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l28et megasquirt running problems


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Hey guys it's me.. again.. 


I finally got all my megasquirt hardware mods sorted out and now i'm in the garage trying to get it started.

Its a f54 n47

megasquirt 2 v3.57 direct coil control

stock 280z dizzy

36-1 trigger wheel and hall sensor

440cc injectors


The car ran great when it was on fuel only with stock ignition


Anyway, this is how i have it setup in tunerstudio


Spark settings:

Toothed wheel

skip pulses 6

falling edge 

going high

single coil



single wheel with missing tooth



tooth #1 angle 70

crank speed

fixed timing

use prediction set to 1st deriv prediction

fixed advanced 10*

cranking dwell 6

cranking advance 10*

standard dwell

dwell 3.4

spark duration .5


I can start the car if I hold the throttle open but as soon as I let off the gas it dies. it is running bad and smells terrible

I used a spark advanced table from the sticky forum for a standard l28et to get me started. I have not been able to try and set timing to match megasquirt because I cant get the car to idle. What do you guys think. Any help is greatly appreciated 

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Alright UPDATE! I got the car running now. I increased the rpm set screw to hold the idle while I played with the timing. I read a forum(i believe it was extraEFI) that was about the trigger wheel and each gap between the teeth equals 10*. I had my tooth angle 1 set to 70. which would mean 70* before the #1 tooth after the missing tooth. Extra efi also says to set your sensor 6 teeth ahead of tdc for 6 cylinder applications. So I set the car to TDC and counted the gaps between the teeth from tooth #1 to tooth #6 where my hall sensor is and that is 5 gaps or 50*. So I set my tooth angel to 50 and the car ran a whole lot better. I was also having sync loss problems so I tightened the gap on the hall sensor to the trigger wheel. About to go test drive it. 

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dexter72, When I had the car running fuel only with stock ignition I used my wideband and tuned the car really well, 14.7 crusing at all speeds and around 10-11 under 8psi of boost. And now that I have the spark setup the AFRs are even better under boost. My fuel VE table is only set to 100kpa because I just learned that my VE table was not registering boost. So I need to set it up to match my spark table which goes up to 220.


madkaw, because i'm using a 36-1 trigger wheel i cannot set my trigger angle, instead i have to adjust my Tooth #1 angle until timing on the engine matches timing on tunerstudio.


So what I did was I set my timing to fixed at 10* and checked with the light and everyting lines up, however I cannot set my timing any lower. I tried setting the timing in megasquirt to 0 fixed but the timing light on the engine says 10 and tuner studio says 0. But if I set it to 10* or 15* or 20* it all matches up on the car to the computer. I dont know if thats an issue because My ignition map never goes lower then 18* anyway so i'm not worried about that. At idle my timing is 27* (when running the ignition map not fixed timing) but I cannot get a reading on the engine because my timing marks only go from 0-20 so i set the idle timing to 20 or 10 and made sure it was matched up there as well because with fixed timing the car ran terribly.


But now I need to find out why my Car is loosing sync. I do not know why it is doing this. I just remade the mount for my hall sensor and it is rigid. I also re-aligned my trigger wheel on the crankshaft pulley and it looks like it has absolutely no play in it, no wiggle or oscillation, And the hall sensor is mounted as close to the wheel as possible without hitting. But when I drive it megasquirt will loose sync and the car will turn off and on quickly. Just like if I were to turn the key off and on really quick. It'll die but catch itself. I dont know what else to do besides going to a machine shop and having them weld the wheel to the pulley and make a new mount, but i'm afraid that will not fix the problem because the way I have it mounted now, is rigid. And the trigger wheel is mounted and measured to be center. 


The hall sensor is wired 


black- grounded to the sensor mount

white- to megasquirt


What do you guys think? I'm hoping the guys from DIYAutotune will see this post and chime in as well.

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Well I just sent my crank pulley off the the machine shop to get the trigger wheel centered and welded, I will get it back in about 2-3 weeks. I only had the trigger wheel mounted with the 2 bolts that are supposed to be used to remove the pully and at idle the wheel was a little off center. But when I get the wheel back, If it still does the same thing I will bring this post back up with a coppy of my msq and tooth log.

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  • 2 weeks later...

I have high impefance supra injectors. And I will change that ground right now.


The issue I'm having right now is. I still have sync loss. The trigger wheel is centered The sensor is as close as possible and centered on the #6 tooth ahead of the missing tooth just like on the trigger wheel forum. When I set the timing in megasquirt to 20° and then check with the timing light. The timing light shows 18°. So I tried adjusting the tooth #1 angle. Its set at 50 right Now. But if I adjust it, it should compensate for the unequal timing correct? Because no matter how I adjust it, The timing stays at 18 on the timing light when megadquirt says its at 20.


Any ideas on what is going on? Is it just because maybe my timing marks are not centered on the timing cover? And I'm loosing sync because of a bad ground?

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I have the MSQ, Data log and tooth log file but when I try and upload the files to this forum it tells me I do not have permission to upload this type of file.. 


Also, Xnke, When you say to run the sensor ground back to ms sensor ground, you are referring to the wiring harness you get with megasquirt right? Because I do not use the harness, I use the relay board with a db37 connector harness between megasquirt and the relay board and a homemade wiring harness off the relay board to all the injectors/sensors, So where can I run the ground to? The relay board has a power, sqitched power and ground that powers the megasquirt. Can I run the ground to the same ground that megasquirt uses or does it need to be a special sensor ground?

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Alright Here Is a compressed file including data log of a 5 minute drive where the car lost sync about 132 times, a tooth log of my just at idle in my driveway and my msq.  In the msq I have the tooth set to 45 mainly because I forgot to set it back to 50.  For the record the log files are from yesterday and the msq is the latest autosave from today around 7pm.


Right before I wrote this I went and re-routed all the wires away from anything that might cause noise, and mounted the ground to the Megasquirt ground. I also enabled noise filtering that you can see in the msq. I went for a drive and the car drove well and never lost sync until I did a pull in fist gear, as soon as I reached about 5psi at maybe 4500 rpm or so the car stuttered and the sync counter counted about 30 times within that few seconds, however other then that the car ran great. It only looses sync in 1st gear under boost. It didnt do it in 2nd or 3rd.

Data logs and MSQ.rar

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Have you mechanically checked that your timing marks are correct? When you bring piston #1 to TDC, does the pointer aim at the 0 mark?


Next, I would ignore the forums saying that "correct" offset is 60 degrees or whatever. There are so many ways and positions to mount trigger wheels and sensors. Just measure it by eye first, then with the timing light once it's running.


When the engine is actually at TDC on cylinder 1, not just by reading what the pointer is aiming at, you should be able to see what the offset is from missing tooth to sensor within 5 degrees at worst.


While the engine is still at TDC on cylinder 1, have a look to see where the distributor rotor is pointing. Hopefully it's at post number 1 on the cap... You can tweak it a bit once you know what your full range of ignition advance will be, so that you're not ever jumping the spark from the corner of the rotor.


Last, there must be a spec for the sensor gap. It won't be "as close as possible without touching the trigger wheel." Find it and set it.


Getting these things right tends to eliminate most sync issues.

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  • 4 weeks later...

Alright, The problem is getting worse and its to the point where if I let it idle the car will just loose sync until it dies. I set the car to tdc and the distributor rotor is pointing in between the #1 and #5 posts on the cap. I looked over my datalogs and it says I have sync loss reason #2 That means that the missing tooth is at the wrong position, But every time I set my car to tdc and check the sensor it is dead center on the #6 tooth on the wheel before the missing tooth.. Can the rotor being in the wrong position cause this problem? I have been looking for a 280zx turbo distributor because at this point Im done. I have taken the car to multiple performance shops, started multiple forums about this trigger wheel setup and the problem remains. I don't know what to do and I am extremely stressed out. 

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No you cannot, only with a basic trigger setup like the 280zx dizzy. I have to adjust the Tooth #1 angle (beg BTDC) until the timing in megasquirt matches the timing on the timing light, however no matter what I set that number too the timing on the engine and timing in megasquirt are always about 3 degrees off.

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