2004 surging at stoplight

[jpennin217]

This is my first post so here it goes and thanks for any help.

When you come up to a stop light the car surges. If I shift it into nuetral from drive while stopped it just sits and idles no surging or trying to inch forward. I tried to search for some help but did not see anything like this.

Thanks again for any help.

[jackpot]

seems a lot of 04's do this lol

hows your tranny, does it whine/howl? when your accelerate from a stop moderately

mine surges, here and there, somedays better than others, might try cleaning a few sensors, IAC, MAF, TB maybe....maybe

peace
JP

[arthurgoboom]

Torque Converter clutch not disengaging?

Every now and again mine will exhibit similar symptoms. When you come to a stop, instead of the engine coming down to 700rpm as you slow down, it continues dropping and then starts bucking or perhaps it kills the engine?

[arthurgoboom]

Torque Converter clutch not disengaging?

Every now and again mine will exhibit similar symptoms. When you come to a stop, instead of the engine coming down to 700rpm as you slow down, it continues dropping and then starts bucking or perhaps it kills the engine?

[jpennin217]

Transmission seems to be fine. It is just when you are stopped and foot on the brake. It feels like it is surging but it has never died the rpms don't change but if you put it in nuetral from drive it all goes away. I will try cleaning a few parts. Thanks

[arthurgoboom]

Only when the brake is applied, you say? I would guess that perhaps the vacuum brake booster is leaking, allowing the engine to suck air in and try to accelerate. The test for this is to use a vacuum gauge Tee'd into a vacuum line somewhere, observe the vacuum, then push the brake pedal down. When you push the brakes, the vacuum should drop for a moment, but then once you are holding the pedal at a steady location it should recover to the same vacuum level the gauge showed previously. It should hold around 20 inches/Hg at idle when engine is warm.

Edit: I don't think your year of car has a vacuum modulator on the transmission, or I would suggest that might be a possible problem too.

[jackpot]

its a strange issue arthur, not sure it has anything to do with the vac, however I would liek to get my vac sys tested

jpennin, try in P or N, rev the engine to about 1000-1200 then just let go of the throttle(peddle) it might drop right down to 500 then bouce back to 1000 then settle, thats the surging, its wack

peace
JP

[MichaelS]

My 2004 has both kinds of surges. At low speed coming to a stop it will drop to 500 rpm then bounce to 700, then bounce to 500 and back to 700 until i'm stopped.

I also have the surging if I rev the engine to 1000 rpm and let go.

I've been experiementing with the surging; if I unplug the IAT and put a resister in (not sure of the OHMs) that makes the engine think the incoming air is 75c, the surging is not as persistent. Unfortunately, I'm sure its only a matter of time before the SES light comes on for an IAT code for emissions.

I am also watching the fuel economy through the LTFT and STFT's (in closed loop, the PCM seems to be compensating for the resister).

Please let us know if your 2004 is also surging...

Thanks,

Michael

[jackpot]

I think its the same surging issue Michael, except it shows itself in different ways

mine has been doing it infrequently quite a lot more lately, doesnt do it so much anymore when comign to a stop but, atleast 50% of the time if i rev it and drop it, it will bounce back and settle

I havent really had the issue with the bouncing over and over rpm's like you seem to have when coming to a stop, usually its right before im stationary, the car will lurch forward somewhat, havent seen the 700-500 again and again however

do any of you hear any whistling at anytimes when going at low speeds (could be my intake tubes) but have yet to tape them up to find out

peace
JP