MSefi.com read only forum (Jan.15,2018)

Hello,

I am trying to get my 4.3 TBI idling properly.

Question : Will Tune analyze live help with tuning the idle if it idles steady just too high?

Background:
4.3 TBI with MSII version 3.0
TunerstudioMS 3.0
GM HEI 8 pin module
DIYAutoTune 10' wire harness
IAC - GM IAC, 4 wire (square plug)
Engine starts reliably and idle starts at 1500 rpm and increases to 1900 rpm as the coolant temp goes up.
IAC is wired properly according to the diagram and markings on wires in harness (have verified correct wiring about 87 times now and pulled the IAC and watch it fully retract when key is turned to run). The only issue I see is that it fully retracts when the key is turned on and then goes back to its normal position without turning the key off.
I have read through all relating manuals several times, and researched other articles on the subject. Ready to go bald and pull out my hair.

Would appreciate any info I can get

Will

Tune Analyze Live will tune it for a specific AFR, but it won't tell you what specific AFR you ought to be running. So it won't be helpful here. We have some idle tuning tips here:

https://www.DIYAutoTune.com/support/tec ... egasquirt/

Thank you for your reply.

I have read that document backward, forward, and side to side. Even my wife has read that document.

I still have idle frustrations.

Idle starts at 1300 rpms and warms up to 1900 rpms. It seems as if my IAC was going backward. I had it wired backward and then switched the polarity on 1 of the coils so every wire on the harness goes to the pin in the diagram found in the "Idle Control with your MegaSquirt-II™ controller". I have taken the IAC out and turned the key to on. The pintle retracts all the way but then goes back to where it started. However, when I start the engine it still seems to run backward. Idle goes up as it warms up.

Will

It would be helpful if you could post a log and an msq. It sounds like your idle control just needs a little work.

Ken

It would be helpful if you could post a log and an msq. It sounds like your idle control just needs a little work.

Ken

Attached in my log and msq.

Murphy showed up and brought his law with him (no love in NJ). I started it tonight and the idle did not climb but it did not go below 1100rpm either.

Background:
4.3l TBI (injectors 5235209)
MSII V3.0 DIYAutoTune 10' harness
Active flyback and regular flyback circuit as suggested in the manual
I have tried running it at 3 squirts per cycle but the engine would start and then die a second later. After increasing the afterstart enrichment up to 60% (well outside the range suggested in the manual) it would run for 3 seconds then die. 6 squirts per cycle is the only thing I can get it to run on.
Any advice or adjustments would be greatly appreciated

Will

If you get a change at idle with a different number of squirts per cycle, sounds like your injector dead time isn't correct?

I've never found VEAL of any real use at idle.

One trick is to start with all the VE table cells around the idle one at the same value.

Will look into that Dave. Thanks.

Anyone else have any suggestions? [see msq & datalog above]

Thanks everyone!

ironwill11 wrote:Will look into that Dave. Thanks.

Anyone else have any suggestions? [see msq & datalog above]

Thanks everyone!

Your log shows lots of TPS noise?

Thanks Dave. I will check this out.

Will

Hey Dave,

I noticed the TPS noise as well. On the graph it looks like a lot however, it only fluctuates between 3-5%.

Will