Question:

I have an 85 Olds Custom Cruiser station wagon, with a 307 eng., and  a 4 speed Turbo Hydramatic 400 trans.  which I bought "used" a few months ago.  When I bought it, I noticed it tended to jerk alot, especially after getting hot, and at higher speeds.  At that time, I just figured it needed a tune-up.  Since then, I have done a complete tuneup.  New plugs, wires, cap, rotor, air filter, fuel filter, new vacuum hoses, pcv valve, breather filter, and more.

from the sound of things, i guess you got a good deal for a car with "personality" Yet, the problem continued, and has gotten worse and worse. It has gotten to the point that at times, there is hardly any power at all, when climbing a hill, even if i downshift. I have also noticed that sometimes the transmission seems to not downshift when I pull up to a STOP sign, and after a rolling stop, would seem to start out in a high gear, with lots of pinging, and no power.  At high speed the car has the Herky – Jerkys.  (meaning it seemed to continuously be changing gears when in overdrive (OD), but even in a lower gear, it is jerky, and lcaking in power (at times).  I sort of seems like it is getting gas in surges. instead of all the time.

without the computer connected, overdrive won’t engage – Hide quoted text — Show quoted text – For awhile I thought the transmission was failing, but I noticed that there was no slippage when the engine is cold, and it does not appear to shift to a lower gear, but instead, seems the engine varies it’s power load.  Seems like it goes into a high torque mode at times, but lacks the ability to maintain speed on hills. Last night, while on the highway, the "CHECK ENGINE" light came on for several short periods of time, and at that time the herky – jerky symptoms were bad. After getting home, and looking in my auto repair manual (which is not very detailed), I noticed there is a TCC (transmission converter – clutch/torque converter). That got me thinking that the problem appears to be a constant change in torque – loading.

Try pulling the electrical connector off the transmission for the torque converter lockup Just for the heck of it, I decided to try and disable the ECM (computer), and see what happens.  I located the fuses that control it, and removed both fuses.  Since I did that, it feels like I am driving a completely different car.  No more "crazy" shifting, no more downshift problems, no more pinging, no lack of power, or torque changes, and no more herky – jerkies……   In other words, the car seems to run very nicely, with the computer disabled, except the "Check Engine" light is always ON.

Some things i can think of that the computer controls, are the torque converter lockup, some emissions junk like the charcoal canister and smog pump, the mixture control solenoid in the carb, some of the electronic controls in the distributor, and the air conditioner clutch lockout. Does anyone have any idea what may be the problem? Unfortunately, I am required to get emission tests yearly. While it will be many months before I have to get one again, I will eventually have to solve this problem.  Until then, the car runs very well with the computer disabled.

well, your not going to pass emissions without the computer connected. All the systems i mentioned above are connected via modular plugs to the car’s electrical harness, try disconnecting one at a time until your problem goes away and then you’ve located your problem. While I am sure that some GM dealer has some diagnostic equipment to connect, I am not able to afford to take it in, since I am sure it would be very costly.   I also have access to another similar junked vehicle, and can interchange some parts to try and solve the problem. Till then, I will leave those fuses out….

you’ll get pitiful fuel economy though because the carb primary metering rods will be stuck in the full rich position. In order to get some sort of idea what might be at fault, and swap parts, I am trying to get some sort of idea where to begin.  If anyone can suggest what to look for, or have had a similar problem, please post or email me. Thanks NOTICE:  I spamblock, remove the word "SPAM" to email me. whatever Rocky

– Matt

Response:

I am surprised it runs at all with the computer disabled. Is this a carb engine? You can easily check for trouble codes in older GMs with no special equipment. All you really need is a paper clip in fact, as it flashes out the codes on the Check Engine light. I don’t really feel like posting the whole procedure but if you look in Dejanews I gave it out to someone else recently. Even if you did take it to a mechanic it is not a complicated procedure to check codes. It will likely not be many $. If the TCC is in fact the problem – and from the symptoms it doesn’t seem unlikely – I don’t think it costs much to fix. If you are really strapped for cash you could just disconnect the TCC and leave the computer connected so it doesn’t screw up your emissions. — Robert Hancock         Saskatoon, SK, Canada Home Page: http://www.geocities.com/TimesSquare/Arcade/9967 – Hide quoted text — Show quoted text – I have an 85 Olds Custom Cruiser station wagon, with a 307 eng., and  a 4 speed Turbo Hydramatic 400 trans.  which I bought "used" a few months ago.  When I bought it, I noticed it tended to jerk alot, especially after getting hot, and at higher speeds.  At that time, I just figured it needed a tune-up.  Since then, I have done a complete tuneup.  New plugs, wires, cap, rotor, air filter, fuel filter, new vacuum hoses, pcv valve, breather filter, and more. Yet, the problem continued, and has gotten worse and worse. It has gotten to the point that at times, there is hardly any power at all, when climbing a hill, even if i downshift. I have also noticed that sometimes the transmission seems to not downshift when I pull up to a STOP sign, and after a rolling stop, would seem to start out in a high gear, with lots of pinging, and no power.  At high speed the car has the Herky – Jerkys.  (meaning it seemed to continuously be changing gears when in overdrive (OD), but even in a lower gear, it is jerky, and lcaking in power (at times).  I sort of seems like it is getting gas in surges. instead of all the time. For awhile I thought the transmission was failing, but I noticed that there was no slippage when the engine is cold, and it does not appear to shift to a lower gear, but instead, seems the engine varies it’s power load.  Seems like it goes into a high torque mode at times, but lacks the ability to maintain speed on hills. Last night, while on the highway, the "CHECK ENGINE" light came on for several short periods of time, and at that time the herky – jerky symptoms were bad. After getting home, and looking in my auto repair manual (which is not very detailed), I noticed there is a TCC (transmission converter – clutch/torque converter). That got me thinking that the problem appears to be a constant change in torque – loading. Just for the heck of it, I decided to try and disable the ECM (computer), and see what happens.  I located the fuses that control it, and removed both fuses.  Since I did that, it feels like I am driving a completely different car.  No more "crazy" shifting, no more downshift problems, no more pinging, no lack of power, or torque changes, and no more herky – jerkies……   In other words, the car seems to run very nicely, with the computer disabled, except the "Check Engine" light is always ON. Does anyone have any idea what may be the problem? Unfortunately, I am required to get emission tests yearly. While it will be many months before I have to get one again, I will eventually have to solve this problem.  Until then, the car runs very well with the computer disabled. While I am sure that some GM dealer has some diagnostic equipment to connect, I am not able to afford to take it in, since I am sure it would be very costly.   I also have access to another similar junked vehicle, and can interchange some parts to try and solve the problem. Till then, I will leave those fuses out…. In order to get some sort of idea what might be at fault, and swap parts, I am trying to get some sort of idea where to begin.  If anyone can suggest what to look for, or have had a similar problem, please post or email me. Thanks NOTICE:  I spamblock, remove the word "SPAM" to email me. Rocky

Response:

I have an 85 Olds Custom Cruiser station wagon, with a 307 eng., and  a 4 speed Turbo Hydramatic 400 trans.  which I bought "used" a few months ago.  When I bought it, I noticed it tended to jerk alot, especially after getting hot, and at higher speeds.  At that time, I just figured it needed a tune-up.  Since then, I have done a complete tuneup.  New plugs, wires, cap, rotor, air filter, fuel filter, new vacuum hoses, pcv valve, breather filter, and more.   Yet, the problem continued, and has gotten worse and worse. It has gotten to the point that at times, there is hardly any power at all, when climbing a hill, even if i downshift. I have also noticed that sometimes the transmission seems to not downshift when I pull up to a STOP sign, and after a rolling stop, would seem to start out in a high gear, with lots of pinging, and no power.  At high speed the car has the Herky – Jerkys.  (meaning it seemed to continuously be changing gears when in overdrive (OD), but even in a lower gear, it is jerky, and lcaking in power (at times).  I sort of seems like it is getting gas in surges. instead of all the time.   For awhile I thought the transmission was failing, but I noticed that there was no slippage when the engine is cold, and it does not appear to shift to a lower gear, but instead, seems the engine varies it’s power load.  Seems like it goes into a high torque mode at times, but lacks the ability to maintain speed on hills. Last night, while on the highway, the "CHECK ENGINE" light came on for several short periods of time, and at that time the herky – jerky symptoms were bad. After getting home, and looking in my auto repair manual (which is not very detailed), I noticed there is a TCC (transmission converter – clutch/torque converter). That got me thinking that the problem appears to be a constant change in torque – loading. Just for the heck of it, I decided to try and disable the ECM (computer), and see what happens.  I located the fuses that control it, and removed both fuses.  Since I did that, it feels like I am driving a completely different car.  No more "crazy" shifting, no more downshift problems, no more pinging, no lack of power, or torque changes, and no more herky – jerkies……   In other words, the car seems to run very nicely, with the computer disabled, except the "Check Engine" light is always ON. Does anyone have any idea what may be the problem? Unfortunately, I am required to get emission tests yearly. While it will be many months before I have to get one again, I will eventually have to solve this problem.  Until then, the car runs very well with the computer disabled. While I am sure that some GM dealer has some diagnostic equipment to connect, I am not able to afford to take it in, since I am sure it would be very costly.   I also have access to another similar junked vehicle, and can interchange some parts to try and solve the problem.   Till then, I will leave those fuses out…. In order to get some sort of idea what might be at fault, and swap parts, I am trying to get some sort of idea where to begin.  If anyone can suggest what to look for, or have had a similar problem, please post or email me. Thanks NOTICE:  I spamblock, remove the word "SPAM" to email me. Rocky

Response:

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