1985 4Runner - running rich and lost power (1 Viewer)

[bigcorn]

Hey all,
long time lurker, first time poster.
I have a 1985 4Runner and have been having issues with it running a bit rough off and on for a bit now. I’m down here in Baja and don’t have a mechanic I trust and also appreciate doing as much as I can myself and enjoy learning, so trying my best to do as much as I can.
Shes running rich and giving feedback going downhill especially. Has lost some power recently, and the guy I bought it from in Colorado had put some Doug Thourley (sp) headers on it and changed the plugs, which I have changed back to OEM, but noticed today that there is one bolt missing from the new headers, so there’s that.
When I jump the diagnostic, I get 5 flashes, so defective O2 sensor, injector full rich or defective ECU from my research. I have changed the O2 sensor to no avail, and I’m trying to figure out the next logical move. I don’t know much about addressing the fuel injector and am assuming the ECU would be a plug and play switch from the existing if I am able to source one (which I think I can on eBay), but wanted to ask on here for a more knowledgeable opinion.
The loss of power and the engine “slapping” sound is concerning, but I did a block test and the fluid is as blue as it started, so that’s comforting I guess, but the loss of power is not.
Any advice is extremely appreciated.
Many thanks

 

[gnob]

if the slapping sound is an exhaust leak, it will cause a false lean and the ecu will add fuel.
the ecm is throwing the code because it cannot see changes in the o2 signal or cannot see it at all.

missing hardware at the header is a possible cause.

 

[pappy]

Loss of power could be a lot of things. As gnob said, deal with the exhaust leak and see if that helps. Other reasons for power loss:

- air filter
- when was the last time you tuned the engine. Spark plugs, timing, spark plug wires, dizzy cap and rotor.
- if it's running rich, it could also be leaking fuel injectors. You can get them rebuilt for $25-30 each, but of course not from Baja.
- fuel pump
- fuel filter
- valve adjustment

A note on the fuel injectors. I've seen this twice on my truck. When I pulled the plenum off there was fuel ponding in the intake runners after the engine sat overnight. The fuel washing was very obvious.

When timing the engine make sure to short the diagnostic plug on the driver's side fender. It's the same plug you used to pull codes.

It sounds like you might be new to this truck. I would baseline EVERYTHING.

If you are near to San Felipe, and you can't get it back across the border, there is a garage on the road down to Pete's Camp (north side of the road). I think the fella is Mike.

 

[pappy]

Also, love my Thorley header. It's a keeper.

Another thought. Those 35+ year old heads get soft. It's not uncommon for the studs to pull out of the aluminum. Especially around cylinder 4.

 

[bigcorn]

Thanks guys!

The plugs are new before I drove it down here, and the wires look new as well. I’m in Pescadero, so closest places for potential shops are Cabo area or La Paz. I also brought down more Denso plugs and gap tool this trip.

I will lean in on the exhaust hardware and double back to check the filter, as it’s pretty rugged and dusty here.

I have never timed the engine or checked dizzy cap or rotors, but have an online FSM and a Hayes manual in the truck.

Thanks for the reminder about timing the engine with the diagnostic shorted; it definitely sounds different when I short this to get the codes.

Also, the oil pressure gauge seems to be a bit low. Fwiw

Looking forward to learning some things!
Appreciate this.

 

[pappy]

When you pull codes it's done with the key ON, but engine OFF. Yes, when you short the test connector the idle will drop.

Two parts I'm going to suggest replacing when you get a chance. Oil cap gasket, 90430-37140, $2.79 list. You will find out why when you try to remove the old one without cracking the cap. The second is the dizzy cap o-ring, 19127-15021, $6.49 list.

A Baja story. I carry a bunch of junk when I'm down there, including a timing light. Well, I was going through the check point outside San Felipe (Mex 5 and Mex 3) and I got searched. As you know, the males are conscript into the military when they turn 18, so the checkpoints are staffed by kids. Well, this kid is going though my "oh s*** box" and finds my timing light. His eyes got HUGE ... and he screams "chrome pistola." I started laughing my ass off. Anyway, one of the other guys runs over, and you could tell from the inflection in his voice he told the kid "it's a timing light you dumb ass."

Here is my old light. Note I have since upgraded. The new one doesn't look like a "chrome pistola."

 

[bigcorn]

Lol. Good story. The checkpoints can be something else!

Much thanks for the heads up on the parts. They have been ordered.

Will keep posting the progress.

Also, where would Iook to find a checklist for baselining everything?
You are correct, I’m fairly new to this truck.

 

[pappy]

Also, where would Iook to find a checklist for baselining everything?
You are correct, I’m fairly new to this truck.

Baselining involves changing all the fluids. Diff oil, tranny oil, TC oil, engine oil/filter, radiator, brake bleed, clutch bleed. Replace all the belts. Replace the three radiator hoses. Check the heater hoses. There are also a bunch of hoses under the intake manifold connected to the throttle body that get neglected. Plus, there is an o-ring on the coolent tube that goes to the bottom of the intake. It's a royal pain in the butt and you really need to pull the intake (or the engine) to replace it. When you drain the front diff check the color of the oil. If it's gray, you probably have a failed seal at the knuckles (see below). I mentioned the fuel filter already.

Tune up including plugs, wires, dizzy cap/rotor, valve adjustment. I would also replace the rocker arm cover gasket, the half moons (cam seals), rocker arm cover grommets, PCV and PCV grommet. There are also a bunch of hoses I would inspect, especially the hose that goes from the plenum to the rocker arm cover. Also inspect the two rubber connector hoses on the tube that runs from the Air Flow Meter to the throttle body. The hose at the AFM side is NLA, but the throttle body hose is still available (22231-35011).

Inspect the brakes, front and rear. Inspect/replace the three brake hoses. When you pull the rear drums make sure they are not filthy with oil. There is an axle seal that fails. Usually you can see the oil oozing on the backside of the backing plates. When that seal fails it's usually because the wheel bearings have some wobble in them. Replacing the wheel bearings is a big job, but can be done by the common man with a 20T press and a special service tool you can buy on Ebay. When I did mine the cost of the Harbor Freight press, plus the SST, was WAY LESS than a shop quoted me. I now have a press (finally), and the SST has been loaned to buddies. Note that you will booger brake fittings with standard wrenches. I would invest in a 10mm flare nut (line) wrench. You will thank me later.

There is a brake upgrade you can do on the SA trucks. It uses vented FJ60 rotors, V6 calipers, and the V6 master cylinder. But, this is another story for later.

There is a hose that goes to the clutch slave that gets ignored (96814-50260). It's on the passenger side firewall. Check the clutch master for leaking at the pedal.

Inspect the steering knuckles. They are frequently neglected. If they are packed in grease I would take it to the car wash and blast the crap out of them. Get them real clean. Start looking for directions to rebuild the knuckles. It's not hard, and there are a few special tools you need. The first time I did it I didn't think to clean the knuckles and spent hours getting them clean off the truck. It's a big job, but can be done in a day your first time, or half a day if you know what you are doing. The issue here is the axle shaft seal that fails and you start getting grease in the diff oil, and diff oil diluting the grease in the knuckles, and potentially the wheel bearings. Several places sell kits that have all the seals and parts to do the job.

I'm a big fan of OEM and shop the discount dealers. But, I understand that money can be an issue. A good source for maintenance parts at a good price is Rockauto.com. Rockauto sells Denso and Aisin parts for less than OEM. Both are OEM suppliers.

Most of these can be done at your convenience. Be aware you are new to the truck, and you don't have any history with it. It's best to have a starting point. Especially if you are going to Mexico with it.

 

[bigcorn]

Pappy, thank you!

Very impressed with, and grateful for your willingness to share.

I brought down some fluids with me on this drive to Baja with the intention to start down this path. I will attach a photo of some of the things I brought after researching before making the drive. I only wish I had reached out previously, as I am already down here.

I was able to change to oil and filter yesterday, cleaned the MAF, air filter box and plenum to the throttle body. I plan to clean the throttle body today after warming the engine and look to begin changing the other fluids. I would like to switch the coolant to the red Asian coolant as I have read about the other yellow Prestone causing electrolysis, which I think I can see happening on the bottom of the radiator. Do you have any advice on the proper way to flush the system in addition to just emptying the reservoir via pulling the two drain cocks and adding the new variety of red coolant?

I will be pulling the trigger on ordering the seals, etc that you have recommended as well as some of the paper air filters rather than the reusable one that is currently installed and look to fly back with those after making a quick flight back to Colorado to accomplish a few other things. Do you have any other recommendations of things to order or best ways to take advantage of a quick trip back to the States?

 

[pappy]

I've never suffered from running Prestone green. I had somebody way more knowledgeable than me suggest that anything other in our old junk isn't worth it.

I'm attaching a spreadsheet I've been working on. It's far from exhaustive, but should give you an idea of what's still available for our trucks. Keep in mind that Toyota is not going to support us forever. If you see something on this list you need, especially anything plastic, I would get it now while you still can. Since I first made the list several parts have gone NLA. I can think of a bunch of stuff that isn't on the list, but they are drivetrain parts and I don't see them going away anytime soon. I did have a part that was NLA come back to life. So I guess it's possible.

Make sure to shop at one of the discount dealers. My local dealer (American Toyota, ABQ-NM) discounts, and I've used Claremont Toyota in the past (freeship on orders over $75).