ok so a couple weeks ago i posted that after not driving the saturn for a few days it ran rough on initial start for a few seconds. well lately its been doing fine driven everyday. well on the way home a few minutes ago i was doing about 40mph in 5th not accelerating or slowing just a consistent speed. then all the sudden the engine shook for only a couple seconds and it was fine again.it didnt feel like a sloppy sputtering shake it was a very controlled consistent shake. no engine lights and after that it was fine. it didnt seem like it lost any rpm when it did it or anything just shook and then was smooth...... it felt kind of like if your going up a hill to slow in too high a gear and you floor it and the car goes but you kinda get that chug chug feeling instead of smooth power. it felt like that but more noticeable. i have been getting about 34mpg average. idles smoothe revs up smooth starts right up. its kinda throwing me for a loop....any ideas or things/ways to check certain things would be great. thanks guys.
what gives?
- Thread starter Dakota1820
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Sounds like bad gas, really. It happens sometimes.
It does NOT mean you need to immediately go out and buy premium gas, start complaining about ethanol, and insist on Top Tier gas with a fistful of additives though...
I've had that happen with a half empty tank of fuel getting condensation inside as the temperature cooled off at night, which caused water in the fuel, which caused the occasional odd hiccup...
It does NOT mean you need to immediately go out and buy premium gas, start complaining about ethanol, and insist on Top Tier gas with a fistful of additives though...
I've had that happen with a half empty tank of fuel getting condensation inside as the temperature cooled off at night, which caused water in the fuel, which caused the occasional odd hiccup...
What's wrong with top tier?? And ethanol is a major problem. Just doesn't fit his case that's all.
Since it's a stick your inertia kept the engine RPMs the same.
I'm thinking either bad coil or a bad crank pickup.
I went through this on my wife's 2000 SL1, it was rough just occasionally. People will say the crank pickup is binary; it either works or it doesn't. But they're cheap. Right on top of the starter, feel for it blindly, one 10mm headed bolt.
I'm thinking either bad coil or a bad crank pickup.
I went through this on my wife's 2000 SL1, it was rough just occasionally. People will say the crank pickup is binary; it either works or it doesn't. But they're cheap. Right on top of the starter, feel for it blindly, one 10mm headed bolt.
Maybe this can be helpful. Over the weekend I had P0300, P0301,2,3,4 CEL. Random misfires. Shuddering during acceleration, rough idle etc. Randomly then goes away. Investigation showed plugs were "ok" but the piston top and valves of #3 and 4 cylinders were hard baked with oil. Known valve seal problem which will be fixed shortly. I jury rigged a spray nozzle to get some TB cleaner down there. Sprayd the entire combustion chamber a few times. Closed it up, started it. Struggled for a while, then was quite a bit better but still a little rough. Gave it 3 bottles of techron concentrate for 3 tanks. Changed the oil. Acceptable idle and performance again. No return of the CEL in a week.
So I guess in addition to the plugs being clean there needs to be a fairly clean combustion chamber to get a proper spark. For now on I will be adding 2X bottles of techron concentrate at the end of every OCI to maintain.
So I guess in addition to the plugs being clean there needs to be a fairly clean combustion chamber to get a proper spark. For now on I will be adding 2X bottles of techron concentrate at the end of every OCI to maintain.
yea but in 500 miles its done it twice and only for a couple seconds each time. its really strange. i wish the cel would have came on at least then i would have an idea where to look.
here is what i got from my scanner. i just bought it and love it lol.
abslt tps 0.0
eng speed 849
calc load 2.04
map "hg" 8.6
coolant 203f
iat 93f
ign adv 15.0
st ftrm1 0.8
lt ftrm1 -19.5
veh speed 0
fuel system 1 clsd
fuel sys 2 n/a
02s11(v) 0.275
st ftrm11 1.6
02s12(v) 0.330
obd2 stat ca
i understand some of it but some of it i do not anyone want to chime in? also i noticed when my cooling fan kicked on my gauge went from 221 to 226 degrees and the needle did go up as well as the scanners reading. not sure why it does that but other than that nothing out of the ordinary when doing the checks. unless something above looks off and i am not aware of it.
abslt tps 0.0
eng speed 849
calc load 2.04
map "hg" 8.6
coolant 203f
iat 93f
ign adv 15.0
st ftrm1 0.8
lt ftrm1 -19.5
veh speed 0
fuel system 1 clsd
fuel sys 2 n/a
02s11(v) 0.275
st ftrm11 1.6
02s12(v) 0.330
obd2 stat ca
i understand some of it but some of it i do not anyone want to chime in? also i noticed when my cooling fan kicked on my gauge went from 221 to 226 degrees and the needle did go up as well as the scanners reading. not sure why it does that but other than that nothing out of the ordinary when doing the checks. unless something above looks off and i am not aware of it.
Originally Posted By: chevyboy14
here is what i got from my scanner. i just bought it and love it lol.
abslt tps 0.0
eng speed 849
calc load 2.04
map "hg" 8.6
coolant 203f
iat 93f
ign adv 15.0
st ftrm1 0.8
lt ftrm1 -19.5
veh speed 0
fuel system 1 clsd
fuel sys 2 n/a
02s11(v) 0.275
st ftrm11 1.6
02s12(v) 0.330
obd2 stat ca
i understand some of it but some of it i do not anyone want to chime in? also i noticed when my cooling fan kicked on my gauge went from 221 to 226 degrees and the needle did go up as well as the scanners reading. not sure why it does that but other than that nothing out of the ordinary when doing the checks. unless something above looks off and i am not aware of it.
I don't know what all the fuel trim stuff means either, but your coolant temp seems a little high too me. It could just be your aluminum head engine, or FWD layout, but I'd be worried at 226*F in my truck which has an all cast iron engine. Mine has never been above 209*F. Hopefully it's just the different engine material.
Scan Gauges are great tools and give you all kinds of info you wouldn't get otherwise. Enjoy it!
here is what i got from my scanner. i just bought it and love it lol.
abslt tps 0.0
eng speed 849
calc load 2.04
map "hg" 8.6
coolant 203f
iat 93f
ign adv 15.0
st ftrm1 0.8
lt ftrm1 -19.5
veh speed 0
fuel system 1 clsd
fuel sys 2 n/a
02s11(v) 0.275
st ftrm11 1.6
02s12(v) 0.330
obd2 stat ca
i understand some of it but some of it i do not anyone want to chime in? also i noticed when my cooling fan kicked on my gauge went from 221 to 226 degrees and the needle did go up as well as the scanners reading. not sure why it does that but other than that nothing out of the ordinary when doing the checks. unless something above looks off and i am not aware of it.
I don't know what all the fuel trim stuff means either, but your coolant temp seems a little high too me. It could just be your aluminum head engine, or FWD layout, but I'd be worried at 226*F in my truck which has an all cast iron engine. Mine has never been above 209*F. Hopefully it's just the different engine material.
Scan Gauges are great tools and give you all kinds of info you wouldn't get otherwise. Enjoy it!
Since it happens under a load such as 5th gear at 40mph...I am gonna go with plugs/wires. That us usually where they will show up when just starting to wear...they will behave fine under WOT at this point. Coil is also suspect. I have witnessed this several times and it is cheap to do.
The comment about the temp being high is not valid. Today's cars will run in the 210-225 range by design intent for emmissions. Nothing wrong with the 203 yours says.
The fuel trim at -19 is a little odd..could be taking fuel away due to small misfires you cannot feel yet.
The comment about the temp being high is not valid. Today's cars will run in the 210-225 range by design intent for emmissions. Nothing wrong with the 203 yours says.
The fuel trim at -19 is a little odd..could be taking fuel away due to small misfires you cannot feel yet.
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40mph in 5th gear? Lugging the engine? What were the revs at?
Originally Posted By: GMBoy
Since it happens under a load such as 5th gear at 40mph...I am gonna go with plugs/wires. That us usually where they will show up when just starting to wear...they will behave fine under WOT at this point. Coil is also suspect. I have witnessed this several times and it is cheap to do.
The comment about the temp being high is not valid. Today's cars will run in the 210-225 range by design intent for emmissions. Nothing wrong with the 203 yours says.
The fuel trim at -19 is a little odd..could be taking fuel away due to small misfires you cannot feel yet.
what does the ltft and stft mean? i know nothing about that stuff
Since it happens under a load such as 5th gear at 40mph...I am gonna go with plugs/wires. That us usually where they will show up when just starting to wear...they will behave fine under WOT at this point. Coil is also suspect. I have witnessed this several times and it is cheap to do.
The comment about the temp being high is not valid. Today's cars will run in the 210-225 range by design intent for emmissions. Nothing wrong with the 203 yours says.
The fuel trim at -19 is a little odd..could be taking fuel away due to small misfires you cannot feel yet.
what does the ltft and stft mean? i know nothing about that stuff
Long term fuel trim, short term fuel trim.
Long term fuel trim takes long term averages to account for stuff like fuel pump pressure variations as the system wears out or filters limit flow.
Short term fuel trim takes averages to account for minor things effecting fuel delivery volume, like temperature, so that injector pulses are appropriate for all environmental factors.
Doesn't sound like a fuel pressure problem because that normally comes up under hard acceleration as a lack of power, not intermittent issues, unless the fuel pump is dying.
And if its dying you'll get a lot more of a problem then an odd rumble every 500 miles. Your LTFT, however, does indicate that the engine is compensating and leaning (trimming back) every injector shot. Usually beyond 25 points you'll get a code (positive or negative).
Its very possible a bad O2 sensor is causing a false rich condition and the engine is pulling fuel to compensate, but I seriously feel you just have bad fuel. I wouldn't throw parts at this just yet to try to fix it since its rather intermittent.
Long term fuel trim takes long term averages to account for stuff like fuel pump pressure variations as the system wears out or filters limit flow.
Short term fuel trim takes averages to account for minor things effecting fuel delivery volume, like temperature, so that injector pulses are appropriate for all environmental factors.
Doesn't sound like a fuel pressure problem because that normally comes up under hard acceleration as a lack of power, not intermittent issues, unless the fuel pump is dying.
And if its dying you'll get a lot more of a problem then an odd rumble every 500 miles. Your LTFT, however, does indicate that the engine is compensating and leaning (trimming back) every injector shot. Usually beyond 25 points you'll get a code (positive or negative).
Its very possible a bad O2 sensor is causing a false rich condition and the engine is pulling fuel to compensate, but I seriously feel you just have bad fuel. I wouldn't throw parts at this just yet to try to fix it since its rather intermittent.
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i thought negative percents were rich and positives were lean?
Negative indicates its pulling fuel to lean out the mixture, positive indicates its adding fuel to richen the mixture.
With your numbers being negative, it means at zero, the computer believes the engine is running too rich (if it actually is or not).
Negatives mean its leaning out the fuel charge because it thinks the motor is running too rich. I know its confusing sometimes.
With your numbers being negative, it means at zero, the computer believes the engine is running too rich (if it actually is or not).
Negatives mean its leaning out the fuel charge because it thinks the motor is running too rich. I know its confusing sometimes.
so it means it thinks its running rich therefor its leaning the mixture? that is confusing
I'm thinking ignition or 02 at this point, if anything. It may even be simple timing pull if there is enough carbon in your combustion chamber.
Have you ever done the foam spray top-end cleaners? They can work wonders for removing carbon deposits in the combustion chamber. A can of the Amsoil stuff is more than enough. That, fuel filter if it hasn't been done in a while(if applicable), maybe spark plug inspection for fun(being sure to use OE when possible). I forget what signs to look for if the coil were broken, but I'd imagine things along those lines would have caused stalling by now. So, I'm at the point of 02, perhaps plugs/wires, or something pulling timing such as carbon deposits in the combustion process. (I recall you have relatively new 02 sensors so scratch that atm)
Maybe worth looking into that sensor mentioned before. Is there any surging of power or in a lower gear is power immediately there and you can get performance?
Have you ever done the foam spray top-end cleaners? They can work wonders for removing carbon deposits in the combustion chamber. A can of the Amsoil stuff is more than enough. That, fuel filter if it hasn't been done in a while(if applicable), maybe spark plug inspection for fun(being sure to use OE when possible). I forget what signs to look for if the coil were broken, but I'd imagine things along those lines would have caused stalling by now. So, I'm at the point of 02, perhaps plugs/wires, or something pulling timing such as carbon deposits in the combustion process. (I recall you have relatively new 02 sensors so scratch that atm)
Maybe worth looking into that sensor mentioned before. Is there any surging of power or in a lower gear is power immediately there and you can get performance?
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