Car bucks and surges under load

["Turbo-T"]

Found out today my car bucks and surges under load. It's more noticable in OD but I also noticed you can feel it if you drop the trans to D3 and put it under a load.

When not under load you can't notice it as much.

No codes, FP looked ok, AFR's were in the 14's-15's when it happened. Not much throttle.

After I floored it a few times, it seemed to smooth out the bucking/surging though i won't say it's not still there.

The coil is 4 months old and less than 500 miles on it. I checked the plug wires but didn't see any cracks or any melted areas.

I want to say I read that a bad MAF can cause this?

What about a malfuncioning cam sensor? Crank sensor maybe?

 

[Drewster]

i had a bad TPS sensor that did just that. if you have a scan master or some other scan tool that can watch the TPS voltage, slowly press the throttle and and watch for drop outs as the voltage increases. (engine not running, key on)
you can even use a volt meter to see the voltage (dont remember what wires to pin).
mine would drop to 0.2 vdc at certain throttle point and was most obvious when the torque converter was locked. any more or less throttle would not have a problem.

 

["Turbo-T"]

Thanks. I used the Scanmaster to check TPS voltage w/o the car running and it looks to steadily increase.

The bucking is more noticeable with the TC locked but never felt it in 3rd gear at cruise.

Anything else I should check?

 

[Drewster]

unfortunately you will just have to make a list and eliminate the possiblies, if you have a scanmaster you can look at different sensors while bucking, AF, TPS, BLMs, O2s. I saw another post where your fuel milage is very poor. the 2 problems may be related. pull the plugs and look to see if you find one or two different plugs than the others, black or glazed, smell like fuel, might have stuck injector (s) You can also listen to each injector with a stethiscope or hose and make sure each one clicks . if you have a friend with another TR you can easily swap some parts that wont show on Scanmaster like coil pack /module, or ECM/chip.
one tip, try to do all the free stuff first and trouble shoot as much as possible. when you have a good idea then you can buy parts.

 

[Grunk]

Pull all the plugs and check for cracks. My car did the same thing and the plugs only had a few thousand miles on them. NGK's out and AC Delco back in. Solved that problem. Do you remember ever hearing any loud bang or pop under load. Mine did that and I thought it was loose intercooler hose connections but after double checking everything else swapping new plugs was the cheap 15$ answer. 2 or 3 of the old plugs had cracks in them. Might have cracked when I pulled them but car ran fine after the new plugs.

 

[TurboBuRick]

Sounds like torque converter solenoid is on it's way out.

Unplug the connector on the passenger side of the trans and go for a ride.

RL

 

[626gn]

Another vote for TCC Solenoid...

 

["Turbo-T"]

Thanks...question....if the torque converter solenoid were going bad, would it get progressively worse to the point of where it would cause issues even if the transmission were in D, and not OD?

Second question....if I were to unplug them solenoid, is it ok to leave it unplugged? or will it eventually cause converter and/or transmission damage if left unplugged while being driven?

Thanks in advance.

 

[626gn]

I'm no expert on this subject by any means but having gone through this problem myself, I would say yes to the first question and no to the second.

If the TCC Solenoid is in fact your problem, leaving it unplugged should only be done temporarily as the transmission will run hotter than usual. Luckily, replacing the TCC is easy enough to do that there is no good reason to leave it that way for any extended period of time anyway.

First step is to unplug the solenoid and go for a ride, as suggested by TurboBuRick, to confirm this is your problem.