1990 T4r 4x4 w/ auto.

Over the past 2 days when I start the vehicle the RPM hovers around 1200 rpm and once the thermostat kick in RPM hovers around 700 RMP; however, once I apply the accelerator pedal the RPM jumps depending upon how much pedal I apply and remains at that RPM, I can reduce the RPM by manually pressing the accelerator cable in the engine compartment to the normal position but again once I apply the accelerator pedal the RPM again jumps, I found it very hazardous in that when driving the vehicle speed remains at the RPM I had applied the accelerator and the brakes become an issue, but only when the RPM jumps? I have ordered all of the Toyota tune-up components but I am afraid it is not a tune-up issue.

Engine and trans rebuild approx. 15,000 miles ago.

Comments/Suggestions appreciated!!

 

your accelerator cable might be binding, or full of dirt/grime, causing it to stick.

 

... or dirt elsewhere in the linkage, probably right at the throttle body.

Start by disconnecting the throttle cable at the throttle body. If you open the throttle with your finger, does it snap right back? If you press the throttle pedal in the cab, does the cable come back or just sit where you advanced it to?

Throttle cables "can" be cleaned, but for the money I'd just replace any sticky one.

 

I greatly appreciate your comments! Hopefully, it is a matter of replacing the accelerator cable I believe I know where the throttle body and accelerator cable are located but first thing in the morning I will break out the shop manual to confirm and if in doubt I will post pics of what I believe to be the components and also what is involved in replacing the part(s).

When I press the pedal in the cab the cable does not come back rather just sets where I advanced it to. I seem to recall when the throttle is advanced from under the hood it returns to the around 1200 rpm or idle position, I will confirm tomorrow morning.

Oh, located the throttle body? Dah
Again, I thank you's all !!

 

I watched a couple of online 'how-to' videos on removing the throttle body and also how to test the throttle position sensor, not sure I am testing the TPS correctly because I am not getting a reading what so ever. As to be expected I can not remove the TPS w/out removing the throttle body so my question to members who are familiar with the procedure is there problem areas I should look for during disassembling and should I replace any additional items once the throttle body is removed?

Comments/Suggestions appreciated.

 

If your problem is a binding throttle cable (or transmission throttle cable or cruise control cable) you don't need to remove the throttle body to test that.

It is not possible to "not getting a reading what so ever" with a multimeter. You can get 0 ohms or "OL" (over-limit) or infinite ohms or 200ma or 300VAC ... but you cannot get "nothing."

If you are certain you have a binding TPS (not common), well, you'll need to replace it. Short of that, why don't you tell us just what you did, and perhaps someone can help you.

 

I used an analog meter and referred to my 1990 repair manual FI page 86 with zero readings at various settings?
If I understand the TPS video once I have taken the connector at the TPS and determined which wire is positive and which is negative I can tap into the 2 and should read around 0.5 volts and as the throttle plate is gradually increased the volt reading should peak at around 5.0??

I have checked and lubricated the cables in the engine compartment however it is clear I need to break out the manual again and do some further research to determine the routing of the cables particularly the cruise and accelerator pedal cables?

From under the hood, I can open the throttle and it snaps back to the close position, it is when I press the accelerator pedal from inside that the rpm increases and remains at that rpm until I manually press the cable to the close position. Rarely, if ever, do I use the cruise control however recently I did but possibly after I started having the problem thinking to engage the cruise control would possibly resolve the problem??

I appreciate the input, I will not be removing the throttle body or TPS until I have checked the condition of all the cables and any other possible options in solving the problem.

 

I am now fairly certain the problem is with the accelerator cable, I attempted to clean and lubricate the cable w/out removing and it now slowly returns to the close position but to do it properly I intend removing the cable and hopefully have the vehicle on the road this weekend???

Thank you for tine advice, it was very helpful!!

 

Good luck with cleaning. Ultimately, you will probably need to replace it. They cost about $100 https://parts.lakelandtoyota.com/p/T...552035050.html (that's for a 3VZE; I think the 22re has a different cable).

 

I purchased an aerosol can of graphite for lubrication and an aerosol can of brake cleaner at the advice of auto parts counter person. I am considering it as a temporary fix and I appreciate the link. The local auto part store is checking on the cost for a replacement thru the local Toyota Dealership and I will compare the cost with Toyota Overstock, to include shipping, is $84, if there is no a significant difference I will likely go local in the event there's a fitment issue.

I thank you!!

 

If you think you have a tps issue google 4crawler tps, thats the best full write up. He also has a kit switching the bolts to allen heads so you can test/adjust on the vehicle.

 

Pulled the accelerator cable this a.m. 3/10, and found the cable is seriously frayed at the firewall and now awaiting notice from parts store the replacement arrived. Hopefully, in my infancy stage of learning about the throttle body and TPS I have not damaged them, in the event appreciated the 4Crawler article, very informative bookmarked for future reference. And yes, if it comes to cleaning or replacing the TPS definitely intend replacing the screws anything but Phillips or straight slot heads.


Just finished installing the replacement, smooth operation, on the road again, well not quite, need to break out the repair manual on 'how to' adjust timing and rpm?


Again I thank you!!