02 Bonneville SLE/Transmission

[ChippaT]

I'm new the forum so bare with me. I own a 2002 Pontiac Bonneville SLE w/170,xxx miles. I've had a hard shift between gears for as long as I could remember but showed no immanent threat of leaving me stranded so I've payed no attention to it. A new issue has occurred, as I'm leaving work I put the car in reverse and it starts chugging(as if I unplugged the MAF sensor), put it into drive(chugging stops) and I take off for about 50 ft until I reach a stop sign. If I try to accelerate too quickly thru the intersection, it seems to stutter and slam into gear(without ever leaving drive). Once it happens it wont happen again the entire drive home. It only happens when the car is cold as it never happens when I leave for work because I allow my car to warm up. If I baby it around it seems to minimize the impact, but id like to get it fixed before any real damage happens, if it hasn't already.

The only codes that are being thrown are related to an evap leak that trips the check engine light. I don't have an OBD II reader that will read transmission codes and the tranny shops around my city will not give you the codes as they will tell me, I need to have the tranny rebuilt(which may or may not be true).

Symptoms that could be related or unrelated:
Chugging only in Reverse
During cruising speeds 45-65, small shutter in the "trans"(surge about 200 rpms, barely noticeable)

I've read shift kits may help eliminate hard shifting between gears, but I'm unsure if it will help the stutter/slam into gear during a quick take off. The car still runs and drives so I plan on installing one anyways because they're relatively cheap and easy to do, and while I do that I'll replace the tranny fluid and filter, but otherwise it's full and clean.

Could be the PCS or tranny mounts, but id like to see what others have to say before I start throwing money at the issue.

[nos4blood70]

You are experiencing two things, possibly 3.

Hard shifting can be cause by a worn front transmission mount, or the common P1811 code which is fixed by installing a TransGo shift kit.

Your slamming into gear from first is known as delayed engagement. No real cure for it, but I used to have this issue and some Lucas stop slip and Castrol High mileage ATF got rid of it completely (knock on wood).

[ChippaT]

I found out the front transmission mount was broken. Replaced it and dumped a bottle of lucas transmission fix, took it on a test drive. It ran really well, and shifted well. Until I sent it through an intersection a little too hard and broke the input shaft in the transmission.

[mikesica]

I have a question for long term owners of 2000 to 2005 Bonnevilles that have not needed to replace their transmission or have gone lots of miles without replacing their transmission. How often do you drain your transmission fluid?

[mikesica]

Well, my transmission just went out at 158,600 miles, and I got a reman transmission. The rest of the car is running well. Hopefully my Bonneville will get me a lot more miles.

[nos4blood70]

I've been draining my fluid about every 50k miles. I've also added a transmission cooler, and a TransGo Shift Kit. I do my best to drive the car gently for the most part. It's been in my care since 40k miles, and we are approaching 230k.

My car is also an 03, so I understand it received many updates for that year, including a hardened 4th gear hub.

I have no idea how long it'll go, but for the most part it shifts nicely.

[mikesica]

I've had my '01 since new. I have been easy on the transmission all along, and I've been changing the trans fluid every 30,000 miles. However, I don't have a trans cooler or the shift kit. Hopefully I'll get many more miles.