I have a MSII/V3 running a SBC 383 with TPI in a 1977 Blazer. It was previously running fairly well (about 2 years ago before I overheated the engine). After a fresh rebuild of the engine and rewire of the chassis, I can't get it to idle without an irregular miss. This seems to be related to ignition because I see tach dropouts. I've tried a spare module and coil, and the problem persists. The plugs, cap/rotor and wires are all new. I need to get this running well enough to get across town to our new house, please help.
In the datalog, you can see that the dropouts go away when the rpm increases above ~2000rpm. The tach dropouts seem to go away when I disconnect the vRef signal from the module. I generate the VRef using the fIdle instructions.
Thanks for any help.
The tune is messy, but I need it to run without missing to fix it...
HEI 8 Pin Low/No throttle miss
Forum rules
Read the manual to see if your question is answered there before posting. Many users will not reply if the answer is already available in the manual.
If your question is about troubleshooting, configuration, or tuning, you MUST include your processor type (MS-I or MS-II) and code version in your post. If your question is about PCB assembly or modifications, you must also include the main board version number (1.01, 2.2 or 3.0). For tuning/troubleshooting questions, please attached a datalog and your MSQ file to your post.
If you have questions about MS1/Extra or MS2/Extra code configuration or tuning, please post them at www.msextra.com Such questions posted here will be moved to: a temporary MSextra sub-forum, where they will be removed after 7 days
The full forum rules are here: Forum Rules, be sure to read them all regularly.
Read the manual to see if your question is answered there before posting. Many users will not reply if the answer is already available in the manual.
If your question is about troubleshooting, configuration, or tuning, you MUST include your processor type (MS-I or MS-II) and code version in your post. If your question is about PCB assembly or modifications, you must also include the main board version number (1.01, 2.2 or 3.0). For tuning/troubleshooting questions, please attached a datalog and your MSQ file to your post.
If you have questions about MS1/Extra or MS2/Extra code configuration or tuning, please post them at www.msextra.com Such questions posted here will be moved to: a temporary MSextra sub-forum, where they will be removed after 7 days
The full forum rules are here: Forum Rules, be sure to read them all regularly.
-
seafarer76
- MegaSquirt Newbie
- Posts: 5
- Joined: Mon Apr 18, 2011 7:32 pm
HEI 8 Pin Low/No throttle miss
You do not have the required permissions to view the files attached to this post.
-
Matt Cramer
- Super Squirter
- Posts: 2951
- Joined: Sat Jul 03, 2004 11:35 am
Re: HEI 8 Pin Low/No throttle miss
How is your input circuit set up for the HEI?
-
seafarer76
- MegaSquirt Newbie
- Posts: 5
- Joined: Mon Apr 18, 2011 7:32 pm
Re: HEI 8 Pin Low/No throttle miss
The input circuit on the V3 is set up like the megamanual says to set it up.
-
seafarer76
- MegaSquirt Newbie
- Posts: 5
- Joined: Mon Apr 18, 2011 7:32 pm
Re: HEI 8 Pin Low/No throttle miss
Like this.
V3.0 main board:
DB37 pin #36 to the E pin on the HEI module
DB37 pin #24 to the R pin on the HEI module
On the V3.0 main board:
use the 'Hall sensor circuit' (step #50 in the assembly guide),
jumper OPTOIN to TACHSELECT on the bottom side of the PCB, near the DB37 connector, opposite the heat sink,
jumper TSEL to OPTOUT on the bottom side of the PCB, near the center.
jumper JS10 to IGN (this uses the processor port for the outgoing timing signal directly),
jumper XG1 to XG2 on the bottom side of the PCB, near the 40 pin socket,
V3.0 main board:
DB37 pin #36 to the E pin on the HEI module
DB37 pin #24 to the R pin on the HEI module
On the V3.0 main board:
use the 'Hall sensor circuit' (step #50 in the assembly guide),
jumper OPTOIN to TACHSELECT on the bottom side of the PCB, near the DB37 connector, opposite the heat sink,
jumper TSEL to OPTOUT on the bottom side of the PCB, near the center.
jumper JS10 to IGN (this uses the processor port for the outgoing timing signal directly),
jumper XG1 to XG2 on the bottom side of the PCB, near the 40 pin socket,
-
Matt Cramer
- Super Squirter
- Posts: 2951
- Joined: Sat Jul 03, 2004 11:35 am
Re: HEI 8 Pin Low/No throttle miss
Try these mods:
http://www.DIYAutoTune.com/tech_article ... _v8_v6.htm
We've found they give a stronger signal on many installations. You need to change the Ignition Input Capture to Falling Edge with them.
http://www.DIYAutoTune.com/tech_article ... _v8_v6.htm
We've found they give a stronger signal on many installations. You need to change the Ignition Input Capture to Falling Edge with them.
-
seafarer76
- MegaSquirt Newbie
- Posts: 5
- Joined: Mon Apr 18, 2011 7:32 pm
Re: HEI 8 Pin Low/No throttle miss
I changed the input using those guidelines and it still gets the same tach dropouts, unless I disconnect the timing override plug. When it's disconnected, I don't get any dropouts.
-
seafarer76
- MegaSquirt Newbie
- Posts: 5
- Joined: Mon Apr 18, 2011 7:32 pm
Re: HEI 8 Pin Low/No throttle miss
Well,, thanks for the help. I'll check back in later if I am still having the problem after I figure out why the No 2 cylinder was full of coolant on my new rebuild. Hopefully it's just the intake gasket...