Low RPM Issue

[mike7869]

I have a 99 v6 with about 201k. The engine does not burn or leak any fluids, and the tranny shifts fine. I am having a problem though when the car is at low rpm. like driving through town at 45 or under, esp in overdrive.

its hard to tell in the video, but the tack moves up and down slightly. you can hear it more then see it on the tack. even though sometimes the tack moves a lot. you can also feel the car jerking back and forth as you drive.

i have tried changing fuel brands. 10k miles ago, i changed the valve cover gaskets. while doing that i took of the intake manifold and cleaned everything out. the car ran fine after that though. i dont get any cheack engine lights either. the plugs have been changed about 20k ago. i have not tried running injector cleaner through it yet, bc i dont see why this would help. the problem goes away once the rpm passes 2k, or if i give the car more throtle.

here is a video of what the car is doing. quality sucks, bc all i have is my phone. its hard to see the tack go up and down. but i figured it would help.

http://www.youtube.com/watch?v=-EvxQkdmwkU

thanks, Mike

[slpr1mz]

hmm, check to see if your intake is clogged any. if not, use some MAF sensor cleaner, while the intake if off, spray throttle body cleaner into the throttle body. use fuel additaves such as octane booster, injection cleaner, gas treatment. i had a problem with mine idling really really low at start up. i personally had to rev to the rev limiter and bring it bck down because my egr pipe was dirty. but take a day and a beer or to and take everything and clean them.

[JohnGD]

I noticed that your speed at the time was 0. So while sitting there the idle swings up like that?

It's almost like you have a vacuum leak somewhere. How's the PCV valve, rubber grommet, and hose? How is the air intake hose? Any cracks? Are all vacuum tubes in good condition and connected? etc etc

Go to a parts store with a free loaner program and borrow a vacuum gauge (like Mityvac). Plug it into the EVAP port and read off the vacuum. See if it's much lower than 17-22 in/Hg the typical range of a healthy engine.

Note: evap hose lets off fuel vapors.

Originally Posted by mike7869

I have a 99 v6 with about 201k. The engine does not burn or leak any fluids, and the tranny shifts fine. I am having a problem though when the car is at low rpm. like driving through town at 45 or under, esp in overdrive.

its hard to tell in the video, but the tack moves up and down slightly. you can hear it more then see it on the tack. even though sometimes the tack moves a lot. you can also feel the car jerking back and forth as you drive.

i have tried changing fuel brands. 10k miles ago, i changed the valve cover gaskets. while doing that i took of the intake manifold and cleaned everything out. the car ran fine after that though. i dont get any cheack engine lights either. the plugs have been changed about 20k ago. i have not tried running injector cleaner through it yet, bc i dont see why this would help. the problem goes away once the rpm passes 2k, or if i give the car more throtle.

here is a video of what the car is doing. quality sucks, bc all i have is my phone. its hard to see the tack go up and down. but i figured it would help.

http://www.youtube.com/watch?v=-EvxQkdmwkU

thanks, Mike

[mike7869]

Originally Posted by kjb4rmdcc

hmm, check to see if your intake is clogged any. if not, use some MAF sensor cleaner, while the intake if off, spray throttle body cleaner into the throttle body. use fuel additaves such as octane booster, injection cleaner, gas treatment. i had a problem with mine idling really really low at start up. i personally had to rev to the rev limiter and bring it bck down because my egr pipe was dirty. but take a day and a beer or to and take everything and clean them.

my intake is spotless. the egr is clean as well. i will try some injector cleaner and the maf cleaner today. this seems to be more prevalent when the car is under load. like going up my drive way at really slow speed.

[mike7869]

[QUOTE=JohnGD;2765129]I noticed that your speed at the time was 0. So while sitting there the idle swings up like that?

It's almost like you have a vacuum leak somewhere. How's the PCV valve, rubber grommet, and hose? How is the air intake hose? Any cracks? Are all vacuum tubes in good condition and connected? etc etc

Go to a parts store with a free loaner program and borrow a vacuum gauge (like Mityvac). Plug it into the EVAP port and read off the vacuum. See if it's much lower than 17-22 in/Hg the typical range of a healthy engine.

Note: evap hose lets off fuel vapors.[/QUOT


i think i either flicked the throtle or i was pulling up to the exit in the parking lot. at idle i have no issues, and the car starts right up with no hesitation. all my vacum lines are in great condition. i looked over everything when doing my valve cover gaskets. i will go to advanced auto. and ask to use their vacume gauge.

thanks, to both of your for the help.

[slpr1mz]

yea, other than something being blocked, it could be a leak...
let know whats up and good luck.
BTW, any CEL on?

[mike7869]

Originally Posted by kjb4rmdcc

yea, other than something being blocked, it could be a leak...
let know whats up and good luck.
BTW, any CEL on?

if it was a leak, would it not be consistant?
and no, not a single CEL.

thanks, will do.

[bigbird]

hmm strange. my 97 V6 does the same thing. but it throws a code and its the ERG system. specifcally the EGR VSV. try cleaning the EGR system with some carb cleaner.

[mike7869]

Update,

so, i ran some injector cleaner but that didnt seem to help much. at least not at first. the cleaner is stil in my tank. i also sprayed carb cleaner into the vacume lines running into the intake. that didnt seem to help too much either. so then i decided to spray carb cleaner into the egr systmn, and let it sit over night. when i started the car the next day, all hell broke loose. my CEL came on and the car ran as if i threw in the biggest cam possible. so i figured that was just the carb cleaner burning off. NOPE. when i ran the codes i got P0402- excesive egr flow. P1411 was something long and more complicated. after that i decided to take off the EGR sensor it self, (the three little nuts that hold the sensor at the top). when i pulled the sensor off, it was soaked in carb cleaner and there was a pool of carb cleaner in the chamber. i then started the car with the sensor out, and it ran like new again. so, i let the egr sensor dry over night and put it back in. now the car runs fine.

if anyone has this problem, DO NOT SPRAY CARB CLEANER INTO THE SENSOR OR ANY VACUME LINES LEEDING TO THE SENSOR. rather, take it off and clean it and let dry, before putting it back on. the problem of spraying the carb cleaner into the egr is that, the sensor is sealed in the chamber it sits in. if you spray the carb cleaner drirectly into the sensor, the carb cleaner will not evaporate and will just pool up. at least that is what i ran into.

i want to thank everyone for helping me get to the buttom of this issue.

ps, car has 202k and still gets 28.1 mpg!