Hey y'all, finally got the yota on the road and put some miles on it. After about 30 or so I found only a few things. When I put it into neutral for example coming off the freeway. the engine begins to fluctuates its rpms, going up and down about 200-300 rpms every 2 seconds or so until about 20 mph it stops.

Also I noticed in the first 3 gears the oil pressure light goes on for a few seconds near the end of the gear until I shift to the next. It does not happen in forth and fifth.

The final thing is my temperature gauge does not react at all. only stays at cold. Heater works I will add tho.

Any help would be appreciated. Thanks guys

 

So I was letting the pickup warm up and noticed in neutral the oil pressure light would flicker abd I've the idle went down it still flickered. My idle is high, around 1100-1500, I haven't been able to diag that quite yet.

Drove it home from my folks place today, put 300 miles on it also had to take it up a pretty decent grade. Drove awesome.

When coasting and the surge begins I noticed my brake pedal world go in and out on its own in sync with the surge. Not sure If that's a coincidence or not.

But there's a little update after a good trip was put on it.

 

check your throttle cable, it may be too tight and won't let the throttle close for idle. To test this remove the cable and see if it drops idle. Do you have an oil pressure gauge or dummy light? does the sensor match the gauge?

 

I've only got a dummy light, no gauge itself. just a water temp gauge that currently isnt working. Ill test the idle in the daylight. The brake thing going in sync with the surges is really confusing me tho.

 

Found out the surging ONLY happens when i use the brakes while coasting if anybody has had that problem?

 

Any codes? that's gonna be your biggest help.
I had to replace my tps twice before my swap would idle right also clean the IAC valve and TB plate.
X2 on the throttle cable routing was a pain for me.

Also check your vacuum hoses and get some hose diagrams off the interweb i got mine wrong the 1st time around ran like @#%$.

 

I will guarantee you either have a bad Brake booster or you do not have the check valve installed correctly to the booster, that is your surge and why the brakes feel weird.

At the intake from the booster, you should only be able to suck not blow back into the booster, if you can your check valve or you booster is leaking, if you tossed it they sell inline ones at most part stores.

That's an easy fix IMO

 

did you use the 3.0 Oil pressure sender, or the 3.4.

I would swap the 3.0 sender into the block, if still no love check the plug end they get smashed easily.

 

I checked if you have only a light then you should use the Small oil sender if you had a guage then you use the Large style sender they have the same plug on both.

 

I was thinking it might be the booster too. Would that also cause high idle? But I'm using an sr5 3.0 oil pressure sender. I plan on getting an sr5 cluster soon too.

 

Ended up replacing the booster, I've still got the surge.

 

Do you have the check valve inline with the hose for the brake booster? is it facing the right way? If you just have the dummy light leave the 3.4 sender for oil. If you swap to a gauge style cluster you will need to swap the oil pressure sender to a 94 3.0 sender so it will have the same plug.

 

I believe it's facing the correct direction. Flipped around it makes the brakes super hard. And I plan on keeping getting a sr5 cluster so I'll probably just keep the 94 3.0 sender in it

 

Hard brakes is a sign that its getting Vacuum. You need to make sure that the Check Valve is holding as

 

How is this tested? How exactly is that valve check supposed to be connected?

 

It's a one way metal valve between the brake booster port and the brake booster. It allows vacuum to draw into the booster, but not escape back into the manifold after the truck is shut down.

 

So after checking what and everything what mentioned on the thread I still drop 500 rpms while braking. I honestly am completely lost at this point.

 

Ended up putting the 3.4 sender bak in and the dummy doesn't pulse anymore thanks! I still haven't figured out the water temp gauge tho. How can I test to see if my gauge is functioning correctly?