FI Tech Frustration is back again

CopperNick

Royal Smart Person
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Feb 20, 2018
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Canada
So i had finally figured out how to get the IAC to respond and cooperate to get the idle down to the point where the van will shut off without dieseling. It ran fine on Saturday, no issues with starting idling or shut off. Did not drive it again until yesterday, and it DIED.

Started okay, warmed up, went into gear, got about half a block down the street as far as the corner, stopped, tried to turn the corner, and ZILCH. Took several tries to get it to refire, got to the next block, and it did the same thing. This has now happened so many times in the last several days that I am now very afraid to try and drive it lest i lose fire in traffic and get rammed from behind by some moron who isn't paying attention.

I can sort of get it to cooperate by feeding in more accelerator pedal that I normally use but if I try to accelerate away slowly or gently. Off it goes and I am coasting with no power steering or brakes.

The only thing that the Programmer readings are telling me is that the IAC reading at idle is 0. It can and does bounce up from there to 3-4 and back down again.

I don't think this is an ignition issue as it will crank and refire but it almost seems like the fuel system is starving out. Right now I am using that goofy booster pump assembly that FI Tech suggested as an option as opposed to going with an in tank electric pump and I just finished changing out the in line fuel filter JIC.

Apart from turning it into a paperweight and going back to a carburetor, which I am Not in favor of as I got to the point years ago where having to retune the carb every weekend to account for humidity and temperature and all that ya gotta do that B_S baggage that carbs come with does anyone on the forum have any solid suggestions that I can check out? This is supposed to be my go to work vehicle and right now it looks like I will be walking there. NOT HAPPY.


Nick
 

ck80

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Feb 18, 2014
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So i had finally figured out how to get the IAC to respond and cooperate to get the idle down to the point where the van will shut off without dieseling. It ran fine on Saturday, no issues with starting idling or shut off. Did not drive it again until yesterday, and it DIED.

Started okay, warmed up, went into gear, got about half a block down the street as far as the corner, stopped, tried to turn the corner, and ZILCH. Took several tries to get it to refire, got to the next block, and it did the same thing. This has now happened so many times in the last several days that I am now very afraid to try and drive it lest i lose fire in traffic and get rammed from behind by some moron who isn't paying attention.

I can sort of get it to cooperate by feeding in more accelerator pedal that I normally use but if I try to accelerate away slowly or gently. Off it goes and I am coasting with no power steering or brakes.

The only thing that the Programmer readings are telling me is that the IAC reading at idle is 0. It can and does bounce up from there to 3-4 and back down again.

I don't think this is an ignition issue as it will crank and refire but it almost seems like the fuel system is starving out. Right now I am using that goofy booster pump assembly that FI Tech suggested as an option as opposed to going with an in tank electric pump and I just finished changing out the in line fuel filter JIC.

Apart from turning it into a paperweight and going back to a carburetor, which I am Not in favor of as I got to the point years ago where having to retune the carb every weekend to account for humidity and temperature and all that ya gotta do that B_S baggage that carbs come with does anyone on the forum have any solid suggestions that I can check out? This is supposed to be my go to work vehicle and right now it looks like I will be walking there. NOT HAPPY.


Nick
Not that you want to, and, in your neck of the world I don't know how plentiful things are, but. The gm "g" series van style went from the late 60s all the way up to 1995ish.

Point is, they went to a factory 350 TBI. You could swap your dash harness/gauges, not many wires, and just put in the whole shebang of a gm tbi wiring setup in a weekend including the intake swap, getting a serpentine belt on front to boot.

Down here they're cheap. Up there? Maybe all rusted out, made into appliances, or in farmers fields as storage.

Thats just a throw in the towel suggestion. I'm not a fi tech guy.
 

CopperNick

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Feb 20, 2018
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Actually it is not that bad a suggestion. I had been thinking about doing some harvesting from an 85 and newer G-10 simply to get the newer steering wheel/mast assembly that has the locking ignition and the cruise control. The 'while i was there" acquisition would have been the rest of the complete cruise control assembly from the engine. Problem is, as you noted, they are not thin on the ground here, they were already sent to be shredded and turned into Priuses decades ago. Would be curious/cautious about the TBI from one of them in any event. My S-10 runs the TBI system and it works well; just that it is old technology and hard to find information and service parts simply due to age.

However, perseverance and obstinancy in equal amounts led me to run a search or two and from there I went back to the programmer and tweaked the fuel map a bit and then went after the IAC adjusting screw on the FI body as well as resetting the "Learn" routines. Then took a loot at the max idle and found it had gone negative, which is something that it is not supposed to do. The min for that datum is ). So I reset all that and went for a hot lap and it seemed to be working okay again. The high idle is back to being over a grand but also seems to want to come down like it is supposed to.

Evidently my problem is not unique and several other forums have threads running on the matter. Most of the consensus is that the Technical Support for the product sucks, horribly. The knowledge base for it has come from trial and error on the part of many and there is no one single library on line that contains all the questions and answers. I did touch base with my Indie that soild me the unit and even they have quit carrying the line due to all the negative feedback that has appeared.

I actually had considered a Sniper at one point but with all the grief that McLellan? has had with his, I am not looking for another stress generator. I'd re-carb the thing in a New York minute but I am done messing with Hollies. My last one is gathering dust on the bench; it is on its third throttle base and been through more tear downs and jet changes to try and get it to play happy when the temperature and humidity mover around. Think if i ever went carb again it might be to a Quick Fuel or maybe an AVS if i can get one that will tolerate the cold and damp. Also contemplating the FAST system but would need a budget for it for sure.

And anyone who might be considering the LS route, yes, and no. Yes, I do happen to have one, and no, the amount of useable real estate in the engine bay of a van is retardedly small as it is. Even block hugger headers are a tight fit and changing sp plugs is an exercise in literally climbing onto the motor and doing the touchy-feely for most of them.

Will keep this thread posted on my trials and tribulations with this.



Nick
 

64nailhead

Goat Herder
Supporting Member
Dec 1, 2014
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Upstate NY
What's the AFR and where's it heading when it quits?
 

CopperNick

Royal Smart Person
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Thread starter
Feb 20, 2018
1,924
113
Canada
12.75 AFR is the ratio that I loaded in as the original default. it was chosen as the best compromise for an engine that does a lot of stop and go driving and gets very little WOT time. As to how it changes just before calling it quits, that I do not know as I have no way of watching the maps as they function. A laptop is on the agenda but, I have also identified another option.

That is, as mentioned at some point, trashing the whole business and reverting back to a carburetor. Only this time I would be using the Edelbrock unit, either the 1406, or the AVS 1906. The 1906 flows 50 cfm more than the 1406, putting it at 650 cfm and it comes with annular boosters as opposed to the primary versions that the 1406 has. i am pretty sure that I can get one ready to use from my local indie. They are supposed to be available from Amazon but they come with horror stories about bad packaging and damaged contents so not my first choice of vendor here. Either one will bolt up to the Performer 2101 manifold that has been in residence on that motor since the 80's. And they both appear to be able to operate a 700R4.

Removing the FI unit is the reverse of installing it. The fuel delivery reverts back to the mechanical fuel pump which is still installed. if I had to I could get fancy and run an electric pump but the default unit also solves the problem of having to modify the fuel tank for an in-tank pump that was on the agenda for the FI unit. The original installation was matched to the booster pump accessory and to this day I have never been happy with it. At this point I am almost wondering if it is telling me that it is about to fail and that is why the off idle stall out during acceleration.



Nick



Nick
 

V8 Rumble

Royal Smart Person
Jan 7, 2010
1,289
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Connecticut
I've had my fitech 6 years with zero issues. When you try to adjust the iac do you shut the car off until the display shuts off? This had to happen in order to learn the setting.

Also you are always checking the iac is between 3 and 10 at idle or neutral?

Also have you tried resetting back to factory and redoing the initial setting and letting it relearn that way.

It sucks yours is giving issues. A friend has the fitech ls set up and works like a champ.

I wonder if that fuel set up is not supplying fuel fast enough.

I am using a gn tank set up with an aeromotive fuel pump.
 
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Fleming442 also had terrible experience with the FiTech. Many parts just died out of the blue and it ran pretty crappy. He ended up going to a carb on his 67. The Sniper also has issues and a really slow and inaccurate O2. Neither system is worth spending money on. The GM TBI is a good reliable system. The problem with it? I found the 204/214 114 LSA cam I ran, borderline too big. Closed loop ran pretty good. Open loop was never great and the colder it got, the worse it ran. If your cam is 220 duration and a 110 LSA, it isn't going to like it. I am going SEFI, either the Holley Terminator or Dominator or an AEM system. Not cheap at all but not the nightmare these cheap systems seem to be for some. Hopefully something works out.
 
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Clone TIE Pilot

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Aug 14, 2011
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If you go with GM TBI, the 9C1 version is the best performance wise.

Not sure why you had to readjust your former carb all the time? That is something that should not happen. I have a 1946 farm tractor that gives me zero carb tuning issues. Aftermarket carbs tend to be a Jack of all trades design which bringbcertain issues not found in using factory spec carbs.

Is the engine you are having your FITech issues with the same engine you had problems with your old Holley carb? If so then perhaps there is an underlying issue with the engine itself?
 
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stew86MCSS396

Not-quite-so-new-guy
Aug 1, 2022
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Couple of thoughts... I don't own this system but it would seem if the IAC goes to zero=fully closed, your idle throttle opening may be opened too much. IAC is trying to adjust idle air by closing off IAC passage but loses control once shut. Other possibility that causes an IAC to behave this way is a vacuum leak. Setting the AFR at 12.75 probably would mask a vacuum leak. By comparison my TBI engine provided the stock narrow band sensor is doing it's job correctly, my idle/cruise hovers at stoic 14.7. I have lean cruise enabled so with ideal conditions (mainly very light loads), the ECM pulls fuel down to 19.x but thats besides the point. When PE (power enrichment) kicks in, my ECM is set to target an AFR of 12.5 so I don't see how setting it to 12.75 is beneficial. 100% WOT fuel delivery at all times!!! My other vehicle albeit TPI, it runs just fine with a bigger than stock cam. It started just fine on the stock tune but it was pig rich. A stock cam may pull 18" of vacuum at idle but with a bigger cam like in my case pulls 12" at idle. At 12" on a stock cam, it would be fueling the engine as if it's under load hence pig rich. Soooo...basically in the fuel map idle rpm vs map, I had to remove fuel in that area to bring my idle fuel to stoic. How big is my cam...idk the lift as it was already in the engine when I bought it but the PO had shared this pic with me.
 

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64nailhead

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12.7 is a little rich when the engine is warm. The only time you should see something that rich at idle is when the engine is below 80-100 degrees. Strongly recommend targeting 14 +/- .2 at idle.
 

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