Help. Engine/Transmission Problems

My 2001 Grand Am has some serious issues that I really need some help solving. It's the 3400 engine with automatic tranny.

Problem:
Severe studder when accelerating
Surging when holding speed at 80km/hr @ 2000rpms
Rough Idle

The studder seems to occur the most after the engine is warm and only when shifting from 1st to 2nd gear. The harder/faster I accelerate the worse the studder. It kinda feels/sounds like the transmission is unable to find the right shift point or is just plain slipping. The fluid and filter were changed about 15,000kms ago. I've read that the torque converter can cause this and that the car does not use the TC when driving in 3rd. My problem occurs in both drive and 3rd gear.

So far I've cleaned the throttle body and the IAC and it calmed my rough idle a bit and increased pedal response but the rough shift and surging is still a problem.

I'd be very happy with any and all help anyone can provide.

Welcome to Af Brass GA !

HAve you had the trany scanned for codes?
Most trans codes dont trip the SES or SVS.

The simptoms you are describing sounds like a CV joint issue. Lets Hope :D
On the surge check and make sure all the vacum lines are connected, and none are cracked(like the thin gray hard lines on top of the TB). Make sure your pcv is working.

No. I haven't taken it in to have the transmission scanned. I'm going to see about getting it in soon.

I did notice something odd when cleaning the IAC and TB. There is a bracket that mounts to the top of the TB that supports the yolk and cables for the throttle plate. There is a line that runs underneath it that continues to the PCV. Off of that line directly under the bracket is another connection. If I remember correctly it enters the engine just after the TB. It was quite loose, to the point where it looked like air could be brought into the line from the engine bay. I don't know what that device is but it seems to me that it shouldn't be loose.

Yes it gets loose another fine engineered part.

They arent supposed to leak but it will and it will affect the performace of your motor just like a vacum leak.

It connects to the O2 device under the ciol packs. Thiers also another vent on the back valve cover that connects up front to the manifold(i think) by the fuel pressure regulator.

You can take the part under the TB off and pull off the rubber sealthats loose, and goto a parts store and find a replacment if you need. The rear one(on the rear valve cover) is the same size and shape.

also, sometimes a shudder is the trans though and its not good :nono:
But you can check those CV joints by jacking up the car and checking them out.
Make sure the boots are in good shape and not throwing grease everywhere , thats messy.
Might hav the trany fluid checked too, maybe a little low and causing some shudder/vibrations.

But your best bet is getting it scanned, then go from thier.

get it scanned look for a p1811 a bad pcs can cause a launch shudder.

Just a suggestion in addition to the good advice above but check into the possibility of a flaky intake air temperature sensor (IAT) and/or the electrical connector to it. A flaky IAT sensor will make the tranny look bad such vibration, shudder, poor upshifts and going into reverse.

Normally it throws an odb-ii error code and SES light but not always. It has been a common problem with Grand Ams and Aleros with the 3.4L V6 and 4T45E tranny.

Good advice Bob, totall forgot about the IAT :iagree:

Guess one cant always think of everything :lol:

Good advice Bob, totall forgot about the IAT :iagree:

Guess one cant always think of everything :lol:

No problem Xero. Keep up the good work. :thumbsup:

It was fresh in my mind since we just had two similar issues over at the Alero forum. Plus some Grand Am owner PM'd me yesterday inquiring about IAT and tranny issues.

Thanks to all of you. I should at least be able to check into the IAT myself. Any idea what a new one should cost me?

Thanks to all of you. I should at least be able to check into the IAT myself. Any idea what a new one should cost me?

Aftermarket around $10. GM AC Delco $18.96 list price, PN: 12160244.

Checkout these two posts and see if your symptoms are similar.

http://www.automotiveforums.com/vbulletin/showthread.php?t=600280

http://www.automotiveforums.com/vbulletin/showthread.php?t=605788

Good luck.

No problem Xero. Keep up the good work.

It was fresh in my mind since we just had two similar issues over at the Alero forum. Plus some Grand Am owner PM'd me yesterday inquiring about IAT and tranny issues.

Thankx I'll try :D

I have heard of folks pulling the MAF off and spraying TB cleaner in while its running :eek7:
thats not good ! kills the IAT about everytime.

Well that would be my fault for following the directions on the TB cleaner...
Although the problems I'm having started long before my "cleaning"
I wouldn't be surprised if I have a vaccum leak somewhere. Unfortunately that would seem to be a tough thing to find.

Hey Brass_GA,
vacum leaks can only happen on vacum lines,
does that simplify the search :D
haha Just Kidding!

Most of the time you can hear the "hiss" of the leak if you listen close.
If you hav a long tube(or pipe) just follow the lines while listening and it'll help pick up the sound(s).

Well it's show and tell time guys. I'll show you some pics and you can tell me what you think :)

I was doing some investigating tonight when I spotted what I think to be a possible vacum leak. I noticed what looked like carbon deposits on this line and I'm pretty sure I could hear a hissing that got louder as I increased the throttle.

PIC 1 - Main concern. Looks like a leak to me. Not sure what the line is for.
http://i90.photobucket.com/albums/k242/Brass_GA/DSCF1888.jpg

PIC 2 - Lower view.
http://i90.photobucket.com/albums/k242/Brass_GA/DSCF1887.jpg

PIC 3 - Unknown Port. Looks like a line should be connected here. Maybe for a different engine config?
http://i90.photobucket.com/albums/k242/Brass_GA/DSCF1890.jpg

Let me know what you think. Is there a safe way to test this for leakage?

TIA.

the pics, the metal tube running down that has blackish stuff on it would be your power steering hose, not a vacum, and its getting a small leak started.

Not bad enough to cause concerns at the moment.

that port on the back of the intake isnt used and should be caped like it is.

Most of your vacum lines are on the left side(drivers).

I'm having the same tranny issues in a 2001 Grand AM (except mine is slamming from N to D and when it's shifting from 1st to 2nd and 2nd to 3rd) with the IAT sensor code reading high. I replaced the sensor and it's still doing the same thing. Is there anything else I need to do? Do I need to reset the light? Do I need to replace the wires as well? It seems like it would be too much of a coincidence that the IAT sensor code would show up at the same time that the tranny starts acting up and the solution not being replacing the sensor.

If the IAT tripped the SES or Svs light then it needs cleared/reset.
when the Iat goes out it puts the car in a rich fuel mode by telling it that its 32deg, which can lead to other troubles.

But the wires dont need replaced unless they are broken.

I'm picking up my new senser today so I'll post the results tonight. I doubt that the plug and wires are the problem. I looked them over for damage but the wires are good and the plug fits snug onto the senser.

Well my new IAT is in but I haven't noticed any improvment. I'll clear any codes that might be stored just to double check but it looks like I'm headed for a tranny scan.

Update:

I may have been too quick to judge. It might just be me but it sure felt like I was getting more power and better performance as I left work today.

Lets say that the IAT was my problem. Could that fault potentially cause damage to my transmission?

Not really, it probly just making your trans pressure raise and making it shift funny.

Keeping your trans fluid & filter changed regularly helps keep the trans in good running condition.
OUr manuals recomend the F&F changed every 50k mls(83k kilo) I try and do mine @ 30-40k. Doesnt hurt anything that frequent.

Hope you got it fixed though :cheers:

Resetting the codes and changing the sensor worked for me. Thanks everyone!

No prob merrittjr, and youre welcome!

Well, I spoke too soon. It worked fine for a half day, now it is doing the same thing again. Any ideas?

OUr manuals recomend the F&F changed every 50k mls(83k kilo) I try and do mine @ 30-40k. Doesnt hurt anything that frequent.
I have been changing mine every 15K miles.
Otherwise it starts doing the same thing as described in this thread.

I think the tranny itself is just junk.
Look for a new thread about mine in 10 minutes. :lol: :lol:

Well, I spoke too soon. It worked fine for a half day, now it is doing the same thing again. Any ideas?

If that sensor keeps going out, and you are using a K&N (or other oil type air filters) it could hav to much oil thats getting on that sensor.


I have been changing mine every 15K miles.
Otherwise it starts doing the same thing as described in this thread.

I think the tranny itself is just junk.
Look for a new thread about mine in 10 minutes.


Yes the 4t40-45s are pretty weakass transmissions.
Nothing I can do about it :lol:
I'll check for your post.


You both probly hav some other transmision problems.
Thiers plenty go wrong in one of these 4t40's.