Drivability mystery problem - ignition timing

General discussion about our beloved Tercel 4WD cars
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eightyfive4WD
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My tercel:: 1985 Tercel 4WD 5 speed wagon
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Re: Drivability mystery problem

Post by eightyfive4WD »

Thanks Peter, I have the vacuum lines routed properly now; one from the Weber to the lower vacuum advance, and another from the manifold port to the upper vacuum advance. After reviewing the FSM more, as well as a couple different posts here on the forum, I realized how silly my original setup was. I believe my confusion was seeing that "just one vacuum line was needed to run the Weber" in posts here and on the FB page, and somehow I interpreted that as meaning the weber was supposed to feed both vac advance ports. At any rate, it's set up correctly now. I have a much clearer picture of how the vacuum advance and other vacuum powered components operate now, after doing a bit more homework.

I've got spring break from my college courses this next week and a bit of an unexpected dry spell in assignments so I should have time to get the ignition timing set properly here soon.

Nordical25, I would have to double check but I think on my Tercel, that red circled port is part of the messy vacuum manifold between the carb and valve cover that helps to redirect all of the emissions & vacuum hoses. I haven't removed that ugly part yet, so it's still sitting on top of my engine. Either that, or that opening might be for the EGR.
1985 Toyota Tercel DLX 4WD 5 spd wagon (manual swapped, daily driver)
2007 Toyota Tacoma TRD 4WD access cab long bed (road trip/adventure-mobile)
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Nordical25
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Re: Drivability mystery problem

Post by Nordical25 »

Ok, it could be worth of blocking until you remove it. I don't know exactly where it is going but that could be an additional "air leak".
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eightyfive4WD
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My tercel:: 1985 Tercel 4WD 5 speed wagon
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Re: Drivability mystery problem

Post by eightyfive4WD »

Progress! I'm on the right track.
It's still not running totally right yet but it's better. I learned a lot today using my timing light and vacuum gauge. I'm on the right track with the timing and carb adjustment but I still don't have it dialed in just right yet. Can't seem to get the timing advanced where I need it to. After taking the distributor out and rotating it a tooth in both directions I'm still not able to get to 10deg BTDC. So it seems my cam gear is off a tooth.

Tomorrow I will get the front timing cover off, ensure proper timing from the cam gear and hopefully finally get back to good running order. This completely explains the strange behavior, my timing hasn't been set right for a long long time.

In addition, I think part of my issues were caused by bad spark plug wires. Earlier while setting timing I got zapped by the #1 and #3 spark plug wires, and I saw them arcing across the top of the distributor cap. $27 dollars and a trip to Autozone later, I've got new made-in-USA spark plug wires and no more arcing & misfire.

Hopefully tomorrow I can get the timing 100% dialed in. Many thanks to all who have helped me in this process, I have learned a tremendous amount!
1985 Toyota Tercel DLX 4WD 5 spd wagon (manual swapped, daily driver)
2007 Toyota Tacoma TRD 4WD access cab long bed (road trip/adventure-mobile)
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dlb
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Re: Drivability mystery problem

Post by dlb »

Glad to hear you're making progress.

Just thought of another thing that can affect timing that I have come across a few times -- remove the cap on the distributor and try twisting the rotor counterclockwise. It should twist a few mm, and snap back to its original position when you release it. If it doesn't, the grease that lubricates the mechanical advance inside the distributor is gummed up and causing it to get stuck in spots. If that's the case, you can either replace the distributor with a known good one or disassemble the bad one, clean out the gummed up grease, and re-grease it.
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eightyfive4WD
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My tercel:: 1985 Tercel 4WD 5 speed wagon
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Re: Drivability mystery problem

Post by eightyfive4WD »

Image After much frustration and further disassembly, I've got my Tercel back to good running order. Even better than before this recent issue, I'd say! I removed the radiator, valve cover and upper timing cover in order to properly inspect and set timing. After a bit of frustration, I realized that a previous owner had chipped the crank pulley where the timing mark was meant to be, so after verifying I was indeed at TDC on the compression stroke, I added my own series of timing marks to the crank pulley.

Image Using the timing marks on the upper timing gear, and after removing the #1 spark plug and looking for the piston surface in the hole, I was able to ensure TDC on the compression stroke.

Image Once at this position, I rotated the distributor until the rotor pointed "northwest", towards the #1 spark plug.

Image After reassembling the Tercel, it fired right up and sounded much happier! I set the timing to 10 degrees BTDC, and then used my vacuum gauge to set a proper lean mixture at the Weber 32/36 carb. I was able to get 22 inHg of vacuum at idle which is fantastic!

Image I took the Tercel for a test drive, the first it has had since January (notice the layer of grime :mrgreen: ) It feels GREAT! It's snappier and more responsive than it's ever been. No more throttle lag, hesitation, backfiring, sputter etc. and I am certain to see an increase in fuel economy.
Initially the spark plugs were coated in carbon deposits when I was setting timing, and based on the increased performance I see and feel after setting my timing and carb mixture, I'm certain that the car will burn its fuel more efficiently. I am so very happy to have this back on the road, and I learned a great deal over the course of the past couple of days.

Thank you to everyone who helped me in this process!
1985 Toyota Tercel DLX 4WD 5 spd wagon (manual swapped, daily driver)
2007 Toyota Tacoma TRD 4WD access cab long bed (road trip/adventure-mobile)
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Nordical25
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Re: Drivability mystery problem

Post by Nordical25 »

You are welcome. I am glad to hear that you got it running properly by a little adjustment.

I had to do similar checks when I bought my second 1987 4wd Tercel. It is unbelievable what wrong timing and random air leaks can do to idle and for throttling until you see, check and fix.

It is also good to know this procedure in case you end up buying more of these wagons. Sometimes these are sold as not properly working ones but all they need occasionally is some proper adjustment and minor parts.
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Nordical25
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Re: Drivability mystery problem

Post by Nordical25 »

And nice looking Tercel 4wd by the way. Tercels tend to get rusty at least here in Finland so it is nice to see such a rust-free example.
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NWMO
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Re: Drivability mystery problem

Post by NWMO »

Nice work 854WD,

It would appear a PO tried to pry the harmonic balancer off instead of tap/pull it, thus chipping the backside in a few spots. They aren't easy to find, buy if I were you, I would start looking for a new balancer. Those smaller chips likely don't make a huge difference, but it doesn't take a lot to throw the balance off some. Keep up the good work.

Chris
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eightyfive4WD
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Re: Drivability mystery problem

Post by eightyfive4WD »

dlb wrote: Sun Mar 06, 2022 10:17 pm Just thought of another thing that can affect timing that I have come across a few times -- remove the cap on the distributor and try twisting the rotor counterclockwise. It should twist a few mm, and snap back to its original position when you release it. If it doesn't, the grease that lubricates the mechanical advance inside the distributor is gummed up and causing it to get stuck in spots. If that's the case, you can either replace the distributor with a known good one or disassemble the bad one, clean out the gummed up grease, and re-grease it.
Thank you dlb, this was something I checked as well yesterday.
1985 Toyota Tercel DLX 4WD 5 spd wagon (manual swapped, daily driver)
2007 Toyota Tacoma TRD 4WD access cab long bed (road trip/adventure-mobile)
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eightyfive4WD
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My tercel:: 1985 Tercel 4WD 5 speed wagon
Location: Arizona

Re: Drivability mystery problem - ignition timing

Post by eightyfive4WD »

Thank you Nordical25, it is far from pristine but I try my best to take care of this T4. That’s a great point - I am satisfied that this is now a task I no longer fear or dread. In my eyes the most valuable thing you can “own” is your knowledge. I love to learn and I’m glad this is something I understand how to do properly now.

Chris, that’s a great point about the harmonic balancer. I won’t be in a rush, but I will certainly keep my eyes out for sourcing a new intact crank pulley for the future.
1985 Toyota Tercel DLX 4WD 5 spd wagon (manual swapped, daily driver)
2007 Toyota Tacoma TRD 4WD access cab long bed (road trip/adventure-mobile)
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dlb
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Re: Drivability mystery problem

Post by dlb »

eightyfive4WD wrote: Mon Mar 07, 2022 11:28 pm
Image
Congrats on getting this figured out, and I'm glad the solution was an easy one.

Where did you find that rear window louver? It looks custom made for the tercel wagon but I've never seen one before. I adore it, looks Mad Max-ish.
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eightyfive4WD
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Re: Drivability mystery problem - ignition timing

Post by eightyfive4WD »

Dlb,

I am very glad it was an easy solution as well. And I feel confident in knowing that I can properly set ignition timing & the carburetor mixture in the future, which is a big accomplishment for me. I'd consider myself reasonably mechanically inclined, but as someone younger than my Tercel it's been a bit of steep learning at times. I am more and more grateful each day for the support of this group.

The window louver is AutoPlas branded, produced in the UK I believe. It is period correct; I purchased it from someone on Facebook who found it stored in an old warehouse. It was shipped from Denmark. I can send more pictures of the documentation it came with or close-ups of the louver if you're interested. Haven't been able to find any others since I purchased this one, but there is a group I'm part of on FB where more are sold. There might just be another for a Tercel that will pop up some day.
1985 Toyota Tercel DLX 4WD 5 spd wagon (manual swapped, daily driver)
2007 Toyota Tacoma TRD 4WD access cab long bed (road trip/adventure-mobile)
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dlb
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Re: Drivability mystery problem - ignition timing

Post by dlb »

Ah, of course it's from Europe. I should have guessed. There are some 80's Euro brochures for Tercels somewhere here on the forum, and the stuff these cars could come with over there was amazing. The hidden winch inside the front bumper is my fave Euro option but that louver is right up there. How did you attach it?
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Nordical25
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My tercel:: 2 4wd 1987's. One with 4a, other with 3a
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Re: Drivability mystery problem - ignition timing

Post by Nordical25 »

Window louvers in Europe were really popular during 1980's and 1990's in many 1970's and 1980's cars. However, this is first time to see a Tercel 4wd louver. That is really cool.

In that time it was popular to have Louver, tinted windows, custom rims, side stickers and for example sports steering wheel.

And hidden winch inside front bumper is found from German Tercels. We had never here such an option in Finland as far as I know. So Germany is the land for best Tercel options in Europe, I guess.
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eightyfive4WD
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Re: Drivability mystery problem - ignition timing

Post by eightyfive4WD »

Dlb, those European & Japanese brochures from the 80s are really something, I love seeing all the features & aftermarket parts that were offered!
For the moment I just have the louver attached to my back window with 3M double sided adhesive. It seems to be holding up quite well, although I am debating removing it since my Tercel is not garage kept. I don't always have shaded parking and sometimes my Tercel bakes out in the hot desert sun here in Arizona. My paint can always be refinished, but I'd hate to have the louver fall apart with no replacements in sight.

Nordical25, it was quite a lucky find. Cost me a good amount of $$ though, which is another reason I'm debating removing it. I would hate for it to be vandalized or ripped off of my Tercel by someone. Side decals are definitely appealing to me. I have debated hiring someone who makes custom decals to design some for me, but I can't decide if I want to do that yet with my not-so-perfect paint.

Some members on the FB page have suggested using this louver to form a mold so that others can be made. I am certainly not opposed to that, but I don't have any access to those kind of resources at the moment.
1985 Toyota Tercel DLX 4WD 5 spd wagon (manual swapped, daily driver)
2007 Toyota Tacoma TRD 4WD access cab long bed (road trip/adventure-mobile)
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