Sputtering when taking foot off gas on highway? Stumped
 

I got a 99 limited 170k approx. the thing runs and drives good but has a lot of issues im trying to hunt down. The latest being when i am on the highway and i take my foot off the gas shes decels nicley say from 2-1k rpms then jumps back up to to 2k where it holds and decels from there very slowy. Does it every time and when i put my foot back on the gas even a little it downshifts immediately Never holds gear. I take care of the truck always do routine maintenance Have cleaned maf tb and iac thoroughly Did 2 seafoam treatments and a redline fuel system cleaner in the past month Also recently put a flowmaster big block on. Could this be the issue? Cat clogged? Iac? Any ideas? Thank you in advance!

I'm thinking shift solenoid or fuel pump. Pretty sure there's a YouTube video on checking your shift solenoids

When you de cel if its safe place it into neutral to try to isolate it some from the transmission. If it is a Transmission issue ensure the fluid levels are proper. Keep hunting.:juggle:

This actually sounds normal to me...

If you are going from cruising in 4th/OD with the torque converter locked to coasting, a few things happen - first, the torque converter unlocks (the drop in RPMs to ~1k), then the engine/transmission/torque conveter sync up in 4th/OD and the engine speeds back up a bit to the correct 'coasting' RPM. When you re-apply throttle, you go from coasting on the torque converter to power on the torque converter and the RPMs go up (that's what torque converters do!!), then if you are going back to low throttle opening (cruising), the torque converter will re-lock and drop the RPMs a few hundred again back to where you were before lifting and re-applying throttle.

More modern engine/transmission combos often keep the torque converter locked while coasting and you wouldn't see this RPM 'dance' that the 4Runner does...

-Charlie

Thank you for the replies! So i just bought a 98 2.7 4x4 just as a side beater (256k burns a lot) It does not do this strange rpm dance it behaves like a normal vehicle and it has the same trans. The rpms only ever go up when i control it with my foot. In fact in general the trans on that one is better shifts way smoother. My v6 ever since i got it bangs or pops hard when it shifts and now it feels like it wants to drive itself sometimes. This all started for me after i put the muffler on and after i played with all my cables. I think i messed up the cruise control cause it bucks and jerks downhills in a consistent pattern it used to just engine brake now it seems confused. I also get a vibration with intermittent thumping under my ass at idle and feel the same vibration at high speeds if anyone cares lol i have done all of the common maintenance suggested on this forum. Please help i dont want to sell the v6 its so sexy in every way!

not sure what the exact measurements are but the should be just the slight amount of slack in both those cables. The way I look at all three of the cables should have tension on them and just a slight amount of slack.:frog:

You have the transmission line pressure cable (also refered to as the throttle kickdown cable) too tight. Get the vehicle up to operating temperature and then loosen that cable until the shifts are smooth enough for youunder normal driving.

sorry for taking so long to reply but this was very helpful thank you for whatever reason before I was being an idiot and not loosening it past whatever thread locker they have on there but it shifts a lot smoother now! unfortunately I am still having the original problem with the rpms jumping by itself on the freeway. its like it thinks Im putting my foot on it to maintain speed but I'm not. I always screw with the accelerator and tranny cable but never the cruise I touched it for the first time recently did I confuse the module? the bucking downhill in cruise is just weird as hell.

Your list of maintenance seems to lack any tranny maintenance.

Have you ever replaced the tranny lube or filter.

since owning it ive put on 60,000 kilometers done 2 drain and fills but never cleaned or changed the filter.

Have you tried driving with OD off and seeing what it does?

Sounds to me like your tranny struggles to hold OD, or as mentioned the throttle position sensor setup is off.

I’d drop the pan and replace the filter just to see what’s what and get a baseline.

I have not tried that but I will! what do you mean by tps setup? when you turn it on the throttle body it acts weird but when you screw it in place doesn't It automatically line up and seat where it should? i should have taken some videos of my issues before I took it apart! I noticed about 6 months ago it developed an issue when I start it, it revs up a bit, then down, then back up to normal and proceeds to do its warm up thing. very strange. did it randomly one day and does it every time now. this was long before I had the sputtering problem.

just following up on this when I put the vehicle in neutral at high speed it does the same thing just faster so rpms drop shoot up and then back down very rapidly when its in drive it drags down slowly then when it hits a certain rpm shoots up. I drove with the iac unplugged and it was doing very weird stuff slow off the line and all kinds of sputtering. when I have the iac out and I shake it in my hand should the valve jiggle around and make a rattling sound is that normal? I drove with cruise control unplugged no difference. I cannot figure this out it never used to do it. I'm also having a weird vibration problem that I've been chasing for a long time (have another thread for this) and im just chalking it up to something broken in the tranny like tc malfunctioning or something and guessing this is all related to the sputtering issue. When I take it to a tranny shop do I just tell them to inspect it and figure it out?

It does sound a bit like a torque convertor issue. Problem is, I believe the torque convertor locks or unlocks due to the flow of fluid... I know there's solenoids but I'm not sure there's one that controls the lock up of the torque convertor.

If you want a cheap solution, go to your local pick and pull, find the same year (99 or 00) and pull the shift solenoids off the transmission. All you have to do is drop the pan and they are right there on the valve body, just one 10mm bolt and a wire clip for each, should be 3 total I believe. Should not cost more than $10 or so per solenoid. Put them on your rig and see if that fixes it. Way cheaper than handing your wallet to a transmission shop and not hard to do, just messy. Also, make sure your fluid is fresh and clear.

thank you for replying. yeah considering I have a vibration and its really bad in overdrive im guessing the tc is damaged and or just not locking/unlocking fully which would explain why it feels sluggish all the time. if a solenoid is going bad but not throwing any codes is there any way to test them? will anything show up on a fancy mechanic scan tool? fluid is clean. this also happens when I hit the brake. gonna try the solenoids. I've always had a hard shift.

I found this thread also a 99 auto dude was having the same problem but he said it didn't happen in neutral or with od off but it happens for me all the time. they then think its a sensor issue but I've tried all that.

Torque Converter?