It's Alive - Delco 173

[stevemc32]

Finally had the first attempt at starting my red 173 with the VK gear and Delco 808. Fired up after a bit of coughing and farting on the starter but couldn't do any decent length runs as there's no exhaust beyond the headers just yet.

I've attached a log of the second short run. It's using the OSE_$12P_BLCD_straight6 V111 bin and the 1 Bar - Petrol_calcVE ADX. I haven't changed the bin from the one available in the $12P tunes thread that was pre-loaded onto the NVRam.

Just a couple of quick questions for now. The IAC steps is an instant stand out and I believe a bit of tweaking on the idle stop screw should sort this out as per the FAQ to get 20-30 steps. The second issue I have is that I don't see any information in the "Item Lists" section when I play back the log. The dash, monitors and history tables all show data but nothing in the lists. I'd at least expect to see an Oxygen sensor fault as I don't have one connected yet. Any ideas on where I've gone wrong?

I haven't got as far as setting up the Field Service Mode to check the timing yet but it seems to be a fair way off. Should get to that tomorrow.

[Holden202T]

well I don't have the calcve adx to test but with the normal $12P v1.11 1 bar petrol adx it is showing the list view fine and map sensor high error code is logged!

your spot on with the IAC steps, its going to need a lot of turns hehehe either that or the IAC is not functioning properly.

im not sure if your alternator is all that healthy either, battery volts only reading 12-12.4 V ... but might just need more revs too.

[stevemc32]

Thanks for the help.

I think your suggestion that the IAC might be rooted is probably correct. Went to do another run and it was clicking away before I started the engine like it was stuck but still trying to move, while the TP dash said it was at zero steps. The idle stop screw was not having any effect on it during a run then half way through it decided to go from 0 to 196 in one ramp up.

The map sensor high error didn't reappear so not sure on that one and the lists view seems to be a computer issue. I can see the lists on the laptop on which the log was recorded but not on my desktop version. Will need to investigate that further.

[Holden202T]

yeah the map high could just be that the tune is up to shit, but also i do recall in my experience with tuning the 202's i had to change the thresholds for setting that error code, was due to the 202 having totally different map readings v's rpm compared to stock or something similar, but i couldn't be too worried about that till the IAC and such is sorted.

the 196 steps was what made me think there is an IAC issue, it is purely a commanded number, weather the iac actually does that or not is the question, might be worth pulling it off and give the TB and the IAC plunger a good clean with throttle body cleaner to get all the carbon and shit out of it and see if it works, failing that might need to rap one from another TB and test.

[stevemc32]

Ordered another IAC. I fired up the one I have when it was out of the throttle body and it unwound itself and shot the plunger off into the distance while I wasn't looking. I did manage to find it and screw it back in but who knows if it's set properly so for $28 a new one should arrive early next week.

Took another log and it seems to be getting much closer at idle after I gave the dizzy a little tweak to try get the 10 degrees base timing a bit closer. The end of the log shows a big oscillation when the throttle was held open about 5%. Looking at the log is would seem the spark advance is leading the oscillation but I have no idea why that would happen. Would the IAC normally compensate in that area?

[Jayme]

in diag mode, one of the things the ecu does is wind the plunger out and never stop lol you will hear it go click click click when it hits the end of its extension. it will shooot out if you do it when its not in the throttle body. normally you can just wind it back in by hand and it should be ok.

yours doesnt look to be in diag mode looking at your log. im not sure about how stepper motors work but im not sure they would just wind out like that unless there is a buggered ecu supplying power to it to cause it to do that.

[Dylan]

Isn't that only with engine off? I thought even in diagnostic mode with engine running the iac still controlled idle.

[stevemc32]

Thanks guys.

It definitely shot the plunger out before the engine was started and there's a real good chance it was in diag mode at the time as I'd been playing around with it on a run prior to the log I uploaded. That would explain the clicking I heard a few days ago which made me think it was stuffed.

Looking back at my log I now see my question about whether the IAC would help with the oscillations is pretty stupid as it is clearly being commanded to remain still throughout that period.

[Holden202T]

theres two ways the ecm will control idle, one is by IAC steps, this will usually settle once the idle is pretty close to the desired idle, but then the ecm will then use spark adjustments to smooth idle, thats why you'll see the spark jumping around a bit at idle this is called closed loop idle.

[stevemc32]

Thanks for the help guys, sorry about the basic questions, I have read the tuning guides a number of times but it really takes some dealing with the issues for the knowledge to sink in.

Pretty sure I'm understanding what's happening with the IAC now. Every time I do an idle run the IAC starts off usually between 0 and 100 steps, the ECU sees the idle lower than commanded and tries to open the IAC to compensate. The logs all show the IAC steps ramping up but nothing happens to the idle speed so it keeps going until the IAC is commanded to 196 steps and cannot go any further. There's still been no effect on the idle speed so the conclusion is that the IAC didn't do as was commanded and needs replacing.

A new IAC and an intermediate exhaust section should be with me in a few days so hopefully I'll be able to fit the WB and get some time running it. Thanks again, standby for further requests for knowledge.