Thread: Evap leak and surging in 4th

hopefully that got your attention haha. Anyways I need a little help with my car. recently its started bucking. I am taking it to the dealer to call them up on there warrenty. I just dont want to get ripped off so looking at few other opinions.

description
It happens in overdrive, at 30mph 45 mph and 75mph from what I can tell right now. it jumps 200ish rpms, and happens flat ground or up hill. The shifts are good. have a SES light for p0442 for a small evap leak. when revving in park, engine has no issues at all.

what I've tried
lucas fuel cleaner/mobil premium. seemed to help and get less common but now its happening more frequently. other than that not much cause of the warrenty. I do not want to void it.

What i think it could be
I don't believe its the wires or coil pack they look brand new. I am unsure on the plugs because I have no blinking engine light, and when revving in idle it doesn't have any problems at all. I believe its transmission related. but all I could think of was fluid change, vss sensors, and torque converter(dont know if it is for sure cause at all other speeds it stays in over drive just fine)

addtional info
if im in the bucking and tap brakes it stops rpms jump, drop, then start bucking again. mpg is perfect. Speedo bounces about 5mph

thanks for any info help and patients for reading this . Will appreciate any feed back.

Tcc solenoid probably. The torque converter will stay in lock up. Check your codes again soon.

When you say ... you've tried premium mobil fuel. Does that mean that you typically don't run Mobil or don't run premium?

If you answer that you don't run premium, the issue is between the seat and steering wheel. Likely you hurt the motor.
If no to the above, then change the plugs and wires. You are probably running some crappy plugs like Bosch platinums that get destroyed in our waste spark environment.

I'm changing your title... Cause you don't need a mechanic to solve this one. Likely it's straight forward enough thatmy 17 year old neighbor could solve it in ...HER sleep.

LOL at bill I wanted to get your attention along with other mechanics because you guys IMO r more experience, I'm tight on cash and when dealing with my local dealerships and C.A.R.S's certified mechanics you need to tell them what you want. Otherwise they do something completely pointless, don't touch it and say your car is destroyed then offer you 300 dollars to "take it off your hands", or charge you the price of a new engine then you have the same problem and have to go over it again. I don't mean to offend any mechanics/ car dealers on this forums. These are just for the mechanic that I can take it too. If I could I would trust my car to you guys instead.

Ok on to answering questions.
car has only used premium from me.
I work at autozone just an fyi lol Guy needs to work
And going to try to find a few trust worthy garages tomorrow under the warrenty and drop it off


Now what to have them check
tune up/Sparks/ wires/ coils. if problem is still there/not needed
tcc solenoid / tranny fluid change/ if that doesn't work/ not needed
??take it like a man and let them do their thing??

as for evap I don't care about it. Its my gas cap the gasket in there is gone. I'm going to replace it with one from a dealer soon. Just wanted to throw that in there. Cars r funny and the littlest things can cause the largest problems. I had one evap hose pop off once and that threw like 12 codes 2 of which being misfires.

Also If the issue is spark/injectors wouldn't you have a blinking engine light for misfires? I suspected those right off the bat but after driving in it for a while and not having a light that would indicate a misfire, I wrote it off.

Originally Posted by fry626

Completely disrespects and belittles new member...

Is that how you read it? That's not how I wrote it. Maybe you need to hang out with me to understand how I would have put tone and inflection on that blurb.

His title was in all caps as if he was screaming for help from a mechanic. I'm pretty well versed in these cars and am not a mechanic. My mechanic buddy calls me when he has a question on this kind of car though. What hsi titls would get from veteran members is skipped by. It's the "OH GAWD MY CAR SUCKS, HELP ME!!!!!!" that most vets roll their eyes at and skip until they are bored. By changing his title, he'll get a lot more views and insight. It's odd...it's reverse psycho though.

Experience (and searching if done) will tell us this issue is 85-90% likely to be the plugs. These motors run well for so long, that people often forget them. Then parts slingers often sell the guy the Bosch plug, which is known to break down super quick in the waste spark ignition system. Poof.. month or two in you have surging, maybe misfires, etc.

first off, swap them plats out for iridium plugs, and if that dont fix the surging, chances are its the TCC/ pcs in the trans going bad.

you could go with copper core plugs if you want to cheap out, they run about 2 beans a plug, and these engines love them to death, only down side, is they only last 15,000 miles, where iridium will go 90 ish.

these engines just dont like platinum plugs, most seem to misfire from them.

and im pretty sure they never came with platinum plugs from the factory at all.

Ac delco part number is 41-101 for stock plugs.

4th gear its a very high load gear, its possible something internal with the trans is wrong and causing the surging/bucking you are talking about.