1999 Tacoma Rebuild Over the Years

I’m satisfied with it so far. Exhaust guy explained to me why any packing type mufflers I’ve had keep dying. It’s due to the open loop of Toyota being rich and my extended use in open loop commuting for hours at a time. Basically turns the fiber packing into a cat…sort of.

On with the show.
https://youtu.be/VjXFlinPd5A

 

https://youtu.be/eS6e5u6OW4I

 

I was crawling around underneath greasing up last week and noticed the rubber on my center support bearing was looking worse for wear. I had replaced the OEM with a RockAuto unit a couple of year back and at least 60k miles ago. So I figured it couldn’t hurt to put in a new one. Ordered up a National HB-26 and slapped it in this morning. Güdentïte cause you can’t get a torque wrench square on those bolts without pulling the entire driveshaft.

 

As long as the truck is in closed loop it drives as it should. As soon as it hits open loop at any RPM it enriches out and shows 0.9v from both o2 sensors (catless). This is using Torque App to monitor things. Being I commute this long distances on the interstate it has become a nagging thorn in my side. I scooped up a set of used pink tops from a member here in hopes that my aging dual jet injectors could be an issue. Every plug change looked ‘OK’ aside from the constant running rich none were ever lean burnt or wet fouled. Same with the pink tops after 900 miles of rich open road conditions for hours on end.

So, the only ways I can see altering AFR is either by fuel pressure changes, ECU changes, or MAF changes. Easiest for me was MAF changes. Either diode alteration or tricking the sensor physically. So I ordered one of those 3” Spectre MAF sensor housings and gave it a try. The largest insert is about 2.75”/69mm ID. Basically the same as the stock ‘99 3RZ and results were unchanged.

So I removed the insert and let it be full 3” and closed loop was the same as expected. Open loop dropped to 0.0v and came back up to 0.1v on both o2 sensors. Wouldn’t call it a win but it is a change. Was hoping for 0.2-0.5v but I’ll take what I can. Just hope it doesn’t lean out too bad at higher RPMs because from a low RPM pull it’ll start at 0.8 and drop off to the 0.1 by 5000 RPMs.


This kit


And this adaptor for the stock air box.

 

This is where I’m at. Got the coupling installed and it looks a little cleaner. I used the middle sized restrictor and cut it down at the initial bevel. Made a pass on the highway and pulled over after seeing the numbers still rich. I cut back little by little over the course of 4th gear low to high RPM pulls. Got the volts down to 0.3v low RPM open loop pull up to 0.7-0.9v in the upper RPMs near redline. I’d imagine an airflow straightener would help smooth this out.

I’ll be making a long commute tomorrow and see how this fares. I have the stock housing in my tool box.

 

Upper/lower ball joints, upper/lower control arm bushings, tie rod ends, and new cv axles yesterday. PITA but done. Axle nut is just the right size to press out the lower bushings. Uppers I used a socket.

Waiting for the alignment right now. Got the complimentary talk about it being lifted and camber adjustment is maxed out. “Do you want us to proceed?” “Absolutely. Been that way for 15 years or so.”

 

Ran into some trouble using the latest iteration of parts house axles. Nailed a deep wash on hard pack and tried to throttle out. Ended up high centered with only drivers getting a bite.


Changed that and then tackled the steering alignment that I destroyed. It took that much to correct it to keep it on the road. Toed the drivers side back in 1.5” and had it straightened up nicely. Get 5 miles down the blacktop and realize something else was wrong. It had apparently jammed in the rear side of LCA camber and only half the wheel was making good ground contact. Eyeballed that roadside and brought the toe back out. (good thing I counted rounds) Then made two more stops a few miles apart to get it where it wouldn’t pull one way or the other.


Get to the alignment shop and tell them what happened. They get her up on the machine and then come get me. Passenger inner tie rod has some slop. Drivers CV to diff has some flop and that seal is leaking. I change the tie rod that evening along with pulling CV and changing the seal. Discover what I had suspected and the diff bearing/race is failing. Drain the diff oil and the magnet plug is covered. Maybe a thimble worth of metal. So I top it off and put it back together. I go ahead and drain the rear diff and it has just a little bit on that magnet.

Having ADD and not locking hubs I knew this day would come. Also by adding the lunchbox locker at 120k the passenger bearing is likely 100k+/- miles behind since I’m at 202k.

So looks like a bearing change is in my future next month possibly. Also considering a regear while it’s out this time.

 

Did an ECGS driver side bushing 4-5 months ago…or so. Truck just has felt like it’s been getting weaker and weaker as the years go by. Yesterday I changed the engine oil and lubed all the driveshafts and upper/lower ball joints. I had a 3x2” 45* silicone elbow I was going to use on my Audi project and realized it’d fit where the silly OEM rubber accordion looking intake hose is between airbox and intake mani. Put that in and the truck feels a little peppy. Could be placebo from the new intake sounds or maybe the cooler weather. I was feeling frisky so I bought some gear oils.

Today I changed the transfercase for the first time ever at 225k. Then used MT90 in the w59 trans that had been wanting to get a little grindy 4to5th and 5to4th when shifting quickly. This cleared up. Last change there was about 62k ago. Did both diffs in parts house brand Dino and will change those again in 10-15k for some better stuff. Last on them wasn’t too long ago.

No pic of silicone coupling installed but imagine replacing that rubber junk from post #85 with a proper length coupling. If you’re using the OEM MAF housing you’d need 3.25” to 2” with a longer leg on the 3” side.

Edit: trans had a little bit of gold in it. Diffs had some metal but not bad. Driver side CV seal leaks bad and it’ll need changing ASAP. Going to pick one up tomorrow it’s that bad. Front diff has been running on oil only as deep as the CV and it’s got a lunchbox locker, too.

 

These didn’t age well. That support bushings already sagging bad and has dry rot cracks. All the rubber boots on the ball joints are also dry rotted. Looks like I’ll need to drop some coin at the Stealership soon enough.

I’ve been having a hard start issue of the last year or so. If I rev it before parking for the night it’ll crank the next day fine. But I have to keep on the gas or it’ll stall then take a couple key cycles to reprime the fuel rail or whatever the issue is. Otherwise it just turns over for 30-45sec and still wants to stumble and stall. So I changed fuel pumps yesterday and so far so good. It acted funny at first but after maybe 10 miles it’s smoothed out.

 

Made a key today.

 

Revisiting the richness in open loop. Hoping for a turbo setup before the year is out but wanting to tackle this sooner than later. The MAF reading/sizing/scaling is the trick. The URD MAF scaler would be ideal for reigning in the fuel trims NA.

As for hard starts etc I discovered the generic plastic Spectre MAF housing warped under heat and was allowing some unmetered air to enter the system. I applied a liberal bead of gasket maker to it and put it back together. So far it’s been cranking fine. Have a high idle when warm and low idle when cold. Gonna redo the vac hose today and play with the MAF housing.

 

So primary and secondary O2s read the same basically as it’s catless. There are fluctuations between them as well as up and down which is normal. Granted, this is a 1999 ECU and not a normal, more modern o2 and ECU. Closed loop voltage hangs between 0.3-0.7v. As soon as it goes open loop with the OEM MAF housing it shoots to 0.9v and stays there. Presumably pegged out and rich as a pig. The secondary on my Audi will read 0.4-0.5v when the primary shows a perfect lambda/stoich reading. So this is my litmus….

Yesterday I tried a piece of air straightener cut to fit. No changes were observed.


Today I removed the little plastic piece from the 3” housing and took a piece of 2.5” tubing and cut it to length. Then a split and notch for MAF sensor. I spread it open and slid this in the 3” housing to illicit a reaction hopefully. Still got the complimentary 0.9v.




Next I cut up a piece of 3” tubing and removed a section so that it would fit once squeezed together. Then a notch. Also hit my pinky with the cutting wheel through a pair of Mechanic gloves…pretty gnarly.

So 65mm


Instead of 73mm.




pretty good fit if I do say so myself. I left the coupling bead but don’t think it’ll make much of an effect. If anything will possibly cause more turbulence. I should’ve made this 3” piece extra long.


With the 3” piece inside the 3” housing I did get some change. Instead of immediately going crazy rich it instead went as high as 0.9v, but for the most part of a 3rd gear pull to 6000rpm it bounced between 0.7-0.8v with an occasional 0.9v. Hey, still rich, but not pegging the sensor rich.

 

If only there was a way to get locked in to closed loop under load. Both my old VW and now Audi remain closed loop until deceleration. How simple is that..?