ignition or transmission?

[MurderMitten]

So yesterday my bonne did this weird thing and it did it just now on my way home. When it's about to shift into fourth gear only at about 40-45 MPH, the car sort of draws back, picks up, draws back and picks up. It doesn't feel like anything with the motor because its smooth. Its like going on the highway and having three huge gusts of wind in a row. Only going into 4th gear. Could this be a side affect of my shift kit PCS bandaid fix because the shift kit is for 1-2 ans 2-3? It still shifts smooth into every gear and it seems to only do it on even the slightest incline. Not sure if I should be worried

[nos4blood70]

Sounds like something ignition system related. Check out the common problems thread for the 2000+ in the 2000-2005 section.

[MurderMitten]

I guess friday I'll pull the plugs and check them out maybe the wires should be replaced? any good way to check wires? or if the plugs are all good wouldnt that mean the wires probably are too? I have a couple extra coils I could swap out

[nos4blood70]

Try swapping coils. You can test if the wires are good by using a screw driver to arc them to a piece a metal under the hood.

[MurderMitten]

I'll try, only have one coil extra for sure maybe two so if I have two coils acting up I think id still be experiencing problems. My grandpa has a computer monitor ( cant remember what the brand is) but its brand new and reads avg mpg, KR, maf readings, throttle position etc. Pretty much a plug in version of bobgto's carputer, wonder if it could give me readings while driving.

[ChibiBlackSheep]

Personally it sounds like it's a Torque Converter lock-up problem.

Put the car in 3 and drive. If it doesn't do it, then don't worry about your engine, it's the trans.

[MurderMitten]

Ahh don't say transmission

[MurderMitten]

Spoke to my mother with a bonneville, hers was surging due to a clogged EGR. Read a couple reports online of EGR malfunctions also

[nos4blood70]

Surging at 47+ mph while going up hills
Problem: You have a noticeable surge at 47+ mph while going up hills when the tranny is in OD.
Solution: While this problem feels like a transmission issue, 99% of the time, it is an ignition issue. There are 4 basic components in the ignition system: spark plugs, spark plug wires, ignition coils and the ICM (ignition control module) mounted under the coils. If you don’t know how old the plugs/wires are, replace them. Coils next, followed by the ICM.
Estimated Cost: NAPA Belden Premium Wires, $30-40
Spark Plugs (NGK TR55 or Autolite 605) (Never Bosch), $12-48
Ignition coils, used $10-15 each, new $30-70 each
ICM, used $30, new $130+

[MurderMitten]

Yeah I read that. My mom just had the same problem. got brand new plugs wires, coils and ICM and turned out she had a clogged EGR. I'm going to clean the EGR and then drive it, if it still happens I'm going to swap out my mom's plugs and coils. Or test the torque converter by pressing the brake while cruising and seeing if it locks up

[MurderMitten]

So I read something on 3800pro.com about testing the torque converter while driving by barely pressing the brake to engage the brake lights and accelerating from 40-50. Well I did that and it dropped a gear and the rpms went from about 1500 cruising to 2200-2400. Not sure what this test does it says to test if the torque converter locks up. Anyone know about this technique? Let me know if this can help me out at all. Will check egr and icm tmrw just figured I'd try this cause it said to do it driving.

[erickaltman]

Check all your vacuum lines too

[MurderMitten]

So bringing this thread back up because I did not do anything for a while because the problem seemed to disappear, only coming up on rare occasions. Recently It has been surging, or so I think. I can never tell if its wind or the car because I never really see the rpm's move at all it just sort of draws back. I thought it was the trans because the trans did have a little bit of a hesitant shift during that period but I could just be paranoid. transmission has been shifting perfect lately so I'm leaning against that. My question is, if the coils or ICM were the problem would they just go out or would it run rough? I don't have a ton of money for those parts but I'm driving 2062 miles round trip to florida next friday and would rather suck it up and replace something than paying for it brand new down south when I can pull junkyard parts..

[MurderMitten]

bump.

[bs009]

I would expect you to notice issues elsewhere too and not just at lockup at that speed if it were ignition related. Sounds more like a TCC solenoid issue; all of the transmission solenoids seem to go bad somewhere around 150,000 miles depending on they type of driving they see.

I would:
- Check transmission fluid level
- Make sure plugs and wires are in good shape. Pull out the plugs and observe the color and gap size.

If that doesn't work, this might help out but it's a bit of a longshot:
Pull off the negative battery cable for a minute to let the pcm reset. I've heard there's a variable that the pcm learns over time that adjusts how much pressure is used during each shift. If it learns the wrong pressure because of a shift that took too long or a shift that was too quick then it could cause problems when there isn't really one to begin with. It's unlikely that this is the issue but it's worth a shot considering that it's free.

I actually noticed my car doing something similar a few months ago with a fresh transmission rebuild including all new solenoids and a new torque converter. It only did it at around 45-53ish and it was doing it for about 2 weeks. I unplugged the battery and it's been fine ever since.

[MurderMitten]

I'll check tomorrow. I have noticed the past couple days I have a more firm shift but no where near hard or harsh. As in I know its shifting its not super smooth. I have a transgo in there and fresh fluid/filter as of 1.5-2 months ago. It does not only do it at a certain speed anymore its quite random. Doesnt always happen and doesn't always happen under same conditions. I feel like I can feel the motor vibrations more at stops as in its a lower RPM idling which is why I'm not sure the problem. Has symptoms of trans and ignition. Tmrw I will, check plugs/wires/coils/clean EGR and check tranny fluid and color. Checked it a couple days ago and it was full. Good color and no burning smell, probably hasn't changed..

[bs009]

As long as you're at it, I'd check for broken/loose vacuum lines too.

[MurderMitten]

I have been getting the occasional SES light for P0440 EVAP leak (small)...

[bs009]

That could be something as simple as a loose gas cap or as big as a mess as replacing the entire 3rd fuel line(vacuum line really) all the way back to the tank.
If you're fuel lines are looking pretty rusty, I wouldn't be surprised to find that third line leaking. Otherwise that's probably a leak underneath the hood.

Hopefully that's something simple like a leaking vacuum line though. I wouldn't lose sleep over it if you can't find it, but it will help your gas mileage if you can find it.

If you see any of the rubber vacuum lines falling apart underneath your hood, I'd just get some rubber and go to town on all of them you can get to easily. Rubber vacuum hose is cheap.

[MurderMitten]

So, Checked plugs and wires, both good. Put my mom's brand new coils and ICM on, no surging. Drove fine yesterday but now today its been acting up. I have a feeling it's transmission but I'm not 100% sure. my ICM and coils are on now but I still cant figure out what is the source of it. Not sure if it is the ICM and Coils because it doesnt do it every day so yesterday might of just been a day it didn't act up...