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Engine Misfire
https://slantsix.org/forum/viewtopic.php?t=55812		 Page 1 of 3
Author:  jacmifish [ Sat Jul 19, 2014 12:55 pm ]
Post subject:  Engine Misfire
Hi all.

I'm running Megajolt ignition via EDIS and TBI injection via Powerjection 3 system.

Currently I'm driving around while data logging on my fuel injection software and trying to tweak things after checking things out afterwards.

Wanted to get someones opinion on my ignition map vs. my last datalog.

Ignition Map:

Image

Datalog:

Image

What is happening around 2000 RPM the engine feels like it hit a wall and I heard almost like a weird gargling (no pinging I believe). The motor is also hitting almost 100KPA, which should mean full manifold flow? I would assume this is completely a timing issue I'm having issues trying to guess with this because I don't have a copilot to change these realtime =P.

Any suggestions are appreciated.
Author:  jacmifish [ Sat Jul 19, 2014 1:14 pm ]
Post subject: 
Running a 904 Transmission and unknown gearing in the stock rearend.

Engine:
268 Cam
Weisco high comp pistons.
Stock crank.
Clifford manifold and headers.
Author:  jacmifish [ Sun Jul 20, 2014 7:03 pm ]
Post subject: 
I replaced the spark plugs and now its seems to run better. Still having issues with ping on higher RPM though.
Author:  Jerame_c [ Sat Sep 06, 2014 10:16 pm ]
Post subject: 
What plugs are you using?
My Megasquirt ignition still doesn't seem quite right either, id like to try different plugs.
Author:  Dart270 [ Sun Sep 07, 2014 3:23 pm ]
Post subject: 
Smells like Sam Powell's issue from several months ago. He ended up taking his turbo off and has not seen this problem again. He is/was running MSII, which is what you have?

Lou
Author:  Jerame_c [ Sun Sep 07, 2014 10:13 pm ]
Post subject: 
I just noticed your running throttle body instead of multi port. If you are hitting full atmosphere are you not getting good fuel atomization? I know with carburetors if you have less than about 4" of vacuum you wont run well. If you stay just a little bit out of the throttle (90kpa ish) do you run stronger?
Author:  Matt Cramer [ Mon Sep 08, 2014 9:52 am ]
Post subject: 
21 degrees of total timing isn't much...
Author:  Sam Powell [ Sun Sep 14, 2014 6:48 pm ]
Post subject: 
From looking at your data log, every value is jumping around like crazy. RPM could not possibly be varying that much. You are getting rpm misreads at the cpu, most likely caused by electro magnetic interference from some source under the hood. What kind of pick up are you using? Do you have suppression plugs and wires? It is hard to clean up the electrical environment enough for a weak, sensitive rpm trigger like the Mopar pickup to not get false reads. Grounds are very important. In spite of what you are told, it works better to take all your sensor grounds to the ecu itself, and not the engine block.

Sam
Author:  Pierre [ Sun Sep 14, 2014 9:18 pm ]
Post subject: 
There is some noise but it doesn't seem to be jumping around like crazy. Seems for the most part a change of rpm and pw correlates with a change of tps.

I'm guessing that the crank pickup from 36/1 wheel is driving the EDIS module. What's driving the efi system rpm input?

Have you looked at a megajolt log to see what its doing? May be hard to interpret unless you can get the scales to match up between the two logs.
Author:  jacmifish [ Tue Sep 16, 2014 9:06 pm ]
Post subject: 
Thanks for the input guys.

Dart 270, I'm running powerjection 3 with megajolt.

Jermame_c, yes that has happened before.

Sam Powell: I will check through where my grounds go, I am using a hall sensor, the plug wires I'm using are just stock replacments which fit this coil pack.

Pierre, the megajolt has a RPM output and that is being sent to the efi system. I have taken logs with the megajolt at the same time as the efi. Unfortunately I had one serial to usb adapter burn out just recently so I now can only do one at a time until I buy another.

I will be trying to get a friend to ride with my this weekend so I can safely watch the laptop :roll: haha. Also I can try to take some videos too.

Thanks.
Author:  Sam Powell [ Sun Sep 21, 2014 3:53 pm ]
Post subject: 
If you are in gear driving down the road, I do not see how is possible that the RPM actually jumped repeatedly between 1000 and 2000 rpm at the rate shown in your datalog. The RPM signal is getting messed with, as is the TPS. You were not pumping the throttle were you? I understand you to say you were at WOT. The TPS signal would have been rock solid. I still say you are getting interference from under the hood there somewhere.

You might start by putting a ferrite choke on the alternator output. They are about 3 bucks at Radio Shack. You can set the filter rate a little higher. Do you have it turned on? Is your pick up wired with shielded cable? My BMW has shielded cable on all sensor grounds, and no high voltage spark exposed under the hood.

Sam
Author:  Pierre [ Sun Sep 21, 2014 4:32 pm ]
Post subject: 
The map line doesn't show the same pattern that rpm/tps does. I don't think its a general noise issue, but unless we know the conditions the log was taken we are just guessing. Judging by the time scale that log is about 2 min. That's a very low frequency noise, if that's what it is.

Jac, was this log taken while driving, or at a standstill revving the throttle?

Yikes about the serial adapter. Get a second asap so you can match the logs up and go from there.
Author:  Sam Powell [ Mon Sep 22, 2014 3:32 pm ]
Post subject: 
Pierre, I suppose you might be right. The datalog says it is 17 seconds which is longer than I thought. Until we know if this is a steady state, all is just a guess. I am eager to hear more from him.

Sam
Author:  Pierre [ Mon Sep 22, 2014 10:44 pm ]
Post subject: 
17 seconds is where the cursor is at (the red vertical line). That's how I estimated the total log shown was about 2 min worth.
Author:  Sam Powell [ Thu Sep 25, 2014 10:59 am ]
Post subject: 
Thanks Pierre. I'm going to demonstrate my ignorance here again. Why does the rpm scale in the datalog only go to 2000? Does it display only the highest attained value? You have to assume it is trying to go higher and cannot.


Sam
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