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How To Adjust Ignition Timing On 1997 Corolla?


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#1 Guest_toyota4now_*

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Posted 18 October 2005 - 02:27 PM

Hi fellow Corolla owners,

I am hoping that someone can tell me how to rotate the distributor on a 1997 Corolla 1.6L. The Chilton manual states that the distributor can be rotated after loosening the mounting bolts. There's only a single bolt for my distributor, and when undone, the distributor is loose, but cannot rotate. ?? The opening in the base of the distributor where the bolt goes through is _not_ slotted; therefore, the distributor is fixed in one position only. If the bolt is removed, the distributor can obviously rotate freely, but then there's nothing to hold it in place.

Perhaps the ignition timing on this car is adjusted somehow without rotating the distributor. If so, then the Chilton is incorrect. Any advice or information you can provide will be much appreciated.

Thanks.

#2 now_driving_VW

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Posted 18 October 2005 - 03:52 PM

that's how you do it on the 4A motor. Loosen the distributor and mess around with the timing light

#3 DaveAclm

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Posted 18 November 2005 - 10:07 PM

I had the same problem on my '95 with the 1.8L (7AFE, I believe) engine. I can't for the life of me figure out how to turn and re-secure the distributor to adjust the timing, for the same reason you gave--the hold-down bolt only goes in one way. I'm experiencing pinging that I think could be solved by retarding the timing just a few degrees. Does anyone have a solution for us?

-Dave

#4 fishexpo101

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Posted 19 November 2005 - 07:37 AM

That only works for distributors with two hold down bolts. If you have a single bolt (usually the case with newer 4AFE and all 7AFE, includes OBD-II cars) - then you need a Toyota handheld test to adjust the timing.

Basically the tech plugs in the scanner, connects timing light, jumpers two pins on the diagnostic port in the engine bay, tech will raise RPMs to 1000-1500 RPMS for several seconds, verify RPMs return to regular idle speed and reverify timing. If timing is off, check timing belt hasn't jumped teeth. Some have reported good luck with adjustable camshaft timng gears to adjust the timing.

#5 DaveAclm

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Posted 19 November 2005 - 08:44 AM

I'm a bit confused. Can even the dealer adjust the timing on our cars, or can they can just verify that it's where it should be? Or does the scanner let them adjust it? Would an independent shop have a compatible computer?

On the DIY front, would it be possible to put an earlier, two-bolt 4AFE distributor from the junkyard on my 7AFE engine, or would that just confuse the computer? My car isn't OBD-II, by the way...

-Dave

Edited by DaveAclm, 19 November 2005 - 09:01 AM.

#6 fishexpo101

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Posted 19 November 2005 - 10:33 AM

The timing is fixed on the 7AFE by the ECU - dealer can only verify if the timing is OK or not. The computer can run a self test - but bases all timing on bedefined maps in ROM. Not sure if you can adapt a two bolt distributor or not - good chance that the computer will be confused.

Tooyta ECU ROMs are notoriously difficult to crack. Your options to advance or retard the timing yourself are piggyback ECU (which intercepts and modifies signals coming into the factory ECU) or an adjustable timing gear for the camshaft.

#7 DaveAclm

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Posted 19 November 2005 - 09:17 PM

Hrm. That's what I suspected. Well, maybe I'll look into an adjustable camshaft gear. I just love it--newer cars are, by far, more reliable, but when even the DEALER can't do something like adjust the timing, that's just too much a black-box scenario for me. I can do that in 5 minutes on my old BMW!

Oh, well. Thanks for the info!

-Dave

#8 DaveAclm

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Posted 21 November 2005 - 07:35 PM

...And just out of curiosity, where does one find an adjustable cam gear for the 7AFE? I can't seem to locate one on eBay or a Google search. Probably won't get one, but I'm curious.

-Dave

#9 fishexpo101

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Posted 22 November 2005 - 01:59 PM

There are a few vendors, like AEM, make ones for the Toyota G-heads (4AG/E) - they can be modified to work with the F-head.

Probably won't not suggest an adjustable cam gear for pinging or performance on a F head Toyota engine. The way it is set up - an adjustable cam gear will advance or retard both intake and exhaust together. Some have mentioned that they slotted the OEM cam gear to make it adjustable. Not sure how good that turns out unless you get it done on a CNC machine or good machine shop.

#10 DaveAclm

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Posted 23 November 2005 - 10:50 AM

Ah, oh well. I think I'll just run high-test. But thanks for the info!

-Dave

#11 Bikeman982

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Posted 25 November 2005 - 11:28 PM

Dave,
I have 5 Toyota Corollas and I just checked all the distributors. They all have two bolts with slots. I have a 1992, 1993, 1994 and 1995 with a 1.6L 4A-FE engine and a 1994 witha 1.8L 7A-FE engine. I also have a spare 7A-FE engine in the yard and they all have similar mounting. All I can say is the timing is dependent on the position of your rotor within the distributor (rotating the distributor alters the rotor firing position) and the position of your cylinders which is controlled by the crankshaft and connected to the camshaft(s) by your timing belt. If your car timing seems to be off and your distributor absolutely is not adjustable, then I would look into altering the position of your timing belt or even changing the ECU (if that is possible) to accomodate. Symptons of a poorly running engine could also be the fault of fuel, bad spark plugs, wires or distributor cap, as well as the timing. You can get a timing light and check that portion and if still is running bad, look to other areas. I am not an expert but I understand your pain. Hope this helps.

Edited by Bikeman982, 25 November 2005 - 11:30 PM.

#12 DaveAclm

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Posted 28 November 2005 - 09:35 AM

Plugs, wires, cap and rotor are nearly new, and the fuel filter was just changed as well.

But I know I need to triple-check my timing belt position. I changed it a year ago. When I checked it last spring (trying to track down the pinging), I at first thought it was advanced a tooth, then when I got it partially disassembled checked again and saw it to be correct. Hrm... <_<

If checking again reveals nothing amiss, I'll try to find a two-bolt distributor in a junkyard. If I can get it cheap enough, it's worth a try.

Thanks for the input!

-Dave

Edited by DaveAclm, 28 November 2005 - 09:46 AM.

#13 the99contour

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Posted 30 November 2005 - 05:18 PM

Hrm. That's what I suspected. Well, maybe I'll look into an adjustable camshaft gear. I just love it--newer cars are, by far, more reliable, but when even the DEALER can't do something like adjust the timing, that's just too much a black-box scenario for me. I can do that in 5 minutes on my old BMW!

Oh, well. Thanks for the info!

-Dave


Dave there is a very good reason why Toyota won't let the dealer change the ECU. If they did, dealers would mess with it all the time to "fix" problems that weren't ECU related. Ford cars don't have hard to crack ECUs and dealers mess with the ECUs all the time, sometimes causing major problems. We once had an Explorer with an exhaust rattle that we took to Ford. All that was wrong was that the muffler was loose and it vibrated when the vehicle idled. Ford fixed the problem, but not by fixing the muffler mount. Instead they reprogrammed the idle setting in the ECU to 1700 RPM instead of 900 RPM. It fixed the problem, but then the car got terrible fuel economy and sounded revved up all the time. Eventually that car will have engine problems, and Ford will pay to fix it. Toyota doesn't want to be put into that situation.

BTW, the "black box" is coming. Anybody with a 2005 Model read the first few pages in their owner's manual? Our cars have a monitoring system that records seatbelt usage, speed, brake pedal travel time and a bunch of other things in case we are involved in an accident. Toyota says it is so they can learn to better protect us. I say bull. I personally don't like the "black box", and I'd remove it if it weren't so wired into the car that I believe the car wouldn't even start without it.

#14 Bikeman982

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Posted 01 December 2005 - 03:03 AM

It seems like the technology that is out there supposedly designed to gather data is also the same stuff that will point out what we already know - people are generally lazy or stupid. They don't always use their seatbelts, stay within the speed limits, drive gradually without excessive braking and a bunch of other things. Not only does it make the automobile more complicated and more difficult for the average owner to fix on his own, but it also will eventually give us enough rope to be hanged, should it be used as evidence in a trial. It is more and more like "Big Brother" watching us all the time - 1984??