of the story: Don't guess and start replacing parts. Buy, beg, borrow, or steal a proper scan tool and learn what the numbers mean.
I have seen threads on here about various issues these Vulcan engines can have. My issue started 3 years ago, when I noticed rough idle and a little hesitation when the engine was under load at low RPM. The engine would ping a lot, so I had to switch to 89 and 92 octane fuel. Sometimes, when it would idle rough, it would almost stall, but not quite, and the CEL would light up and throw P0172 (rich bank 1). I also got a general misfire code once in a while.
I replaced and cleaned all the usual things. I replaced an injector on cylinder 2 (it's been so long now I don't remember why I chose cyl 2). No good. I replaced the coil, replaced all plugs, and replaced all ignition wires. No good. I then cleaned the MAF sensor, and cleaned the IAC valve. Still no good. I took the wires back and got new ones. Still no good. I took the coil back and got a new one. Still no good. I bought a new MAF sensor, thinking that had to be it. No good. I bought a new IAC, thinking that had to be it. Still no good. I figured it had to be a bad O2 sensor telling the engine it was rich when it wasn't (since it was pinging). Still no good.
Finally, I borrowed a proper scan tool that gives real time data. Duh. The numbers were fairly normal except for long term fuel trim bank 1.
ABSLT TPS % 18.4
ENG SPEED RPM 701
MAF FLOW 4.09
COOLANT F 190
ST FTRM1 % -4.9
LT FTRM1 % -27.2
ST FTRM2 % .8
LT FTRM2 % -10.4
Obviously, the data above was at idle (RPM 701), so I drove it around. While driving, the LT FTRM1 would go down to about -18%, but still very high.
That ruled out coolant sensor being bad, since it read a nice 190 degrees. Good to know. That also ruled out the TPS, since it was consistently the same percentage at idle. Had to be an injector.
I read about how the Vulcan trims fuel in rich conditions. It can't limit fuel to a specific injector. Instead, it limits the open time of the entire bank of injectors, in this case cylinders 1,2 and 3. Ah ha! So, if there is an injector stuck open, it would overall cause a rich condition at the O2 sensor. The PCM would want to limit the open time of all that bank's injectors. That means one cylinder would be running on the rich side (stuck open injector), but the other two would be running LEAN (pinging!).
I pulled spark plugs, and sure enough, the plugs on cylinders 1 and 2 were white (lean), and cylinder 3 indicated rich.
I replaced cylinder 3 injector, and now it's fixed. No pinging. Relatively smooth idle for a Vulcan. Smooth under load at low RPM.
This story has a lot of "shoulda" moments, I know. I shoulda done this and shoulda done that. Moral of the story: Don't guess and start replacing parts. Buy, beg, borrow, or steal a proper scan tool and learn what the numbers mean.
#2
10-02-2015, 01:12 PM
New User, but you joined in 2008, anyway welcome back to FTE.
^+1 on coming by & using a scantool on a trouble shoot. Good spark plug read, find, fix & feedback.
The inexpensive ELM scantool, running FORScan, or the like software to the viewing device of our choice, is a good investment for our electronic tool box. It would have been a good choice for your tranny problem trouble shoot, as it can scan & or monitor the tranny computer/controller too.
^+1 on coming by & using a scantool on a trouble shoot. Good spark plug read, find, fix & feedback.
The inexpensive ELM scantool, running FORScan, or the like software to the viewing device of our choice, is a good investment for our electronic tool box. It would have been a good choice for your tranny problem trouble shoot, as it can scan & or monitor the tranny computer/controller too.
#3
05-11-2017, 06:36 AM
MAF sensor, and cleaned the IAC valve. Still no good. I took the wires back and got new ones. Still no good. I took the coil back and got a new one. Still no good. I bought a new MAF sensor, thinking that had to be it. No good. I bought a new IAC, thinking that had to be it. Still no good. I figured it had to be a bad O2 sensor telling the engine it was rich when it wasn't (since it was pinging). Still no good.
Finally, I borrowed a proper scan tool that gives real time data. Duh. The numbers were fairly normal except for long term fuel trim bank 1.
ABSLT TPS % 18.4
ENG SPE
Finally, I borrowed a proper scan tool that gives real time data. Duh. The numbers were fairly normal except for long term fuel trim bank 1.
ABSLT TPS % 18.4
ENG SPE
#4
05-11-2017, 06:40 AM
#5
05-11-2017, 07:09 AM
#6
05-11-2017, 08:31 AM
#7
05-11-2017, 06:30 PM
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