Ignition Timing

Tiny
PYROMENGER
  • MEMBER
  • TOYOTA CELICA
I have a 1986 Toyota Celica GT (2.0L 2-SE engine SOHC, auto transmission) and noticed that the timing is set to about 25 degrees before top dead center, when it should be at around 10 degrees BTDC. If I move the timing down to 10 degrees, then it runs horribly with no power whatsoever.
I am measuring the timing with a timing light, so I know that it is the exact timing going to the spark plugs. Also, I checked all the ignition resistances and they are within specifications.
Does this mean that my timing belt is off by a notch or two, and so the ignition timing is advanced to follow the messed-up valve timing? I can't think of any other possibility than the camshaft timing being off.
Do you
have the same problem?
Yes
No
Wednesday, August 1st, 2007 AT 10:56 AM

14 Replies

Tiny
KIN CHAN
  • MEMBER
Once engine warm up . Terminal E1 &T on the diagnostic port should be jump across with a wire, saftey pin, paper clip. Whatever that is metal. Then chk ur timing.U were not reading the true timing til u jump across those 2 terminals.
Was this
answer
helpful?
Yes
No
Wednesday, August 1st, 2007 AT 11:14 AM
Tiny
PYROMENGER
  • MEMBER
Kin chan:

I did read the manual and checked the timing correctly. Meaning I jumped E1 & T with a wire. The reading was accurate. The problem is something else.
Was this
answer
helpful?
Yes
No
Wednesday, August 1st, 2007 AT 11:49 AM
Tiny
KIN CHAN
  • MEMBER
Hoow's mileage?
Whats the vac reading at idle?
Whats it idling rpm?
Was this
answer
helpful?
Yes
No
Wednesday, August 1st, 2007 AT 11:52 AM
Tiny
PYROMENGER
  • MEMBER
Mileage is 133,000. If you meant gas mileage it's decent, about 24 mpg city and 28 highway.

I set the idle rpm as the manual instructed at 700 rpm with that plug disconnected. Normally it varies from 600 to 800 or so.

I don't know what you mean by the vac. If you mean the vacuum hoses, I haven't checked any of them.
Was this
answer
helpful?
Yes
No
Wednesday, August 1st, 2007 AT 12:00 PM
Tiny
KIN CHAN
  • MEMBER
Find a central intake vac port. Like the 1 that is used by the vac hose for the pwr booster on ur brake. Get a vac gage n tell me the readin. Movements of the needle --> steady, wandering. Bounce around. Do it at idle n 2500 rpm.
Was this
answer
helpful?
Yes
No
Wednesday, August 1st, 2007 AT 12:21 PM
Tiny
PYROMENGER
  • MEMBER
Alright, I can probably do that tonight if we have a vac gauge. I'm at work right now.
Was this
answer
helpful?
Yes
No
Wednesday, August 1st, 2007 AT 1:39 PM
Tiny
PYROMENGER
  • MEMBER
At idle the pressure from the brake booster line was at 21 in. Hg (53 cm Hg) at first, but after it was revved to 2500 rpm it increased to 24.9 in. Hg (62 cm Hg) and stayed around 24.9 during the rev and at idle afterward.

The needle was steady at all engine speeds with practically no movement.
Was this
answer
helpful?
Yes
No
Wednesday, August 1st, 2007 AT 8:41 PM
Tiny
KIN CHAN
  • MEMBER
Okay 2 question on my mind.
90% sure ur engine is running perfect. No timing cpts misalign.
Now here what I wanna be sure.
1.) U chk ur timing when it is warm up & at drive holding the brake?
2.) Have u set the harmonic balancer at TDC n chk the timing mark on the cam gear. What I am gettin is a possiblity of the harmonic balancer inner rubber ring spun & gave u false readin.
Also my alldata said ur timing should be 16 deg btdc on an automatic transmission spec.
Was this
answer
helpful?
Yes
No
Wednesday, August 1st, 2007 AT 9:00 PM
Tiny
PYROMENGER
  • MEMBER
1) I have not checked it while in drive- I can probably do this tomorrow if you think it will make a difference.

2) I am not certain about this, but I think that on this engine the crankshaft pulley (which has the mark) is attached to the shaft with a keyhole. Meaning it can't come out of place. I'm pretty sure that's how it worked. I changed the timing belt a couple months ago. Unfortunately when I changed it I kept the camshaft pulley where it was and didn't even look at the mark to make sure it was in the right place.

I'm not sure why your alldata says 16 deg. The book I have says 10 deg. Even still, it runs badly at 16 deg. Anyway. Has to be around 20-25.
Was this
answer
helpful?
Yes
No
Wednesday, August 1st, 2007 AT 10:05 PM
Tiny
KIN CHAN
  • MEMBER
Most harmonic balancer has an outer ring which timing mark was etched on the it. The outer ring is attached to a rubber layer of ring to the inner pulley core. Rubber is used between core & ring to absorb the recipocal vibration from the crankshaft & moving cpts. Thru years n age. Rubber gets harder and started separation which is what I mean by spun. So by lining up the TDC on harmonic bablancer n cam gear marking. If there are differences. Most likely the mark of the timing was shift becuz of the rubber seperation ---> cause of a false reading from u timing gun. Another word it would have the same result as u remove ur marking on the balancer n place it a few inches away. So when u timing gun flash. Instead of showing let say 10. The new marking will be 25 deg. But actual timing was 10. Clear enuff?
Was this
answer
helpful?
Yes
No
Wednesday, August 1st, 2007 AT 10:39 PM
Tiny
PYROMENGER
  • MEMBER
Makes sense, thanks for the detail. Is there any way to know if this is what happened other than checking the timing of the cam gear?

Also, I read that perhaps the distributor advance could be stuck, causing it to need to be very advanced at idle to run well at higher rpms. Is there any way to check and know if that's working right?

Basically, I'm just trying to figure out if it's worth my time to try to fix this, or if it's probably fine. Through the next 8 months, I'll probably put 15-20,000 miles on the car and I want to be sure it's working well and I'm not destroying the engine.
Was this
answer
helpful?
Yes
No
Wednesday, August 1st, 2007 AT 10:52 PM
Tiny
KIN CHAN
  • MEMBER
1.) Pull the balancer out n physically examine the rubber linen
2.) Turn ur balancer timing mark by hand and line it up at 25 deg or whatever u think ur timing gun indicate @ idle. Pulll the cap out. Chk the rotor. The outer edge of the rotor metal parts should be just directly under # 1 cyl where plug wire goes. If n only if it is really firing at 25 deg advance. If not then it will be either pass or almost pass the #1 cyl plug wires connection to the cap. But this only kinda eyeball educated guess when u have such a big difference in error as ur suspected
3.) Line up ur TDC. Pop valve cvr. The cleareance of ur valve should be at factory spec. If not. Ur balancer is spun

to verify is ur advance is stuck. Just aim ur timing gun back on the balancer. If u rev u mtr up to around 2500 rpm.U should see around 20-26 deg og increase in timing. The timing mark on the balancer will move backward( counter clockwise) as opposite to the balancer turning

I usually have a 8 sec attention to answer post. And a pretty mean atitude against idiots who can't fix a carbureted car n want to know how to fix a 03' model with 15 DTC on engine performance overnite.I am ASE L1 certified. Cuz I do this to practice my diagnostic skill in my own shop. And I am not accepting pay here. So I don't have to listen or sided to no1. U are the 1st enquirer who answer exactly the way I expect from my mechanics. Which is rare. On toyota. If u logged over 20 K n no driverability issue.I wouldn't worry too much. Over advance in timing normally will shown signs as knocking under load(detonation), high Nox on emission. Probably under power. Idle surging. Good luck man
Was this
answer
helpful?
Yes
No
Wednesday, August 1st, 2007 AT 11:46 PM
Tiny
PYROMENGER
  • MEMBER
I appreciate all of your help, it has really been useful. I will try out the techniques you described, and hopefully I will find the problem (and hopefully it's free or cheap to fix).

Thanks.
Was this
answer
helpful?
Yes
No
Thursday, August 2nd, 2007 AT 10:56 AM
Tiny
PYROMENGER
  • MEMBER
I checked the advance by revving the engine and it advances great, by about 20 to 20 degrees. So that's not the problem.

I also looked at the pulley and saw no signs of slippage in the rubber.

Finally, I turned the crankshaft to where the distributor was exactly lined up at the contact point for cylinder #1, and it was at about 22 degrees BTDC on the timing.

What that tells me is that 1) the spark is actually timed at 22 degrees, so it's not a false reading and 2) the advance is working, so the timing must be lined up with the valve timing. Also, the engine does misfire about once every second and surges a lot at idle. The way I see it, the problem MUST be the camshaft timing.

So. How urgent is this to fix? I would think running it with the valve timing off has got to be horrible for my engine, not to mention lots of lost power.
Was this
answer
helpful?
Yes
No
Saturday, August 4th, 2007 AT 6:30 PM

Please login or register to post a reply.

Recommended Guides