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KeyserSosa2000 09-23-2009 09:45 AM

Surging, Hesitation, Revving, Slippage, Idle
Good morning all. It's been a while since my last visit. While in school this site was my regular hangout but I graduated a few years ago.

My problem, as evidenced by the title, is my transmission, or at least I think it is. After reading several posts regarding Surging, Hesitation, Revving, Slippage and Idling it seemed appropriate to gather some consolidated thoughts.

  1. On a cold start my car fires up no problem but has an irregular idle. It slowly increases a few hundred RPM and then drops off. It repeats this cycle until the engine is warm.
  2. From a complete stop if I get on the throttle hard the entire car shakes and a horrible thumping/hammering/chugging noise ensues. If I roll on the throttle and don't "push it" the car rolls forward just like normal, no problem.
  3. 1st, 2nd and 3rd gear all "surge" while accelerating over 3000 RPM. Example: Stopped at a light in the right lane and on the other side of the intersection it becomes one lane and you want to be in front of the car beside you.

    The light turns green and you "roll on" the accelerator (see #2). 1st gear is ok, with only miled RPM drop and gain. 2nd gear roars to life but power does not seem to make it to the wheels. There are three individual stages that I call "Roar and Drop" during 2nd gear. The RPMs go up to 3000 then down to 2500, then up to 4500 and then down to 4000 then up to 5500 and down to 5000 before shifting into 3rd. Third gear exhibits the exact same behaviour if accelerating with power.

  1. Transmission line pressure too low.

    Originally Posted by videoman (Post 1054149)
    Well for my 2002 GAGT that was having the surging issue. I have reprogramed the PCM and increased the line pressure, so that the shift is a bit more firm and voila. No more surging.
    Everytime I would reset the PCM it would default back to the manufacturer specs, which call for a higher pressure level. Then after a while as the car learns, it would lower the pressure to provide smoother shifts. this would then cause the surging issue because the pressure would be low.

  2. Gasket issue / clutch packs

    Originally Posted by videoman (Post 916643)
    One test I went through and it seemed to localise the problem had to do with resetting the PCM. Reset you PCM and then drive your car normally( aka no heavy WOT runs). If the issue arrises immediatly then you can be pretty sure its the clutch packs. If not and it seems to go away for a week or more then its the gasket. The reason why the gasket issue might not show for some time, deals with the relearn process. The PCM is trying to learn how much pressure the TC will provide around certain shifts. Then you accelerate hard the pressure is supposed to go up, but after it reaches a certain point the failing gasket allows the fluid to leak, causing the pressure to drop. The PCM tries to compensate and that is the revving that I saw, and could be the same issue you have.

  3. Changing Transmission Fluid / Flush

    Originally Posted by jnugg69 (Post 916213)
    Alot of mechanics around my parts do say though, not too tinker with changing you tranny fluid cause that can bother the tranny because it's so used to shifting in the same fluid, etc. I'm starting to think they may be right, even if you fluid is ugly. I'm hesitant on doing a tranny flush. Coolant flushes are one thing.


    Originally Posted by mattamd_xp (Post 852798)
    my 2000 GT just started surging from 1st to 2nd under a load and I took it to a transmission place and they did a complete flush of the fluid and a new filter and the problem didn't go away (what a waste of $130 -the fluid looked brand new when they drained it) If I get my PCM reprogrammed would that fix the problem or is it a fluid leak somewhere inside the tranny itself that causes the PCM to change the shifting?

    This is also the first thing I did when my Transmission started acting up and the result was fresh fluid and a new filter, no change in surging/hesitation.

  4. Spark plug wires, spark plugs, coils, and/or IAT

    Originally Posted by Badblack04GT (Post 1072904)
    Turned out to be the plugs, i forgot that it had Autolite Platinums in it. They didn't look too bad for 20K but a set of spare Iridiums from my 3500 build took care of it. It runs like a top again. :)


    Originally Posted by AaronGTR (Post 1085982)
    Fuel filter, and the spark plugs and O2 sensor... that stuff just HAS to be done. I recommend every 30k for t he fuel filter. The other two at least at 100k.

  5. MAF

    Originally Posted by redhotalero (Post 969912)
    Mine did that for a while -- I cleaned the MAF gently with some elctrical contact cleaner, as well as the Air Intake Temp Sensor. Hasn't been back since, maybe that will help you too - quick $5 fix if that is the problem.

  6. Clutches

    Originally Posted by AaronGTR (Post 1085800)
    A sudden full throttle input with the accompanying increase in torque and the downshift could cause the clutch plates to slip while the engine would pick up a lot of revs, making it seem to "not go anywhere". A more gradual throttle increase would make it downshift without as much torque and give the clutches a chance to grab before the power comes on.

  7. Fuel Delivery
    Fuel Pump possibly needs replacing , injectors may need to be cleaned and a new filter should be purchased as preventative maintenance.

There are probably a million ways to diagnose the problem my car has and another millions ways to solve it. I'm going to start with the least expensive and move down the list of possibilities. I have already cleaned the MAF and checked the IAT and taken it to a transmission shop to no avail. They changed the fluid and filter but I still have the issue. They would be happy to rebuild my transmission for $2500, (ouch). Fuel filter is next and spark plugs and wires will follow. Hopefully it's not the clutches.

This is by no means a complete list, please feel free to post other ideas and comments. Thanks for your help.


AaronGTR 09-23-2009 10:55 AM

Hmm, well the surging idle during cold start that goes away... my first thought would be dirty MAF sensor or O2 sensor is on the way out. Since you said you cleaned the MAF already, how old is the O2 sensor?

Transmission, does kinda sound like worn clutch plates, but it's very hard to diagnose those problems without tearing the transmission apart... at which point you are already incurring some cost and already at the point where you should be replacing parts since it's already torn apart.

KeyserSosa2000 09-23-2009 11:00 AM

Thanks Aaron. I asked a friend of mine to quote me on taking the transmission apart for a 'look-see' to help diagnose vs doing a rebuild if it explodes...the price difference is nominal.

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