I have a '02 Camaro with A/trans. It has all the "SLP" bolt on up grades and a Torquer 2 cam 232/234, .595"/.598", 113 LSA, and 225cc 2.5 CNC Ported Heads, and an after market SLP 3300-3500 torque converter. The dynojet shows 425 wrhp and 380 ft. pounds torque. It runs pretty well in my estimation, however, I am experiencing "Bucking", "surging" or "grabing" when I am at speeds of less than 40 MPH when I let off of the gas or when I am going slow with very little or no gas pedal. I have resorted to down shifting into either 3 or 2 when at low speed to keep up the RPM's and then the problem goes away. When I am accelerating I do not experience any problems.

I have had several tuners look at and fool with the tune, all with little to no improvement. I have also drilled out the small hole in the throttle plate by an extra 1/16 with out any improvement. I was told to enlarge in very small steps, so I am reluctant to go any larger without more feed back.

Then this A.M. I was watching the "Speed" channel and they were talking about the Converter and described the "Grabing", which is exactly what I am experiencing. My car only has a total of 6,000 miles and only 2,000 miles since all the mods were done.

From what I have tried to describe, could I be experiencing converter problems. Can this be fixed via tune?, is there a lock out switch? or do I need to change out converters?

I do have a new performa built trans T-3 with a 3000 stall still new in the box in the garage. Is it time to make the change over? and when I install the new trans & converter do I need to change my tune at the same time? Is the 3000 stall the correct stall for mostly daily driving and an occasional trip to the track??

I understand I have asked more than one question in this post, but I would appreciate some input from you veterans.

 

Does your converter lock up at 40mph? or is it still unlocked at that speed?

 

TCC was the first thing that came to my mind as well. Might want to raise the tcc operation in your tune. Lets try this the next time it does it. Lightly touch the brake pedal while keeping a steady foot on the gas and see if the condition goes away. If so it is more than likely an issue with the tcc or it's operation. This will give you a place to start. Vince

 

Good question!

What I can say is after letting off of the gas the "grabbing" does not start until under 40MPH or I can be in light traffic with just a tiny bit of pedal and I will experience the "grabbing" generally below 40MPH. Sometimes when slowing down for a corner or turn I will also experience the "grabbing or lurching".

I am sorry but I do not have enough experience or knowledge to tell you for sure when the stall is locked or unlocked at 400MPH.

I will also go out this afternoon and apply the brake as suggested in the other reply.

Thank you for your interest and time.

 

You should be able to tell when it locks. its fairly obvious. The converter wont feel loose anymore. The car will feel more sluggish. like putting a manual trans in 5th or 6th gear.


what i was thinking was maybe someone set your lockup speed lower around 40mph and what your experiencing is just some cam surge from the very low rpms. stock conveters are set to lock up around 47mph.

 

Thank you!! Your explanation helped me a great deal. I would say the Converter is locked around 40 MPH.

I will have to have someone look at the tune specks.

I have been waiting to install the new PerformaBuilt Trans at the same time as a new rear end, but that is going to be down the road another 6+ months. Just love the economy, it is killing me, as Mama is watching the cash flow like a Hawk.

I have read and reread the different threads on the converters. On my 4L60E is the converter set only on MPH or does RPM have anything to do with it?

Yes, the cam surge has been mentioned, however, when I heard the explanation this A.M. about locking and unlocking the converter, I just about jumped out of my seat saying "Yes, that is exactly what I have been experiencing".

Again, thank you for your time and input.

 

Yeah these guys are steering you the right direction. When mine locks at 40 with light to no throttle it surges just as you describe. Its pretty normal as far as I know. I know my tuner could raise my lock speed but it doesnt bother me much. Reminds me I have a cam

 

01Red,

Yes I understand about the Cam and I too am living with it, however, I have to take my wife out for a drive every now and then, and she is not into any sort of cars or performance, so her I am.

I greatly appreciate the help.

I will try taping the break and see what happens.