Overdrive slipping when shifting down and then back up 2004 1st Gen

Makes perfect sense. I don't mind paying for it to be cleaned if it's going to pro-long the life of the trans. I am so new to this forum. I tried to search on the local area here in middle, ga to find recommended shops, but couldn't find anything. I will ask around. Thanks again. You've been very helpful.

 

No 5th gear on the 04 Tacoma. 4 gears; the 5th "shift" you feel is the lockup clutch. 4th should engage around 35-40 and the Lock up at 50 with ECT Normal and 60 with ECT Power engaged.

TBH, it sounds like axel wrap, especially with the "thud" but never heard of that during highway driving. Do you get it at launch and when stopping?

Fluid changes on transmissions are always good but before you go to a trans shop and start throwing money at this, try greasing up your drive shaft, especially by the splines (where it connected to the rear axle). Grease this one until you see the slip yoke expanding and grease start coming out along the shaft. If this "fixes" the thud, its only temporary but its cheap. Consider new leafs or helper leafs as well as new shocks.

 

Remember you don't want to let the shop do a 'flush' or 'power flush'. You specifically want a 'drain and fill'. If it's a shop worth anything they will understand exactly what you're saying, as they know drain and fills are much safer on a tranny with unknown maintenance history. Your symptoms, to me, sounds like a very good chance some fresh tranny fluid will help

 

Make sure the driveshafts u-joints and center bearing are squeaky fresh and I’d throw some new shocks on the old girl. Stock replacement KYB shocks

 

@StAndrew I do not get it at launch (well I have not noticed it). I am only experiencing this when pulling a hill, driving 50-60 AND when I have to slow down and then speed back up (on an incline). You'd be surprised at how often you have to do this... I live in the Middle, GA. (Piedmont area) small rolling hills-not a flat region.

 

Definitely grease your u-joints, it's easy and just costs the price of a grease gun and some grease. The u-joints should be greased regularly but it's one of those things that gets overlooked by most and it will really exaggerate the feeling of axle wrap.

 

Fluid change won't hurt but I would expect bad fluid to manifest itself through all gear changes. Could be a bad lockup clutch.

Before going down that long and expensive road, do yourself a favor and hit this grease fitting with a grease gun until that slip yoke starts moving and you see grease come out at the seams as expertly illustrated below:



Other zerk fittings on your u-joints won't hurt.

Glove and many disposable towels are your best friend here.

 

If you haven’t already, throw some new spark plugs into it

 

Same exact issue here, but AFTER an expensive trans rebuild. Only under load at 60mph and 1900rpm on a hill. Drive line is lubed, axle shimmed. It’s a 2001 with 2.5” lift on 32” tires. I’ll be doing plugs and wires soon, then taking it back to the trans shop. I too can avoid it if I disengage OD to get through that range. Driving me absolutely nuts. Any thoughts on whether this could be due to gear ratios being off with a lift and slightly oversized tires?

 

Found the cyl 5/6 coil was out of spec resistance. Swapped it and I’m good as new.

 

I have an automatic, and I hope it is merely that you are noticing the torque converter unlocking and relocking. It will occur as you first encounter resistance, beginning a slight incline. It amounts to about a 300 RPM change in engine speed. If it becomes a significant hill, eventually, assuming you are applying gas to maintain speed, it will fully down shift, which will be a more significant change in RPM's. And once over the top, it will upshift first, and lastly, the converter will relock. Hope this helps (and this is the only problem)

 

This sounds an awful lot like what happened to my 04 Tacoma. I thought it was a transmission problem but ended up the #4 spark plug was misfiring. I replaced plugs and wires and it runs great with no more overdrive issues.