New setup oscillating at low to mid RPMs

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TheBassman
MS/Extra Newbie
Posts: 4
Joined: Mon May 25, 2015 8:54 pm

New setup oscillating at low to mid RPMs

Post by TheBassman »

So this is a new setup. Ford 302 from an 88 mustang in and 84 Supra. New GT40 heads, 24 lbs injectors, and an after market intake. I am using EDIS8 for spark. MS3 with MS3X and sequential fuel.

Background:
Timing when set to "Fixed" is spot on. If I change the advance, the light shows the correct degrees.

The engine runs, but oscillates quite a bit at low to mid RPMs. Can't seem to get a steady RPM. I have changed the req fuel all over the place, and tried several VE and Ign tables. All have the same issue. Surging from almost dead to 1200 RPM at idle. Looking at the logs, It seems that the MS is hunting for something. It does this with the idle valve unplugged as well.

It seems to smooth out when warm, but any change to the throttle starts it oscillating again. I need to get this resolved so I can begin the real tuning process.

I have disabled AFR control, set to fixed advance, and set the lag values for TPS, MAP avg lag, and Lambda to higher values (90ish). Loaded tunes that are for mustangs and many other things. Right now, I have wiped the tunes, set the req fuel, and basically started fresh. Attached are the logs from the last attempt. I had to restart the engine a few times due to the surge falling so low that the engine died,

What can I do?

Logs: http://supranut.com/Surging.msl
Matt Cramer
Super MS/Extra'er
Posts: 17499
Joined: Thu Apr 16, 2009 8:08 pm

Re: New setup oscillating at low to mid RPMs

Post by Matt Cramer »

It looks like the spark advance comes in a bit too early and you have lean spots in the VE table at idle. I might be able to tell more if you post the MSQ.
Matt Cramer -1966 Dodge Dart slant six running on MS3X
TheBassman
MS/Extra Newbie
Posts: 4
Joined: Mon May 25, 2015 8:54 pm

Re: New setup oscillating at low to mid RPMs

Post by TheBassman »

This tune file has a "generated" VE table, but the results were the same. http://supranut.com/Temp/2015-05-29_16.49.28.msq
Matt Cramer
Super MS/Extra'er
Posts: 17499
Joined: Thu Apr 16, 2009 8:08 pm

Re: New setup oscillating at low to mid RPMs

Post by Matt Cramer »

That tune also has a different spark table from the logs you posted. I would rather evaluate the MSQ and data log as a matched pair.
Matt Cramer -1966 Dodge Dart slant six running on MS3X
TheBassman
MS/Extra Newbie
Posts: 4
Joined: Mon May 25, 2015 8:54 pm

Re: New setup oscillating at low to mid RPMs

Post by TheBassman »

I'm pretty sure that the only table that changed was the VE, because I don't want to be changing a bunch of stuff at once. What make you think it's different? Maybe what is making you believe it's different is my issue.

I have been build the headers for the car so I haven't run it for a bit.

I guess I'll get another log and MSQ together. Maybe tomorrow night.

Thanks!
Matt Cramer
Super MS/Extra'er
Posts: 17499
Joined: Thu Apr 16, 2009 8:08 pm

Re: New setup oscillating at low to mid RPMs

Post by Matt Cramer »

The spark advance shown as spark table 1 does not match the spark table in the MSQ posted.
Matt Cramer -1966 Dodge Dart slant six running on MS3X
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