1987 4Runner- Expedition Build Up.

[Grim Reaper]

Idle is smooth except its gone back to revving up to 2000.

NEVER disconnect the battery without reading the codes first.

You have lost any information it could have offered as to what caused the problem. Run it for a while and read the codes as the first step.

Remember a code is not necessarily where the problem is but where the ECM detects a reading out of range. Example. A EGR problem will often throw a O2 code because the actual reading is outside the expected reading. The code is where to start diagnostics for the problem. No part should be purchased till the diagnostics are done. There have been many a o2 sensor bought that didn't fix the EGR problem.



A surging rev when foot is on the brake or just steady?

Surging when applying the brake is idle set above 850rpm.

A vacuum leak will NOT cause the idle to go up it will stall at idle. Sounds like one of the following, the throttle is sticking, the Idle air bypass up under the plenum is screwed up,TPS is bad or the the AFM is hanging .

The AFM and ONLY the AFM controls the fuel. When you push the throttle the TPS is telling the computer how far you have opened the throttle. The AFM door being pulled open is what adds the fuel. No air going through the afm (vacuum leak) would cause the motor to lean out and at idle it would stall because the door in the AFM would not open enough to keep the fuel pump on. The computer then looks for the AFM to catch up with and equalize with the TPS position.

A Bad TPS (from getting carb cleaner in it) Would play hell with it. Getting a CEL? Read the code.. Read the codes regardless as some codes do not throw the light. Look for it to throw a code for Idle circuit or a code showing an out of range reading between the AFM and TPS. It may populate as a AFM code not TPS.

I am thinking you need to look at the throttle and TPS first since that is the last place you were tinkering. http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=FI&P=100 has how to meter out the TPS. Supra 7MGE has the same values and that is a much easier to use online manual.
Here is a 4Runner manuals. http://www.ncttora.com/fsm/index.html

If the TPS looks bad As long as it hasn't been damaged the gasket between the throttle and the intake is reusable. You will have to take the throttle loose to change the TPS. I bought a TPS from Autozone that came in a "Wells". Wells apparently is buying these from Toyota or ND as the TPS was a ND with Toyota logo. It was $90 verses the dealers $180 quote.

 

[LaOutbackTrail]

Thanks for all the great info and suggestions, Grim and others. We're going to figure out the problem this week...

But for now, we are back home, after a grueling 194 mile tow behind Mr. Leary's truck....

So here is what happened.....

We wheeled pretty hard all day with the truck running absolutely fine, at the end of the day we get out on the hwy and the truck starts sort of chugging when cruising at about 50-55mph. It then got to where it was just loosing power.

We woke up this morning to figure out what the deal was, with no resolutions found. So we just decided to limp back to Texas. In the 30 miles prior to deciding to tow, the truck got progressively more and more sluggish. The point of not being able to hold 30 mph.

Other than that I dont know what to say until we get it diagnosed.....

But we had a great time until it went to pot.... or METH anyways...

And, the meth reference here... having to drive through a fiery road block.

 

[RU55ELL]

Dumb question, but how old is the cat?

 

[LaOutbackTrail]

Dumb question, but how old is the cat?

No idea. But a new noise has also come about and the cat has become rattly. The noise (besides the rattle) is a bwwwaaaoooooommmmm sorta sound when truck is under load... no exhaust leak noises or anything either. Also, my muffler is trashed, hole in the bottom now. Water was pouring out of it when stopped, if that matters.

 

[RU55ELL]

If the cat is rattling, it needs to be replaced. That may solve your problem, but it might not. I am in the same boat, just a matter of me getting off of my butt and doing it.

 

[Grim Reaper]

If the exhaust is stock you can pull the cat off and see if it will run.

Did you add any fuel? Its possible that all the bounding around broke free sediment in the bottom of the fuel tank and plugged up the fuel filter or possibly the fuel pump. Its also possible that the fuel pump may have had the hose that it is attached to fail due to age.

 

[RU55ELL]

Let me know if you figure out what it is before I do. Mine did the same thing on the way back from Mexico. At first I thought it was just the hills, but like you said, I started to have trouble maintaining constant speed on semi-flat ground. The fumes were horrible though. They were bad enough to make my eyes start tearing up. Hasn't done it since though. Of course, I haven't driven it more than 15 miles at a time since.

 

[Scenic WonderRunner]

This 4Runner needs a good Flogging.....!.....:littlefriend:



.

 

[Mr. Leary]

If the exhaust is stock you can pull the cat off and see if it will run.

Did you add any fuel? Its possible that all the bounding around broke free sediment in the bottom of the fuel tank and plugged up the fuel filter or possibly the fuel pump. Its also possible that the fuel pump may have had the hose that it is attached to fail due to age.

We will test the fuel system thouroughly this week, as well as test compression again with some oil... a trick a friend of mine just told me about.

Older trucks have more quircks. Hopefully this is not a very expensive one.

 

[LaOutbackTrail]

I just want everyone here to know that Mr. Leary is an outstanding fella. Great adventurer and super nice guy. I mean hell, he hauled my junk almost 200 miles from Oklahoma back to Texas and I never once heard him complain! Well, except pulling my junk around corners.... jerkily! It took 194 miles to figure out how to make a corner!

Anyways, Kacy and I want to thank you and the Mrs. so much for all your help, patience, and companionship! I already have a bucket full of I.O.U.'s to you guys!

So Thanks AGAIN Mr. Leary!

 

[LaOutbackTrail]

I just went to a local shop that services import cars, chose there because they always have 4runners, cruisers, pickups, etc in the parking lot.

They said $90 to run the diagnostic test.... does that sound right or should I call around to a few shops?

 

[LaOutbackTrail]

Just looked on Auto-Zone's website and found this info....
Items in BOLD we have checked.

1 Inspect Spark Plug Fouled, Damaged, or Broken Spark Plug(s).

2 Inspect Hose (PCV)at Clogged or Collapsed PCV Hoses.

3 Inspect Wireset Worn, Damaged or Faulty Spark Plug Wire(s).

4 Inspect Distributor Worn, Damaged or Faulty Distributor.

5 Inspect Catalytic Converter Clogged or Faulty Catalytic Converter.

6 Inspect Fuel Pump Low Fuel Pressure.

7 Inspect TimingSet Slipped TimingChain or Worn TimingGear(s).

8 Inspect Knock Sensor Improperly Connected or Faulty Knock Sensor.

9 Inspect M.A.P. Sensor Faulty M.A.P. Sensor.

10 Inspect Throttle Position Sensor Faulty or Incorrectly Connected Throttle Position Sensor.

11 Inspect Mass Air Flow Sensor Damaged, Loose, or Faulty Mass Air Flow Sensor or Circuit.

12 Inspect Air Cleaner Tempature Sensor Damaged or Faulty Air Cleaner Tempature Sensor.


13 Inspect Fuel Injector Pressure Regulator Faulty Fuel Injector Pressure Regulator.


14 Inspect Piston Ring Set Worn or Broken Piston Rings.


15 Inspect Timing Specification Incorrect Ignition Timing.


16 Inspect Fuel System Pressure Incorrect Fuel Pressure Being Delivered to Carburetor or Fuel Injection System.


17 Inspect Fuel Filter Clogged or Dirty Fuel Filter. replaced this ~500 miles ago


18 Inspect PCV Valve Plugged or Damaged PCV Valve. replaced ~600 miles ago


19 Inspect Valve Burned, Worn, or Sticking Exhaust Valves.

 

[corax]

$90 sounds about right for initial diagnostics depending on the area you live in -> usually equates to 1 hour labor.

Before you go that route, a learning experience may be in order and save you some cash. The single easiest diagnostic tool to hook up (and most overlooked) is a vacuum gauge - costs ~$20 or less and can tell you all sorts of info about the health of your engine and what's going on with it.

here's on article on use/interpretation - at one point I also found a page with an animation of the gauge, but can't find it now

 

[journey]

Here is a drawing I did of a roof rack supported between the top and bed. I think it would seal fine along the side but the top might leak where it meets the cab.

 

[corax]

at one point I also found a page with an animation of the gauge, but can't find it now

here's one

a really good one