I have tried switching tfi modules. from a new msd to a known working used motorcraft.It's ok they are 2 separate signals, ECU gets the pip, tach gets the negative side of the coil. I assume you have swapped the tfi to try a new one right? The tach is seeing the coil drop...
Try this pull the spout and set the timing locked at 26* see if it still breaks up.
The mention of ecm controlled dwell having problems with low resistance coils stuck with me. I'm gonna look into it further but I do believe that the pro-m ecm takes over the control of dwell. I do have perimeters in the software to adjust dwell but I'm not sure if they are employed with the distributor ignition. The same ECM supports coil on plug and this parameter may only be in use for that.The Tfi still produces the idm signal and controls the dwell remember only the later 94+ tfi modules are ccd. Dwell is mucho important
Make sure you have dwell settings set to "fixed duty" and 50%The mention of ecm controlled dwell having problems with low resistance coils stuck with me. I'm gonna look into it further but I do believe that the pro-m ecm takes over the control of dwell. I do have perimeters in the software to adjust dwell but I'm not sure if they are employed with the distributor ignition. The same ECM supports coil on plug and this parameter may only be in use for that.
Well.... this is looking like a programming issue that was masked by a week coil.
First problem appears to be the fact that the ecm was configured for a vrs sensor instead of the 3 wire hall effect. I'm not totally sure what difference this will make as it was still working off of both the rising and falling edge.
The other issue looked to lie in the timing curve and an over lap in where 10*s are pulled for idle. Watching with a timing light, there was an overlay between 2500 and 3000 rpm where I saw 46* of timing. With the old coil I never saw any indication of this and have spent a lot of time listening and checking plugs for signs of detonation. In addition there were areas where timing was perhaps a bit high for the compression I'm running. I made some revisions to the part throttle curve and all appears to be remedied, but I can only rev in the garage right now as the weather has taken a turn.
I'm honestly a little dumbfounded. I was only replacing this coil as a bit of maintenance. The car was running good with the old coil. I'm very curious to see if it picked up any. Thanks for the direction on this.
The Pro-m EFI with wideband controllers. When I say throttle position I'm afraid it's a little misleading. It's adjusted on a load table. Load equal to air ingested vs engines potential for air at a given rpm. Lower loads reflect part throttle. The Wideband controllers have a/f readout for stoch display. Timing is adjusted by the same type load table.It appears that you are self-tuning? What method do you have to read and record AFR along with RPM and throttle setting?
I'm waiting for download of the mega viewer. I have been able to view the spreadsheets for the data log on excel, I just haven't been able to copy, print, or share. Thanks for the link, I'll see if it works.This datalog software supports many systems, if your is not supported they can find a version that will much easier to read than any excel spreadsheet. It is also intuitive and you can use the log information to auto build scatterplot's and histogram's.
Maf tuning can be tricky, 45* timing is normal at low load/cruise but above 50%TPS or more you want timing to fall off linearly up to wot... dont ignore the TPS % you should use it as a reference for load against maf during tuning. If nothing else use it for a sanity check.
I tune a lot, datalogging is my most important tool in fact I have tuned from nothing but datalogs.
The megalogviewer lite is free to try and use. If it is not supported buy exel you NEED datalogs
https://www.efianalytics.com/MegaLogViewerHD/
No problem, I am going to post a link to a datalog video I did a few years ago. I go over alot of the settings and how to interpret information in them. I watch them sometimes and cringe at my lack of editing but they convey the information. Lol.Viewer works. Gonna take a little learning to put it to use but great tool. Thanks again.
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