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my story had been told on here and I have had much help from members so again...Thanks!  Will re-cap but keep it short.  I inhereted a non running 82 280zxt with MS3 that had previously been on the road and then died. I am old school, but am learning this tuner stuff as fast as I can.  Anyway, have had the car running for a while (thanks again) but have had some various issues so it now has me questioning my spark advance table.  I did not build this table, it was given to me amongst all the data I got with the car so I don't know its origin.  I have compared it to a few others I have found on line and it looks quite different.  Can someone with a similiar setup compare to what theirs looks like an tell me if this table looks reasonably close?  The values seem high to me based on what I have read and somewhat backwards in some ways as well...

 

I attached a pic of the table as well as the ign settings.  

 

I expect there are more questions that I will need to answer to get help so feel free to ask them and I will answer to the best of my ability.

 

Thanks

Jeff

 

 

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Posted (edited)

From one Old school gent to another.

 

Ummm... yeah. That table leaves a lot to be desired. It can be improved upon quite a bit.

 

1: First off. Scaling under boost is all wrong It goes from no boost  ( 100 KPA = zero lbs boost )  to full boost ( 400 KPA = 43.5 lbs ) in two steps!!. Those are just huge jumps. No good at all.

 

2: At higher RPM's but under no boost you can carry the maximum timing all the way from 3,500 to Redline. No need to reduce it at Load values under/equal to 100KPA. 

 

3: Cruise values are actually too low. At cruise, because of reduced mixture density and leaned out AFR's, the flame front ignites and combusts much slower. Thus additional advance is required. It is quite common to see Cruise Spark Values in the 42 to 45 BTDC range.  People often don't understand this, but that is why old Dizzy's had a vacuum advance. To provide additional advance under light load at cruise RPM's ( typically 2,000 to 3,500 RPM )

 

4: He's using a lot of advance ( 25 BTDC ) at idle, but the reasoning on that is sound. Larger cammed engines require a LOT of ignition advance at idle. That is because the valve overlap causes a Natural EGR that dilutes and contaminates the incoming Air Fuel mix. This requires a lot more advance at and just off idle. It usually clears up by 1,500 to 1,700 rpm . You will often see that big cammed engines will pull more Vacuum at cruise than they will at idle. This is just the Nature of the Beast.

 

Now Turbo cars with low compression also sometimes require a lot of idle and low RPM ignition advance. But the reason is a bit different. the 280ZX Turbo has an abysmally low CR. 7.4 to 1. The result of that is that they are a dog off the line. Stock ignition on a 280 ZX Turbo ( depending on year ) is 20 BTDC. So the guy has raised it to 25 ( Not an issue at all ) in an effort to get the fat slug off it's perch and get the Turbo spooling faster. A common strtegy with Turbo cars.

 

The thing is, every car is different. The tune really has to be developed for each individual car. One slight difference in specs can make all the difference in the world. That's why it can be dangerous to grab other peoples tunes off the Internet. IE: "  I used XYZ's tune and my engine went boom. Oh wait... That tune was with Water/Meth injection??. I don't have that ... " 

 

For that reason I will not post any Tunes on forums and I ask that anyone that I help out does not post up my Tunes or Tables. I can help you out and will PM you with some contact info. I'll need ALL of the information on your engine specifications, expected boost levels and usage. The more info the better

 

I'm old school as well and have been Racing since I was 18. I'm 63 now. Been tuning Mikuni's , Webers, Su's Holley's and Quadrajets all that time. Getting into EFI more and more since about 2006 ( Vw/Audi ) EFI is just a different tool. Instead of changing jets with a screwdriver, you'r just changing values with keystrokes. 

Edited by Chickenman

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PS: On the Trigger Angle setup it looks like he has the distributor rotor 180 degrees out. Normally the Tooth #1 angle will come out to approximately 360 degrees BTDC with the DIY Trigger Wheel. The fact that his table shows 180 degrees BTDC leads me to believe that he juts got the dizzy installed 180 degrees  and didn't bother to fix it properly. So he effectively did the old wire switch aroo with the TS software. 

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Jeff ,

Do yourself a favor and contact Richard( chickenman) to help you out . If that part of the tune is wrong, other parts of the tune are also probably wrong . I am also old school and just converted to MS3 on my L24. Richard helped me to get the ball rolling. He can walk you thru a tune and knows MS well enough to get me tuned in one evening. It was a basic tune so I can enjoy my car while I learn more.

An hour an half conversation and some team viewer work and I was driving to Coffee and Cars the next day.

It's a steep learning curve to make the change, but you should be able to enjoy your ride while you are learning

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