timing belt replaced, now 5 deg atdc??

[asm]

Hi,

I have just replace the timing belt on the Gen4 I4 Camry. I swear I have check the timing mark about 20 times over the course of 3 days. Both in the morning and night. Now everything is put back together, the car is running very smooth at idle, no noticeable loss of power at acceleration. Compression checked at 170psi on all cylinders with 20 cranks each, or 160 psi with 3 cranks each. Just when I though I have archive the greatest acomplishment in my life. I found something odd...

I use my timing light and discovered I am running 5 degree ATDC???!!! The manual says 5S-FE should run 10 degree BTDC with TE1 and E1 terminal shorted. So, it look like I am 15 degree off... Is there something I forgot to do?? By the way, the original timing belt broke while at the stop light. Well, it didn't actually break, there is section about 3" long without any teeth. Needless to say, the car was tow back to my house.

I am trying to avoid tearing everything apart again to check the timing mark. The following are soem theories

1. Could the ignition timing, which is control by the ECU needs to be adjusted after a timing belt is broken??
2. Or perhap the 42mm spring the dealer sold me is actually wrong?? Since the factory manual ask for 46mm. By the way, I try to buy the same spring from 2 different dealer and they are all 42mm for 1997 I4 Camry. I checked the 2001 Solara 5S-FE manual, it does call for 42mm...
3. Broken timing light??
4. Wrong timing Belt??


Help!!!! Please, the Toyota factory service didn't really going to detail on how to correct a ignition timing problem.

ASM

[88 LE]

Are you absolutely sure that the belt is installed correctly?

There is no way to adjust the ignition timing on a gen 4 with 5S-FE. The ignition timing is controlled by the ECU and determined by sensors (cam and crank position sensor).

[johnnyzee]

it should actually run better with the timing advanced a bit. you can tell by your idle if something aint right. if you're concerned about your timing light, use someone elses to see if they get the same reading. if so, make sure you read the manual right. if all that checks out which it mostlikely does, here's the solution to your problem:

your actual distributor has to be turned to retard the timing to your specs. by this i mean, slightly loosen the bolts holding the distributor (the unit itself not the cap), once loose, and i mean barely loose, just enough to be able to give it a twist, twist it clockwise or counterclockwise. when your timing needs to be retarded in your case(opposite of advanced) look for your idle engine rpms to drop, for advancing timing, rpm will raise. have someone watch your tachometer to advise you if there's a lift or drop in rpm as it only goes up or down 100-200 rpms. then check with your timing light where you need to be, and tighten up the bolts again.

good luck

[asm]

Found the problem....

I forgot to reset the the timing on my timing light gun back to 0 degree.... I am glad I didn't get the chance to rip everything apart before I discover my mistake.

Anyway, You mentioned the ignition is controlled by ECU by reading the Cam/Crank position sensors. Do you happen to know which one does it read?? Since if it reads the Cam sensor, the timing light test would show up with screw up result even if the timing belt is off by just one tooth. However, if it reads Crank sensor, incorrectly installed timing would still yield correct timing light reading.

What I am getting at is to see if one can use timing light to verify a timing belt job, assuming ignition timing was not manual changed by rotating the rotor cap. In the case of electronic ignition control, as you pointed out, ignition timing cannot be change.

Comment?

ASM

[zoni]

^for those who dont know its called distributorless ignition system (DIS) or coil on plug (COP) ive heard both but DIS is much more common.

you CAN however adjust timng if you mess with the camshaft and crankshaft position sensors (never ever do this)


its possible that you are measuring at the wrong idle speed... make sure you are at the rpm that matches what the book says for timing...

[88 LE]

^ Your engine has DIS (distributorless ignition system). There is no distributor.

The ECU uses both sensors (cam and crank).


Read this:

http://www.yotarepair.com/5S-FEtimingbelt.html