Setting timing on '88 4AF Auto

[her94previa]

Hi Guys, I changed the timing belt on my girls corolla with the 4af engine, now I'm having trouble setting the timming.

According to the book, it said to plug two vaccum on the distributor, but I see three, two on top and one on side of the vaccum advance unit.

Then it said to put a jumper wire on the diagnostic box between "E1 and T", but there are only three cables on the diagnostic box one black one on the "Ox pin, the other on the "E1" and the third on the "Ev", there is no cable in pin "T"

So , which two vaccum hose should I plug and what should I do with the diagnostic box jumper wire.

Any Ideas will be helpful.....thanks

[SCT]

For the diagnostic box pins, that's for the 4AGE. The Factory Service Manual doesn't state that procedure for the 4AF.

Don't forget you need a timing light and tachometer.

5 degree BTDC @ Max 900 RPM (with vacuum advance hoses disconnected).
10-16 degree BTDC @ Max 900 RPM (with vacuum advance hoses re-connected).

[her94previa]

Thanks for the info. and the diagram that will help me a lot.
I'm following the hayes manual ignition timing for the '88-'89 4A-F (DOHC), but I'll take your info to be more accurate.
I dont have a tach, I'm going with the rpm reading on the dash. Will I be off by a lot if I do it like that? The sticker on the hood is gone, the hood was replace a while back when she hit a deer

Thanks Again.

[verlaryder]

Put a little white, yellow or orange paint (e.g. typewriter correction fluid) on the section of the plastic timing mark tab where 13 degrees BTDC would be located. Then hook up the timing light and rotate the distributor until the moving timing mark lines up with the 13 degrees BTDC timing tab mark you painted. This will give you the correct ignition timing.

The '88 and '89 factory manual for the 4A-F engine explains that setting the timing to 13 degrees BTDC without any hoses disconnected and plugged is equivalent to setting the timing to 5 degrees BTDC with certain hoses disconnected and plugged.

[retiredat44]

I found it useful to make a scratch on the block where the distributor sits when in proper timing. That way if the dizzy is removed, you can see where to put it back..

IMHO

[BeatupRolla]

i got a quesiton, i have never done timing light check befor and want to do it... but do we need to take off the timing belt covor to do it? and is the tachometer a must? i dont have one.

[BeatupRolla]

so i checked the timing, i didnt need to take off the belt covor which saved lots of time.. i have a problem though

the problem is if i set it at 15 degrees BTDC it would idle really low(500-600rpm), and when i drive it, it just accelerates really really slow..

i had no choice but to bump it back up to 30-40 degrees BTDC(900-1000rpm), where it has the best acceleration..

im not sure what is wrong, maybe the crank shaft pully was not put on properly? im confused.. not sure if i should set at 15 degrees BTDC(very slow), or leave it at 35-40 degrees BTDC where it picks up speed nicely

[BeatupRolla]

i think i might know why it does this now, it all makes sense when i think of it.

the car did make poping noises from the exhaust pipe, which might be a clogged muffler or catalytic converter.. and this does reduce performance, which is why when i set the timing properly it would lose so much acceleration..

now im thinking the previous owner didnt want to fix the clogged exhaust and covored it up by increasing the ignition timing, which then increases acceleration... which then makes the car drive like almost normal?

anyone agree? i noticed whoever previously timed the ignition, they made a mark on the distibutor so you wouldnt need to time it again... when i lined it up it seemed to be the right timing degree but it just doesnt run properly(slow acceleration) because of the clogged muffler or catalytic converter..

[SCT]

It could be just running rich. Mine runs rich, even though in runs fine, it backfires (POPS) out the exhaust. And my entire exhaust is all new.

[BeatupRolla]

i geuss we can say that the clogged exhaust system is not the cause of the slow acceleration while the timing is set correctly.. and that my car must be running rich.. i didnt know the poping noise could mean the car is running rich, thanks for the info..

maybe i should try to set the timing with the vacuum hoses disconnected this time, doubt it would make a difference though.. still thinking of what could cause this bad timing problem hmm

[SButler83]

That haynes manual stumped me too on the E1 and T connectors. Glad to have found this.