Buick Surging When Accelrating

When my car is at operating temprature and I am in either in 3rd or 4th gear ( 1st and 2nd doesnt do it ) my 97 Buick LeSabre will start to surge when I slightly accelerate. If I let off the gas and activate cruise it doesnt do it unless I am going up a hill. When it starts surging and floor it will stop. Also I just noticed when I am going at high speeds like 65+ and the cruise is active I can feel a little bit of surging as well. Hope this makes since and someone can help me out thanks.

When was the last time you changed the wires & plugs?

This a surge or a misfire?

The car surges is the best I can discribe it. You can see the tach flucuating about 500 RPMs when it is doing it. There are no codes for both the engine nor the transmission according to my snap-on scanner I have.

I had these same symptoms occuring on my wife's Lesabre. Apparently it was related to the lockup torque converter. I did a tranny pan drop, new filter, then a GM version of a friction modifier. I have since experienced maybe 2 or 3 "surges" in the last year, but it's been much better.

What do you mean by a GM version of a friction modifier? Do you mean an additive? If so I didnt know they made one what is it called?

It was an additive. I believe some tranny shops use DrTranny Instant Shudder Fix. I know yours is not a shudder, but one shop told me to use it. Then a GM parts guy told me the shop uses their version. I'm sure both work.

Would love to get a scan tool on this and see the data to see transmission slippage or misfire when this happens....

Would love to get a scan tool on this and see the data to see transmission slippage or misfire when this happens....
Agreed, but on this forum diagnostics like that rarely happen as it requires 3rd party help or accessing a highline scanner.

Luckely for me I have such a scanner but there are no codes the tcc sensor works just fine and the solinoids on the transmission are working fine. When it is surging it doesnt come up as a missfire but when you look at the misfiring data something will be misfiring but not the whole time it is surging it will surge for about 1 minute ( thats the longest I can get it to do it without going too much over the speed limit ) and maybe misfire randomly 1 to 4 times. My plugs and wires are fairly new and my coil resistance it is execellent when hot and the ignition module is working fine according to both advanceauto and autozone ( thought Id get two opinions ). I am a mechanic its just tranmissions, which I think is the problem, is not my strong suit. :banghead::crying: My favorite additive for tranmissons is Trans-x just dont plan on keeping it for too much longer.

We may be getting caught up in a chicken/egg debate here. Is the misfire the cause of the surge, or is the surge triggering a misfire? Sometimes, a "near misfire" can be the cause of light throttle surge. Perhaps this shows an incomplete burn of the mixture, causing a loss of performance but not a full misfire code set. The fact that your wires & plugs are fairly new, means nothing to me. What brand of plugs & wires did you install & does the wire resistance check within recommended range per ft.?

It will surge and the tach will flucuate about 500 RPMs when going up a hill and lightly accelerating when driving straight on the road. It will keep surging then all of a sudden according to my scanner #2 may misfire then nothing, keep driving still surging no misfires what so ever still surging then maybe # 5 or #6 will misfire. Thats the best I can describe it to you. This surging will only happen in 3rd and 4th gears. Im going to try replacing the transmission filter and see what happens I just thought it may be a common solinoid or modulator problem cause like I said im not so hot on diagnosing transmissions but I sure can rebuild them tho :screwy: Oh yeah the resistance in the wires are a good 4k Ohms or so been a while since Iv checked them and didnt write it down.

A lght misfire under load with TTC on sometimes feels like a "fishbite". A surge while TCC is partially applied is easier to see on the tach than it is to feel sometimes, not as sudden of hit, just a smooth feeling of speeding up and slowing down a bit as it slips. When the surge is happening, you need to watch the TCC Duty Cycle if possible with your scan tool and if it is 30%-80% it is likely the converter or valve body. If it surges with the TCC at 0% or 100% look toward engine drivability. Even better if you can control the TCC with your scanner. You can use the brake pedal to disengage the TCC also and see if you can isolate anything by feel. The TCC is commanded on in 3rd and 4th gears, so this very much sounds like a trans issue the way you describe it.

Is there any possibility the TCC sensor is bad or would overdrive not work at all if it was? Also when you say to look at enigne drivability will it say either 0 % or 100% at all times or will it flucuate a little bit or alot?

If it surges with the TCC full on or full off it is probably an engine controls problem. If it only surges with the TCC partially applied, the clutch in the torque converter could be burnt or warped. TCC's will not surge when all the way on or off. Since it happens in 3rd and 4th it is likely to be a converter clutch. I'm not sure what you mean by TCC sensor? There is a TCC On/Off solenoid to enable TCC and a TCC Pulse Width Modulation solenoid to control the application and release of the clutch. You need to COMMAND the TCC on 100% to eliminate or condemn the coverter/valve body, etc. A misfire will get worse at 100% lockup. Do you know anybody with a Tech 2 that can ride with you or drive for you?

I do not have anyone with a TEch2 but I belive my scanner will do all of this. I will try it tomorrow on my way to and from work.