Edmunds Answers

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  • avatar karjunkie 12/12/09 3:43 pm PST

    The good news is that the shifting problem doesn't sound tranny related from those codes. The P0128 is for coolant temp and the pcm sets this when the car has traveled enough distance at a high enough speed and has taken in enough air and the engine isn't hot enough yet. It measures air in grams per second which it arrives at using the reading from the MAF sensor for air velocity and the IAT sensor for air density and calculating the g/sec with some complicated formulas. If you have a CAI, you could be throwing off the air volume reading enough that the pcm thinks enough air has entered the engine by now that it should be hotter. I would definetly clean the MAF sensor wire. You also want to check your coolant level, and it might be a sticky thermostat too. That's not that uncommon a problem and it's a cheap part to replace.

    The P0404 code is for EGR open position performance. The pcm reads the EGR pintle open position and compares it to the commanded open position, and if it's not within 15% it sets the code. This usually won't happen unless there is an actual problem with the EGR so you shouldn't have to look anywhere else. Check the wires on the harness going to the EGR solenoid and make sure there's nothing melted or cut. Take the plug out and clean the contacts on the solenoid as best you can and put some dielectric grease on them then plug it back in. That will make sure it doesn't get shorted by water or corrosion, and that it gets good contact. If that doesn't work then the EGR valve might have carbon build up and need to be cleaned, or it might be defective and have to be replaced.

Answers

  • karjunkie 12/11/09 8:48 am PST

    When did you last check the fluid level and color? You may just be low on ATF fluid or need a fluid and filter change. That should be your first step. The brakes have nothing to do with it. Also, do you have a check engine light on?

  • screwedbygm 12/11/09 10:06 am PST

    Sounds like the trans is getting tired and clutches are starting to slip and burn up. It's rare for these units to lose fluid level without a seal failure -- do you see oil drips where you park? First step is to check the condition of the fluid. Is it bright red and clear or brown and smelly? The darker and smellier the fluid, the greater the confirmation that clutches are slipping and putting a hard, carbon sheen on them from friction heat that makes the slippage even worse. On the one hand, a fluid and filter change will be in order but it may not help much if the clutches are burned beyond redemption. There are specialty, high-carbon solvents available that can dissolve out carbon sheen from clutches if they're not burned so badly that there's no useable plate thickness left when it's removed, thereby permitting somewhat of an extended life; check with your local transmission service shops or supply houses. The procedure is to add the treatment to the tranny and operate the vehicle gently for a couple of hundred miles. Circulation of the treated fluid (the old fluid) and heat will dissolve off the carbon sheen and may improve (lessen) the slippage; conversely, if the symptoms get worse you know there's little option but to rebuild the trans. If the solvent treatment works, the fluid appearance and smell will get rapidly worse. After a couple of hundred miles with the solvent in the old fluid, get it drained and thoroughly flushed, plus replace the filter. It's a gamble. This procedure may not help if the clutches are too far gone but I've witnessed successful situations where tens of thousands of miles of extended useful life were achieved.

  • snowball2 12/11/09 9:23 pm PST

    have this car scanned for codes and repost,there are a couple of things on this transmission that could cause this problem,also there is somethings engine related that wouls cause this problem

  • jstark3 12/11/09 11:45 pm PST

    There is no trany fluid on the ground. My check engine light is on and has been for a while. It used to come on and go off with other dash lights (security, washer fluid, change oil). This last time it came on when my washer fluid was low. I refilled it and the check engine light didn't go out this time. My check engine light was blinking just before this tranny issue started. I will get the codes read tomorrow and repost

    Thank you.

  • snowball2 12/12/09 2:39 pm PST

    best place to start

  • jstark3 12/12/09 3:08 pm PST

    Had the codes read today. P0404 EGR fault and P0128 Coolant temp is always low. Does this help explain anything or am I still looking at a tranny?

  • karjunkie 12/12/09 3:43 pm PST

    The good news is that the shifting problem doesn't sound tranny related from those codes. The P0128 is for coolant temp and the pcm sets this when the car has traveled enough distance at a high enough speed and has taken in enough air and the engine isn't hot enough yet. It measures air in grams per second which it arrives at using the reading from the MAF sensor for air velocity and the IAT sensor for air density and calculating the g/sec with some complicated formulas. If you have a CAI, you could be throwing off the air volume reading enough that the pcm thinks enough air has entered the engine by now that it should be hotter. I would definetly clean the MAF sensor wire. You also want to check your coolant level, and it might be a sticky thermostat too. That's not that uncommon a problem and it's a cheap part to replace.

    The P0404 code is for EGR open position performance. The pcm reads the EGR pintle open position and compares it to the commanded open position, and if it's not within 15% it sets the code. This usually won't happen unless there is an actual problem with the EGR so you shouldn't have to look anywhere else. Check the wires on the harness going to the EGR solenoid and make sure there's nothing melted or cut. Take the plug out and clean the contacts on the solenoid as best you can and put some dielectric grease on them then plug it back in. That will make sure it doesn't get shorted by water or corrosion, and that it gets good contact. If that doesn't work then the EGR valve might have carbon build up and need to be cleaned, or it might be defective and have to be replaced.

  • screwedbygm 12/13/09 1:07 pm PST

    Great info from Karjunkie on the codes but I don't see where coolant and EGR issues effect gear selection or clutch slippage in the tranny. What is the condition and level of the trans fluid?

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