It's Alive - Delco 173

[Holden202T]

also check the ports in the TB where the IAC is, they may be blocked up!!

[stevemc32]

Got the exhaust sorted today and will wire in the WB controller tomorrow. I also took the throttle body off for a clean up and noticed that the idle stop screw doesn't really have any effect on the butterfly. Here's a photo of it adjusted so that it is just short of actually touching the throttle bracket.

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It has less than one turn of actual adjustment left before the spring bottoms out and this barely opens the butterfly maybe half a millimetre. Should I block it up to get a bit more adjustment out of it. It would seem at this stage that all of the idle air flow is going through the IAC and it certainly does sound that way when it's running.

I did take the butterfly out of the throttle body earlier to give it a bit of a clean but I was pretty sure I got back in the same position when refitting it. This is how it looks now when the throttle is closed, there's nothing getting past it.

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Ignore the beer spill on the lower half, that may have happened during the photo session but it has since been cleaned up.

[vlad01]

you can tell which way it goes in by the bevel of the throttle plate edge.

[stevemc32]

I read your message vlad and hoped that it was that simple. Did a quick beer run to the shed and the bevel is definitely installed correctly so I'm still stumped as to why the idle stop screw has virtually no effect on the butterfly position.

[Holden202T]

well I guess my first question is, was it right before you removed the butterfly, im guessing probably not hense the massive iac steps at idle! in the past I have ground a turn off the spring so you can get more travel out of the screw.what you want to do, when its running, remove the fuel pressure regulator hose or something similar, this will make it idle higher, then then iac should close to compensate,now you want to get the iac to zero, then unplug it, then plug the vaccum hose back in and get the idle down to just below desired using the screw (eg. if desired is 800rpm, get it to 700rpm) then plug the iac back in and it should be pretty close.

I reckon you'll find the thing will start a lot better too!

and make sure you put it in diagnostic mode and confirm the static timing is 10 degrees!

[stevemc32]

Checked the timing mark on the balancer and it was a fair way off so the static timing has now been adjusted properly and it's starting to run much better. I also changed out the IAC for a new one and stuck a little block of wood on the idle stop screw to get a bit of adjustment out of it.

Here's a log with the wideband sensor finally fitted up and it's a bit scarey. It shows the idle to be very lean and I'm not sure if it's correct or not. It's an LC-1 and I followed all the fitting instructions including the free air calibration. I've got it connected to both the WB and NB ECU inputs using the simulated NB output. It's showing a mixture around 20:1 for the idle and I didn't think it would actually still run being that lean.

I've also noticed the IAC takes a long time to come back down after a quick throttle crack which leaves the RPM hanging after closing the throtte. I found the IAC - Throttle Crack Decay Rate is set to 3.13 steps per second and wondered if I can raise this to make it come back down a little faster. Checked the $5D and the rate is 6.25 steps per second.

[Holden202T]

Can't look at the log at the moment but did you set the wide band 0v ad 5v settings in the calibration To match the sensors settings ?

[stevemc32]

I hadn't changed it as I thought it was already set for the Innovate gear but just looking at it now the original numbers were very close. The bin had 7.3 to 23.4 and the LC1 is set as 7.3 to 22.4. I'd expect this to knock the 20:1 records down to about 19.5:1 so still way too lean.

[antus]

Yep. Once your sure of the wide band, real time edit the injrate a bit to get the actual far somewhere near the target afr and it should idle a lot better. Then let it idle and warm up to running temp (watch clt in the logs) then set injrate again and see how things are looking. When you start it cold next it'll probably be out again but that will be injector opening time settings or other warmup items.

[Holden202T]

im surprised the tune is that lean !! what injectors are you using ?