I set my timing at 12* (w/ wire unplugged). After a good amount of driving time, i'll check the timing w/ the plug plugged in, and it'll be around 16* What is the deal w/ that? On long drives it makes my car wanna run a little hot and to make the temp go back down, i'll have to unplug, then replug the timing contol to set it back to 12* I know that a simple fix would be to lower my timing...but i wanna know WHY it's doing this. It's an '89RS w/ an '88 350 TPI setup. Thanks

 

That's what it's supposed to do. That's why you disconnect the wire to set the base timing: with the wire connected, the timing goes somewhere else besides the base timing.

That isn't causing the car to "run hot". Advancing the timing will cause it to run cooler, if it has any effect at all.

Check your air dam if it is in fact "running hot" at high speeds.

Timing marks are notoriously inaccurate. It would be worthwhile to see if yours is right or not.

What makes you think it's "running hot"?

 

I know it's supposed to adjust the timing.....for knock, running rich, lean, etc. But not up to 16*! And advancing the timing will make your car run hot....if it made the car run cooler, then why isn't everyone running outrageos timing? If you advance your timing TOO far...the car will start overheating and giving symptoms like a blown headgasket would. And no it's not the air dam....I know better than that. You say that the timing marks are "notoriously inaccurate"....I have a new crate motor.....could that be the case w/ my motor as well, or is that just something w/ the L98s? When I say running hot....I run a normal temp. of about 190-200*....well it'll start running around 230-240 and rising.....but if I pull over real quick, disconnect the timing control and hop back in, it'll go back down to my normal temp and stay there till the SES light goes back off an hour or so later. (SES light came on to set a code 42 for timing control). My gauge was off, so I've been using a mechanical gauge...so it's correct.

 

OK, sorry, I don't know what I'm talking about. Good luck! Sounds like that's what it's going to take, knowledge won't help.

 

Whats wrong with the factory setting for timing or maybe 2 degrees more advance? When a person advances his or her timing without changing the timing values in the spark advance tables U can run into problems as U just did. Your car, I believe should be set at around 6 degrees. As U said in your original statement your going from 12 base timing to 16 degrees when U hook up the wire. Now if the car was set at the stock # of 6 degrees U would now have 10 - 12 degrees of timing at idle & all of your cars timing tables would be in a much better setting for making its calculations.

 

I'll try that thanks. But you said "what's wrong w/ the factory setting for timing or maybe 2 degrees more advance?" Well isn't 10* is the factory setting, in which case my timing is only 2* advanced....but I've also heard the factory setting is 0*...which is it? Or is it really 6* like you said? thanks

 

Man, I'm not flaming or saying you dont know what you're talking about.....but through my experience, if the timing is advanced too car the car will overheat. I've seen it happen, and I accidentally did it myself once. That's all I was saying....

 

I'm not sure about the base timing on the year of your car, but if you're using the LO3 ECM then that may be your problem.

1. Did you change the knock sensor? The frequency of the 4" cylinder walls and the 3.875" walls are gonna be different and the knock sensors are set up accordingly.

2. Are you getting knock counts? Use that program that JPrevost and other guys have used. I don't remember the name of it, but it'll tell you stuff like that.

3. What does the little sticker under the hood say that the base timing should be set at? That's obvious.

Mine's a 92 (obviously ) and my stock base timing with the plug undone is 0*. I have a timing light with one of those little dials on the back so I can check how far my timing's advanced up to ~50*. Just outta curiosity I checked my base timing with the plug connected, and I got a reading of 22*. That was with the base timing set at 0* (plug disconnected) and with my Jet Stage II chip installed.

I set mine to 6* BTDC (unplugged) and still got 22* plugged in. I don't know how the ECM did that. You'd think that by advancing unplugged 6* that the reading plugged in would be 28*. But that's why I'm not burning my own chips yet either. I got a lot to learn about ECMs.

What I'm thinking is that by setting your base timing so high, that your knock sensor is telling the ESC to retard the timing. I dunno though.

AJ

 

No...i'm using an L98 computer out of an '88.
1. Did change the knock sensor to a 350 sensor
3.

what you said about the knock sensor telling the ESC to retard the timing makes sense....but it's advancing the timing?
Oh, and about you not burning chips becuase you have a lot to learn about ECMs....me and you both man...haha

 

All TPI engines used 6 deg BTDC for base timing. If you advance the timing too much it will try to ignite the air/fuel charge before full compression is reached and will make the engine work harder and overheat.

 

Well if my setting of 12* is too much, wouldn't the computer retard it rather than advance it even further? Oh, and thanks for the info on the stock timing.

 

No, the timing is handled by a preprogrammed advance table within the prom. The only way the computer retards timing is when it hears knock.

 

Someone already answered this if what you said here is correct, but you ignored it. I'll try and make it a little more simple:
The timing advance you read will be different with the plug connected and disconnected, no matter what RPM, no matter how long you drove the car for.
6 is the base setting for a TPI car, 305 or 350. Unless you get into prom programming, I wouldnt go past 10 with it.

 

I know that the timing advance you read will be different with the plug connected and disconnected....I didn't IGNORE anybody's answer....I already knew that. I just want to know why it is so far advanced w/ the plug unplugged. Though maybe it was a result of something else being wrong w/ my car. Good idea about not going past 10*....i think I'll reset it at 8*.

 

OK. I think what you have to understand is that even though the base timing reads higher with the plug plugged in, that doesn't mean that it's advancing as much as it could. Know what I mean?

Like my car, as I said, is set at 0* BTDC unplugged and 22* plugged in. So let's say, if you remember, that when I advanced my base timing to 6* unplugged, and it still read 22* (instead of 28* like I thought it should) plugged in, then it may have been detecting knock at 28* and retarded it back to 22* to get rid of the knock. That would be the ESC retarding the timing 6*. So that's why I left mine at 0* unplugged.

So yours may be knocking SO much that it's retarding back far enough to only give 16* plugged in while the base is 12* unplugged. Try setting it at 6* unplugged and check it while it's plugged in. It may go up to 22*, 24*, etc. because the knock sensor isn't detecting any knock.

BTW, I think I answered my own question earlier about why the plugged in timing stayed at 22* even after I advanced it 6* unplugged.

AJ

 

For some strange reason my post did not go through, here it goes again