Wanting to see if anyone has tuned a Jbody ECU without having a IAC. Can it be done? If so any issues?
I realize iac controls idling. A car I will be working on does not have a IAC currently because of a larger TB. I do not know if this will work or not, so I'm asking if anyone has tried.
FU Tuning
i dont have iac on my car but im also running standalone and its mainly a track car i didnt have any problems tuning mine i had to drill a hole in the throttle plate to allow air to enter
RIP Cpl Derek Kerns And Cpl Robby Reyes
24th MEU VMM-261 (REIN) V22 Crewchiefs
11 April 2012 Morocco (African Lion)
John what tb is on the car? I'm curious about the setup.
JUCNBST wrote:John what tb is on the car? I'm curious about the setup.
BBK 80mm. The car has not been started for the first time yet (new motor). Should be anyday now. I guess we will see how this works.
FU Tuning
Probably not impossible but I would think getting the idle and coming to a stop would be tricky.
Drilling TB plate or if it has a set screw would be a start, however if the idle is not right where Pcm wants it you may see a (possibly dangerous) timing fluctuation or swing.
As far as I have seen, the Pcm likes to use timing along with Iac to stabilize the idle.
Interesting for sure and will be watching for updates.
http://www.weatherallsautomotive.com http://www.planethax.com/j-body
Weatheralls Auto wrote:Probably not impossible but I would think getting the idle and coming to a stop would be tricky.
Drilling TB plate or if it has a set screw would be a start, however if the idle is not right where Pcm wants it you may see a (possibly dangerous) timing fluctuation or swing.
As far as I have seen, the Pcm likes to use timing along with Iac to stabilize the idle.
Interesting for sure and will be watching for updates.
The coming to a stop is what I'm really worried about. I think getting it to idle off of start up will be fine, but when driving and letting off the gas how the car will act is what I do not know. I also do not think we have much that we can do to fight it on a stock ECU.
FU Tuning
My car runs MS-II so the IAC only does anything during warmup. After the idle gets back to ~1000rpm it doesn't do anything else. Coming to a stop seems fine to me, it doesn't need to raise the idle.
i find it amusing that SHOoff has nothing better to do but follow me around & be an unhelpful dick in even cross-forum. - Jon Mick
SHOoff wrote:My car runs MS-II so the IAC only does anything during warmup. After the idle gets back to ~1000rpm it doesn't do anything else. Coming to a stop seems fine to me, it doesn't need to raise the idle.
So when you let off the gas, and push in the clutch the car goes down to 1000RPM's?
FU Tuning
Correct me if I'm wrong, but you will probably have issues when the a/c turns on at idle as well.
Mr Newb wrote:Correct me if I'm wrong, but you will probably have issues when the a/c turns on at idle as well.
This car was made from the factory with no ac, and it's use will not require ac, but you could be right.
FU Tuning
Addicted to meth wrote:SHOoff wrote:My car runs MS-II so the IAC only does anything during warmup. After the idle gets back to ~1000rpm it doesn't do anything else. Coming to a stop seems fine to me, it doesn't need to raise the idle.
So when you let off the gas, and push in the clutch the car goes down to 1000RPM's?
Right. I've never had an issue with stalling.
Now... How angry the factory PCM will be if you take off the IAC, I dunno.
i find it amusing that SHOoff has nothing better to do but follow me around & be an unhelpful dick in even cross-forum. - Jon Mick
It prob wouldn't be too hard to make something that the IAC could bolt into and have have a vac line going to it, in effect allowing you to keep the IAC fully functional, but not on the TB. Basically a remote IAC in sense. As you know, the IAC is just a plunger valve. Just drill an aluminum or plastic block into the basic shape the stock TB has. Vac line in one side and out the bottom with the IAC bolted on top so it can seal inside.
12.6 @ 114.6 MPH
if the ECU sends the singal to move the IACV and there is no response the ECU will throw a fit.
I'm running Megasquirt MS1 without the IAC hooked up (just adjusted the throttle for a 1150 rpm warm idle) and the car does well. just let it warm up some before you decide to drive off or you will run the risk of the engine stalling (basically when using the brakes)
I would suggest going with megasquirt (MS-II or higher) and you can control the IACV and still be able to have a pile of tuning capability at your fingertips.
2.2 L Ecotec, P&P Head, Stage 3 Comp Cams, Supertech 76 lb Spring kit, Supertech Oversized Valves, Wiseco 8.9:1 CR Pistons, Eagle H-Beam Rods, Home-Built Turbo Kit T3/T4 57 Trim Intercooled, 78 lb/hr Racetronix Hi-Z injectors, Aeromotive FPR, Racetronix f body fuel pump,MEGASQUIRT MS3 + MS3X Finally street tuned on 21 lbs! Now if only I could get it to hook....
--Boosted Z-- wrote:It prob wouldn't be too hard to make something that the IAC could bolt into and have have a vac line going to it, in effect allowing you to keep the IAC fully functional, but not on the TB. Basically a remote IAC in sense. As you know, the IAC is just a plunger valve. Just drill an aluminum or plastic block into the basic shape the stock TB has. Vac line in one side and out the bottom with the IAC bolted on top so it can seal inside.
That's an interesting idea.
Something like this:
http://www.amazon.com/ACCEL-74779K-Flow-Remote-Control/dp/B001CTBF4S
- Your not-so-local, untrained, uncertified, backyard mechanic. But my @!#$ runs
Wow, I din't know something like that as even in production, but yest, exactly like that. Maybe another barb instead of the filter is though so you can still use it on boosted apps.
12.6 @ 114.6 MPH
Is there no adjustment for the idle stop, John? That would be a better way of allowing air in at idle than permanently modifying the throttle blade (via drilling a hole). Otherwise, there are fast idle solenoids you can always use with MS-II to bypass the throttle at idle. I believe they are a little bulky, but they will get the job done for a street car.
I believe DIYAutotune sells some idle control boxes you can interface with MS-II when the throttle doesn't have provisions for idle control. It's been a while though, so I don't know.
I have no signiture
Whalesac wrote:Is there no adjustment for the idle stop, John? That would be a better way of allowing air in at idle than permanently modifying the throttle blade (via drilling a hole). Otherwise, there are fast idle solenoids you can always use with MS-II to bypass the throttle at idle. I believe they are a little bulky, but they will get the job done for a street car.
I believe DIYAutotune sells some idle control boxes you can interface with MS-II when the throttle doesn't have provisions for idle control. It's been a while though, so I don't know.
It does have a idle adjustment on the TB. This is not my car and I'm not around it. It has been started and idles fine. Have not been able to drive it yet to see how it will act. At this time it will be on a factory ECU, but tuning with HPT. I can turn off any codes from no IAC. I was more concerned about how the ECU will act when it knows it does not have a IAC. I'm starting to thik it will be ok, just maybe some good old tuning work in the low RPM's of normal driving. We will see and I will update once we get to that point.
FU Tuning
i am almost 100% sure paul ran his car on the ford taurus SHO 65mm tb without an iac... or was it the TPS? crap i cant remember but one of them was not used and he adjusted the idle via a set screw. worked fine for him.
* edit * just talked to him.. he said it was for sure the IAC he didnt use. now this was on an n/a car but it did idle just fine.
Edited 1 time(s). Last edited Wednesday, September 26, 2012 10:19 AM
I choose the technology built for land speed records... not the technology built to save on emissions and gas mileage.
