1988 Pontiac Grand Am 2.3l Quad 4:
If I put my car into gear too soon after starting it, it sets a trouble code 26 "Quad Driver Module". I recently replaced my computer because of other problems I'm still having. (no acceleration in reverse, bad gas mileage, code 13"O2 sensor", slow up hills, and poor acceleration from a stop). I recently replaced my computer, oxygen sensor, spark plugs and wires (boots). Could code 13 be being set either because there's a strait pipe where my catalytic converter was cut out from a previous owner, or from the bad leak where my exhaust pipes connect before the muffler? Could those things also affect my poor performance? I'm currently shopping for a catalytic converter and should have it on soon. I just noticed it was cut off. Thanks for your time.
Reading your question it sounds like you have some transmission issues. A scan tool should be used to help diagnosis these problems.
Code 26 is a quad driver code that involves many other circuits. The second and third gear switches in the transmission and the brake switch are included in the quad driver code 26. They control the function of the torque converter clutch (TCC). Faulty TCC operation will give poor fuel mileage. Other components of the quad driver are low and high cooling fan, a/c clutch, canister purge solenoid, service soon fault line. These should also be checked out for proper operation.
It is possible for the car to start out in second gear. A bad torque converter can also give the indication of no power or acceleration from a stop.
A poor running engine or rough idle can be caused by a vacuum leak at the intake manifold gasket, partially open EGR valve, cracked vacuum lines and leaking vacuum brake booster. These can all contribute to the code 13. If you changed the oxygen sensor and still have a code 13 these should be checked out.
The oxygen sensor is installed before the catalytic converter so not having a converter is not likely to be the problem. The problem is that federal law requires the vehicle to have the catalytic converter and it can't pass inspection without it.
If the exhaust pipes are rotted before the oxygen sensor this can fool the sensor and force it to give the wrong signal which can also cause poor fuel mileage and performance.
No power in reverse is a sign that the low/reverse roller clutch or sprag clutch could be faulty. The engine will seem to race in reverse and you probably will move slow or not at all.
No power or acceleration can be caused by other things like poor fuel pressure. Causes of low pressure can be a clogged fuel filter, bad fuel pump, clogged fuel sock in the gas tank and fault fuel pressure regulator and clogged fuel injectors.
I hope all this information helps. Good luck.
Last edited by TechHelp2 (3/2/2010 2:53 PM)
I'm still having. (no acceleration in reverse, bad gas mileage, code 13"O2 sensor", slow up hills, and poor acceleration from a stop)..
This year Quad-4 engine had a very, very common problem with a leaking head gasket. Very often a rough running (rich) condition is the first symptom, due to the coolant burned in the engine's combustion chamber contaminating the oxygen sensor.
Could be two expensive problems, one with the transmission, the other with the engine.
Thanks for your response, I've got some new info on it.
Today while my wife was driving the car it wouldn't change gears at about 40mph, so she let off on the gas a little hoping it would shift, when she returned to push the gas it acted as if it was in neutral. After a minute it reengaged.
After reading your response and researching this new symptom on the internet I found this is probably a Torque Converter Clutch Solenoid, which would cause the lack of power, bad gas mileage, code 26 and stalling (I forgot to mention that when we come to stop lights it acts like it wants to stall sometimes we have to put in neutral to keep it running).
So looks like this could be the problem, problem is I have no knowledge on this subject. If this sounds like it could be the correct diagnosis, could you share some insight on the TCC, anything will help. Where is the solenoid? How do I test it? How do I replace it if necessary? Where's the wiring, so I can check the ground and such?
OK. You're describing a lot of symptoms.
"when she returned to push the gas it acted as if it was in neutral"
This is a description of "slipping", and if the fluid is full, it's most likely an internal transmission failure which is going to require a rebuilt unit.
When a TCC does not disengage it typically happens after slowing down from a highway drive. It feels exactly like you're coming to a stop with a standard transmission, but it's still in gear and you forgot to depress the clutch. It will shudder hard, and stall -- run in neutral -- but stall again when you put it in drive. Not always, but usually caused by a bad TCC solenoid.
But if the engine is ever running rough in neutral, or you see smoke (black, blue, or white) out the tailpipe, those symptoms are engine related.
You can usually get a free inspection at most transmission shops. You don't want to install a TCC solenoid on a transmission that's slipping.
And remember, a repeat oxygen sensor failure (code 13) is often caused by coolant contamination from a bad Quad-4 head gasket.
Thank both of you for your help!
I just checked the trans. fluid, and it was brownish and had a burnt smell to it. My wife just got home from running to town so the fluid registered way high (that's normal right?). Anyways, looks like this fix is going to cost a bundle. I'm strapped for cash and also have an 89 Honda Civic I could use some help diagnosing. Should I begin a new thread for that car or continue here? I can't thank you guys enough for your advice. While this car's at least getting us back and forth to town for now, I think I need to focus on repairing our Honda, I've gotta provide some reliable wheels for my family, the Honda's looking like our best bet. So if you guys will continue to help me, just let me know where if I should post my Honda's problems.
By all means. Post a new topic in the Honda Civic forum.