😂😂 that’s what I’m saying. So based off what you know about the system do I need a whole new fuel system or not? Are they getting this mixed up with the LS system ? I’m lost on this. My understanding is it works on a stock vehicle.

 

I don't know anything about the FiTech system.

No you don't need a entirely new fuel system.

58 to 60 PSI is 100% absolutely wrong for a stock Tuned Port Injection system unless the car has been fitted with injectors that require 4 bar fuel pressure.

Their tech support people don't know their azz from a hole in the ground.


This video doesn't apply in your case or in the case of anyone running a 1985 to 1988 TPI system with factory stock injectors. I don't know what the early type injectors will do at 4 bar.

It does apply to 1989 to 1992 TPI systems with RP Multec injectors or the Delphi Multec style replacements for those. Also applies to anyone that has replaced their injectors on 1985 to 1988 with the Delphi Multec style injectors.

At higher pressures than the rated 43.5 PSI they start to slow down and at 4 bar they lock up.

 

Thanks for reaching back out. I appreciate the info. Too bad there’s a discrepancy in the info I’m getting from fitech.

 

I have gotten nothing but conflicting info from fitech. I can’t get my car to idle correctly and they tell me I have a vacuum leak. I did the smoke test and don’t have a leak. The idle control doesn’t respond to input on the control panel. The only thing that affects my rpm is playing with the throttle body opening screw. I’ve replaced my tps iac, ignition module,etc. it starts to run ok then I drive it and have to keep my fingers crossed. No consistent issues, always a new one. Had my computer back to them, they say it’s perfect. I say different. I have a zf6 trans in my c4 corvette and the speedometer wouldn’t work. The setting says t56 or other. I put in on t56 ,which is what I do not have, and all of a sudden it works. They are inconsistent with their answers. It’s so bad that I even know the technicians name. I haven’t driven the car lately because I can’t stand the unreliability of the system . But they won’t refund my money so I can buy a Holley system or something else.

 

And they always say, I’m not familiar with this system, I’m an expert on the ls system. Guess what, I don’t have an ls, if I did, I would run from this company.

 

Any specific tips on how to make the speedometer work? I barely got the ecm engine harness out and was surprised to see the vss wire was not part of that harness but part of the electrical harness that stays. The connector on the fitech harness won’t fit my vss. Original looks like regular weather pack style. Would I need to find a way to split the vss signal so the original vss wire and fitech vss wire get hooked up? This is on an 87 trans am gta.

 

Use the original connector and cut the FITECH connector off. I did that with my 1989 corvette. Solder the ends on

 

you cut off the vss connector from the fitech harness and put the correct end on it? Which makes sense. But I still have the vss wire on the car still also. It’s part of the electrical harness. I’m questioning if I should use the original wire for the Speedo. Or somehow have both wires going to the vss. Like maybe modify the adapter so I can plug both in.

 

I just used the stock speedometer vss connected to the transmission. I originally put the factory vss wires on the FITECH harness and used the wire from the FITECH to my speedometer. It didn’t send the signal and my speedometer showed 0 mph. I have a stick car so I just used the factory wiring and not the FITECH. If you find that the connection from the FITECH computer to your factory speedometer does not work. I would splice in both wires. In other words , connect the speedometer to the vss and tap off two wires to the FITECH to control your lockup of your automatic transmission.

 

that’s what I was thinking. I think I’m going to try and make something out of the adapter that was supplied to get the signal to my speedometer and the fitech. I have weather pack connectors so probably be easy to do. I do have an automatic. Going to need lockup control.

 

Modified the adapter that was supplied. Question is will it work. One way to find out when I get there

 

This is the way.

 

So I got the fitech up and running. But I do have an issue with the Speedo. I got it to work being hooked up to the stock wiring. Just had to ground the one ground wire that went to the 15 way connector that went to the ecm. But it’s making the fitech read false speed just sitting still. And caused my idle not to go down. Disconnected the stock vss wire from the splitter I made and the fitech is good on the speedo. Tried hooking up the output wire from the fitech to get the speedo to work at the buffer. But I got nothing. Tried the speedo wire and both vss wires. Thought someone said it would work there. Am I missing something?

 

so I’m not running my vss to the fitech. Guess you can disable it in the settings and torque converter lock up works off of tps percentage only. Which you can adjust what percentage it comes on.

 

I'm hoping to start an install tomorrow. I have question. The oem drivers side injector harness plugs into the alternator, while the Fitech doesn't. Is that a problem?

 

what year is your car? My 87 didn’t have that issue. But there was a 2 terminal plug on the driver side that connected the oil pressure and ac to the ecm harness

 

It's a 92. I have a few more connections underneath the car. I mounted the fuse box on the firewall and will mount the end on the frame. The remote coil will just have a single connection, right?

 

Yeah your 92 is probably way different with how it’s wired. I know my 87 the coil wires were separate from the computer engine harness. So when I removed that harness the coil wire stayed.

 

Hey folks,

beeing in progress of installing my fitech 38351 system in my 88 Firebird. Can someone help what the right multiplier and VSS to Speedo correction values are that I once found one here?

Someone got the Stock Speedo working with the fitech system. Mine is also working but I cant get it dialed in correctly that itbhas a precise speedo reading...

 

In my previous posts, I had many initial issues with the fitech TPI system. If you can’t get the idle correct, do as they say and buy a smoke machine.i had the tiniest leak under one of my runners. Even using carb cleaner did not affect the rpm. Once the smoke identified the leak and I plugged it, I was able to set the idle and other parameters on my car. One other note is that the car ran horribly at the factory timing setting. It runs great at what appears to be 20 degrees retarded, I’m in process of buying a new harmonic balancer because with 85k on the motor, it’s very possible that it has slipped. If I set it to 6 btdc it runs rough, and if I shut the car off, the starter strains to turn it over, even if the car is cold.

 

Not running at factory base timing doesn't surprise me that much. The last SBC I built liked 16 degrees of timing with the computer unplugged. Depending on the engine build, stock timing might not keep it running.

 

You should use a piston stop to find true TDC and figure out what's going on there.

 

sounds way advanced

 

Since you were able to get you car to run good. Would you be willing to share your AFR, spark advance and fuel settings?

 

Sure. Nothing special. I leaned out the AFR some and left the rest to Fitech preset data. The biggest improvement for me was setting the IAC correctly.

 

How did you set the iac with the fitech? Certain amount of iac steps? My car runs good. But I do get an iac fault. And the AC kills it when I turn it on. Have to run idle higher so that don’t happen.

 

Thanks! Could you also show me your crank fuel, accel pump and timing pages?

 

With the engine up to temp Fitech wants the IAC steps to be between 3 and 10, if I remember correctly. So, set IAC and TPS on large gauges on the handheld. Drive around up to temp, find a parking lot, put in P and let the IAC settle. If its above 10 then you need to shut the engine down and adjust the screw (can't remember the name, see screenshot) so the TB will let a little bit of air in. If some (minimal amount) air sneaks past the throttleblade the IAC will return its amount of turns.



Depending on where your IAC steps are it could be a half turn on the screw. Start the engine and see your new results. You can not alter the TPS screw with the ignition on, that's why you need to shut it off between every adjustment.

It also depends on where you want your idle rpm to be. I chose 750. Do that first, before doing anything else.

Initially my IAC was on like 60 turns and I had a hard time starting the car. Now it starts right away.

I hope the above makes sense?

 

Sure but I haven't altered anything. It should look like yours, more or less

(I do have a mild cam, heads, lingenfelter intake and headers, which might alter the data some. I dunno what Fitech actually learns? Will get back to you with shots of the screens)

 

Can anyone on here who has successfully installed and tuned a Fitech 38351 for a mostly stock l98 show me some pictures of their tuning pages?

 

It doesn't matter what we have; read the manual, watch the videos, and tune your stuff how you like it. If you're mostly stock, the base tune should get you started just fine.

 

I second watching those videos, they helped allot. I started with cam 3 since the manual says to go by intake duration. The videos say to use vacuum. So the engine was making 12in at idle, I switched to cam2 and everything fell into place.

 

did you connect the speed output directly from the fitech? Or was a converter box connected also. Trying to get mine to work on an 87 trans am and it’s driving crazy.

 

Ok after driving myself nuts I think I figured out the speedo for myself. Granted this is something I’ve never dealt with. And after seeing some info here and other places. I bought a used Dakota digital speed interface. Sgi5e. Looked similar to the one being offered now. Must be an older model. This is what got it to work. Have to use the calibrated output. Which is 1 or 2. 2 seemed to be the one that worked after doing the output test. Also have the module in L-L mode. And also have P-U turned off. I don’t know if the vss buffer is truly needed or if I can unplug it at this moment. But for now let’s just say it works this way being plugged in. I’ll try it with it unplugged also later. Currently I just put a couple terminals into the plug to test. Output going to speedo green wire. And using the ground from the plug for a ground source for the moment. I couldn’t get the speedo to show any activity until I also messed with the fitech settings. The speedo to vss count was originally set to 27. I lowered that setting and speedo started reading. Got it down to 2 and it was very close. Then had to calibrate the Dakota itself on the fly to get it spot on. Which is just pressing the + or - buttons. This is on an 87 trans am. I could easily leave my existing vss wire plugged in for my speedo. But I wanted my lock up control to be better than without the fitech VSS being plugged in. Hopefully I can get the cruise figured out also. But I’m a little doubtful at the moment.

 

Does anyone have Fitech 38350 ecm connector pinout?I'm trying to figure how to make cross connection harness from fitech to Camaro original harness.