Boggling IAC issue

[Matt Cramer]

I'll be glad to have a look at the log once it's posted.

[maverickh1l]

I have a question: What exactly is the purpose of dielectric grease? Should I use it in my harness connectors? It seems like my problem seems to lie with a screwy connection in my C-D connector (harness has 2 plugs, A-B, and C-D, I'm not using the DB37 for harness connection due to needing additional parts similar to the GM 1227165, which I have an adapter for between the MSII DB37 and the wiring harness). I've already tightened the terminals in both connectors, but it still seems like I have an issue in the C-D connector, which has the engine data sensors, fuel injectors, IAC connections, and a couple of the ignition wires. If dielectric grease won't help, then my only other option is to replace all 32 terminals in the connector bodies.

[maverickh1l]

Okay, this is getting weirder by the minute...

I can get the engine to run just fine when hot. IF...

1. I put my foot on the accelerator for approximately 3-5 seconds after starting (get up to about 6% TP) and let off slow
2. I take approximately 65-80 steps OUT of the cold IAC step table (currently 190 steps hot and about 265 cold)

Notes:
1. Adjusting crank PW and starting IAC steps when hot doesn't help... The engine will crank to run just fine but acts like it's getting too much fuel to transition between crank and run properly without the added air from opening the throttle. Adjusting the VE table doesn't help.
2. The system almost acts like it wants a dual IAC table or some sort of IAC steps to starting CTS temp adder table...

I was too busy getting the software sorted out and I forgot to get a datalog... I'll get one when the engine cools off again.

Also having trouble getting the O2S to read above .02 V (narrowband sensor) no matter how much fuel I add... I'm going to take care of the tiny exhaust leaks at the header primaries on the odd cylinder bank to see if that helps any but I had been getting the O2 to better than .5 V (should be .45 stoich).

[Matt Cramer]

Sounds like there may be a little too much fuel in the cranking pulse width at that temperature.

[maverickh1l]

New problem!

I'm getting FALSE spark knock readings as reported by TunerStudio. I currently don't have the knock conditioning module even hooked up and the MSII/TS is still reporting that I have spark knock. I'm pretty sure I have the wire connected right because I had to add it to the harness (factory harness didn't have knock controls), but I will double check (been meaning to but haven't gotten around to it yet due to the weather).

Tuning this thing is becoming a pain. I can't seem to get the crank PW and IAC steps right no matter what I do. The idle speed seems to be fairly close between hot and cold now but that's not saying much. I still have the "hole" when accelerating, in every gear but First. I'm not sure if I'm leaning out the engine or overfueling it. I did, however, get the O2S to read about .2V unloaded (had to remove and reseal both exhaust headers).

I need to get a log viewer...

[Matt Cramer]

If you don't have a real knock circuit hooked up, you won't get real knock readings. You get random noise instead. Just leave knock control off.

[maverickh1l]

Um, my MS to GM 1227165 adapter board has a knock sensor circuit installed and I have a knock sensor in the passenger's side of my engine block connected to a required "conditioning module" which is wired to the MS. As per the assembly instructions. And I do currently have the knock sense disabled but the MSII is still showing spark knock but not retarding the timing to match the "Knock Retard" numbers...

Also, is there any way to set the VE Analyze Live to only work above 1500 RPM? I'd rather turn it on and forget it until I get to my destination and then burn the results into the flash memory, and I would really like it to leave my idle mixture alone...

[kjones6039]

Also, is there any way to set the VE Analyze Live to only work above 1500 RPM? I'd rather turn it on and forget it until I get to my destination and then burn the results into the flash memory, and I would really like it to leave my idle mixture alone...

Under the Advanced Settings tab in VEAL, set the Minimum RPM to what ever you like.

Ken

[Matt Cramer]

But you said it was not hooked up - at what point is it disconnected? I'm confused.

[maverickh1l]

But you said it was not hooked up - at what point is it disconnected? I'm confused.

Well, right now, the knock sensor itself isn't hooked up to the wiring (connector is dangling next to it since I had to replace the starter). And that's one of the confusing things about this system... Why is the MSII still reporting spark knock with knock sense DISABLED and the knock sensor DISCONNECTED?

Not sure what happened, but the IAC issue may or may not be at least partially resolved... I hope. And I finally replaced the thing only to get the same results.

Autotune currently not helping at all. Even with the O2S reading between .3 and .4, and .5 and .7V, the system keeps saying "O2S Out of Range" and not doing anything to correct it.

[Matt Cramer]

Well, right now, the knock sensor itself isn't hooked up to the wiring (connector is dangling next to it since I had to replace the starter). And that's one of the confusing things about this system... Why is the MSII still reporting spark knock with knock sense DISABLED and the knock sensor DISCONNECTED?

Some logging variables are tied directly to port voltage readings and will give a reading regardless of whether the MS is set to do anything with the reading.

Autotune currently not helping at all. Even with the O2S reading between .3 and .4, and .5 and .7V, the system keeps saying "O2S Out of Range" and not doing anything to correct it.

What parameters have you set up there?

[maverickh1l]

What parameters have you set up there?

Min RPM: 1600 (because I don't want it touching my idle mixture) Max: 7000 (never going to go above 6500)
Min kPa: 5 (IDK why it's set that low... My engine almost never gets below 20) Max: 110 (max reading for GM 1 BAR MAP)
Min CLT: 160 (to ensure narrowband unheated O2S is warmed up)

Oh, and since I made this thread, I've updated the MS firmware to MSII V2.92, since my MS for some reason wouldn't take the 3.70 or whatever it is that is recommended for distributorless ignition systems (got some ridiculous error and only just barely managed to get 2.92 back).

Still having the IAC issue, UNLESS I restart the engine, after a cold start. Currently, if I start the engine when it's completely cold, it will begin idling at 1500 and climb to about 2500 when warmed up. After any restart, the idle speed goes down to the about 12-1300 I set it at and stay there. I can't set the IAC steps cold or it will never run when hot (likes 190 steps when hot and around 235 when cold started to warmup temp). This is between 2 IAC motors and no vacuum leaks.

I haven't tried to autotune in a couple weeks. I haven't even had the car out of the driveway in the last week due to brake work, bad weather, and other things I need to get done. I need to try again now that I have reset my fuel pressure regulator to where it was before (was running a bit on the lean side whereas I was running rich but that may have been due to leaking diaphragm).

I know, I know, need to post up my MSQ and a datalog... I can't wait until I get the wireless card for the tuning laptop so I don't have to copy the file onto a memory card and transfer it over to this one...

Oh, and another question: Does the free version of MSLog Viewer have a calendar time limit? Because mine's not working now (it was a couple weeks ago) and it's unregistered... Keeps trying to go to the EFI Analytics website (but can't because there isn't a wireless connection... lol).

[Matt Cramer]

Still having the IAC issue, UNLESS I restart the engine, after a cold start. Currently, if I start the engine when it's completely cold, it will begin idling at 1500 and climb to about 2500 when warmed up. After any restart, the idle speed goes down to the about 12-1300 I set it at and stay there. I can't set the IAC steps cold or it will never run when hot (likes 190 steps when hot and around 235 when cold started to warmup temp). This is between 2 IAC motors and no vacuum leaks.

First, try increasing the IAC time step size, and if that doesn't fix it, increase the minimum number of steps to move.

[maverickh1l]

Well, I went through the IAC page and found the answer to that particular issue.

From the MSII IAC page...
"For some IAC stepper motors, you might need to make some adjustments because the power resistor values may not be quite low enough for your application. This could cause sporadic problems. To see if this is the problem, cut the leads off a resistor or use a small piece of wire and solder it across the two power resistors on the bottom of the your MegaSquirt-II™ controller board. (That is, jumper each resistor separately, don't jumper one resistor to the other resistor.) These are the two large brown units on the BOTTOM of the board, on the end opposite the side of the board with the 2x3 pin header (typically they are marked 1R0). These have large solder pads on each side - just jumper across each one so you get 0 Ohms across the resistors and see if this improves operation. If it does, leave the resistors and jumpers in place. This is very likely to be the problem for those who see the proper step commands given in software but inconsistent response from the motor, such as requiring a restart to lower the hot rpm after a cold start. "

I apparently have to bypass the output resistors on the bottom of the MSII daughterboard (mine are BLACK and marked "R00"). My question is... If, say, 90-95% of applications don't require the resistors, then why are they there? Seems to me they are just an additional headache.

I have purchased an Innovate LC-1 but haven't installed it yet. Almost ready to (too cold). Hopefully either later this week or this weekend. And hopefully the AutoTune will finally want to cooperate.

[DonTZ125]

Unless I'm out to lunch, R00 indicates a jumper - there ARE no resistors on this card.

[maverickh1l]

Well, still having minor issues with the IAC and I can't figure it out for the life of me. Still one idle speed hot and about 300 RPM lower cold.

New issue. I have finally found good enough weather to install the Innovate LC-2. Now that I know what the AFR is, I can tell I'm running rich from one side of the table to the other. I'm currently running about 12-13.5:1 at idle and around the same at cruise. It doesn't seem to matter what settings I change, I can't get a stable idle at stoich (missing like crazy). I've been messing with settings for about 3 days and now I finally have eliminated most of my issues and gotten about 2/3 of my power back, but I need to get the AFR down. I think I shouldn't be going any richer than about 11.5-12:1 at acceleration and cruise needs to be leaner than stoich for economy. Stock, this engine was pulling 30 MPG while throwing a DTC for running rich, and I know I'm nowhere near that.

Attaching today's log and current MSQ in a zip file.

Keep in mind that this engine is a GM 3100 with about 11.4:1 compression running Corvette TPI 22# fuel injectors with a fuel pressure approximately 38 PSI, and GM 3100 DIS (except no 24x crank trigger or cam sensor) ignition.