Fitech Wont pass Smog all the sudden

[wilcom]

looking for some help with my fitech not passing smog. Been working on it off and on since 2024. Any help would be great.

• 1970 Bronco
• 302 engine rebuilt years ago with RV Offroad cam and better pistons. I had the heads and ports polished and valves reworked to accept unleaded gas. Pistons were matched to each cylinder and stock 4-barrel manifold was matched to block.
• Milage since rebuild around 90K or so.
• Dual exhaust.
• NP435, 4-speed manual with granny 1st and reverse.
• PCV valve only.
• Fitech 30003 carb. (sent back to Fitech 7 months ago for newer remoted ECU module update and new handheld. I replaced all 4 injectors 600 miles ago.)

Fitech replacement Parts;

• IAC Valve
• TPS sensor
• Map sensor rubber gromet. Made sure it was seated properly with the nipple cut off flat.
• Replaced throttle position sensor.
• Carb/manifold gasket.
• Fuel regulator. Blocked this off with rubber plug as told to by Fitech techs.
• 100-micron pre and 10-micron post fuel filters. (just installed 60 miles ago)
• Replaced 4 injectors

Other replacement parts;

• Summit Racing™ Billet Distributors SUM-850075 2- wire Distributor, Magnetic Trigger, Vacuum/Mechanical Advance.
• MSD 6AL box (I did not make any changes to the switch settings. Standard wiring to 2-wire dist)
• MSD 8mm plug wires
• MSD Coil
• Replaced all Vacuum lines.
• Added and/or replaced all engine, chassis, frame grounds.

Fitech settings;

No Fault codes.

IAC 6 to 7 at 750 rpm idle and TPS is either 0 or .5 if it goes down to 5.

AFR set to 14.7 bounces around at 750 rpm idle from 14.5 to 15.1 but is pretty much stable right around 14.7 This tells me the 02 sensor is working ok? I replaced it about 700 miles ago when driving to set the carb parameters after doing a software update and deleted the original settings and started from scratch.

Reset and aligned throttle blades. Removed carb for this and also replaced manifold carb gasket. Torqued carb/manifold bolts to 16ftlbs.

Relocated and shielded Blue tac wire down under radiator frame to battery, then to external relay box and plug connections on opposite side on firewall by driver’s air intake for floor vent.

Carb is powered by 12v relay direct to battery.

Bosch electric fuel pump located 15” from rear tank fuel nipple output and powered by relay direct to battery.

Output at fuel line gauge under hood is constant 62 psi. All fuel line is EFI spec with barbed connectors and hose clamps.

Smog Tests when I had time to work on it

9-3-2024 Smog test failed; set AFR to 13.2 and idle @ 680 rpm and IAC 6 set properly.
Idle speed HC, 1371 greater than 700 ppm. Failed

10-4-2024 Smog test failed; Replaced spark plugs, coolant temp sender, dist cap and 8mm plug wires, thermostat and fitech handheld. Cant remember what I did for fitech settings. Dist timing was probably 12 to 15 deg, AFR probably around 13.3.
Idle speed HC 1121, greater than 700 ppm

4-13-2026 Smog test failed; Set Fitech AFR to 13.8 and idle to 800 rpm. IAC normal. Dist set to 12 deg base = 32 deg “all in” at 3300 rpm.
Idle speed HC 1533, greater than 700 ppm.

4-13-2026 Smog retest failed; Set AFR to 14.2 and 800 rpm. IAC normal. Dist the same.
High speed CO 9.32% greater than 3.5%.
Idle speed HC 1455, greater than 700 ppm.

7-16-2026 Smog test failed; Set AFR to 14.7 and 1100 rpm. IAC normal. Dist still set to 12 deg base = 32 deg “all in” at 3300 rpm
High speed CO 10.39%, greater than 3.5%.
Idle speed HC 2173, greater than 700 ppm.
High speed HC 791, greater than 700 ppm.

My thoughts;

• Maybe go back to an AFR of 13.2 or 13.4. and reset IAC. (I wrote down the ARF setting back years ago when the engine did smog and it was set to 13.4 and idle 725 rpm)
• Make Base timing for 302 is 6-10 deg. Web search says with RV cam 15?
• Maybe recheck the IAC motor I replaced to see if its installed correctly. I have the IAC set at 5-7 with minor movement and never under 4 or over 10, so I would think if I installed in wrong it would not allow me do so?
• Could the RV cam be lopy than I think? It have some overlap sucking in more oxygen from the exhaust so the sensor thinks to add more fuel? I have the fitech cam setting at 2.
• I set the throttle plates properly before reinstalling the carb so I am sure I did it right. If the IAC gave me problems and would not allow me to properly set it then I would think to go back and check it. But the IAC gave me no problems setting it and it bounces between 5-7.
• High speed and Idle HC all boil down to lopy cam and distributor timing and richer AFR?
• read an article that said due to RV cam overlap

Thank You,

 

[DirtDonk]

What’s not passing? Strictly a sniffer test?
I’m guessing that because a 70 bronco didn’t have much smog equipment/requirements to begin with, and didn’t have ultra tight specifications to begin with. So seems something’s going on.
Frankly, with all of your other modifications, including the cam, I’d be surprised if it ever passed!
But you’re saying it has passed in the past?
Do they do a visual, or just sniffer?

 

[73azbronco]

What state? What were/are the emission rules for the 1970 in that state? Smog pump?
Is fitech new to the problem, did it pass emissions before fitech? Or fitech passed then didnt?
AI says:

Your engine is failing due to an extreme rich-running condition, meaning it is dumping massive amounts of unburned raw fuel into the exhaust.
A High Speed CO of 10.39% is extraordinarily high (normal running is usually under 1.0%), which indicates the FiTech system is completely flooding the cylinders under load. This massive excess of fuel prevents proper combustion, which is exactly why your Idle HC (2173 ppm) and High Speed HC (791 ppm) are spiking way past the legal limits.

Why Your FiTech is Flooding the Engine

• False Lean from an Exhaust Leak: This is the most common culprit on vintage 302 engines. If you have even a tiny exhaust leak near the headers, collector gaskets, or the O2 sensor bung, outside air gets sucked into the exhaust pipe. The FiTech O2 sensor reads this extra oxygen, falsely thinks the engine is starving for fuel, and forces the injectors to stay open.
• Incorrect Fuel Pressure: FiTech throttle bodies strictly require 58 PSI of fuel pressure. If you are using an frame-mounted inline pump without a baffled tank, or if your fuel pressure regulator is failing/stuck, high fuel pressure will bypass the ECU's control and force massive amounts of fuel through the injectors. [1, 2]
• Mismatched Engine Setup Parameters: If your handheld controller is programmed with the wrong engine displacement (e.g., set to a 350 or 400 cubic inch engine instead of your 302), or if the "Cam Selection" profile is set too aggressively (e.g., Selection 3 or 4 for a mild/stock cam), the base fuel map will be drastically over-enriching the mixture.
• Faulty Engine Coolant Temperature (ECT) Sensor: Look at your FiTech handheld while the engine is fully warmed up. If the ECT reading is stuck below 170°F (76°C), the system stays in "Warm-Up Enrichment" mode. This acts like a stuck mechanical choke on an old carburetor, constantly flooding the engine with fuel.
• Leaking Injector: A mechanical failure where one of the internal fuel injectors is physically stuck open or dripping will bypass all computer commands and pour raw fuel directly into the intake manifold. [1]

Immediate Troubleshooting Steps

1. Check Handheld Diagnostics: Plug in your FiTech handheld with the engine running. Look at the AFR (Air-Fuel Ratio) and Target AFR values. If your Target AFR is 14.7 but your actual AFR is reading incredibly lean (like 16.0+), yet you smell heavy fuel, your O2 sensor is being fooled by an exhaust leak. [1, 2]
2. Verify Fuel Pressure: Hook up a mechanical fuel gauge directly to the FiTech inlet loop to ensure it reads exactly 58 PSI under load, not higher.
3. Verify Basic Setup: Re-check your initial setup wizard on the handheld. Ensure the engine size is correctly scaled for a 302 and that your cam profile selection matches the vacuum characteristics of your engine.

To help pinpoint the exact setting or mechanical failure, what are your Target AFR and Actual AFR values on the handheld at idle, and what Cam Selection (1, 2, 3, or 4) did you choose during setup?


Non AI my second thought, buy an autolight 2200 carb, try that. But, do you smell fuel in the oil?

But really, why is fitech not helping you? Sounds like you have a lot to chase, my first thought get your fuel pressure down to 58psi.

 

[73azbronco]

What’s not passing? Strictly a sniffer test?
I’m guessing that because a 70 bronco didn’t have much smog equipment/requirements to begin with, and didn’t have ultra tight specifications to begin with. So seems something’s going on.
Frankly, with all of your other modifications, including the cam, I’d be surprised if it ever passed!
But you’re saying it has passed in the past?
Do they do a visual, or just sniffer?

Depending on state, my OEM stock 1966 6 cylinder, had an operating smog pump and associated tubes and horror. California.

 

[DirtDonk]

OP is in Nevada I believe. Yes, the '66, '68 and '76 CA trucks had smog pumps. Not sure what other years got them, and what DSO's other than CA. But even here, they were hit and miss depending on the year.
But that's still pretty minimal stuff for a '70.
Visually speaking, a working PCV valve, potentially a "Thermactor" (smog pump), a dual-diaphragm vacuum advance, and potentially different ignition timing settings. Fully enclosed air cleaner housing. And, depending on what month it was built in, an EVAP setup with charcoal canister.
I never saw a '70 with pump, but have no idea where each one of those was originally delivered. Lots of full-size trucks didn't get EVAP until much later, but I think by mid-'70 all Broncos had the canister.
But that's all hearsay until we find out what the OP's troubles actually are. Some areas don't even do a visual. Just a sniffer test. Here in CA, at least in mostly urban counties, you don't even get hooked up until you pass the visual.

Paul

 

[JB Fab]

Wow! emissions requirement on a '70? that's nuts!
I put diesels in our '66 and our '95. When I registered them they cheerfully changed the tile to "diesel fuel" and didn't bat an eye.

 

[Soylent]

OP is in Nevada I believe. Yes, the '66, '68 and '76 CA trucks had smog pumps.

Paul

Wow. That early? Was that just for trucks? I remember my dad bought a new 67 Camaro RS in Los Angeles and it had zero smog. In about 1970 it had a small 2” box installed with a few wires, I assume to retard the timing.

 

[DirtDonk]

No, the first smog pumps appeared on cars in '66. My CA '66 Chevy had a pump.
Good examples can be seen on restored muscle cars, especially Corvettes where the pump sat up high. A big 427 sitting there with the pump sitting right there. Not sure when they started on that model, or if it was engine-specific, or based on some other criteria.
So by default, the Bronco, as a light duty utility vehicle, was a "car" in some areas because of it's GVWR, whereas it was a "utility vehicle" and sometimes fell off of the smog requirements of passenger cars and got lumped in with the heavier trucks. You can see the difference in criteria with Broncos especially, where some got passenger car plates/tags, while others got commercial plates.
This back and forth over GVWR smog limitations went on and on through the seventies until about '80 or thereabouts. So one year got the pumps, and the next year did not. Even in the same jurisdiction.
For example, your dad's '67, and our CA '71's and '72's did not have smog pumps. my '79 F350 has a smog pump, but does not have catalytic converters because it's got an over-8500 GVWR. Anything below that got cats. Lighter trucks got cats, like Broncos got them by the '74/'75 timeframe.

Along with all that other stuff under the hood, that changed year by year and model by model. Lots of craziness back then!
This is why I still think that the whole late-73 Bronco changes (see Viper's "Mind your P's and Q's" thread) were sometimes delayed. Probably lots of uncertainty, and trying to get a few more "pre-smog" Broncos produced, and maybe even parts that were in short supply.

Paul

 

[DirtDonk]

Even the OBDII changeover that supposedly happened in '96, did not happen all at once. Had a '95 Mustang with a V6 and it already had an OBDII scanner port (whatever it's official name is) under the dash.
Same for R12 to R134 changes. Supposed to happen by a certain year, but many O.E.'s started several years earlier.

Paul

 

[EPB72]

71 across the board would have evap part of the 1970’clean air act.. and evap systems continued to evolve throughout the 70’s into the 80’s’ to meet new standards , thenn in mid late 90’s again evap evolved again as well as obd2 which made new possibilities in fuel management and enhanced emission systems

So in Nevada they require tailpipe test but apparently not or no visual ? CAlifornia ther would be no test on op’s 70 ! 76 is first year for testing .

Op even in 2024 print out show high HC’s .. did the state add CO #’s since 2024 this 2026??

10% CO is very high. Would expect to 1.2- 2.0% range ,, but as mentioned need to look at fuel pressure, is there a way see if FI tech is in fuel control, fuel trim #’s? coolant temp sensor data? MAP sensor data (engine load). Cam profile can greatly skew this , low engine vaccum reading .,

 

[EPB72]

Even the OBDII changeover that supposedly happened in '96, did not happen all at once. Had a '95 Mustang with a V6 and it already had an OBDII scanner port (whatever it's official name is) under the dash.
Same for R12 to R134 changes. Supposed to happen by a certain year, but many O.E.'s started several years earlier.

Paul

Yep 96 for passenger cars 98 for light duty trucks ,, heavy duty is mostly obd2 but not all had a 2000 f350’that was in and was obd2 exempt,,

2016 was a another big year in the program new machine DAD ( data acquisition device) 2000’and newer cars no more tailpipe emission testing just visual and plug in …diesels wer plug in and visual tested upto a certain weight..

In 2022 new regulation and on plug in test would flag aftermarket programming on performance. Chips and programming And fail them

 

[DirtDonk]

Sometimes I scare myself with how lazy I’m getting these days.
The OP put in all the pertinent details of the sniffer test and I totally overlooked it. Got all glossy eyed and then went onto answer mode when I didn’t have all the data.

 

[73azbronco]

Ha, I am more impressed with how spot on the AI answer was to the problem, and as always step one of induction problems with EFI, check fuel pressure. However, not sure 4 psi is make or break with fitek.

Well found the answer at fitek:

No Sensor Feedback: Your FiTech ECU does not actively monitor fuel pressure. It assumes the pump and regulator are delivering the exact pressure programmed in the initial setup.

OP set regulator to 58PSI at the carb, no less no more.

 

[DirtDonk]

Interesting pic just showed up over in CHAT.
NGA Bronco (I think it was?) posted a pic of his buddy's '68 or '69 Vette, which does not appear to have a pump.

Paul

 

[Oldtimer]

68 Bronco with 289 first sold in Moutain View CA. came with smog pump.

 

[bronco italiano]

Straight from the FiTech site:
-Not legal for use on pollution controlled vehicles. This system is designed to be installed into vehicles that do not require emission controls.
-https://fitechefi.com/product/30003...jew4AHhAZmgtipg_-IPWejSywYXpuFx4U00aJHpnlfq_S

 

[EPB72]

Straight from the FiTech site:
-Not legal for use on pollution controlled vehicles. This system is designed to be installed into vehicles that do not require emission controls.
-https://fitechefi.com/product/30003...jew4AHhAZmgtipg_-IPWejSywYXpuFx4U00aJHpnlfq_S

absolutly in california this would fail visual would need a CARB EO#,, same with sniper .. and pro flo 4,,,,,, unless someone at a referree inspection oked it and assigned a referree emissions label, I've seen some questionable approvals from referee labels over the years ,, ,,,, But in california the OP's 70 bronco would'nt need to be inspected so NO one to stop him. but still not legal,

 

[gnpenning]

Op hasn't been back since posting so I'm not sure if this is a waste of time.

What does the remote say about engine temperature?

How responsive is the O2 sensor for both RPM and engine temperature?

Hook up a vacuum gauge and take readings at idle, 1500, 2000 RPM.

Hook up your timing light and aim into the throttle body. ( Yes you have throttle body not a carb.) Watch for droplets off fuel versus mist.

 

[DirtDonk]

Yeah, but hard to say with weekends in the summertime. Maybe they’re on a family vacation, or on a work project. Hard to say, but I hope your comments don’t end up being a waste of time after all.
Be nice to hear back from the OP at some point!

 

[SLOWnEASY]

my 77 has a smog pump