Do I need a new transmission

So I just got my 2000 tundra running. Needed a new starter and battery terminals. Was having a misfire and a bad 02 sensor. Figure out that the misfire was due to a spark plug not being gapped correctly. Fixed and no more misfire. As for the 02 sensor not really sure haven't driven it enough to get it to pop a code yet. Old seemed okay, but I'm not really sure I kept it just in case. So the reason I ask if I need a new transmission is because when I drive it it drives just fine, but I punch it it struggles really hard. It almost sounds like it's smacking a rod if that makes any sense and it takes a while for it to shift into the next gear. The reason I think it's a transmission is because (correct me if I'm wrong) when its in park and I rev it it's does just find and doesn't sound like there is anything wrong with it. Even when I put it in neutral and punch it. It runs smoothly. It only bogs down and makes a rod smacking sound when in gear rolling down the road and punching it. Going up hill when it down shifts it does the same thing, but it will hit 80mph on a flat highway. I have no clue when it comes to this so if it sounds like I do I don't it's just from what I have gathered. Maybe there something wrong with the engine and not the tranny. My plan is to bring it in to a tranny shop the down the road from me that offers free tranny diagnosing to see what they say. If they say it's bad what are my options? I can turn a wrench would it be worth finding a used one or just having the rebuild it? I mean I know it comes down to money, but for those that have swap them. Was it worth it or is it going to being a crazy pull the engine out kind of job? Any inght or tricks to figure out if it's the tranny would help. Either way thanks and sorry this is so long.

 

An EFI engine and automatic transmission both work together. If the engine is not running right the transmission will not either. The system is complex and takes into account things like air pressure, fuel octane, etc to shift and rev and provide the right amount of fuel at the right time.

I'm not sure what the o2 sensor thing you are talking about is but some of the o2 sensors are critically to the engine running so you need to lock that down before getting too excited about anything else.

As for replacing the transmission, yes, you just drop the transmission. Its not fun but its technically simple.

 

Okay I'll look into the 02 sensor some more. It was throwing a code for bank 1 and so I replaced it. I haven't been able to run it enough for it to throw a code if it's going to throw a code if that's even a thing. I didn't realize that the engine and transmission worked so closely like that with an EFI Engine. I assumed that both just did there job and that one wouldn't affect the other. I for sure am learning a lot about it now.

 

Just for the heck of it, try briefly flooring the accelerator while cruising on flat ground. Don't hold it there, just tap it down and release, this should force the transmission to downshift a gear, a feature designed to build more power for passing. The transmission should immediately drop down a gear, and stay there for two or three seconds and then shift back up unless you follow through with more gas, its interesting to do because it shows how the transmission is acting without increased rpm or load from the engine.

But in any case, this sounds more like an engine problem than a transmission problem at this point. But having a pro check it out could certainly help and save a lot of time.

How an engine performs in neutral with no load really tells you nothing about how it works under load. Because the ECU knows that there is no load, it provides very little fuel and air at 4k in neutral than it would at 4k going up a hill. Something like say, a poor fuel supply, would allow an engine to run fine with no load, but make it fall on its face when it actually needed torque.

 

I remember hearing many accounts of what the owners thought were transmission issues on the 05+ f150. I think most of those issues were actually coil or spark related misfires that were then manifested as a jerking that felt like the trans or torque converter was bad. I'm just going off of memory with that anecdote, but @Aerindel is correct that the transmission/ engine relationship is like a symphony of sensors more than a duet or solo.

 

Remove spark plugs and coils and take pics and post them up.

How many miles on truck?

FYI I drove on a bad 02 sensor for a few years. Can’t remember exactly but think it was the rear drivers. Truck seemed to operate normally except for CEL. Was it the proper thing to let it go? Nope.

 

I was under the impression that the post cat sensors were to check function of the catalyst and the upstream sensors were more vital air/fuel/etc adjustments. If that's a correct assumption then the post cat sensors would be less likely to make the engine do strange things when they are bad.

 

Good point and reason I did not replace it right away. I think I have a new one on the pass side near the engine, as well. Not only that, all of these were replace during recall in mid-2000’s so I’m on my 3rd sets. All mis-matched. I was going to type this, but figured it would come up.

 

As others mentioned, start by fixing the known problems before throwing parts and money at it. Get the engine running right first. As cheap and easy as it is to change spark plugs on this truck, get that done. I don't understand why people don't start with this. As PHM mentioned, exam the coils/boots for damage or cracks.

Have you checked the trans fluid for level and condition? Extremely easy to do a drain and fill if it needs changed. Again, as cheap and easy as these trucks are to work on, I'd be doing all the fluids anyways along with an oil change, fuel filter and air filter. Dump a can of seafoam in it while you are at it.

 

Did you just get the truck? It's possible if the PO let the o2s go bad the ecu compensates by dumping more fuel in. That can kill the cats causing them to break up and clog. Which can lead to a loss in power. Happened in a grand prick I had. Would cruise up to 80 all day but did not liked being floored.

You might check your MAF too. If it's reading too little air it's gonna run lean which could cause knock. But I think your knock sensors would pick up on that. Not sure. Hopefully someone smarter than me will let us know.

 

In your first thread about your starting problem you mentioned that the truck was sitting for about a year. Along with what was already mentioned about doing a full service if you haven't done so yet check the air filter box for a rodents nest, check for any chewed on wires and clean the throttle body.

 

So I have removed then and they looked fine for the most part. They have all been replaced with in a 1000miles before I got the truck. Currently no check engine light is on. They were replaced at the dealership so all new OEM packs and plugs where put in.

 

So I have not checked the tranny fluid which makes me look stupid, but I will for sure when I get back to the truck and the only reason I had not replaced spark plugs or coils was because it was already done, but I am thinking of replace plugs for sure coils seem okay, but the. Again they could be back. I'll feel so dumb if I check the level and it's low. I'll have to YouTube how to change the tranny fluid and give that a try and well.

 

Oh I have a feeling the cats are shot, but was trying to avoid having to change those out. I'm pretty sure they drove it with a flashing check engine light before and killed them. Trying to rule everything out before swapping the cats.

 

Good point I'll check that as well. I cleaned the throttle body when I first pulled it off to get to the starter.

 

Sweet. So you have all new OEM coils and new plugs. Thats huge money.

Check that transmission fluid. The level and freshness of the fluid is critical to shifts.

If your cats are bad I’ve read that your engine performance becomes better when they are removed. You can do your own research on that one.

 

Not stupid at all. It's something a lot of people over look. No need to google it, it's stupid simple. Drive it till the truck till you feel the trans fluid is at operating temp and then check the level. I've always been a fan of measuring what comes out of the trans and putting that back in for a starting point. If it measures within the good lines, put in the same amount you removed. If it was over/under, adjust as needed. It's one bolt (14mm?) right on the trans pan you'll need to remove.