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Discussion Starter #1
so ive done some searching and have not come across any info or posts about this problem happening with anyone elses rav, so im putting it here, if it has been addressed and i missed it i apologize.

so my rav is losing its fragile mind. it has done this once or twice before, time of year, weather, fuel, warmed up/cold, nothing seems to affect this as it just happened at random one or two times so i didnt worry about it but the last few days its happened almost constantly, so now im concerned.

basically, under acceleration it runs fine, albeit seemingly lacking in power (what little there is to begin with) but under constant throttle, on occasion it will seem to miss, like it will buck hard almost like everything in the engine goes dead for a second. its not an electrical issue, as nothing in the vehicle shuts off or resets, just once in a rare while it will do this, and then afterwards for the next several times i drive it, its stuck at a high rpm, it will idle at 1500-2000rpm and will not decelerate on its own, so like if im in 3rd gear at 3500rpm if i let off the throttle it doesnt engine brake, and pushing in the clutch results in an idle at that rpm for a few minutes. it runs perfectly fine the rest of the time and after starting and driving a few times it will slowly normalize, until it stumbles again and then we start all over again.

it only does this under maintained speed on the highway, doesnt do it at lower speeds, and never under accel, only sustained throttle. it did it once or twice over the time ive had it, but like i said this week its done it several times, leading up to thursday where it did it several times on the way to work and several times on the way home. i have a 3sgte that i want to swap in, so i mean if its a major fix i just wont drive it until i start the swap, but if its a simple thing i can fix to keep it going for a few more weeks, then groovy.
 

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This has happen to me too. It might be the electrical system. Check the rotor and the ignition cap and especially the rotor if you are running a 1997 or the Spark plug wires. It might be jumping current.

Check the fuel delivery. It's as simple as using a Lucas Injector cleaner. It cleans and lubricates, and very inexpensive.

Has there been any drastic climate change or are you driving in different altitudes in your part of the world? This happen when the OBC is resetting itself. These quick fix, try them and let me know. After this, there are some more drastic measures you might have to do.

 

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Discussion Starter #3
thanks, ill try some fuel system flush and check the cap/rotor, and see where that gets me, bottom line right now if i cant improve it ill just park it until the swap gets underway. lol ive taken this as a sign, that its time to blow the dust of that 3sgte and just put it in the damned car already. im super excited about the sawp, i feel really good about the engine i picked up, i think its going to suit my needs perfectly!
 

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Have you used a scanner to see if any diagnostic codes are present? It would be nice to know it is not an electrical or sensor problem, just in case you need some of the old parts in the swap.
 

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Discussion Starter #5
none of the sensors will swap over, completely different sensor bank in every way. i would run a diagnostic on it, but its got the old toyota style obd1 brand specific style diagnostic port rather than the universal obd2 port, even tho its obd2, and nobody around here has those anymore.
 

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none of the sensors will swap over, completely different sensor bank in every way. i would run a diagnostic on it, but its got the old toyota style obd1 brand specific style diagnostic port rather than the universal obd2 port, even tho its obd2, and nobody around here has those anymore.
Since you don't need them; that was easy. :D

Maybe a dirty linkage keeping the engine from returning to idle sometimes?

Maybe just time to upgrade.

Enjoy.
 

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I suspect it is your Throttle Position Sensor (TPS). This device tells the ECM how far down you are pressing on the accelerator. It is just a variable resistor, and after 1000's of miles of driving at the same speed, that one particular spot on the resistor has probably become worn out from the constant small movements in the pedal.

Next time the problem occurs, pump the pedal several times. This will sometimes clean the resistive path of the TPS and it should work normally for a short period. If the pumping does return the idle speed to normal, I think you have diagnosed the problem.

You could also check if there are any stored diagnostic codes in the ECM. Here are a couple of YouTube videos that may help explain the process for OBD1 Toyota vehicles.
 

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Discussion Starter #8
thanks guys! drove it today, just to town and back (8 miles round trip) and it seemed to run fine. got lots of things to check up on from this post, much appreciated! i think what it really comes down to is ill keep dicking with it when i have time to do so, until next week when the engine, harness and ecu get ripped out of her anyways haha. think shes about gte swap time, this is a sign from the car gods, that engine has been sitting here waiting for months, might as well just put the damned thing in haha.
 

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Check you pcv valve. If its clogged, its depriving the intake of air it expects to be there. The fact that it only happens at cruise speed when vacuum is the greatest, makes me think pcv. Most anything else womuld cause the stumble in all situations.
 

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Discussion Starter #10
the problem ended up being a tps, which i changed, and everything was better, but now im losing power rapidly. every day it has a harder time doing highway speed, today with a slight headwind i had to drive it in 4th to do 110km/h (75mph) and all the way through the rpm scale its acting like its getting about half throttle. no power at all and getting less powerful by the day. lol so back to square one. id love to be able to scan it, but its obd2 with some weird obd1 style diagnostic port and no mechanic shop within 100 miles of here has a scan tool with a connector to scan the ****ing thing. the tps was a 200 dollar sensor so im not really interested in gambling with maaaaybe its this or maybe its that, i need to know whats wrong but i dont know how to get this thing hooked to a scan tool. ****ing toyota.
 

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I didn't dig thru all your posts so it may be there, but where are you located and at what air temperatures are you having loss of power?
 

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Discussion Starter #13
temperatures here are not abnormal, its cooled off a bit but not enough that it should affect change like this. the air filter is fine, i clean the pre filter every oil change and the filter when it needs cleaning, its got a c.a.i. that i made myself with a k&n cone filter and a prefilter sock. its always clean.
 

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Lugnuts hit an accord that I think you should check. My Dad has had many gas station for almost all of his life. Bad gas is possible. Do you live close or near of any station that has had its 10,000 gallon tanks under water? Or get your gas from any gas station close to a river? It's a long shoot, but you never know. I even knew once that some bad gas was shopped to different gas station to evade lost and government penalties. It happens.
 

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Discussion Starter #16
plugs have been changed recently, along with all new plug wires. new fuel filter is on its way because its past due anyways. as for fuel stations being near water, lol where i live all fuel stations are near water, saskatchewan has more fresh water rivers and lakes than the upper 30 states combined. but yes, we are right between two rivers and three lakes where i live. thats never been an issue before, because of that all gas stations here have state of the art filtration systems, they have to where we live, its the law. all my other vehicles run on the exact same fuel and all running perfectly, its not running poorly actually its just short on power, otherwise runs perfect. i need to get a scanner hooked up to it but thats going to be problematic as nobody here has an adaptor for 97 toyota obd2...

o2 sensor could very well be gone bad, cat shouldnt be plugged as i drive 40 miles of highway every single day, but it is at 350,000km so it probably needs to go soon anyways or at least get gouged out with a torch. if i had to guess, id say its likely the map sensor or the o2 sensor but i need to get it hooked up to streaming air/fuel/sensor data before ill know for sure whats acting up. like i said, cost of sensors here is through the freakin roof so throwing new parts at it until its fixed is not an option.
 
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