Rough idle and studdering when accelerating
09-21-2017, 09:30 PM
#1
Thread Starter
Join Date: Aug 2017
Location: Florida
Posts: 38
Rough idle and studdering when accelerating
98 GT.
My car had a rough idle to the point where it would stall. The RPM would jump from 750 to as high as 1500, then could go under 500.
Recently I noticed that my car would studder, shake when I accelerate in 2nd. When I drove 30-35 mph with 1500-2000 rpm. I think I have a misfire.
I replaced the MAF sensor and it helped with the rough idle but not completely. Instead of the above mentioned jumps, I would sometimes have idle go from 750 to 500 or 450 and then come back. I don't feel it unless I actually look at the RPM gauge. As for the stuttering, sometimes it happens but it's much milder and not that long.
Right now I am thinking about replacing my TPS.
Also, after I replaced the MAF sensor, I can sometimes hear a wind howling noise in the cold air intake area when driving. Do I have a vacuum leak anywhere? Do I have a misfire?
My car had a rough idle to the point where it would stall. The RPM would jump from 750 to as high as 1500, then could go under 500.
Recently I noticed that my car would studder, shake when I accelerate in 2nd. When I drove 30-35 mph with 1500-2000 rpm. I think I have a misfire.
I replaced the MAF sensor and it helped with the rough idle but not completely. Instead of the above mentioned jumps, I would sometimes have idle go from 750 to 500 or 450 and then come back. I don't feel it unless I actually look at the RPM gauge. As for the stuttering, sometimes it happens but it's much milder and not that long.
Right now I am thinking about replacing my TPS.
Also, after I replaced the MAF sensor, I can sometimes hear a wind howling noise in the cold air intake area when driving. Do I have a vacuum leak anywhere? Do I have a misfire?
09-22-2017, 11:16 AM
#2
4th Gear Member
Join Date: Nov 2009
Location: SoCal
Posts: 1,826
Very likely vaccum leak. Running like that I would think your check engine light is on and/or flashing at times? If so, have the car scanned and post up with whatever code(s) pop up. In the meantime, save yourself some frustration and money by not throwing parts at it. Let's see if we can actually diagnose something.
Possibilities I see, and it could be more than one - is vac leak, ignition component, fuel filter, injector malfunction, O2 sensor (do not just replace for the hell of it, there is a lot that goes into making an educated guess much less any sort of pinpoint diagnosis here), exhaust leak (throwing off O2 sensor reading), plugged convertor. And probably at least a couple more I'm not thinking of. Scan it and get us some codes please.
Possibilities I see, and it could be more than one - is vac leak, ignition component, fuel filter, injector malfunction, O2 sensor (do not just replace for the hell of it, there is a lot that goes into making an educated guess much less any sort of pinpoint diagnosis here), exhaust leak (throwing off O2 sensor reading), plugged convertor. And probably at least a couple more I'm not thinking of. Scan it and get us some codes please.
Last edited by Z28KLR; 09-22-2017 at 11:22 AM.
09-22-2017, 01:02 PM
#3
Thread Starter
Join Date: Aug 2017
Location: Florida
Posts: 38
When I replaced the MAF sensor, I disconnected the battery and it reset everything, so no codes are showing up right now. Prior to that I would have the P0135 code (o2 sensor). That code has been there for a while. My friend told me it is because the car has a full exhaust without catalytic converters and it shouldn't be anything to be worried about. Now, that I have learned a little bit more about cars, I strongly doubt his statement.
How can I diagnose a vac leak?
Yesterday, when I opened the hood just after I drove the car, I saw some liquid on the drier and on one of the lines with rubber around it going to the drier. I think it is just condensation but I don't know. I did not touch it because the car was hot. What could it be?
More importantly, is it okay for me to drive the car? I only use to drive to school (10 min drives) or should not drive it? When I feel the stutter, I don;t feel any loss of power, so it might not be a misfire.
Let me know what you think.
How can I diagnose a vac leak?
Yesterday, when I opened the hood just after I drove the car, I saw some liquid on the drier and on one of the lines with rubber around it going to the drier. I think it is just condensation but I don't know. I did not touch it because the car was hot. What could it be?
More importantly, is it okay for me to drive the car? I only use to drive to school (10 min drives) or should not drive it? When I feel the stutter, I don;t feel any loss of power, so it might not be a misfire.
Let me know what you think.
09-22-2017, 03:42 PM
#4
4th Gear Member
Join Date: Nov 2009
Location: SoCal
Posts: 1,826
P0135? See, now we're diagnosing some ****...
Your friends assessment is/was incorrect. P0135 refers to an upstream sensor (bank 1, passenger side of vehicle) located before the cats. The upstream O2's are responsible for monitoring air/fuel ratio stuff and reporting back to the PCM, they are essential to proper engine management. Issues with upstream sensor readings will absolutely impact driveability, unlike downstream O2 sensors which do nothing but monitor catalyst efficiency and have zero effect on how the engine runs.
Below is some info on P0135. Like I said, there is a lot that goes into properly diagnosing an O2 sensor related trouble code that can involve equipment that guys like us lack access to, and there are at least a few different trouble codes related directly to O2 sensors and it's not uncommon for people to replace what they thought was a faulty sensor and find out 5 minutes later that it wasn't the problem.
I'm not any sort of expert on the subject though, but based on the following info if it were my car and money I'd say you could make an educated guess that you have a faulty sensor. I advise that you continue to research P0135 on Google or whatever and see what others' solutions turned out to be.
www.obd-codes.com/p0135
Your friends assessment is/was incorrect. P0135 refers to an upstream sensor (bank 1, passenger side of vehicle) located before the cats. The upstream O2's are responsible for monitoring air/fuel ratio stuff and reporting back to the PCM, they are essential to proper engine management. Issues with upstream sensor readings will absolutely impact driveability, unlike downstream O2 sensors which do nothing but monitor catalyst efficiency and have zero effect on how the engine runs.
Below is some info on P0135. Like I said, there is a lot that goes into properly diagnosing an O2 sensor related trouble code that can involve equipment that guys like us lack access to, and there are at least a few different trouble codes related directly to O2 sensors and it's not uncommon for people to replace what they thought was a faulty sensor and find out 5 minutes later that it wasn't the problem.
I'm not any sort of expert on the subject though, but based on the following info if it were my car and money I'd say you could make an educated guess that you have a faulty sensor. I advise that you continue to research P0135 on Google or whatever and see what others' solutions turned out to be.
www.obd-codes.com/p0135