84 T4WD Carb update

[Mark]

I just double-checked the manual and if I'm reading it right, the Canadian manual trans version and the 3A have the smaller gap for some reason. Mine is a 3AC automatic.

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[Phatcat]

I’ll check the gap here soon when I pull them to see how we’re doing with mixture. It’s not a simple as everyone makes it sound on a daily drive car, but if it’s obvious one way or the other, then changes can be made. I’m guessing the gaps are closer to .04” then .03” by how I do it, but good to know and check. Thanks Mark

[Phatcat]

My car is a California emissions version. Not my favorite.

[Nordical25]

Lots of posts on this one. It is good to see how many factors can include idle including spark plug gap.

I would like to go back to fuels for a short time. According to my knowledge three factors affect petrol fuel: octane rating (land specific), additives (again land specific) and ethanol rating (universal).

Mark had also a good point on complete burning of ethanol.

However, it would be good to specify how high ethanol fuel content works and which does not. I bet that E5 or E10 can run as good as 100% petrol but there will be a limit, which will start to cause some trouble. That is why also modern car makers specify always critical limit for ethanol content allowed in their car models. 2000's every single Saab can handle even 85% ethanol but original petrol models need at least remapping of ECU for 85% ethanol fuel, because E85 fuel increases consumption by one third according to Saab drivers. The E85 is cheaper too.

Therefore, I am sure that there is critical ethanol limit also for Tercel, which will require adjustment of carb just because of ethanol. It can be anything between 10% and 85% ethanol content.

In this case ethanol had no diffence according to Phatcat but it would be interesting to hear, how high ethanol content you have used in your Tercel Phatcat. My guess is 10%. It could help others if they are suspecting ethanol content for idle issues in your area.

[Phatcat]

Hey Nordic,

Yeah, so I use whatever is typically at the pumps here in the U.S., which I believe is the 10% ethanol, and often fill it with the ethanol free stuff too. And yes, I’m glad to see so much discussion for this topic.

I bought my car just this past early spring, I believe it was March. Anyway, this was my first carbureted vehicle other than an old 81 pickup with a Weber conversion, I learned quite a bit while fixing up that pickup, but my experience with the factory Toyota carbs was zero. However, my experience with older Toyota’s is fairly extensive. So I did a lot of YouTube videos and reading to get my Tercel running better, hence, finding this forum and why I’m here. Many of the videos I watched, some are members here etc, they never seemed to have the 3-A running absolutely perfect. Most of the feedback I got was heavily on the side that these cars often just don’t have smooth idles, and while I absolutely appreciate and respect everyone’s help and opinions, I know that it’s possible to get these cars running smoothly, even at idle. I’d experienced similar help when working on my 86 4Runners and 95 pickup over the many years, but was always able to make things right with persistence and patience. The systems for the Tercels are over complicated by the vsv’s, emissions, and vacuum systems, but it is possible to get them running well, especially given such a well kept vehicle with everything operational. Toyota didn’t sell them running poorly in the 80’s. So I knew there had to be an answer for why my car wouldn’t idle perfectly smooth, despite every FSM test and procedure checking out good. Well, aside from the vacuum advance diaphragms I replaced with new ones.. I’d been through the carb and systems several times and couldn’t find a problem. So after a discussion with an extremely experienced mechanic about the topic, he convinced me to investigate the idle mixture, as I mentioned above. Well, it’s been much better now with the change and runs perfectly I’d say. I’ll check the plugs here shortly too for a visual of how the mixture is doing. And I’ll check that gap as well. The plugs did seem just ever so slightly lean while going through this process over the spring and summer, but my experience says that older Toyota’s typically run a bit lean and do so fine. I’m hoping the spark plugs don’t look too dirty from an overly rich mixture now. We will see. I will keep you all updated here as I go too. Mark could be correct, and I could stumble on something I missed here. I’m confident I don’t have any vacuum leaks, but there may be a something I overlooked. I’m not done playing with this situation yet.

[Mark]

Since you have the feedback version of the carb like me, I wonder if you could put a volt meter on the oxygen sensor connection and see if your idle mix is rich or lean. If I remember right, the feedback system is disabled at idle, but the oxygen sensor should still be putting out its milivoltage. I've never tried it myself, but I wonder if you could watch the voltmeter reading as you adjust the idle mix screw and see it get lean or rich. I assume the needle (I don't know if a digital meter would give proper results, since the value bounces around a bit) on the meter should wiggle up and down a bit around the .5v mark.

[Phatcat]

I’ll try this. I can say that I replaced the O2 sensor too. Through trying to fix this idle issue, I tested the sensor at the diagnostic port for the sensor, and even after completely warm and driving it around couldn’t get a reading at all, per the FSM. The sensor wire was bent and missing insulation at several places. So I should test it again, and while making adjustments. Not a bad idea.. I’ll see what we get.

[Phatcat]

The other thing I’ve considered is installing a wideband O2 sensor. They’re not bad in price and would definitively allow accurate tuning.

[dlb]

I’ll try this. I can say that I replaced the O2 sensor too. Through trying to fix this idle issue, I tested the sensor at the diagnostic port for the sensor, and even after completely warm and driving it around couldn’t get a reading at all, per the FSM. The sensor wire was bent and missing insulation at several places. So I should test it again, and while making adjustments. Not a bad idea.. I’ll see what we get.

At one time I fixed up a neglected automatic Tercel for a friend. It was the only time I've had one with the carb feedback system, and I also had trouble testing some of the components in that system. It was a long time ago but I believe I wasn't able to get any results for the o2 sensor or EBCV. The car ran well though so I moved on, but it was still frustrating and made me glad the manual Tercels here in Canada don't have the feedback system.

[Phatcat]

Okay yeah, it was weird. I tried testing at both the diagnostic port and directly to the sensor and didn’t get anything, and then decided to replace the sensor. Engine fully warm, of course..

Yesterday I was able to get in there and look at all four spark plugs. They all look really good. However, there’s also other factors to consider on this mixture topic. First, if I do have a vacuum leak that is causing me to have to enrich the mixture, the air/fuel ratio may still be good and not foul up the plugs at all. So I’m going to keep playing with this to see what else I can find. Second, we’re only talking about idle, which is only a fraction of the engine running time. To see a rich or lean condition on plugs you’d have to have it occur throughout the RPM’s, I would assume? Reading plugs is a challenge unless the condition is fairly persistent. It’s not really even feasible on a daily driver with all the different driving conditions. The plugs didn’t look overly rich though and things looked normal. All this said, I’m running my mixture screw just a hair under five turns out. So that’s about one full turn out from where it was at 3.75 turns when I removed the factory mass plug. Lastly, my gap was well above .8mm and around .9-1mm. So not terribly far off of 1.1mm to have caused an issue. I opened them up a smidge further to 1.1 mm and drove it about 50 miles to get dinner. The car ran great the whole time.

Off topic here, but I’d also been dealing with a relentless rattle in the back hatch somewhere. After removing the interior panels and fixing or removing a few broken clips, I still had an annoying rattle at speed, for weeks. I finally had someone drive while I crawled around searching it out. It turned out to be the shock mounts back there. The PO had installed the shock bushings incorrectly without a washer underneath. Anyway, I was able to get that switched around and the shock bushings are quiet now.

[dlb]

You beat me to it, yes idle mixture only affects idle, so unless you let the car idle for an entire tank of gas, the plugs won't be able to tell you how lean or rich it is idling. But if your idle sounds and feels good already, plus you don't do a lot of city driving, I think you're already good (in terms of idle -- how it runs at other times is a different kettle of fish, of course).

I have run into countless similar things to your incorrectly installed shocks. The most recent fun finds on my latest Tercel are that a PO installed the fuel filter backward, and when I replaced the PCV valve I saw a spring and small metal rod under the hole for the PCV valve. I didn't recall any reason those things should be there so I got a small magnet and fished them out. Turned out a PO had broken a PCV valve and the spring and rod from the inside of it had fallen into the hole, and the PO didn't bother to remove them. I was aghast at such an oversight but very, very glad that they never managed to migrate to the valve train. What kind of person leaves broken parts in an engine??? *end rant*

[Phatcat]

As I read I was thinking the exact same thing. Luckily there’s a baffle in there to sorta prevents things from falling into the rockers. Crazy.

Yeah, the bushing thing was stupid. I could not figure out why the hell it was rattling. No washer at the underside part of the top of the shock meant that the top mounting nuts ran down and out of threads before there was adequate clamping force to alleviate rattling. So the top mount was rattling against the rear wheel well mounting surfaces. I’m guessing that initially when new the lower bushing was new enough that it held tension and was quiet, but as the weight and bumps piled up over time the lower bushing worked it’s was down onto the upper shock more and more, eventually causing no clamping and loose mounts. I thought about throwing in some unused poly energy suspension bushings I had in the parts bins, but I like the rubber better for vibration dampening, so I was able to use the rubber bushings that came with the shocks. Being installed incorrectly they honestly were in really good shape. They’d never had clamping force on them really.

I’ll be adding some butyl crap sheet stuff to the rear spare compartment and hatch area, and to the side quarters where the Jack and stuff are etc. My car has a wicked hummmmmmmm when at speed on the freeway. Despite all my fluids and LUBE being changed and tip top. I’ll get the tires balanced better here soon too. I suspect that will help, maybe not. Anyway, I’ve used the butyl goobers before and had great results. My old Toyotas trucks benefited tremendously from a few sheets of butyl. Usually they only sell that junk in 10 or 50 sq ft bundles on Amazon to rope a guy into buying more than he needs. I bought the 18 sq ft bundle of Kilmat for about $30. That should get me where I need to be to quiet down the freeway cruising. I freakin love this car though. It’s stupid fun to cruise. Can’t wait for some snow here to mash it in 4WD and rally it a bit. It’s almost criminal how fun these cars are..

[dlb]

The hum in the back end might be a bad bearing back there. To diagnose those, I've had my wife drive the car at the speeds the sound is most noticeable while I ride in the cargo area like you did to find your shock mount problem. Then I listen closely to each side to see if it's louder on one side. They're a little annoying to change but not too bad. My axle shafts were stuck in there and I didn't have a slide hammer so I used thick, heavy rope tied around the axle shaft at one and and a big brick at the other, and used that to break the axle shaft free. Wish I took a picture, it was pretty funny but very effective.

Anyway, it might just be road noise but wanted to throw the bearing idea out there because that's been the cause of my rear end hums in the past.

[Phatcat]

I’ve suspected a bearing back there as well. I’ll use my stethoscope to see if I can get an idea. They may both be bad though. Not a bad idea to do them. and I’ve done enough stuff like that, it shouldn’t be too terrible. I have a good collection of idler, pitman, tie-rod pullers that may help. And I can always fab and weld a tool to make things happen. I’m fortunate to have access to scrap metal and odds/ends from the hatchery here where I live/work.

I’m gonna do the air ride shocks in the rear next year sometime and that wouldn’t be a bad time to tackle the bearings. Any diagrams to point me where to look exactly? Which ones are they, inner/outer? Both? Seals? Give me everything you remember having to do and buy to get those done. You can’t overload me in detail, as you probably can tell by now.. After thinking on it, I’m almost certain they need love. But…..

The other thing I’ve suspected is driveline u joints, which I’ll do here next year probably. They don’t feel excessively loose when shaking the driveline, however I’ve seen bad ones that were very hard to diagnose on the vehicle. Those I’ve done many many many of, destroying them with lifted trucks.. I’m too old and smart for lifting things nowadays.. I’ve spent more time the past few years unlifting my trucks….. The air ride is more a slight lift and for fun rather than clearance for wheeling. Extra weight bearing potential.. that kinda thing. And just because. I do question how that slight 1-1.5” will impact driveline angles though. I messaged Luke aka Bearded Wrencher for his input, but never heard back. I assume he left his dailies at stock height etc. So if you’ve done the air ride rear/ coil front lift, let me know how it went and drives. How much lift did you end up with? Honestly, I’d do it just for the fun, and keep it closer to stock height if possible, but wouldn’t cry about another 1-2” lift either.

My car is a daily more than anything else, but will get rallied as I do all my rigs. I want it to drive smooth enough on the roads though. Maybe I’ll just throw Bilsteins under there or something quality and call it good. If Bilstein makes a setup that will work for the stock configuration, you all may know? Im sure they have a rear shock that’ll work, but front struts I’d be surprised if they do. I can speak from experience that Bilstein makes superb shocks and struts. Old Man Emu OME/ARB makes great suspension as well, and tougher than anything Bilstein makes, but I prefer the ride on the Bilstein absolutely. Both are good though. All my old Toyotas had one or the other over the years. My 95 pickup has OME shocks and they’re the business. I don’t think I could ever kill them even if I tried. It would be very cool if ARB made parts for the Tercels. Many of you would benefit, but I doubt there’s a market worthy of the investment for ARB.

The tires probably could use a good balancing. I’m not running a mud or A/T or anything larger, but they’re probably due for a good reset and balancing. That could also be my humming noise. It does sound a lot like tires being imbalanced, sorta. Thanks for all the input and talks. I’m learning a lot and just enjoying the crap outta this forum and car. I shoulda bought one of these a long time ago.

Lastly, not a computer guy really.. so how the hell do I post images to share my car with y’all? I wanna share this beaut with the people here and have FAILED to post images.

[dlb]

To post pics, click 'full editor & preview,' then below the typing field click on the 'attachments' tab, then click the 'add files' button, pick the pics you want to upload, then hit the 'place inline' button and place them where you want them in your post.

It's been many years since I had to do rear axle bearings. I think the most annoying parts were having to disconnect the brake lines from the brake cylinders and then put the cylinders back on to keep brake fluid from leaking everywhere, getting the shafts out (they're usually pretty stuck in there), and then you have to press the new bearings onto the shaft. If you don't have a press you will need to take it to a shop and have them press it on, but make sure they put the retaining plate on first because that's what holds the whole thing in the axle. I can't remember where the seals are in there, weird. Have you downloaded the factory service manual (aka FSM) from here yet? It's an excellent resource, I would do that and take a look at it for more details on this job, I don't trust my memory here.

The u-joints on the rear drive shaft are not serviceable but I have seen people on the 4wd tercel group replacing them lately so you might want to join that group to look into that. I remember some people on here doing that as well in the past but it was quite a while ago so any part #s from then might no longer be any good.