I just got my 4runner back from having a head gasket replaced and when i was on the highway it started jumping about 500 rpm's it would go from 2000 to 2500 and back and it would do this on and off. It stopped later on that day, its been about a week or two since that happened, but it just started doing it again and its getting checked out now. The mechanic doesn't know whats wrong, he thinks it could be a sensor or a solenoid but he cant even find out which one. He's going to talk to a friend at a toyota dealership tommorow, i'am just baffled and hope it can get fixed soon and was hoping i might get lucky and someone might have experienced this and know what to do.

Thanks for any Feedback, i miss my yota

 

That happened to me when my alt was acting up... I think its an electrial issue... I dont recall where the tack gets its reading, but I wanna say the dist. but thats a 22RE and I dont know what engine you have.

 

throwing codes?

 

Does just the tach. move or is the engine revving up and down on its own. If the engine is revving up and down then it is probably the Oxygen sensor. Have that checked and let us know what happens.

 

I had this happen to me, not long after I bought my 90 4runner a year and a half ago. It would jump from like 3 to 3.5 to 4k RPM at 75 in 5th, where it should be 3k. It was only the tach, cause the speedo and everything else was acting normally. Shortly after, I started having Alt showing negative charge problems and I went to the dealership and got a new Remanned one. Haven't had problems since, infact I forgot about that problem until I read this post.

 

Yea, the engine is going with the rpm's to, and i have a 22re. Hopefully i'll find out later today, i'll post back when i find out the hopefully good news.

 

You don't say if it's an auto or not.

If it's an auto, a 500 rpm difference sounds like the torque converter locking/unlocking.

Try driving it with the O/D off and see what happens.

 

Yeah. Check the ATF level if auto as well.

 

My bad, it is an automatic, i tried alternating the overdrive but it did the same thing whether it was off or on. The tranny fluid was about 3/4 low when this showed up but it continued even after filling it up again.

 

Well, i just got the truck back, its still broken but the problem has been diagnosed. It turns out its a solenoid and its messing with the gears and when they should shift. Its gonna cost 600 for a new one, but hopefully i can get a used one. Anyone have a price idea on a used one?

 

just switch it to a manual transmission.

 

Do a search on here for shift soleniods. Pull the codes watching the O/D light and find out what code its throwing. Solenoids are easy to change and should only be around $150 or so.