I have a 91 4Runner 3.0 5spd 4x4 problem is the longer I drive on the highway more it starts to jerk or a hard miss it does it for second sometimes at slow speeds its like you turned the key off. On Saturday no jerk on city streets on Sunday it did it alot on freeway.NO check engine light and No codes. I changed plugs, wires, cap,rotor,fuel&air filter and fuel pump relay also added grounds "no help". I also just finished heads and timing belt on Friday. It did this jerk problem before I did the heads. It runs great and sounds good but the "JERK" probem not the one behind the wheel. So I don't want to take it out of town or do any wheeling. There was some posts about this problem but I didn't see any fix. Is it maybe the ECU. Thanks for any Help or Input, Glenn

 

Yeah I have had something like this forever. So many suggestions were given to me but I cant afford to keep replacing parts on a hunch. Its like it skips a beat every now and then.

Ive done the plugs and leads and rotor/cap twice in the last 18 months (once while getting the Head Gasket done).

Other suggestions included EGR, Coolant Temp sensor, Oxygen sensor, fuel filter (done), fuel pressure regulator, air filter (done). These all seem to feed the ECU information so maybe thats the culprit?!?

If you figure it out id love to know!!

 

mine also used to do that but seafoam once a year took care of it

 

Hmm, did some of that the other week but I think I didnt do it slow enough, ill try it again next oil change.

 

clean your maf and throttlebody.

 

Its an AFM isnt it? For some reason I didnt think they could be cleaned.......they are different to the MAF

 

I am also having this same issue. It was really bad but a slight adjustment on my tps made it much better. Hope that helps.

 

Sounds like it could be the VSS.

https://www.yotatech.com/forums/f116.../#post51237125

 

Ive read up on the TPS adjustments and it seems kinda complex. The FSM doesnt explain much well (to someone with limited mechanical experience)

But I might give it a go. Or I could suggest it to my mechanic and get him to do it for 50 bucks, as long as he doesnt screw it up.

 

The tps adjustment is not to difficult as long as you have the correct tools, I did have some trouble with it at first, but quickly learned the correct way. Your mechanic could probably do it, but usually the throttle body needs to be removed for the adjustment, and I don't know about your mechanics, but I got quoted $150 for the job.

 

[quote=sb5walker;51480789]Sounds like it could be the VSS.

My bucking happens mostly at lower speeds, but this does sound like it may be an issue on my cousins 86 4runner, so thanks for the link!

 

Cool thanks, might give it a go then. Im sure if you were quoted 150 id be quote 250 up here. 80 bucks an hour is the going rate around here. I thought it was a quick job.

 

Thanks for all of the input it helps alot. Now I will go put it to the test hope it works. Glenn

 

Thanks, Your post back in 9-25-09 really helped. The article in Motor Magazine was great about the VSS signal. Who would think the VSS reed-switch would be built into the speedometer. So if it doesn't work right it tricks the computer into shutting off the injectors for a moment thats the JERK you felt. Now to find a good speedo???? I am new to YotaTech forum. Thanks again, Glenn

 

I'm back still the same problem I have tryed 3 speedometers 90-91-now a 95 not as bad with the 95 but still there. So I will retest or rejust the TPS or just replace it. It has 169,000 on it because the TPS will do the same thing. Next thing going to try is stock size tires from a friend. With the 33's your going faster but the speedo & VSS reads slower so maybe its still tricking the ECU or maybe its the ECU who knows. I see some new posts like this one from about a weekago someone will find the problem I hope. I'll keep you posted on the out come.

 

If you've tried 3 speedos I think you can eliminate the VSS as a cause. The injectors get their power from the ignition switch, so if that's sketchy that could cause your problem. I wonder if the EFI main relay might be a little intermittent? Or a ground somewhere is a bit shaky?

You might also double-check the coil resistance (both circuits) when hot. Disconnect all wires before checking it.

 

I did replace the EFI relay I'll test the coil also. Thanks

 

If you have seen my older posts on this jerk/miss problem. I have had this problem for a long time NOW its gotten very bad it does it ALL the time on or off the gas. I have changed alot of parts from the ECU,speedo,distributor,TPS, coil and all of ignition parts added grounds, tire size, filters. No miss at idle good power but the momentary miss/jerk. I know there is a fix. Glenn

 

If your problem is the same as mine, when this jerk happens in low range gears while stable or accelerating, the effect is that it tries to throw you through the windshield. At highway cruising speeds it feels like a serious gun recoil. That's the speed of the event, its almost instantaneous, then the engine just continues as if nothing happened.

At 326,000 miles, mine is in pieces in the garage and I'm replacing everything from the oil pump to the knock sensor and its wire. Mine has been so much fun, and so reliable that I'm not willing to let it go just yet.

I'll report back here with my results.

 

Yeah, I know exactly what you're talking about. Which is why I replied to your post in this thread. Which you somehow missed...obviously.

Hint 1: It's not the knock sensor.

Hint 2: Check for codes.

Hint 3: Don't forget to read this, and check all the links in it so you know what you need to do to start fixing the problem in the right way.