FI-Tech Running Way Way Too Rich / 302 Ford Mustang
Team,
Greetings, I am new to the forum and looking for some much needed assistance with diagnosing an issue I am having with my vehicle, I suspect the main source of the issue is the FI-TECH EFI unit. Possibly a return line blockage? Vehicle specifics are listed below:
1970 Ford Mustang / 302 V8 Fastback, Non-Boss / Approx. 250 Miles on a Recent Full Engine Re-build
FI-Tech 30003 Go Street EFI 400HP System / In-Line Frame Mount Fuel Delivery / No Fuel Command Center
Pertronix /PNX-D7134600 Ignitor III Distributor with Vacuum Advance
Pertronix PNX-44011 Flame-Thrower III Coil
Automatic Transmission
No Air Conditioning
O2 Sensor Welded to Pipe
The problem originated a few months back about 45 minutes into a weekend cruise around the city. As I entered a highway and started a short climb gradient, around 55 MPH the car started to act as if it was losing power with an accompanying popping sound. I gradually applied more throttle to try and overcome the loss of power but the issue remained. Erroring on the side of caution, I had the car towed back to the house. During my initial phase of troubleshooting I changed the oil, cut the oil filter open. No obvious signs of engine failure, metal shavings, etc. Following an oil and filter change I checked oil pressure during cold, warm and hot idle stages, all tested within parameters.
During my most recent phase of troubleshooting I checked the obvious distributor cap, wires, plugs, vacuum hoses and connections, all checked good. I replaced the Champion Copper Plugs with NGK Platinum plugs. The outgoing Champion Copper Plugs had some black carbon’ing but nothing “significant” on all plugs. The engine fired up with no issue but the popping sound remained, which at this time I was able to narrow down to sounding like it was coming through the intake/throttlebody/shaker air cleaner area. After the engine warmed up I took the car for a drive around the block and the popping/power issue remained, the car did not respond to the increasing throttle input as it should, even with the gas pedal to the floor, the car stumbled/bogged out and did not have a corresponding increase in power response as it should. Over the next few days, while working over the phone with FI-Tech support and browsing through this forum, I looked over ECU settings with the controller, updated my software, made recommended adjustments to AFR, checked wiring, fuel pressure, etc. Fuel pressure to the EFI tested at 44 PSI. O2 Sensor voltage is within parameters and is welded into the pipe. I pulled off the O2 sensor and noticed that it had black carbon buildup on the tip of the sensor but no signs of blockage, leaks, etc. I did notice a very small trace of fuel in the vacuum line running from the fuel pressure regulator to the back of the EFI. I replaced the fuel pressure regulator and accompanying vacuum lines from the regulator to the EFI and the vacuum line running from the distributor vacuum advance to the back of the EFI. I also went ahead and decided to replace the O2 sensor. Initially the engine seemed to warm up better but the popping sound returned with any accompanying increase in throttle. I decided to take the car for another test drive but the issue remained and even seemed to get worse, even died at a few stop signs. When I returned I noticed that the inside air filter lid and air filter were coated with fuel. I pulled the spark plugs from the #1 and #8 cylinders to give them a check and they both contained a thick coating of black carbon far worse than the plugs that were removed earlier in the process. Tail pipes also had an accompanying black residue consistent with an engine running way too rich. I let the car sit for about an hour or so before trying to fire it back up to get a 30 second or so snap shot of the engine run but I was unable to crank it over. After repeated attempts to crank it over a nice concert like flame popped out of the top of the EFI so I decided to stop troubleshooting and seek advice on this forum before moving forward. This is my first experience with the FI-Tech aftermarket EFI systems so my knowledge level of such systems, tweaks, etc. is basic at best. Up until a few months ago when this problem started the car ran great with no issues and there were no onset signs or problems that the car was beginning to run rich. Unfortunately I was not able to get a solid data log during troubleshooting however I have attached settings/reads off of the handheld that I was able to write down prior to the entering this round of troubleshooting. Thanks in advance for all of your help.
Uploaded files:- You need to login to have access to uploads.
Could be a number of things, I developed a small vacuum leak on a base adaptor and was running super rich even at idle, the O2 sensor picked up the unburnt oxygen and added extra fuel to compensate, squirting starter fluid around made no difference as it was already so rich, took a smoke test to find it.
I agree with Ajax, everything points to leak around O2, sucking in extra air, throwing off O2 reading to think it's running too lean, throws more fuel into the cylinders to compensate. Try putting vacuum blower on your exhaust and use soapy water spray bottle to see if you see bubbles around the O2 or leading up to or behind it.
Could well be leak in exhaust [been there] at o2 sensor or directly after it, I picked it up by watching the handheld A/F ratio while cruising, every time I backed off it spiked lean [about 20 to 1] then ran super rich.
Team, I just got back to checking out the car...I unbolted the EFI from the intake, dual plane type intake manifold...it was originally installed with the large black square gasket that came with the kit with no spacer or adapter plate...no obvious signs of anything weird...shouldn’t I be using a 4 hole gasket?