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1999 3.0 Flex Engine // Issues


Joined
Sep 30, 2025
Messages
4
Points
1
City
Cumberland Furnace
State - Country
TN - USA
Vehicle Year
1999
Vehicle
Ford Ranger
Drive
4WD
Engine
3.0 V6
Transmission
Automatic
Just picked up a 99 w 145K, body needs minor work. I see it says misfire in cylinder 6. Compression test showed 152PSI. Lacks power on acceleration & I noticed that when driving fast and/or under load Air vents go to defrost. taking load off goes back to vent. Sounds like a vaccum leak, but checked all the usual suspects. Any thoughts or suggestions? New plugs new wires. Also suspect Injector possibly, but I really didn’t want to have to yank off the intake.
 

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Has it been sitting around a long time? It seems the fuel injectors can get clogged up just like the old carbs can.

I would swap common parts with the other cylinders and see if the problem moves also. Like sparkplugs, coils, etc.
 
Has it been sitting around a long time? It seems the fuel injectors can get clogged up just like the old carbs can.

I would swap common parts with the other cylinders and see if the problem moves also. Like sparkplugs, coils, etc.
Yes did all the regular troubleshooting. Swapped wires, tried new wire. New Spark plug etc…. I am thinking maybe because to the vaccum leak it could be ? I am trying to avoid pulling the intake off unless it’s necessary. I do think it’s a high probability but the way they designed the engine they are impossible to get at. silliness.
 
To answer your earlier question, the fella I bought it from said he drove it quite a bit locally. I did a smoke test by disconnecting the a vacuum line to the Manifold that goes into the bottom right under the Throttle Body. I gloved off the throttle body,I observed smoke coming from the EGR, so that membrane may be bad. I also observed smoke coming from the top of the Idle Control Valve. It looks new, so I was not sure if it has like a one way valve. Now, Also saw a bit of smoke from the Oil Dipstick so I gloved that off to prevent confusion. I also found the vacuum reservoir with deteriorated connectors that broke upon inspection. There was also open lines where they disconnected the hubs in lieu of manual hubs & Another T connector that was completely rotted & brittle smoke poured out of that as well when I pushed it through the feeding tube. Anyone have a diagram on the vacuum systems for this ? I know there is one on the rad support, but I really need something better. No smoke coming from where I figured it would have in the back of the engine where all the vacuum lines come together. Probably important to note that the catalytic converters been cut out & they did a shit job of patching it.
 
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WHY do people "delete" the catalytic converters? Do they think it's going to make their Ranger a Pro-Stock contender in the quarter-mile? :ROFLMAO::rolleyes:🤦‍♂️
 
Unfortunately it's common here because most of the state has no inspections and people had rather have a hacked up exhaust and the money from the cat at the scrapyard than just leave things alone. The number of vehicles I've seen here without even O2 sensors on the road is insane. I know it's realistically probably less than 1% but still.
 
texas is going to be dealign with those same issues more then we used to have to since we no longer have an inspection anymore.

i always try to tell people its a waste to cut cats off too, anymore. its not the old days, cats now days are so well made they don't restrict the exhaust. even on my 89 325i, i kept the cat no matter what exhaust i used and that car won its class in scca 2 or 3 years in a row with minor engine mods (afm, injectors, cat back) and full suspension mods
 
I keep the cats installed also when I can, but they are another component added that can fail.

Have a problem with your engine and it's running rich? The convertor can melt and clog.

Have a engine with a lot of miles that burns a little oil? That can clog the cat also.
To answer your earlier question, the fella I bought it from said he drove it quite a bit locally. I did a smoke test by disconnecting the a vacuum line to the Manifold that goes into the bottom right under the Throttle Body. I gloved off the throttle body,I observed smoke coming from the EGR, so that membrane may be bad. I also observed smoke coming from the top of the Idle Control Valve. It looks new, so I was not sure if it has like a one way valve. Now, Also saw a bit of smoke from the Oil Dipstick so I gloved that off to prevent confusion. I also found the vacuum reservoir with deteriorated connectors that broke upon inspection. There was also open lines where they disconnected the hubs in lieu of manual hubs & Another T connector that was completely rotted & brittle smoke poured out of that as well when I pushed it through the feeding tube. Anyone have a diagram on the vacuum systems for this ? I know there is one on the rad support, but I really need something better. No smoke coming from where I figured it would have in the back of the engine where all the vacuum lines come together. Probably important to note that the catalytic converters been cut out & they did a shit job of patching it.
Sounds like you found your problem of the HVAC going to defrost during acceleration. I would fix all the obvious things first, and then try again. Is the vacuum tree where all these lines go near cylinder #6? All that air coming into the intake in that area may be causing 6 to run a little lean.
 
Yes, I'm repairing the vacuum lines to the canister & the Ts once they arrive. I'm also just curious since the smoke did come out of the EGR, does that mean the diaphragm is bad ? I do see what you mean, there is a large amount of vacuum lines that go into the intake right near the #6 cylinder.
 
They had so many types of EGR's. The older types that did not have solenoids, they did purposely leak vacuum. You can tell these type, they have a felt filter on the underside of the valve you can see in the "windows" cut out of the valve actuator. But these were the earliest type, usually no computer.

Then when the solenoids came out, they usually had a cap with a filter at the solenoid. This filter lets air in when it wants to turn the EGR off. If they just turned the vacuum off to the valve, the valve would "hang" open, they need to relieve the vacuum in the line to the valve so the valve will shut. To relieve the vacuum you have to let air in. This was the first gen fuel injection that used these valves with the cap and filter.

I am not sure how this system evolved through the years. But many vacuum systems have "on purpose" leaks.
 

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