I recently bought myself an obd reader with a data logger for some live data. I was going through it while idling warm and it showed my timing at -4 degrees. Is this normal? Someone told me it could cause issues. Ive had odd idling issues/low speed issues where I think I feel misfires when I idle (Random Vibrations), I was thinking maf sensor.
Might be a dumb question but thanks for the help!
If no cel is on, you are fine.
Weird thing is, when I was misfiring really bad a few weeks ago and went into limp mode, no cel at all.
Are you sure your cel light works?
A bad crank sensor can cause misfire/rough idling and not cause the CEL to come on.
Tester
It totally works, just doesn’t come on for misfires or whatever is going on.
Hey tester, just checked it out, one thing I do notice with my car is with warm starts they feel pretty rough, cold starts are fine, but the entire car vibrates for a sec. Some of those symptoms match what’s been happening, also did notice acceleration isn’t smooth. Id just push the throttle a big and It flies forward, then do it again and drives like usual.
Heat effects bad crank sensors.
Tester
Did a bit more research, seems that uneven acceleration is another symptom and vibrations at idle. Totally going to check that out thanks for the help!
-4 degrees (meaning 4 deg BTDC presumably), that seems a little less than I’d expect in a modern car. My Corolla ignition timing is set at 10 deg BTDC at idle as I recall. My 302 equipped truck is 8. I think my prior VW Rabbit was 10. The service data fro your engine will tell you for certain.
Some folks here have mentioned when they watch the timing (using a timing light on the crankshaft pulley), it bounces around at idle. That’s usually normal, done by manufacturer to improve performance or mpg. There’s usually a test mode available mechanics use to turn that jiggling timing off while they set it to the spec.
Yeah it did bounce from -3.5 to -4 but usually just sat at -4. Other people said that they usually sit at 3-5 with their golf’s at idle so obviously something’s up
Yep something’s up alright. You are right in the ball park with the others.
It’s a 7* difference from other people, I wouldn’t be worried if I was driving but in idle it’s kinda odd
If -4 is before TDC and +4 is after TDC I’d says either they are not mentioning the minus or theirs are the messed up ones. Need to verify if a - is before or after TDC. I don’t recall any automotive engines where base or at idle timing is after TDC. They are probably out there somewhere. Or maybe my memory has finally left me.
OP, if you post the make/model/year/engine someone here will likely know the proper idle timing spec.
BTW, part of checking timing, besides at idle, is verifying the timing advances significantly with higher rpms. Has that been checked?
As mentioned above , the claims you heard that normal idle timing is + 4 degrees, that seems very unlikely.
For unexplained RPM variations at idle, the most common cause is not faulty ignition timing. Usually it is some kind of air leak allowing unmetered air into the engine. Misfires however are often an ignition system problem.
Ignition timing is computer controlled, the amount of advance is in the programming.
If you don’t like the numbers, return the vehicle to the stock configuration.
I’m gonna have to drive it around to see if timing changes. Seems to be normal, only thing I’m dealing with is rough warm starts where the car kinda shakes when started after it’s warmed up or idles. It stops while driving, I’m thinking leaking fuel injector.
I’m thinking IAC (idle air control).
That sounds like the fuel mixture is too lean at start-up. the reason why it runs better after warmed up is b/c the o2 sensors kick in, which tell the computer to boost the fuel flow a little more than would be predicted by the measured intake airflow. A fuel trim measurement would test this idea.
I have a local vw shop that did tell me once that fuel injectors go bad on most vws. I’ll take it in in about a week and tell them what you said to do.