Sputtering under load
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Sputtering under load
Hello,
I have a similar problem as Kaotic.
My 87 2.9l runs just fine except when I try and accelerate up a hill. Then it sputters but doesn't die. If I floor it then the sputtering stops. Once the sputter starts it will still sputter no matter what speed I go. Grey/Black smoke starts coming out of the pipe and really strong gas smell.
But if I turn off the truck for 30secs and restart the truck the sputtering goes away until the next time I try and accelerate up a hill.
Things Ive done;
1. Pulled the codes. None
2. Replaced the fuel filter still sputtering.
3. Checked the fuel pressure it was low at 34psi. replaced the fuel pump now at 45psi but still sputtering.
4. Replaced plugs and wires (friend suggestion) still sputtering
5. Replaced Ignition Module. Still sputtering.
I was thinking the O2 sensor or MAP sensor. But without a Code not sure what do next.
Thanks
Ron
I have a similar problem as Kaotic.
My 87 2.9l runs just fine except when I try and accelerate up a hill. Then it sputters but doesn't die. If I floor it then the sputtering stops. Once the sputter starts it will still sputter no matter what speed I go. Grey/Black smoke starts coming out of the pipe and really strong gas smell.
But if I turn off the truck for 30secs and restart the truck the sputtering goes away until the next time I try and accelerate up a hill.
Things Ive done;
1. Pulled the codes. None
2. Replaced the fuel filter still sputtering.
3. Checked the fuel pressure it was low at 34psi. replaced the fuel pump now at 45psi but still sputtering.
4. Replaced plugs and wires (friend suggestion) still sputtering
5. Replaced Ignition Module. Still sputtering.
I was thinking the O2 sensor or MAP sensor. But without a Code not sure what do next.
Thanks
Ron
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From: SW Va
Acting out TPS sensor maybe, so pull it's electrical connector & check it's resistance with an analog meter. It's resistance reading should be smooth & steady as you slowly go from closed to full throttle.
If the resistance chacks out, measure it's 5volt ref voltage at the connector at KOEO.
After the repairs, have you pulled the battery B- cable to wipe the computers memory, so it can begin to build new fuel trim tables????
I like the fuel pump thought, seeing as how your system uses two pumps, a low & high pressure fuel pump!!!!
Also pull the fuel pressure regulators vacuum line on the fuel rail & check it for fuel wetness inside, if so suspect the regulators diaphragm is leaking, if so replace the FPR.
More thoughts for consideration.
If the resistance chacks out, measure it's 5volt ref voltage at the connector at KOEO.
After the repairs, have you pulled the battery B- cable to wipe the computers memory, so it can begin to build new fuel trim tables????
I like the fuel pump thought, seeing as how your system uses two pumps, a low & high pressure fuel pump!!!!
Also pull the fuel pressure regulators vacuum line on the fuel rail & check it for fuel wetness inside, if so suspect the regulators diaphragm is leaking, if so replace the FPR.
More thoughts for consideration.
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The Filter sock was replaced when I did the Fuel pump.
I did pull the battery cable and reset the computer every time.
I just did the TPS checks. It was liniar the whole way. 0.6k to 3.9k.
Thanks for replies.
I did pull the battery cable and reset the computer every time.
I just did the TPS checks. It was liniar the whole way. 0.6k to 3.9k.
Thanks for replies.
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Fuel leak perhaps? How's your mileage? Have you tried just visually inspectine the lines, both supply and return? Just an idea from the guy that seems to constantly look right past things like that.
EDIT: Ok, scratch that... More I think about this, the more what I just said doesn't make sense. But if you look at it from the other side, maybe a leak on the air side of things. air box, intake plumbing, MAF, etc..
EDIT: Ok, scratch that... More I think about this, the more what I just said doesn't make sense. But if you look at it from the other side, maybe a leak on the air side of things. air box, intake plumbing, MAF, etc..
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From: SW Va
OK good, so it seems that the TPS is ok, so have you pulled the FPR vacuum line to see if it has fuel in it, or rechecked the fuel pressure after installing the new pump???? BTW which pump did you install, the low pressure one in the tank, or the high pressure one???
Have you cleaned the MAF sensor if it has one, or checked the MAP sensor if it has that????
The rough running & black smoke suggest a fuel trim problem of some sort, that seems to be associated with a throttle up command, so thats why I asked the TPS question. So is the TPS reference 5 volts present at it's connector at KOEO????
Have you cleaned the MAF sensor if it has one, or checked the MAP sensor if it has that????
The rough running & black smoke suggest a fuel trim problem of some sort, that seems to be associated with a throttle up command, so thats why I asked the TPS question. So is the TPS reference 5 volts present at it's connector at KOEO????
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The reference voltage of the TPS is 5.4v.
Im a noob but I cant find the MAP/MAF sensor. I have the chiltons manual and it really is crappy.
Also what hose is the FPR vacume line?
Thanks
Ron
Im a noob but I cant find the MAP/MAF sensor. I have the chiltons manual and it really is crappy.
Also what hose is the FPR vacume line?
Thanks
Ron
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From: SW Va
Ok, 5.4 volts to the TPS, so thats good & the TPS resistance checked out good, no unsteady, or open resistance readings anywhere between cloed & WOT, right????
Well if it has the MAP sensor, it'll be back on the firewall, if it has a MAF sensor, it'll be on the intake air tube just before the throttle body.
The FPR is located on the fuel rail & only has one vacuum line running to it.
Well if it has the MAP sensor, it'll be back on the firewall, if it has a MAF sensor, it'll be on the intake air tube just before the throttle body.
The FPR is located on the fuel rail & only has one vacuum line running to it.
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Think I found it.
After checking the TPS voltage and seeing the connector dirty I decided to clean all the connectors. Cleaned all the ones on the engine and as I went under to clean the O2 sensor I ran out of cleaner.
I took the truck to get more cleaner and noticed it was running a LOT better than it has in years. So I took up and down hills. There are 12miles of hills near my house that kills the truck every time.
After going back and forth 3 times 72miles of hills, I thought to check the O2 sensor. Yes I left it unplugged.
So I plugged it back in and the very first hill, the engine started sputtering again.
I have to go to work now. But Ill get a new O2 sensor tomorrow and see what happens.
Thanks
Ron
After checking the TPS voltage and seeing the connector dirty I decided to clean all the connectors. Cleaned all the ones on the engine and as I went under to clean the O2 sensor I ran out of cleaner.
I took the truck to get more cleaner and noticed it was running a LOT better than it has in years. So I took up and down hills. There are 12miles of hills near my house that kills the truck every time.
After going back and forth 3 times 72miles of hills, I thought to check the O2 sensor. Yes I left it unplugged.
So I plugged it back in and the very first hill, the engine started sputtering again.
I have to go to work now. But Ill get a new O2 sensor tomorrow and see what happens.
Thanks
Ron
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From: SW Va
Sounds like your on to something. If you have over 100K miles on these O2 sensors, or O2 sensor switching trouble codes, that suggest they are lazy, then they sure would belong on your suspect list, as they provide feedback to the computer thats used to adjust the fuel injectors squirt time, to control fuel trim.
So all that sorta fits what you say you see in the exhaust when it's acting out.
Will be interesting to hear how it goes.
So all that sorta fits what you say you see in the exhaust when it's acting out.
Will be interesting to hear how it goes.
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