retarding ignition timing?

[Cakky]

Will retarding the ignition timing on your car have any adverse affect? Reason I ask is yesterday me and a guy from my work done an oil change on my car and to get to the filter we had to move the distributor, I left before he had finished doing it but when I went to pick my car up later he said when he put the timing light on it he retarded it slightly and this would make the car go a little better?

It definitely feels a little better, but I'm unsure of how good this is for my car?

[RedMist]

Ahhh the secrets of the butt dyno.

It should in theroy, if its a stock engine, be slower.

[[2LOOSE]]

Depending on how much it has been retarded I'd say it would make it worse, unless its turbo, but no it shouldn't have any adverse affects on your car

[dazzag]

he retarded it slightly and this would make the car go a little better?

advancing the ignition makes the car run better. you only retard it if its pinking

[Cakky]

maybe he advanced it and i heard him wrong.

will ask him tommorow

[slighty_sykotic]

Or you could be running 91 in it and the stock advance would be making the knock sensor go "hhhhhhhhhhhhhhhhhhang on" and retarding it like hell.

And now that its retarded the ecu/konck sensor won't be doing shit all.

--Sykotic

[matt dunn]

Yes it it possible that it will now go better retarded,
depending on where it was set.

If it was a little over advanced or was a 20V and set to factory spec's,
the knock sensor may have been retarding it too much and now that it has been set differently it may not have to retard it.

FYI, 20V's running on 96/95 (no 98 here) run a lot better 2 degress' less than factory spec's.

This has benn covered on here a bit before.

Matt

[ollieboy]

Ahhh the secrets of the butt dyno.

Mmmmm yes, it seems to be quoted alot.

[Cakky]

ok, he said he retarded it about 3º..

I only run it on 95, sometimes 98..

I know its hard to tell without a dyno, but it feels slightly better?

[StuartM]

depending on what RON fuel you use, you will have more driveability and maybe power at low rpm but.. because the base timing has been retarded you will have less total advance at high rpm.

I take it you have a fuel injected & computer spark controlled engine but what engine exactly?

set the timing to the manufacturers specifications because with the base timing off the computer will be unable to accurately control dwell and spark.

[slighty_sykotic]

depending on what RON fuel you use, you will have more driveability and maybe power at low rpm but.. because the base timing has been retarded you will have less total advance at high rpm.

I take it you have a fuel injected & computer spark controlled engine but what engine exactly?

set the timing to the manufacturers specifications because with the base timing off the computer will be unable to accurately control dwell and spark.

And they you go drive your 16v/20v on 95 fuel and kill it or it's preformance. Stupid idea... Would be good to set it to manufactors setting IF you ran it on manufactor's required fuel, which you can't in NZ. So therefore you retard the timing to make up for it.

[StuartM]

And they you go drive your 16v/20v on 95 fuel and kill it or it's preformance. Stupid idea... Would be good to set it to manufactors setting IF you ran it on manufactor's required fuel, which you can't in NZ. So therefore you retard the timing to make up for it.

perhaps you dont realise that spark control is based upon an accurately timed signal received from a variable reluctor sensor inside the distributor. this signal is expected to be at a certain cam angle and if you go screwing with it the ignition coil dwell and computer spark control will be out-of-sync, you can see this with a timing light easily as the timing jumping all over the place at idle. and BTW there are knock-retarding (not ignition retarding) chemicals in most fuels so unless this is a 200+ HP engine he won't be damaging it.

[StuartM]

slighty_sykotic: your logic only reigns true for old mechanical/vacuum advance ignition systems.. or well tuned aftermarket ECUs. The OEM toyota ignition systems are not overly sensitive to having their timing changed but you do risk burning out your coil/ignitor.

[slighty_sykotic]

perhaps you dont realise that spark control is based upon an accurately timed signal received from a variable reluctor sensor inside the distributor. this signal is expected to be at a certain cam angle and if you go screwing with it the ignition coil dwell and computer spark control will be out-of-sync, you can see this with a timing light easily as the timing jumping all over the place at idle. and BTW there are knock-retarding (not ignition retarding) chemicals in most fuels so unless this is a 200+ HP engine he won't be damaging it.

Wah? Explain to me more the difference in coil dwell and computer spark control... Then you go look at my gze with timing set at 2 intial, and watch my timing light sit DEAD still...

Then you get back to the point that we arnt talking about damaging it so much as performance. If the motor in question is a 20v 4age (most likely) IT WILL BE KNOCKING AND RETARDING ITSELF ON 95 OCTANCE FUEL CAUSING A LOSE IN PERFORMANCE.

[slighty_sykotic]

And knock induced retard is hard on ignition componats is it not? So wouldnt it be good to eliminate that?

--Sykotic

[StuartM]

dwell is the minimum amount of time the coil will be charged for, dwell time and ignition advance is entirely controlled by the ECU. therefore for the ECU to be operating correctly the timing must be correct. but im not trying to say your wrong here, you get more economy from retarding your timing, but for power you need a certain amount of advance. your GZE is blown so you really need retarded timing.

[RedMist]

dwell is the minimum amount of time the coil will be charged for, dwell time and ignition advance is entirely controlled by the ECU. therefore for the ECU to be operating correctly the timing must be correct. but im not trying to say your wrong here, you get more economy from retarding your timing, but for power you need a certain amount of advance. your GZE is blown so you really need retarded timing.

I'm afraid Stuart that the ECU doesnt calculate dwell. The igntor does.

And base timing can be altered to alter timing much like an old mechanical advance dizzy. The ECU does nothing but advance the timing additional to the hall sensor base timing. So altering the base timing alters the total advance. It gets a little more complex with squential injection driven off the same CAS (cam or crank angle sensor).. but not much.

Optimal power is not just before detonation point (as is set by the dynamic knock map) but a few degrees before. So retarding your ignition in a vehicle that was close to detonation (but not knocking) certainly can increase performance. The 20 valves are case in point, especially if they haven't had the ECU reset since running on Jap fuels.

Oh, and the reason you see timing on a timing light jumping around is probably because you havent jumpered the ECU and its hunting between two MAP zones. Either that or your engine doesnt run smoothly (much as mine does with big cams) and the cam belt is flexing or shaking. Or option number 3, you're running one of the early Link LEM's 4 or below with poor code.

[StuartM]

I'm afraid Stuart that the ECU doesnt calculate dwell. The igntor does.

thanks for pointing that out im always grateful to learn something.

And base timing can be altered to alter timing much like an old mechanical advance dizzy. The ECU does nothing but advance the timing additional to the hall sensor base timing. So altering the base timing alters the total advance. It gets a little more complex with squential injection driven off the same CAS (cam or crank angle sensor).. but not much.

All the toyota dizzy's ive seen, or scoped signals from use variable reluctor sensors, NOT hall effect.

I still think that changing the timing signal to an ECU which controls fuel injection and ignition based upon a VR sensor is not a hot idea. Consider for a moment that the fuelling and spark calculations inside the ECU must take into account a predefined base timing.

[StuartM]

Oh, and the reason you see timing on a timing light jumping around is probably because you havent jumpered the ECU and its hunting between two MAP zones. Either that or your engine doesnt run smoothly (much as mine does with big cams) and the cam belt is flexing or shaking. Or option number 3, you're running one of the early Link LEM's 4 or below with poor code.

yes i know about jumpering T an E1.
this happened in my sister's curren (1994 3S-GE) and was observed without the computer in diag mode. after jumpering it the timing was seen at ~8 degrees, i set it to 10. Then after taking out the jumper the timing was more stable.

[matt dunn]

The closed loop knock retard function in the ECU's are not as clever as you think.

Better to have the timing retarded by 2 degree's manually than the computer detecting knock and you loose 8 degree's.

And the base timing setting will have no affect on the fuel injection


you said
Consider for a moment that the fuelling and spark calculations inside the ECU must take into account a predefined base timing.

Into account on what? how much fuel is injeted?

That has no effect. Altering fuel injection timing by such a small amount has no effect as the same amount of fuel is still injected as the ECU wont know the triming is out?????