Hello Scotty

I have a 2022 Toyota forerunner SR5. There are less than 35,000 miles. I live in Florida or I would come to you. 

My mechanic doesn’t seem to know what he’s doing so I researched and need to know if I understand what I found. 

I need to know if I am misunderstanding or making any mistakes interpreting what I have seen on videos and found on Google.

I had a code for cylinder 4.

The mechanic used J-W Weld epoxy on 3 of the wiring harness fuel injector connectors.

The mechanic twisted the wires, stuffed them into the connector, and stuffed the J-B Weld on top. 

I told the mechanic that it didn’t look like the wires could possibly connect inside the connector being stuffed in that way - especially cylinder 4. He said he used to be a Toyota mechanic and this is the proper way to fix the issue (a squirrel chewed the fuel injector wire connector).

GASKETS

The mechanic removed and threw away all 6 of the orange rectangle shaped gaskets that are weather-pack seals on the wiring harness fuel injectors. Without them, water, dust, and engine degreasers will corrode the pins and cause the exact throttle issues I am experiencing. The gasket seal connections must remain weather-tight.

The mechanic said the issue was fixed when he plugged in tool that creates error codes. He did not test drive the vehicle. When I drove the techie a few days later, the check engine light came on again and the throttle issue was still there.

BUTT CONNECTORS

The mechanic did not use a butt connector on wires that were  spliced or solder. He used heat shrink, without a butt connector and used a cigarette lighter on the heat shrink that looked too large for the gauge of the wire.

The epoxy did not fix the issue.

On the 2nd visit, the mechanic changed coil pack 4.

He installed a coil pack, but we don’t know which cylinder the new coil pack is on because the mechanic refused to look at the diagram and started out putting the new coil pack on cylinder 2 on the drivers side. Then he moved it around to other cylinders to troubleshoot because the cylinder 4 error continued. He dropped a metal gasket and a bolt and had to take the skid plates off the bottom and then forgot which of the 2 coil packs was the new coil pack. 

The new coil pack did not fix the throttle issue.

ANOTHER NEW COIL PACK

Since the new coil pack was moved around, do I need to ask the mechanic test the resistance or install a known good coil pack to ensure Cylinder 4 is getting the correct spark?

My research:

High performance injectors require flawless electrical signals. Even minor resistance changes will result in throttle hesitation, surging, delayed engine response, or cylinder misfires.

The engine computer uses a switched ground to fire an injector. J-B Weld creates incorrect resistance and electrical shorts that will fry sensitive computer circuits that control injectors. 

Epoxy is brittle. When wires are bonded (“glued”) together using J-B Weld (which does not conduct electricity and remains stiff) engine vibrations will crack the joint, breaking the circuit and disabling the connector entirely.

Fuel rails and injectors are highly flammable and operate in a high vibration environment. Epoxy cannot withstand constant high heat. Using J-B Weld on the fuel injector connectors in the constant very high under-hood heat environment is likely the cause sparks and shorts that lead to engine fires and fuel leaks. 

Using J-B Weld to repair a wiring harness fuel injector connector is a fire hazard, causes electrical shorts, causes erratic engine performance, and severely damages the engine control module (ECM) communication with the electronic computer. 

Rapid 80 volt electrical impulses from the ECU travel through a wiring harness fuel injector connector. Epoxy adhesive (J-B Weld) does not conduct electricity and is appropriate only in low‑risk / low‑voltage application to immobilize. J-B Weld should never be used on a fuel injector connector which is a high-risk / high voltage environment.

J-B Weld is not appropriate for making electrical connections in a vehicle. 

Never use J-B Weld as an electrical conductor. JW Bond cannot conduct electricity. 

JB Weld should not be used in a vehicle engine.

CONNECTORS 

To prevent damage in a vehicle, the correct connector and correct crimp connectors must be used. Epoxy cannot replace proper insulation methods.

Use a heat gun to uniformly and correctly seal the heat shrink. Heat shrink that is not uniformly heated can cause poor electrical connection and moisture intrusion. Without uniform heat, the heat shrink may not be fully and completely sealed.

The factory fuel injector wires on a 2022 Toyota 4Runner SR5 (4.0L V6 1GR-FE engine) use a metric wire size equivalent to 20 AWG (American Wire Gauge). 

An aftermarket OEM-spec repair pigtail replacement harness will almost always come with a 20 AWG or slightly thicker 18 AWG leads.

Upsizing is Safe

An 18 AWG pigtail wire can be spliced onto the 4Runner’s factory 20 AWG wires. The slightly thicker gauge creates less electrical resistance will handle the engine's heat cycles. 

Never downsize to 22 AWG or thinner. 

Butt Splice

Use standard 22–18 AWG (Red) heat-shrink butt connectors when crimping.

Gold Standard

For fuel injector circuits handling fast, constant pulsing from the ECM, solder the wires and seal them with adhesive-lined heat shrink tubing to prevent corrosion from water or engine fluids.

UPCOMING 3rd MECHANIC TRIP

I have purchased 6 fuel injectors. He installed the odd numbered 3 on he passenger side.

I have 6 new fuel injector connector wiring harness pigtails to install. 7 were purchase from PartsGeek. The mechanic removed the orange rubber gaskets from the new connector and the factory original connectors. Are the connectors I ordered from PartsGeek ok or do I need 6 new OEM pigtails? I could not find OEM connector pigtails on the Toyota parts sites that linked to local dealerships. 

I have 18-22 AWG non-insulated butt connectors. The mechanic needs proper ratcheting crimper terminals made for automotive repairs and non-insulated 18-22 AWG metal butt connectors and the correct adhesive-lined heat shrink for 18-22 AWG non-insulated butt connectors.

A crimper for insulated butt connectors cannot be used with non-insulated butt connectors.

I purchased 6 new OEM spark plugs from AutoZone. 

I will ask that the other 3 new fuel injectors previously purchased be installed. The 6 fuel injectors were purchased from PartsGeek.

W-D 40

On the first visit, I asked the mechanic what to clean the engine bay with because it was dusty. He said W-D 40. The mechanic said to spray the black rubber and plastic parts in the engine bay with W-D 40 to clean the area. This never should have been done.

CLEANING

I completed 2 very careful preliminary wash with a toothbrush and Dawn after disconnecting the battery and covering the battery and connectors / wires with plastic bags. I rinsed very carefully with low water pressure specifically on my the plastic parts I put the W-D 40 on in front of the mechanic on the 2nd visit.

MASS AIR FLOW SENSOR

I have W-D 40 Degreaser in hand, but not used yet. New information I see today says to wipe down the inside and outside of the air box and snorkel with a damp cloth. Do not use WD-40 Degreaser or harsh degreasers on these plastics. Harsh degreasers can degrade the material and leave residues that get sucked into the engine.

The Mass Air Flow sensor must be cleaned. The sensor is located on the side of the air intake tube). 

Spray the MAF sensor carefully and let it air dry completely before reinstalling it. Do not touch the delicate wires inside. Do not spray CRC cleaner on the corrugated plastic or general wiring.

HVAC FRESH AIR / RECIRCULATION DUCT (black tube)

There is shiny black tape around the plastic corrugated tube that is approximately 1-inch or 1.25-inch. It is next to the metal frame and right in front of the glove box on the passenger side. 

The tape is not fully covering an area. My finger tips feel an opening between tape and plastic tubing. 

HVAC fresh air / recirculation duct or the A/C evaporator drain line.

Airflow Issue

If it is disconnected, your A/C will pull hot, humid air from the engine bay rather than recirculating the cold air inside the cabin. This may explain why the A/C suddenly stopped feeling as cold after the alignment service.

Inspect and properly re-attach the HVAC ducting behind the glove box.

What kind of tape should be used on the air recirculation duct or is the duct disconnected?

The mechanic told me to use Sea Foam in the fuel tank. I did this 3 times. Will this damage the vehicle?