Potential huge vacuum leak/bad sensor diagnosis

[BoomTexan]

Hey yall, first post on here. I've got an old 1986 2.9L V6 Ranger w/4 speed auto transmission. It was an old Norfolk Southern railyard car and has a ton of issues, so I'll probably be making quite a few more posts. Pretty much replacing all the sensors across the truck, because they're almost all bad.
So, especially recently, I've had a ton of issues with the vacuum system, including some pretty concerning problems. Gonna list some annoyances first that I need help with, if anyone has any suggestions to fix, please let me know!

1. Since I've owned it, it's run extremely rich. I'm getting like 5MPG city and 22MPG highway, so my best guess is that the fuel pressure regulator is just dumping fuel at all times, regardless of AFR detection. Any tips on changing these out? I've heard you need a special tool to remove the metal quickconnect assembly w/ spring, do y'all have like a part number/amazon link to get one?
2. The heater is ALWAYS on. Is there any way to disconnect it, or will the truck just blow hot until I fix the refrigerant lines? I turn the AC/blower off, and it's still blowing hot.
3. After getting it up to about 25MPH in drive for the first time after starting it, it'll refuse to go any faster, and I have to let off the gas entirely. It'll idle really low for like 5 seconds, dumping fuel way more than normal, then start driving normal again. During this, it smells like raw fuel, so I'm thinking the AFR gets so high it starts choking out until the ECM corrects. Is this a vacuum or a sensor problem?

4. I'm not sure if this is a common occurrence, because I can't really find another instance of this. But, definitely the scariest one. When I start the car, it's a very high idle, putting it in drive makes it idle normal, putting in reverse keeps the idle high. When I put it in reverse, the brake booster stops completely, and the high idle means I'm having to slam my foot to the floor to stop it from creeping. Letting up at all makes it creep backwards. During this, it has a huge hissing sound. Thinking this is vacuum, but unsure if anyone else has experienced this too. During the high idle, brake booster goes, so if the truck starts idling high at a stoplight in drive, the same symptom of high speed creep and no booster happens. It happens sometimes in drive, but every time in reverse.

 

[lil_Blue_Ford]

Welcome to TRS!

Fair warning if you haven’t seen it already, the forum will be updating this week so don’t panic, lol.

1. I don’t remember the FPR requiring any special tools to change. The main things that affect fuel is the FPR, oxygen sensor (the catalyst usually only lasts about 10 years), the Intake Air Temperature sensor (IAT), Manifold Absolute Pressure sensor (MAP), and a few other things. Personally, if you don’t know when any of that was ever replaced, I like to replace it, but you can troubleshoot that stuff.

2. When the blower is turned off for the climate control it shouldn’t blow at all. Sounds like a potential electrical problem. Later trucks had a valve to shut off coolant to the heater core when running AC, I’ve been kicking around ideas to make something like that work on the older trucks.

3. That is an interesting problem. I’d maybe concentrate on the other identified problems first and see if this changes.

4. High idle can be a number of things. Idle Air Control valve (IAC) sticking is common. Also a bad throttle position sensor can do it. The computer can also cause weird issues if the capacitors have popped (unfortunately a common problem among older RBVs).

A hissing sound from the brake booster is usually a failed booster and/or check valve. That would also cause a big vacuum leak and associated issues.

 

[BoomTexan]

Welcome to TRS!

Fair warning if you haven’t seen it already, the forum will be updating this week so don’t panic, lol.

1. I don’t remember the FPR requiring any special tools to change. The main things that affect fuel is the FPR, oxygen sensor (the catalyst usually only lasts about 10 years), the Intake Air Temperature sensor (IAT), Manifold Absolute Pressure sensor (MAP), and a few other things. Personally, if you don’t know when any of that was ever replaced, I like to replace it, but you can troubleshoot that stuff.

2. When the blower is turned off for the climate control it shouldn’t blow at all. Sounds like a potential electrical problem. Later trucks had a valve to shut off coolant to the heater core when running AC, I’ve been kicking around ideas to make something like that work on the older trucks.

3. That is an interesting problem. I’d maybe concentrate on the other identified problems first and see if this changes.

4. High idle can be a number of things. Idle Air Control valve (IAC) sticking is common. Also a bad throttle position sensor can do it. The computer can also cause weird issues if the capacitors have popped (unfortunately a common problem among older RBVs).

A hissing sound from the brake booster is usually a failed booster and/or check valve. That would also cause a big vacuum leak and associated issues.

Thanks for the help! I already got the MAP and air charge sensor taken care of, will be spraying some MAF cleaner in the intake airflow sensor pretty soon. Only issue for me is that my O2 sensor is completely stuck, I can't get it off at all, and the headers are an awful shape to deal with that. Any tips you've seen there? Might take my blowtorch to it later on, but hoping I can avoid that.

It's more of a heater core always on kinda deal. When driving fast, the air blowing inside will get forced through to the cab. Such a shame that valve wasn't implemented earlier. Hopefully will be able to deal with the refrigerant lines later on.

I'll go check on that computer, have way more experience with repairing electronics than with fixing cars, if that's the issue, I could probably get that fixed in 15 minutes. Idle air control valve and TPS sensor have been purchased from RockAuto, got lost in shipping, so I'm waiting on a refund before getting new ones, but hoping those will fix it.

Really hoping it's the check valve, I'll give that a look later today. If the brake booster is failing, I'm just gonna have to deal with it until I can get some savings up.

 

[rusty ol ranger]

Thanks for the help! I already got the MAP and air charge sensor taken care of, will be spraying some MAF cleaner in the intake airflow sensor pretty soon. Only issue for me is that my O2 sensor is completely stuck, I can't get it off at all, and the headers are an awful shape to deal with that. Any tips you've seen there? Might take my blowtorch to it later on, but hoping I can avoid that.

It's more of a heater core always on kinda deal. When driving fast, the air blowing inside will get forced through to the cab. Such a shame that valve wasn't implemented earlier. Hopefully will be able to deal with the refrigerant lines later on.

I'll go check on that computer, have way more experience with repairing electronics than with fixing cars, if that's the issue, I could probably get that fixed in 15 minutes. Idle air control valve and TPS sensor have been purchased from RockAuto, got lost in shipping, so I'm waiting on a refund before getting new ones, but hoping those will fix it.

Really hoping it's the check valve, I'll give that a look later today. If the brake booster is failing, I'm just gonna have to deal with it until I can get some savings up.

My O2 was like that too. I used my MAPP torch got it hotter then piss and put a big box end wrench on it, then hooked another wrench to that...im a big dude and i had to crank the shit out of it...but it did come out. My manifolds wernt in good shape either but i dont think you gotta worry about that much.

 

[lil_Blue_Ford]

Yup, oxygen sensors you usually have to heat the bung up to cherry and wrench like crazy. I got some copper antisieze I’m gonna try next time around on the threads. The aluminum stuff isn’t worth a hoot.

 

[SenorNoob]

Copper is much better, but I used it on mine when I did the 1st engine swap and still crushed the y-pipe trying to take a 10 year old O2 sensor out.

 

[lil_Blue_Ford]

Copper is much better, but I used it on mine when I did the 1st engine swap and still crushed the y-pipe trying to take a 10 year old O2 sensor out.

That is disappointing to hear… maybe I need to look for something else…

 

[SenorNoob]

I'm thinking go every couple years and just replace the antisieze...

 

[lil_Blue_Ford]

I'm thinking go every couple years and just replace the antisieze...

So, apparently the real high-heat antisieze stuff is made with graphite and nickel… kind of pricey but maybe I’ll get some just for O2 sensors…

 

[SenorNoob]

IDK about graphite, but we tried the nickel at work. It was functionally the same as the aluminum for us. Our machines maintain 375*-650* 5 days a week. Not extreme by any means, but enough to test anti-seize quite well.

 

[lil_Blue_Ford]

IDK about graphite, but we tried the nickel at work. It was functionally the same as the aluminum for us. Our machines maintain 375*-650* 5 days a week. Not extreme by any means, but enough to test anti-seize quite well.

 

[SenorNoob]

I wonder if the problem on O2 sensors, at least in my case, isn't carbon build up on threads inside the exhaust. I pulled a couple from the junkyard when I first put the 4.0 in pretty easily. Showed no sign of having been changed before but were clean. The one that stuck had a thick coating of carbon. I could see once the catalytic converter was off.