120 injector help

[NY Twin Turbo]

I believe it's one of these.
View attachment 247046 View attachment 247047 View attachment 247048

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Not too familiar with Big Stuff but those look like there used to add fuel to the base and then remove what was added. Not subtract fuel from the base.

 

[NY Twin Turbo]

Well it starts and idles pretty good with the new numbers I can't drive it because of the weather so I don't know about that yet.

It wants to idle around 1500-1800 rpm but is normal when I put it in gear.

So I start thinking I will switch out the modified IAC with a good stock one. I switch it out and try to start car. It starts and only wants to idle at 200-450 rpm's. It dies and is very hard to start. I have to give it input from the pedal to keep it running.

So I put the modified IAC back in. Don't know what to do with it.
I sprayed about two cans of carb cleaner looking for vacuum leaks but nothing.

Open the idle screw with the stock IAC. Through away the IAC you modified in the garbage. I don't think you should have drilled the throttle blade. It's a small hole though so don't sweat it too bad.

Now after you get it to warm up, unplug the IAC. And use the Idle screw to set the idle to just 100-150 RPM under where you want it to idle. Now plug it back in and let the computer do the rest. You don't want the IAC to have to work that hard. You want the throttle blade to be almost open enough to do all the work. From there it's easy for the computer to make slight adjustments.

Check the TPS reading after your done to make sure its in the idle voltage range. If not, re-set the idle voltage in the tune or adjust the TPS accordingly.

To sum it up, if you can get it to idle with no automation, then it will be even better once everything is plugged back in and set.

 

[larry33kc]

I haven't had a chance to do anything with it as of late. To much work, and bad weather.

I have a solid rivet to fill the hole in the TB. I am also going to install my Power Plate.
I have been thinking about enlarging the IAC passage way to the TB as large as I can get it and still have the IAC plunger cover the hole to alow more air in the motor on cold starts.

 

[NY Twin Turbo]

I haven't had a chance to do anything with it as of late. To much work, and bad weather.

I have a solid rivet to fill the hole in the TB. I am also going to install my Power Plate.
I have been thinking about enlarging the IAC passage way to the TB as large as I can get it and still have the IAC plunger cover the hole to alow more air in the motor on cold starts.

There is no need to enlarge the hole. On XFI there is a graph called "start IAC position vs coolant temp". You must have something similar on Big Stuff. If so, just program the IAC position to be fully open at low coolant temps. That will let the air in. Make sure there is enough fuel as well during cranking. You could also have too much fuel.

If you need more air than that to get started open the throttle blade with the screw. It's a balance though. If the blade is open too far, then when the IAC is closed it can't bring down the idle.

That's why I say, if you can get it to run using your foot to start it, get it to idle when warm first. Then tune the start-up after it fully cools down.

 

[larry33kc]

Thanks Joey for the help. BS3 does have the IAC scale you called for. I have 180 in all the boxes to about 120 temp.
When things slow down a bit I will try what you suggested and see what it does. Hopefully it will work out.

 

[NY Twin Turbo]

Thanks Joey for the help. BS3 does have the IAC scale you called for. I have 180 in all the boxes to about 120 temp.
When things slow down a bit I will try what you suggested and see what it does. Hopefully it will work out.

I wish you luck.

Remember, without automation, if you can get it to idle very close to the way you want with just the idle screw after it's warm, the rest is just tweeking.

Let us know.

 

[larry33kc]

Absolutely makes sense I thank you very much.

 

[norbs]

Ever thought of going XFI?

 

[jdpolzin]

Or just a simple modded ECM....

 

[larry33kc]

Yes & yes

 

[larry33kc]

Ok. I did as suggested. I let the car warm up with the IAC unplugged to normal temp. The car was idling at 1400 rpm, Then I went to adjust the TB screw when I noticed it wasn't even touching the linkage.
As with everything with this deal. More questions than answers. Lol

I went ahead and took the TB & dog house off so I can install my power plate and fill the 1/8" hole.

Now what?

 

[norbs]

If it was me I would be listing a BS3 on ebay, and get the XFi after its sold. Put the 83s back in and get the idle back to normal, record the PW at idle., and see if the 120s are even capable of opening 31% less than your current PW.

 

[NY Twin Turbo]

Ok. I did as suggested. I let the car warm up with the IAC unplugged to normal temp. The car was idling at 1400 rpm, Then I went to adjust the TB screw when I noticed it wasn't even touching the linkage.
As with everything with this deal. More questions than answers. Lol

I went ahead and took the TB & dog house off so I can install my power plate and fill the 1/8" hole.

Now what?

OK There is no way a motor can run without air! It's really is just that simple. So get the 1/8th hole closed up and make sure the IAC isn't stuck open and make sure you have no vacuum leaks it's just plain impossible. Lowering the timing will also bring down the idle.

I also agree helping each other with tuning issues is simpler when we're using the same software but the answers are all there in each engine management system. I do happen to prefer XFI. Because I know it.

Also, Norbs has a point on your 120lb injectors. I run 160lb injectors and idle suffers a bit. But I only expect it to be so good. No black smoke and no fuel in the oil and I'm OK with that. I don't have to change plugs more than twice a full season of street driving. So, I'm being optimistic. I think the answer is there somewhere.

 

[NY Twin Turbo]

Wait, just to be sure. Can anyone confirm unplugging the IAC returns it to a closed position?

 

[larry33kc]

Guys I have been round and round with this, and I'm always being told to sell the BS3 and go to FAST. As much as I would love that, that's not going to happen. I just can't afford it. Selling the BS3 system will only get about half the price of a FAST system if that. So that's not an option unless I fall into a bunch of money somewhere.

I can't return to the 83's because I had to sell them to get the 120's.

As far as the tunning goes I have been able to get it all pretty good except the cold start and the high idle issue. It doesn't have any drivability issues.
As a matter of fact when I had the 83's in it, I had it good enough I was ready to start turning up the boost. Hence the reason I went to the 120's, so I had more room to turn up the boost. Not knowing the pulse width numbers was so different.

Trust me I had post all over asking what needed to be changed in the tune to make them work. I would usually not get much for answers.

The numbers I got from Joey seem to be a lot better, so that's a start. The car would be great if I can fix this issue. I just can't seem to get the answers I need to questions I ask. Like the one that has been bothering me.

When I'm logging the car running to see what the IAC is doing, you have a log for
ACT. IAC, and DES IAC.

What I notice is when I'm logging this to watch it I notice the ACT IAC reads 00 and the DES IAC fluctuates with throttle inputs.

To me this seems off the ACT IAC should fluctuate with throttle inputs, and the DES IAC should show what numbers I had imputed in the table.
Is what it's doing normal or am I reading more into it?

I appreciate all the help I have received. There is just something that I'm missing somewhere that I have to figure out.

 

[NY Twin Turbo]

Guys I have been round and round with this, and I'm always being told to sell the BS3 and go to FAST. As much as I would love that, that's not going to happen. I just can't afford it. Selling the BS3 system will only get about half the price of a FAST system if that. So that's not an option unless I fall into a bunch of money somewhere.

I can't return to the 83's because I had to sell them to get the 120's.

As far as the tunning goes I have been able to get it all pretty good except the cold start and the high idle issue. It doesn't have any drivability issues.
As a matter of fact when I had the 83's in it, I had it good enough I was ready to start turning up the boost. Hence the reason I went to the 120's, so I had more room to turn up the boost. Not knowing the pulse width numbers was so different.

Trust me I had post all over asking what needed to be changed in the tune to make them work. I would usually not get much for answers.

The numbers I got from Joey seem to be a lot better, so that's a start. The car would be great if I can fix this issue. I just can't seem to get the answers I need to questions I ask. Like the one that has been bothering me.

When I'm logging the car running to see what the IAC is doing, you have a log for
ACT. IAC, and DES IAC.

What I notice is when I'm logging this to watch it I notice the ACT IAC reads 00 and the DES IAC fluctuates with throttle inputs.

To me this seems off the ACT IAC should fluctuate with throttle inputs, and the DES IAC should show what numbers I had imputed in the table.
Is what it's doing normal or am I reading more into it?

I appreciate all the help I have received. There is just something that I'm missing somewhere that I have to figure out.

So, the actual IAC movement is showing its not actually moving? Is there a sensitivity function? Meaning speed and how much it responds? Maybe you have those settings dulled to far down? Or possibly it doesn't need to move at all because too much air is already entering the motor. Again, like I said earlier. The air is getting in even with the throttle closed. It has to be!

Also, I agree you can do it with the BS3. It's just harder for me to help. The answer is there somewhere. And I'm sticking with you because I want to know what it is.

 

[larry33kc]

You know Joey I totally agree with you. Air is getting in somehow, and I don't think that little 1/8" hole could have supplied enough air to let it run at 1400 rpm either.

At first I thought with the IAC unplugged maybe it was just closed halfway or it was fully open and was letting air in, but when I took the doghouse of I removed the IAC to measure the depth to the seat. That measurement was 1 1/8" deep, which consequently was the same measurement the instructions said to set the IAC plunger before installing. So that tells me it was seated closed. So no air was coming from it.
I have sprayed carb cleaner several times looking for vacuum leaks, changed all the vac lines, even plugged them at the top of the TB one at a time to eliminate for vacuum leaks, and I have found nothing.

As far as your question, yes the ACT IAC isn't showing anything, but the DES IAC does. It is reading like the ACT IAC should. I'm thinking something is wrong here because I would think that the DES IAC would be showing my table inputs for the setting. But I'm not getting that I'm getting what I'm assuming is the ACT IAC reading in the DES log.
Yes it has a rate of change table also and if I remember correctly mine is set in the middle. I will have to revisit that in the manual and read it again.
I have gone through that thing a million times , and I have to say sometimes it's like reading a different language.

Joey if it would help you can read the manual on BigStuffs website. Maybe the would clear things up and help you understand the way it works versus FAST.
I am still a rookie and am probably missing something.
Any help would be appreciated and I deeply appreciate what you've already helped me with.
Thanks again

 

[NY Twin Turbo]

I am reading the BS3 manual. So far it's about the same logic as XFI. I don't know anything about an adjustable IAC. I use an AC Delco.

Close up that 1/8th hole. Close the throttle. Temporarily plug up the IAC passage. Or better yet......Take the inlet pipe off while it's idling and block off the opening with a rubber Fernco pipe cap from Home Depot! If it still idles at 14oo rpm then you know you have a major vacuum leak! If not, then it's an electrical problem or a tuning issue with the IAC.

I hope you have your Idle speed vs coolant temp graph set-up. Dumb question because I assume you do.

Until then, I'll keep reading the manual.

 

[larry33kc]

PMed you Joey

 

[Bobs rare 6]

Hey Larry, Did you ever press. ck. intercooler for leaks? Could be source of vac. leak.