8 pin hei tach spikes

[convertables_10]

Im getting tach spikes on my 8 pin hei in a 350 chevy wit a tbi. I modded a 4.3 harness to my applicaion. I used sheilded wire from DIYAutoTune on the module for pins 24 and 36. It runs until about 6 inches from the distributor. Ive rerouted my harness away from the plug wires. I know its probally simple an im just over looking it. Ill upload my msq and log when I get back to the house.

[convertables_10]

Heres a datalog and a tune. Ive rerouted all my wires shielded the wire except where i spliced into the plug near the distributor. I replaced the module and made sure the pick up inside was clean and getting a good signal. I did notice that most of the time it was cutting out near 14% on the tps sensor reading almost every time. Im running ms2 v 3.0 with 2.890 code. Everything test fine on the stim as well. Its the last bugs i have to work out on it. Can having the trigger angle off a little cause this as well?

FINAL.msl

CURRENT 11-28-10.msq

[Matt Cramer]

Trigger angle shouldn't cause a problem like this. There are several HEI input schematics floating around, some of which are more sensitive to noise than others. Which one are you using?

[convertables_10]

I have since made my own hei mod kit that yall have and have it installed. I was having these issues before I added the 5v pull up. Ill get another log when I leave work. I did get to drive it today but it was running so rough that it was impossable to drive. Im rechecking my req fuel settings after work. I think it spiked a time or 2 this morning but I didnt get a datalog of it. The mod did seem to resolve most of the spikes though.

[convertables_10]

Well did some driveway tuning and seen the tach spikes are still there. What do i need to do to convert my ms2 to run on firing from negative side of the coil? Im ready to yank the distributor and go back with what I had before I swapped it out leaving the tbi unit of course. Unfortunatly im unable to drive it and I dont have a spare vehicle at the time so I need to get it running somewhat correctly to at least tune it. New datalog after updating my req fuel to match my injectors. I found a loose wire on the iat sensor and it has been corrected.

[convertables_10]

Now they seem to come and go on the tach spikes rerouted everything changed ground spots and nothing seems to change. I ried to drive it and it didnt leave the driveway.

first drive.msl

[kjones6039]

Just curious......

I did a quick read of your thread at V8S10.ORG, where you mentioned EDIS8 several times. I also noticed that you mentioned EDIS8 in your signature.

Are you actually using 8 pin HEI or EDIS8? The settings would be quite different depending on which one you are using.

Ken

[convertables_10]

Currently on hei. I have to machine a new trigger wheel. Once i knew i was gonna have to run hei I swapped the ecm around for it. I have a 100 ohm resistor feeding the signal and modded with diy's hei mod kit and using there settings. I can post the msq in jest a sec when i step outside. but im triggering on falling edge. Im gonna start checking solder joints after work cause that might be causing the problem. Just starting to run out of ideas on what to check next. I had it last night where it would rev to redline put it in gear and the signal went haywire and I never got it stable again. See the first drive datalog. If i cant get the problems to go away im swapping to a big cap hei and triggering off negitive side of the coil until i get it figured out.

[Matt Cramer]

With our HEI mod kit, Ignition Input Capture needs to be set to Falling Edge. It triggers on the opposite edge as the normal input setup.

[convertables_10]

My msq settings are correct with falling edge trigger. I followed the manual on the install and trouble shooting.
im lost now and ready to downgrade a little so i can get it driving then readd stuff as i get my new edis trigger wheel made. Any other possible ideas before i go home and rip it back apart? New module vr wires looked good. when i dropped my second distributor in. My harness on has the splice and about 6 inches of wire out of the loom. Shield wire is running to the ground plane in the ms unit. U3 maybe? Im gonna check the solder joints there after work and maybe thats it.

[convertables_10]

Ive pulled it back out until I get it figured out. Ill use a drill to turn the distributor shaft and i should be able to see if its in my harness or the parts. Im rechecking all my work and getting it right out of the vehicle. Do i need to seperatly sheild the saw/pip wires or is the diy wire correct for the job?

[convertables_10]

Getting started on this again. Im pulling the harness and redoing my db37 connector. I will be using 8 pin hei on it for now. Im replacing the plug wires when i swap the distributor. What all can i do to reduce the noise in the saw and pip lines? Ive used the shielded wire for all but the last 6 inches of the harness going to the distributor. Everything else looked good. I just need to get it figured out and get the holley off this motor.

[Matt Cramer]

The shielding should be enough - where's the MS grounded?

[convertables_10]

I grounded the ms unit to the intake. I will have the harness out this week and adding some plugs so i can swap ignitions when that time comes. I can run a new ground back to the ms unit if that will help. Ground from battery runs to both frame and alternator bracket. Also building my own relay box on the firewall since im diving this far back into it.

[convertables_10]

Got it running without the previous tach spikes. I had to relocate and seperate my grounds for the ms unit and the ignition module. Once I did that all signs of my tach issues was gone. It even fired up first twist of the key. Now to read and tune it.