Dual TB Intake Tuning

Chris-Nelson · Post by **Chris-Nelson** » Sun Sep 16, 2007 11:20 pm

I've figured out the timing issue that I was dealing with and now I am trying to get the car driving normally again.

The thing is just freakin' slow. It gets up to 25mph in about 10 seconds at wide open throttle.

I found that with both cables hooked up, the TPS voltage was only going up to around 3.2vdc so I knew something was wrong. I unhooked all of the cables and tested just the TPS and it would go all the way to 4.89vdc so I know the TPS is fine. It's just that the cables are restricting it.

For some reason it is the auto tranny kickdown cable that was the big restriction, so I am going to try and get it running well with only the two TB cables for now.

What is the trick to getting the two throttle cables set up just right? It seems that you have to position them so that the TB plates are open just a hair-probably around 1.0vdc on the TPS.

Also, how important is it to have them open 100% exact? It seems to be easy to get them close, but I can't get them to be identical.

Shaun41178(2) · Post by **Shaun41178(2)** » Sun Sep 16, 2007 11:50 pm

you have your tb's hooked up differently then how I had them.

Also what I did, is I left a smidge of slack in the cable that went to the second tb. That way when cruising at part throttle or leaving a light, both tb's wouldnt' be kicking open which allowed me to ease away from a light instead of take off real quick.

Also with the throttle cables tensioned really tightly, they wont' go open all the way.

When you put your foot down, does your tb's open all the way? I had it setup where the main tb with the sensors opened all the way, but the second one would only go to about 95%, but thats because like I said before I had a tiny bit of slack in the line feeding the second tb.

Chris-Nelson · Post by **Chris-Nelson** » Mon Sep 17, 2007 1:09 am

I noticed that when I first got the stuff from you one of the two springs on the modified TB for cable return was undone. Was this on purpose? I am thinking that it would be a good idea to have one spring on each TB undone to minimize pressure on the cable system.

The Dark Side of Will · Mon Sep 17, 2007 7:26 am

Chris-Nelson wrote:For some reason it is the auto tranny kickdown cable that was the big restriction, so I am going to try and get it running well with only the two TB cables for now.

You're talking about driving around without the TV cable hooked to your throttle?

That could destroy your transmission.

I've never really looked at the way the TV cable hooks to the Fiero throttle, but if the cable is spring loaded to default to the closed throttle position, you WILL destroy the transmission if you drive it without the cable hooked up.

Aaron · Post by **Aaron** » Mon Sep 17, 2007 10:04 am

Shaun41178(2) wrote: Also what I did, is I left a smidge of slack in the cable that went to the second tb. That way when cruising at part throttle or leaving a light, both tb's wouldnt' be kicking open which allowed me to ease away from a light instead of take off real quick.

When you put your foot down, does your tb's open all the way? I had it setup where the main tb with the sensors opened all the way, but the second one would only go to about 95%, but thats because like I said before I had a tiny bit of slack in the line feeding the second tb.

This probably confused the living hell out of your ECU. I'd avoid doing this if you can Nelson. The problem is that 3 cylinders care getting much more airflow, but the ECU is only fueling all 6 the same as if they were getting the same airflow. And I know you have a pressure/vacuum equalizer, but that won't be able to make up for one plate being open, the other closed. Furthermore, I'd also avoid having one only open to 95%. At WOT is when your worried most about your A:F ratio, and having one only go to 95% is going to get 3 cylinders to run rich, or 3 to run lean.

I'd run them in parallel. It will be far easier for your ECU to handle. Then just use one TPS sensor, on one of the TBs, just like it was stock. Just don't plug in the other one. And I don't think there is an intake combination short of a 8-71 blower that can make a 2.8 take off quick.

Pyrthian · Post by **Pyrthian** » Mon Sep 17, 2007 10:05 am

Chris-Nelson wrote:I've figured out the timing issue that I was dealing with and now I am trying to get the car driving normally again.

The thing is just freakin' slow. It gets up to 25mph in about 10 seconds at wide open throttle.

I found that with both cables hooked up, the TPS voltage was only going up to around 3.2vdc so I knew something was wrong. I unhooked all of the cables and tested just the TPS and it would go all the way to 4.89vdc so I know the TPS is fine. It's just that the cables are restricting it.

For some reason it is the auto tranny kickdown cable that was the big restriction, so I am going to try and get it running well with only the two TB cables for now.

What is the trick to getting the two throttle cables set up just right? It seems that you have to position them so that the TB plates are open just a hair-probably around 1.0vdc on the TPS.

Also, how important is it to have them open 100% exact? It seems to be easy to get them close, but I can't get them to be identical.

having a hard time pictureing what you are doing. yes, the autotranny kickdown cable does put alot of load on the throttle cable - but, as mentioned DO NOT drive without it. you WILL wreck 2nd gear. within 2 weeks. and, no, you do not need both plates to be 100% in alignment. the intakemanifold hase the IAC/ColdStart passages, which will force equalization between the 2 sides.

The Dark Side of Will · Mon Sep 17, 2007 10:22 am

Aaron wrote: Furthermore, I'd also avoid having one only open to 95%. At WOT is when your worried most about your A:F ratio, and having one only go to 95% is going to get 3 cylinders to run rich, or 3 to run lean.

The difference in airflow between 95% and 100% is going to be negligible if it's any at all. Remember that EACH throttle on this thing used to feed the entire engine and is now feeding only half. 95% or 100% won't make a difference because the engine isn't pulling enough air to make it matter.

Shaun41178(2) · Post by **Shaun41178(2)** » Mon Sep 17, 2007 12:05 pm

Chris-Nelson wrote:I noticed that when I first got the stuff from you one of the two springs on the modified TB for cable return was undone. Was this on purpose? I am thinking that it would be a good idea to have one spring on each TB undone to minimize pressure on the cable system.

Yes that was done on purpose. Opening 2 tb's with both springs fully tensioned made the pedal really stiff.

Shaun41178(2) · Post by **Shaun41178(2)** » Mon Sep 17, 2007 12:11 pm

Aaron wrote:
This probably confused the living hell out of your ECU. I'd avoid doing this if you can Nelson. The problem is that 3 cylinders care getting much more airflow, but the ECU is only fueling all 6 the same as if they were getting the same airflow. And I know you have a pressure/vacuum equalizer, but that won't be able to make up for one plate being open, the other closed. Furthermore, I'd also avoid having one only open to 95%. At WOT is when your worried most about your A:F ratio, and having one only go to 95% is going to get 3 cylinders to run rich, or 3 to run lean.

I'd run them in parallel. It will be far easier for your ECU to handle. Then just use one TPS sensor, on one of the TBs, just like it was stock. Just don't plug in the other one. And I don't think there is an intake combination short of a 8-71 blower that can make a 2.8 take off quick.

Dude you didnt' have it on your car so you can't comment. I had it setup to keep the driveability exactly like stock. The computer was not confused at all. At 5% throttle, the second tb wasn't open but the equalizer tube could flow enough air to to get to the other cylinders.

The car ran perfectly fine.

If one tb is at 100% then the computer will know and put more fuel in. the one at 95% might run a bit rich, but not on my car. Yep had the wideband on it.

Useing the one tps sensor is totally fine. Its what I did and had no problems. why make shit more difficult then it has to be? The computer only needs signal from one tb!! it doesnt' need signal from two especially if they are hooked up to open up at the same time. Right?

5% is nothing. Hell it might not have even been that much at throttle tip in off idle. i was guessing.

Chris if your car was down here I could set it up the way I had it on mine, but its pretty hard to describe. If you have specific questions though I can probably try to explain what I did. I have pics of how I had mine all setup and stuff too if it will help you.

Chris-Nelson · Post by **Chris-Nelson** » Mon Sep 17, 2007 4:16 pm

I don't have much time to work on it tonight or tomorrow, but hopefully on Wed. I can rework it again-I have both TB's & cables removed in an effort to try setting it up like you had it before. I'll get it running again and take a video of driving the car and ask some questions in the vid again.

Chris-Nelson · Post by **Chris-Nelson** » Tue Sep 18, 2007 1:56 am

Ok, I made a video. I didn't have to work as late as I had originally thought, and the wife is out later than expected. Also, I'm addicted to working on this dumb car.

http://videos.streetfire.net/video/eb64 ... 20302b.htm

Pyrthian · Post by **Pyrthian** » Tue Sep 18, 2007 10:15 am

Shaun41178(2) wrote:
Aaron wrote:
This probably confused the living hell out of your ECU. I'd avoid doing this if you can Nelson. The problem is that 3 cylinders care getting much more airflow, but the ECU is only fueling all 6 the same as if they were getting the same airflow. And I know you have a pressure/vacuum equalizer, but that won't be able to make up for one plate being open, the other closed. Furthermore, I'd also avoid having one only open to 95%. At WOT is when your worried most about your A:F ratio, and having one only go to 95% is going to get 3 cylinders to run rich, or 3 to run lean.

I'd run them in parallel. It will be far easier for your ECU to handle. Then just use one TPS sensor, on one of the TBs, just like it was stock. Just don't plug in the other one. And I don't think there is an intake combination short of a 8-71 blower that can make a 2.8 take off quick.
Dude you didnt' have it on your car so you can't comment. I had it setup to keep the driveability exactly like stock. The computer was not confused at all. At 5% throttle, the second tb wasn't open but the equalizer tube could flow enough air to to get to the other cylinders.

The car ran perfectly fine.

If one tb is at 100% then the computer will know and put more fuel in. the one at 95% might run a bit rich, but not on my car. Yep had the wideband on it.

Useing the one tps sensor is totally fine. Its what I did and had no problems. why make shit more difficult then it has to be? The computer only needs signal from one tb!! it doesnt' need signal from two especially if they are hooked up to open up at the same time. Right?

5% is nothing. Hell it might not have even been that much at throttle tip in off idle. i was guessing.

Chris if your car was down here I could set it up the way I had it on mine, but its pretty hard to describe. If you have specific questions though I can probably try to explain what I did. I have pics of how I had mine all setup and stuff too if it will help you.

exactly. you only want ONE TPS & only ONE IAC & only ONE MAP

I am thinking the 0-25 in 10 seconds is WAAAYY retarded timing - maybe completely wrong timing mark, or didnt jump the ALDL pins

Jinxmutt · Post by **Jinxmutt** » Tue Sep 18, 2007 10:15 am

if you loosen the TPS screws, you may be able to tweak it just a bit so that it shows closer to 5v at wot.

AntiCooter · Post by **AntiCooter** » Tue Sep 18, 2007 12:19 pm

I've got some high res pics of that intake with the cables in the right place and properly connected for an auto trans. Also, there are 10~15 PROMs with different AE settings and VE tables/timing tables around here somewhere. The last few PROMs had good driveability and great performance.

Chris-Nelson · Post by **Chris-Nelson** » Tue Sep 18, 2007 1:10 pm

I would very much like to see those pictures.

Also, I'm not sure the PROMs would do me much good seeing as though I do not have any chip burning capability.

Aaron · Post by **Aaron** » Tue Sep 18, 2007 10:13 pm

Pyrthian wrote: exactly. you only want ONE TPS & only ONE IAC & only ONE MAP

I am thinking the 0-25 in 10 seconds is WAAAYY retarded timing - maybe completely wrong timing mark, or didnt jump the ALDL pins

And where did I say to run more than one of any of these?

In fact, I clearly said to only use one TPS, and to leave the other completely unplugged. I'm pretty sure I didn't say a word about the IAC or MAP. Please learn how to read.

Aaron · Post by **Aaron** » Tue Sep 18, 2007 10:19 pm

Shaun41178(2) wrote: Dude you didnt' have it on your car so you can't comment. I had it setup to keep the driveability exactly like stock. The computer was not confused at all. At 5% throttle, the second tb wasn't open but the equalizer tube could flow enough air to to get to the other cylinders.

You're right. It is quite possible that the equalizer does flow enough air to fully equalize the 6 cylinders, even at WOT, in which case I'd be wrong and the ECU should handle it fine. Depends on the equalizer size and layout.

The car ran perfectly fine.

So did my Z34. THen I saw the WBO2 data, and could easily mistake it for an @rchie tuned SBC.

If one tb is at 100% then the computer will know and put more fuel in. the one at 95% might run a bit rich, but not on my car. Yep had the wideband on it.

True enough, however realize that your WB results were slightly flawed, as it read results from both banks, essentially averaging the two together.

Useing the one tps sensor is totally fine. Its what I did and had no problems. why make shit more difficult then it has to be? The computer only needs signal from one tb!! it doesnt' need signal from two especially if they are hooked up to open up at the same time. Right?

You misread this, I meant only use one TPS sensor (Preferably the one that sees 100%). The running in parallel statement was meant towards the throttle actuation.

Pyrthian wrote: exactly. you only want ONE TPS & only ONE IAC & only ONE MAP

I am thinking the 0-25 in 10 seconds is WAAAYY retarded timing - maybe completely wrong timing mark, or didnt jump the ALDL pins

And where did I say to run more than one of any of these?

In fact, I clearly said to only use one TPS, and to leave the other completely unplugged. I'm pretty sure I didn't say a word about the IAC or MAP. Please learn how to read.

Chris-Nelson · Post by **Chris-Nelson** » Tue Sep 18, 2007 10:46 pm

that's true, You would need a pair of WBO2 sensors to accurately read the A/F ratio of each cylinder bank.

Chris-Nelson · Post by **Chris-Nelson** » Tue Sep 18, 2007 10:48 pm

AntiCooter wrote: Well, Chris, neither one of them will do you any good because hell will freeze over before I send them your way. Here's why:.....onandonandon...

Wow, burn.

Anyway, I paid that much for the setup because Shaun did a wicked port/polish job, direct port plumbing, and proved that it has a power increase with dyno testing.

I'm pretty pumped to get this thing working correctly. Hopefully after tackling it tomorrow night I will see what is keeping it from performing.

Chris-Nelson · Post by **Chris-Nelson** » Thu Sep 20, 2007 12:01 am

Tonight I made another cable bracket so that I could position the automatic tranny cable where I want it. I ended up putting it on the secondary TB because I will need yet another cable for the cruise control eventually! Just trying to even things out.

And here is the other side:

As it sits right now it idles really well and has good throttle response, but it still doesn't have a whole lot of power and I'm not quite sure why.

Within the next week I am planning on getting the exhaust done on it finally and doing some datalogging with my aldl setup and hopefully see what the issue is.

I am supposed to have it at a dyno on the 30th, so if I can get it running pretty good I will bring it up there to get it fine tuned a little more.

Real Fiero Tech

Dual TB Intake Tuning

Dual TB Intake Tuning

Re: Dual TB Intake Tuning

Re: Dual TB Intake Tuning