Ignition Timing

[meijerbrantm]

I have an l28et and I searched around but am having some issues.

 

I read that Ignition Timing for the Dizzy should be from 17-20 at idle. The thing is now I idle at almost 1000 rpms. I'm not sure if this is an issue between megasquirt and the distributor? I know that my dizzy only has one bolt in it and the left side of the adjuster has been cut out so that it could be adjusted higher than what it can from the factory. So I'm not sure exactly why this happening and if anyone has any ideas I'd appreciate it.

[Zmanco]

You just told us what the timing spec is so you're obviously concerned that it's no longer set correctly. Why not measure it and let us know? It would be a lot easier to help if we knew that instead of having to speculate.

 

Also, let us know how spark is being controlled. You mentioned MS - Which version of MS are you running and is it managing spark+fuel or just fuel only?

 

FYI, significantly advanced timing can increase idle speed. So can a vacuum leak ...

 

Being more clear on your end will make it easier for us to help.

[meijerbrantm]

My timing is at 18 degrees. I'm running MSextra, fuel and spark via GM HEI... I wasn't sure my readings were right, i've looked again for it and haven't found any information on ignition timing actual values. I also feel like I can't do it by revving it up to 3k and adjusting the dizzy due to megasquirt adjusting timing differently than what the stock ecu should be. Also, at idle, yes I'm getting 950-1000 rpms but my vacuum is at 21mmHg. Also, my AFR's at idle when warmed up is about 13.1-13.5, and 11's on cold start.

 

Now one thing I do noticed when messing with the ignition timing of the dizzy, if I get too retarded, when you try to accelerate, you will get some sort of weird fire, and vacuum will shoot up to zero for a split second and you can hear it. I can't really explain it well. I was running it at 10 degrees earlier, and it idled in the 800's which i think is more accurate, but there was noticeably no/lack of power. Now with it advanced it runs awesome for power, but the idle being so high concerns me.

[Zmanco]

You didn't say which version of MS Extra you are running ...

 

If you don't already have it, add ignition advance to the megatune screen so you can see what MS thinks the advance is, and then measure it with a timing light. If they're not the same, then find the screen in megatune where you can adjust the crank angle/offset so what MS and your timing light are in agreement. It shouldn't matter if it's idling or 3k - it's important that what's set in MS is the same as what you measure with the engine running. If it's more than a few degrees off, then you may have to move the distributor to get them close and then fine tune in MS. But since you say it has good power with 18 at idle and you're not saying anything about detonation, it sounds like you should be pretty close.

 

Assuming you have the timing correct, I have to ask the obvious question why you don't just adjust the idle speed?

[meijerbrantm]

edit... cached double post

Edited August 3, 2010 by meijerbrantm

[meijerbrantm]

How do I adjust the idle speed? I don't believe the TB has an idle adjustment screw on it at all on the turbo motors. I've also never noticed anything in megasquirt for adjusting the idle, but maybe I'm blind?

 

This is my first megasquirted car, and I've been slowly trying to figure out all the little quirks with it. I'm sorry that I ask such noobie questions but I just don't have a large knowledge base on what I'm currently doing.

[FlatBlack]

How do I adjust the idle speed? I don't believe the TB has an idle adjustment screw on it at all on the turbo motors. I've also never noticed anything in megasquirt for adjusting the idle, but maybe I'm blind?

 

What throttle body are you using?

 

How are you getting TPS signal?

Edited August 3, 2010 by FlatBlack

[letitsnow]

The L28ET TB does have an idle adjustment screw, at least mine does.

 

Also, TPS is NOT a requirement at all for MS, it is not needed for anything. You can use it for accel enrichment if you want, but MAPdot works just fine. It's also nice to have when looking at a datalog, but it isn't needed.

 

 

If your timing light agrees with what the computer thinks the timing is, don't touch the dizzy again. Adjust only the spark maps in the megasquirt.

[meijerbrantm]

I actually believe I'm using a 240sx 60mm throttle body. Do those have idle adjustment screws?

[Zmanco]

I actually believe I'm using a 240sx 60mm throttle body. Do those have idle adjustment screws?

 

Wow, I think you are going to have a really tough time with your car if you can't answer that by just looking at it. Sorry if that hurts your feelings, but if you play around with the throttle for a few moments it will be obvious that it is adjustable, and you'll see where the adjusting screw is located.

 

BTW, I tried in my first response to give you a gentle hint that you should give us a more complete description of what you have and what's going on since none of us are mind readers. This is another example where we're having to pull important information out of you.

 

And just so we know what's going on, what were the results of checking the engine timing against MS? Were they off, and by how much?

 

One last thing: I'm assuming the PO set this all up before you bought the car. You might want to check the idle with the main electrical accessories on before you change it. Headlights, cabin fan, engine efan (if it has one) all on at the same time could drop the idle 100-200 rpm or maybe more.

[meijerbrantm]

The previous owner setup the car and it ran awful when I got it. Claimed he tuned it with a narrowband... Needless to say it runs an awfully lot better than it used to. It's got a random misfire in it that I can't figure out (seems to happen everytime you start it, then cures itself eventually after a few accelerations. So I assume it has to deal with the dwell settings).

 

I also, never looked at the TB itself, I was just reading online before I went out to the car to work on it. Again, I'm not a genius when it comes to MS on its setup, and definitely not when it has to be run of a distributor. I setup a MS-2 on a VW running off the engine speed sensor (60-2 wheel) and that was a lot more straight forward using multiple coil drivers to drive a coilpack and what not. This has a lot more fine tuning adjustments that I'm not completely knowledgeable about. I'm sorry that I'm not complete with my descriptions, but I also am just not sure what exactly is all the required information that you need in order to help me.

 

I will have to dive more deep into this I guess before I ask of any assistance... I just have a hard time trying to find things when I research online that is a tad more specific to my needs.

Edited August 4, 2010 by meijerbrantm

[S130Z]

 

Dude.......you have a lot to learn. I recomend you start reading up on MegaSquirt's websites and do a little reaserch on how the system works.

 

Figure out EXACTLY what equiptment you have on the car and EXACTLY what problems need to be addressed.

Edited August 4, 2010 by S130Z

[meijerbrantm]

I don't honestly know how i wasn't being specific about problems. The ones I have I feel are gremlins for a initially shitty setup megasquirt. Just nudges in the right direction is all that I wanted. Not a bunch of people that are obviously superior to me when it comes to knowledge of the datsun and MS-1 that have nothing good to say... as in the post above me of course.

 

at least the other posts, as negative as they may have been, had some good information in them too.

Edited August 4, 2010 by meijerbrantm

[letitsnow]

I think the 240sx TB has an idle screw, a quick check and it should be pretty apparent.

 

Step one should be to make sure that the timing light and the MS agree, do this by moving the dizzy and/or adjusting the trigger offset. Once you get this right, set the idle timing to around 18 degrees and you should be good. Now adjust the idle screw.

[S130Z]

I'm sorry man....I was at work and was having a bad day.

 

The L28E motor is notorious for having heat soak problems after the car has sat, after running, for about 5~15 minutes. This heat soak can make the car miss fairly bad until enough liquid gas can make into the cylinders. Also, if your warm up enrichment settings in MS are way off, it can possible cause miss fires. I would not mess with your dwell as it can REALLY mess some stuff up if you get it wrong.

 

I also have a 240sx TB and it has an adjustment screw(hex head stud w/ an 8mm nut that holds it in place) on the oposite side of the TPS.

 

And as everyone else has said.....make sure your timing gun agrees with what MS is reading.

[meijerbrantm]

Yeah, so more stupidness. I can see on MS-2 how to check the trigger angle... but ms-1 i'm not having such luck... anyone know where it is?

[letitsnow]

Spark -> Spark Settings

 

It's the first option under the spark menu with tunerstudio and very likely the same with megatune.

[Tony D]

My timing is at 18 degrees. I'm running MSextra, fuel and spark via GM HEI... I wasn't sure my readings were right, i've looked again for it and haven't found any information on ignition timing actual values. I also feel like I can't do it by revving it up to 3k and adjusting the dizzy due to megasquirt adjusting timing differently than what the stock ecu should be. Also, at idle, yes I'm getting 950-1000 rpms but my vacuum is at 21mmHg. Also, my AFR's at idle when warmed up is about 13.1-13.5, and 11's on cold start.

 

Now one thing I do noticed when messing with the ignition timing of the dizzy, if I get too retarded, when you try to accelerate, you will get some sort of weird fire, and vacuum will shoot up to zero for a split second and you can hear it. I can't really explain it well. I was running it at 10 degrees earlier, and it idled in the 800's which i think is more accurate, but there was noticeably no/lack of power. Now with it advanced it runs awesome for power, but the idle being so high concerns me.

 

How did you get it to 10 from 18 without changing the bins in the MS? Read the bins in megatune, read your timing light, compare the two, they should be the same. If you're dorking with the distrubutor to change timing, you will trash your engine as you are moving the ENTIRE MAP when you do that. THE MS references the trigger, and once set, all adjustements are made from the MS Control Panel (Megatune)...

 

I agree with the last: READ ON MS! This sites MS Forum should give you more than what you need. You're shooting blind right now, and run a good chance of screwing something up but good!

[meijerbrantm]

Alright, well I'm trying to read how to set timing via

 

http://forums.hybridz.org/index.php/topic/23244-megasquirtnspark-mssmsns-installation-guide/

 

My setup is at

Trigger Angle - 65

Trigger Angle Addition - +22.5

Cranking Timing - Time Based

Cranking advance Angle - 20

Hold Ignition - 2

Spark output Inverter - No

Fixed Angle - -10

Trim Angle - 0

 

So now on my map I have that at 500/1000 RPM and 20/30 kPa at 25 Degrees.

 

I have my distributor advanced only to 18 degrees, meaning it should be even more advanced to 25 degrees at idle?

 

 

 

Now, this trigger angle, I should be able to put a higher number then I can retard my distributor quite a bit. Because I know the previous owner only has one screw in the distributor and had cut out the one side so it could be advanced more than allowed.

 

Also, I'd say that changing the distributor timing to be more retarded than advanced is "okay" isn't it? The only thing I'd end up damaging my system is if I shift the map that it advances it way too much. Or at least that's what makes sense to me.

[letitsnow]

Alright, well I'm trying to read how to set timing via

 

http://forums.hybridz.org/index.php/topic/23244-megasquirtnspark-mssmsns-installation-guide/

 

My setup is at

Trigger Angle - 65

Trigger Angle Addition - +22.5

Cranking Timing - Time Based

Cranking advance Angle - 20

Hold Ignition - 2

Spark output Inverter - No

Fixed Angle - -10

Trim Angle - 0

 

So now on my map I have that at 500/1000 RPM and 20/30 kPa at 25 Degrees.

 

I have my distributor advanced only to 18 degrees, meaning it should be even more advanced to 25 degrees at idle?

 

 

 

Now, this trigger angle, I should be able to put a higher number then I can retard my distributor quite a bit. Because I know the previous owner only has one screw in the distributor and had cut out the one side so it could be advanced more than allowed.

 

Also, I'd say that changing the distributor timing to be more retarded than advanced is "okay" isn't it? The only thing I'd end up damaging my system is if I shift the map that it advances it way too much. Or at least that's what makes sense to me.

 

Right now, the timing light reads 18 at idle and the computer is commanding 25, right? To get them to match you could either advance the distributor 7 degrees or change the trigger angle 7 degrees, I'd advise moving the distributor and then locking it down. Once they match NEVER move the dizzy, ever, only change timing in the timing map.