Please Help!

I have a 1995 Toyota tacoma 2.4l 2wd truck with 139,000 miles. While driving on the road or the freeway i get this thrusting motion (I guess you would call it a surge) under a load in 1st, 3rd and 5th gear. It usually occurs only when going up a slight grade. If i get up on the gas pedal it will stop or if i down shift and raise the rpms.

For example: while driving on the freeway at 65 mph in 5th gear the truck starts thrusting or surging if i bring the trucks speed up to 75 the thrusting disappears or if i shift into 4th gear it goes away.

The truck idles perfectly now that i replaced a few parts, but the surging is driving me bonkers.

I have taken it to several mechanics and they cant seem to figure it out.

This is what i have done to it so far.
Replaced the following:
Plugs, wires, cap, coil pack, rotor. air filter, oil change, TPS, transducer, pcv, valve cover gasket, fuel pump, fuel filter, clutch kit, changed transmission fluid, replaced a couple of vacuum lines.

I cleaned the throttle body, IAC, MAFs

I get no codes or check engine light what so ever.

I have checked to see if the check engine light works properly and if i disconnect the TPS or MAF the engine light comes on and i also get the codes.

Any help would be greatly appreciated.

 

Does this only happen in a narrow rpm range?? If so what rpm??

As down shifting or speeding up tends to make it go away.

Just how bad is it ?? Does the whole truck shake or is it just a slight miss??

Since no one has been able to find it There were even no ideas what it might be??

 

I am not sure at what rpm it is happening because I don't have a tach

It happens almost all the time except when I am at the top end of a gear

The best way I can describe it is: the truck jerks forward and then back. It does it once then a second later it does it teo or the times then back to one. It has no pattern of how it jerks.

Almost like when pop the clutch or the engine shuts down because of no spark or lack of fuel for a split mila second.

This 8s so frustrating because I am mechanically inclined

 

My wife's uncle is a retired mechanic and worked on toyotas. I described what it was doing and he said it would be called a surge under a load. He would take a look at it for me but he is in Hawaii and I am nevada.

All the local mechanics say there is nothing wrong or don't know what it is. So I reached out to my uncle and he has diagnosed every other problem I have had. That's why I have replaced so many parts along with trial and error.

He thinks it might be the distributor or the engine shorting out somewhere.. I check all the plugs last night and they look goog.

 

I don't want to spend 300 bucks on a new distributor and it not be a fix. I have already spent a lot on trial and error.

 

I think my fuel consumption has increased also

 

Hello. I know this thread has been dormant for a while. I was wondering if you ever found the problem with your rig. I was thinking you might have an injector that is going bad. Have you ever had them serviced?

 

Most likely and loose or unplugged fuel injetor connection.

 

I replace. Vsv switch valve on the purge canister . Located on Fender wall drivers side. It fixed idle flux.

Then this part to fix bucking at 2 to 3k rpms fixed the loss of power, bucking or hesitation issue while driving.


Check these parts 89460 -04010 98 tacoma.
89460- 0w020 tundra via
Also 96 to 98 camry and Lexus es300 will work. Gs300 may as well. It's part no longer made. Cost is to much new go salvage yard. Fuel vapor pressure sensor as original name. Located on driver side firewall on 98 tacoma 2.4l.

 

I have experienced the same iszue with my carb toy. And I am not too familiar when it comes to vacuum hoses n pressure. So all I know is that my brother told me to take off a hose from the distributor and added a bigger one from the brake master to the carb. plugged up one connection on the carb also. Then it just stopped doing the jerks and got stronger when im going up a hill and stretching each gear.

 

its the fuel pump fuse is too low of amps needs to be 20 or higher

 

You must use Toyota OEM plug wires...trust me on this one

 

I had a Toyota pickup 20 years ago that had the same problem. Turned out to be a partial plug in the fuel feed line coming from the tank. It caused the issue of surging/ bogging down only under severe load. Just didn’t provide quite enough fuel in this condition. Recommend detaching fuel feed line from rail and from tank. Don’t want to blow crap back into tank. Use compressed air and blow line out. I heard an audible pop and a noticeable change in air flow rate. Hope this helps!

 

I'm going to try this on my 95 2rz fe. I had to replace fuel pump recently after we it died while driving, and it's always had the hesitation/surge intermittently, I notice it most when passing another vehicle. I just wonder if there's some restriction in the line that killed my last fuel pump, which had been installed by the previous owner. If I do find it to be plugged or restricted and get it cleared, probably should unplug ecu or battery to reset 40 ignition cycle fuel trim .

 

if you clear out fuel lines and find a significant plug or restriction I wouldn’t worry about the fuel trims. Even though it’s a 1995 and may take a little longer to adjust they will adjust themselves via the ecu. The more times you unplug anything the more chances you are allowing for something to go wrong. I.e. a surge or a mistake that can and will fry ecu’s and such. It does sound like a similar situation. It’s possible part of the old failed pump is caught in the line

 

For years I had this same kind of problem with my '91 Toyota PU 2WD 22RE, and it was only when I was working on a customers Toyota truck around the same year as mine did I realize there is a procedure and measurement when installing the TPS (throttle position sensor), the way I understand it is the TPS and MAF (mass air flow sensor) have to be in sink with each other, if they are not, then the conflicting signals from the two components causes an issue with the ECU that can cause erratic fuel/spark delivery, resulting in surging, bucking, hesitation, and even stalling on occasion, so when I discovered this information, the first thing I did was unplug the TPS sensor from my truck, As soon as I did that, my truck came back to life, and it was as if it was having a heart attack the entire time prior to me unplugging the TPS and now I just shocked it back to drivability, it was such a world of difference from the way it was running before that I just said F***it, "I'm just going to leave the TPS unplugged" because it's running and driving so well. I know this sets the "check engine" light, but I didn't care. The "check engine" light is just a scam anyway.
That was probably about five years ago, and my truck still runs and drives excellent to this day.
Now am I suggesting you do this to your vehicle?, No, however if you're having the same kind of issue and have thrown a bunch of parts at it and didn't fix it, you could temporary unplug the TPS sensor, drive it and see if that makes any difference, then at least you'll know and might have a good starting point.
I hope this helps!