Just for reference if anyone else has similar issues. The Maximum MAP load limit and Idle Map Threshold tables seemed to fix it, it was set to around 40kpa and my engine was idling as I was playing with it at around 75kpa so no wonder it was struggling. Seems a lot more stable now. Thanks everyone :)

Thanks mate much appreciated, looks like I'm getting closer, will these adjustments tomorrow!

It will need an LS model IAC solenoid they're a larger diameter pintle Hmmm, that wouldn't change my symptoms though would it? the problem is that the IAC is opening too far not that it's not sealing up at idle. For example if I put it in drive it will open the IAC up to around 150 steps for 10-20 ...

Doing a bit more reading too, some ford guys with big TB's have needed to put restrictor plates in the IAC passage as they are too big and let too much air through and need a smaller passage to restrict the air flow to a more controlable level. Looking at a pic of the throttle body it is quite a lar...

This is from the 11p Overview PDF, Closed Throttle Volumetric Efficiency (VE) On engines with low and varying vacuum at idle it can be problematic using the MAP sensor signal for fueling. A closed throttle VE vs RPM table has been added. To enable the use of this table set “[xxxx] set = Closed Thro...

immortality wrote: ↑Mon Mar 25, 2024 12:56 pm It's cammed right? (I can't remember what you have sorry). What kpa does it idle at?

I wonder if the IAC Kpa Vs RPM threshold needs adjustment.

Thats a good point, with 109LSA it doesn't have much vacuum at idle, it idles between 75-80kpa in park

I believe the normal idle setting is around the 20-30 steps? (or am I thinking V6 stuff?) Throttle showing 0% at idle when coasting? Try lowering the values in the IAC- Throttle Crack Offset Vs RPM table a bit. Yeah I think anywhere from around 10 steps to 30 steps at operating temp is considered n...

Gareth wrote: ↑Mon Mar 25, 2024 11:55 am What ECU? 808?

Is the VSS connected and showing a sane number in Tuner pro?

It's a 424 PCM.

VSS is connected and accurate.

Hi All, Bit of a weird one but I thought I'd reach out to the brains trust for ideas. I'm currently tuning a 304 with an Edelbrock dual plane manifold and an EFI Hardware 750CFM throttle body, it runs the stock GM IAC with the smaller pintle (Pre LS) (taken directly from the OEM throttle body and is...

Hi All, Very weird question but I'm hoping one of the gurus might know the answer. On a 424' Delco does the O2 sensor have any relation/shared citcuits with the transmission solenoids etc. I upgraded to a new set of headers a few weeks back, and due to some different locations of O2 bungs I haven't ...