Thought i'd give TBI a try on the ole 2f

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Hey guys, i have a question for those of you who have this conversion. Any of you have idle problems?

My idle is fine as long as i turn the idle speed screw a bit. BUT, my main issue is that when i set the idle at 750 rpms, the second i turn the wheel my truck studders and will eventually stall. (i have powersteering) NOw with my idle set at 1000rpms, i don't have this problem.

I remember when i had a carb my truck would idle at 500 rpms and i never had problems when turning the wheel.

A fellow mud member sent me a prom designed for a 2f but when put into my computer, the truck idles very high at like 1600 rpms and doesn't drop. Throttle response has a hiccup also.

So i'm thinking about sticking with the stock gm prom, EVERYTHING works great except the only problem i am having is the idle.

Any suggestions?
 
badass said:
My idle is fine as long as i turn the idle speed screw a bit. BUT, my main issue is that when i set the idle at 750 rpms, the second i turn the wheel my truck studders and will eventually stall. (i have powersteering) NOw with my idle set at 1000rpms, i don't have this problem.
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My guess would be the IAC. It should open to account for the drop in RMP as a load is put on the engine. With the air cleaner off, you should be able to hear a change in pitch as more air is bypassing the throttle plates via the IAC and the whole next to the throttle bore.
 
The iac valve was replaced durning the conversion with a new one from advance auto parts. Right before the engine stalls usually it opens up and i can hear a loud whislting noise and the idle picks up again.
 
Did you adjust it? The IAC comes with instuctions on how to adjust it for certain applications.

Did you try to reset it?

It shouldn't stall turning the steering wheel. I've never had that issue.

Did you ever get an ALDL cable?

With the distributor did you lock the counterweights in the bottom of it and tack the top plate?
You also could have an issue with the TPS.

You really need to do some datalogging.
 
Trollhole said:
Did you adjust it? The IAC comes with instuctions on how to adjust it for certain applications.

Did you try to reset it?

It shouldn't stall turning the steering wheel. I've never had that issue.

Did you ever get an ALDL cable?

With the distributor did you lock the counterweights in the bottom of it and tack the top plate?
You also could have an issue with the TPS.

You really need to do some datalogging.
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still haven't got a cable, distributor was done correctly, i just replace the iac with a new one and it still does the same thing. How could the tps have anything to do with this???

Could bad injectors cause this?

Also Troll, are you still able to get your engine to lug down to those low rpms like you used to be able to (like under 500)?
 
Hey, I just read to here and wonder how the TBi is working for you? It's been a great read, thanks!

Stephen
 
Tbi is an amazing addition to a 2f. BUT, BUT, BUT, BUT, BUT,BUT, i don't care what anyone says, even Jim at Downey, which i bought the kit from him. YOU HAVE TO GET A CUSTOM TUNED CHIP IN ORDER TO GET THE BEST MPGS POSSIBLE, CORRECT IDLE FUNCTIONS, AND JUST FOR THE MOTOR TO RUN RIGHT.

I have driven my truck everyday (its my dd) since i did the tbi, and even though it drives and is very reliable, it doesn't get that much better milage before the conversion, runs rich, misfires in lower rpms and doesn't idle right. In city driving is the worse, highway is where it does best. BUT i'm getting a custom tuned chip this weekend in atlanta and will finally haver her running right.

All i'm saying is, tbi is amazing, if its done right, do the conversion yourself so you can learn but factor in a few hundred dollars for a custom chip.

so far i've had no issues with the tbi components themselves. Since the beginning i've been searching for problems in my wiring or sensors. NO!NO!NO!NO!

ITS THE CHIP. The chip is designed to run on a chevy v6, not toyota inline 6. I have alot of respect for Jim at downey offroad, but he is wrong everytime he says the stock gm chip works best. It doesn't, Jim will tell you that the computer will learn as you drive and run much better, he is right, but it won't learn enough to the point where it will run correctly. His kit is very well done though. If you need anything let me know and if ya wanna talk, send me a pm and i'll give ya my number. I've takin this s*** apart so many times, i've practically memorized every wire color in my head. later, Sean....
 
I'm interested to see how the custom chip works for you. My speculation has been that your performance issues were not related to your TBI system. Now you can tell us for sure: if it still runs like crap when your wiring and sensors are fine and your chip is tailored to your engine, it ain't the ECU.

x2 on the fuel efficiency issues. It should be at least as good as a perfectly-tuned carb, but there are physical limits to how good it can be ...
 
Mr. Toad said:
I'm interested to see how the custom chip works for you. My speculation has been that your performance issues were not related to your TBI system. Now you can tell us for sure: if it still runs like crap when your wiring and sensors are fine and your chip is tailored to your engine, it ain't the ECU.

x2 on the fuel efficiency issues. It should be at least as good as a perfectly-tuned carb, but there are physical limits to how good it can be ...
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Toad, i talked with they guy and he has done many 2f tbi conversions at his shop, and many tunings. He told me what problems he has experience with his conversions when he runs the gm chip. And i'm having the exact same problems. I'll report back!!
 
badass said:
Tbi is an amazing addition to a 2f. BUT, BUT, BUT, BUT, BUT,BUT, i don't care what anyone says, even Jim at Downey, which i bought the kit from him. YOU HAVE TO GET A CUSTOM TUNED CHIP IN ORDER TO GET THE BEST MPGS POSSIBLE, CORRECT IDLE FUNCTIONS, AND JUST FOR THE MOTOR TO RUN RIGHT.

I have driven my truck everyday (its my dd) since i did the tbi, and even though it drives and is very reliable, it doesn't get that much better milage before the conversion, runs rich, misfires in lower rpms and doesn't idle right. In city driving is the worse, highway is where it does best. BUT i'm getting a custom tuned chip this weekend in atlanta and will finally haver her running right.

All i'm saying is, tbi is amazing, if its done right, do the conversion yourself so you can learn but factor in a few hundred dollars for a custom chip.

so far i've had no issues with the tbi components themselves. Since the beginning i've been searching for problems in my wiring or sensors. NO!NO!NO!NO!

ITS THE CHIP. The chip is designed to run on a chevy v6, not toyota inline 6. I have alot of respect for Jim at downey offroad, but he is wrong everytime he says the stock gm chip works best. It doesn't, Jim will tell you that the computer will learn as you drive and run much better, he is right, but it won't learn enough to the point where it will run correctly. His kit is very well done though. If you need anything let me know and if ya wanna talk, send me a pm and i'll give ya my number. I've takin this s*** apart so many times, i've practically memorized every wire color in my head. later, Sean....
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That must have been you asking about a chip on YouTube. I'm very curious to know how you're running once you install it. My application is a little different - sbc350 converted to TBI and I'm generally happy with the way it runs, way better than with a carb. But, I know it can run better and I believe it will take a new chip to make it sweet. I've considered buying the equipment to make my own - I understand that it sometimes takes more than one try to tune it correctly. But do I really want to spend the time and headache to learn all what all that code means??? Did you ever get the cable and do any data logging with WinALDL?

Good Luck, keep us posted :cheers:

Ed
 
badass said:
Toad, i talked with they guy and he has done many 2f tbi conversions at his shop, and many tunings. He told me what problems he has experience with his conversions when he runs the gm chip. And i'm having the exact same problems. I'll report back!!
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Glad you found someone. I wish I could have helped but I'm not making chips right now and still trying to get my act together before I involve anyone else. I'll be in ATL Sat also. Give me a shout if you get done early. We are doing a Help A Member of the Month. We are putting a 55 back together.
 
badass said:
Regarding the purple wire (from the gm harness) that is supposed to hook to the starter, which wire is it supposed to hook up to on the starter? Is it the black and white wire (toyota harness) that only gets power in starting mode?

Does hooking up that wire actually affect the idle speed during cold start?
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Just read thru your entire post. Good job, you obviously learned a lot. Question...I also used the GM harness on my conversion but I sure don't remember a purple wire going to the starter??? I am having an issue with it running very rich at idle, no black smoke but enough so that I bombed an emission test. I wonder if this could have something to do with it? Can you tell me more about this wire...what pin is it on the ECM? How did you end up connecting it to the starter?

Thanks for your help.
Ed
 
I too just read through this whole thread and found it very interesting. Thanks for the insight. Will continue to monitor your progress with the new chip. Question: How much coin should one expect to invest in a project like this?
 
In regards to your truck running rich, make sure your fuel psi is not too high at idle. How did you run your return line and where to?


If i did the project again, I could do it again for 500 easy...

Toad turns out this whole time my harness was bad. It all looks good, but Oscar says that the copper inside the wiring is broken in many places. So i'm getting a new harness and were going to retune saturday.

Also, i take back what i said about a gm computer not working good. We put the stock gm chip computer in Oscars truck and it ran fine, it doesn't work in mine cause the harness is bad.:mad:
 
badass said:
In regards to your truck running rich, make sure your fuel psi is not too high at idle. How did you run your return line and where to?


If i did the project again, I could do it again for 500 easy...

Toad turns out this whole time my harness was bad. It all looks good, but Oscar says that the copper inside the wiring is broken in many places. So i'm getting a new harness and were going to retune saturday.

Also, i take back what i said about a gm computer not working good. We put the stock gm chip computer in Oscars truck and it ran fine, it doesn't work in mine cause the harness is bad.:mad:
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Good to hear. (Well,it's good to know, no?)

What 74 said x2. Also, is there any way to plug a laptop into the GM computer and watch the sensors for bad signal in real time? I can do this with Megasquirt. Or maybe a reader/scan tool of some type? Seems like that would have saved you a lot of grief even w/o an ohm meter.

I'll tune in next Sunday night.
 
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