Thread: 93 4.0 engine bogs???

How did you attach the MAF when you did your new setup? Could it be on backwards?

Haven't had a chance to get out yet probably be a couple weeks cause of work unfortunately but ill let you guys know thanks for all your help and I know for sure its not in backwards I double checked just to make sure! Lol

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Finally got a chance to get out yesterday iit still bogs bad I made another intake the way I had it before changed that still bogged changed the maf sensor same thing cleaned the crank sensor same thing changed the coil no luck checked plugs grounds still no luck pulled the plugs and found them extremely white and looks like either the porcelain or the electrode is burning away right where they meet which means its running really lean any ideas to why? Intake manifold vacuum leak bad o2 sensors?

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it's not bad O2 sensors, cars are capable of running in open loop.

check fuel pressure and check for vacuum leaks.


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That's what I thought too gotta check vacuum leaks and check the fp when I get off work I heard these engines have problems with the lower intake manifold coming loose anyone else heard of this?

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Also forgot that it bogs all the time now doesn't have to warm up or even after its at running temp hit the gas hard and it starts bogging the more throttle you give it the worse it gets if you kinda feather the gas it will slowly build a lil speed but soon as it reaches aprox 35mph that's all its got

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Nobody has any other ideas? I checked it out last night no codes with the scan tool o2 sensors are reading correctly it will bog in the driveway now when you rev it up tried revving it to where it bogs and spraying a lil Carb cleaner in the intake and it made no difference so I don't think its a fuel issue now checked the fuel press it was good with the regulator hooked up or not no fuel coming out of regulator I'm thinking its ignition now I picked up a module and a crank sensor that I'm gonna try when I get off work?

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What have you done to check for vacuum leaks?

Disconnected the Pcv valve and plugged the hose sprayed Carb cleaner all over the intake where it meets the heads and where the lower meets the upper intake around the throttle body checked the only two vacuum lines it has for cracks and sprayed them too tried a propane torch too in the same areas no difference at all

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Could the fuel pressure regulator be stuck open?
Are you running a second fuel pressure reg? Because the stock one is on top of the fuel rail passenger side.

I'm thinking maybe the fuel pressure is insufficient while the engine is under load.


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Originally Posted by letsgetthisdone

it's not bad O2 sensors, cars are capable of running in open loop.

check fuel pressure and check for vacuum leaks.

This. I ran mine with no o2 sensors, iac, tps, cam position sensor, and other random shit missing lol.

Originally Posted by half-ass astronaut

Could the fuel pressure regulator be stuck open?
Are you running a second fuel pressure reg? Because the stock one is on top of the fuel rail passenger side.

I'm thinking maybe the fuel pressure is insufficient while the engine is under load.


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When mine was bogging, I tried changing the fuel pressure regulator with a known good one. I know it ran like complete shit when I put it back together the first time with out an upper intake manifold gasket lol.

The intake manifold gaskets are know for going on these engines. Mine just crapped out on my 91 explorer. A complete top end gasket set (to include head gaskets and exhaust manifold gaskets) was $75 for a felpro on rock auto. Either $75 or $90. My expo started bogging and leaking coolant really bad over the last couple weeks. Even in neutral when you lightly hit the gas, it would die or sputter and rev up. After it warmed up it was golden.

Not sure if I posted this yet (probably already did), but did your motor run like this? Mine bogged then would clear out. You can hear it at at 0:10 to 0:15 , then clears out.

Jumping across from devils slide in oco - YouTube

Good point considering he said it does it now, even when warm.


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I only have the stock fuel pressure regulator on it I checked when it starts bogging the fuel pressure it has 35 psi when its bogging. I have heard about the intakes leaking I watched your video a few times and can't really hear the bogging that your talking about crappy phone speaker

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Well tried the icm and the crank sensor didn't think it would help which it didn't so pulled the intake off looks to me like number 5 is defintely leaking and possibly number 2 are leaking I sure hope this is my problem!

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Changed the intake gaskets and no difference I'm outta ideas anyone have any? I'm ready to fix it with a can of gas and a match

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You didn't get any water in the fuel by any chance did you?


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This is a long shot, but try posting a pic of your motor.

BUMP! i was wondering if you ever fixed this problem? im having the exact same issue. i also have a 93 4.0 ranger 5 speed. i was coming down the freeway and it started bogging like i was out of gas but i wasnt. got home and let it sit. i tried starting it today,when its cold it took me 15 tries to finally get it to start,now thats its warmed up it will start every time but as soon as you give it gas it will fall on its face and want to die. i tried driving it and couldnt even get out of the driveway... every time i give it gas it just wants to die. it idles normal and sounds good.. sounds exactly like the same problem to me.

i cleaned my air filter and my MAF sensor when i got home and still does it. next ideas are fuel filter may need to be cleaned,plugs?,or intake gasket?

Good chance your MAF is bad.
Unplug it and see how it runs.

There is a way to check to see if the MAF is out of range , you need a volt meter with ohms,



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alright ill give it a shot

well,that didnt do it. whats the possibility that the fan clutch has gone bad? it spins freely when the truck is off... would that cause some kind of timing issue or...?

The fan clutch should move freely when the engine is cold
the fan clutch has thermal sensitive gel inside it, when the engine is cold, it doesnt spin as fast as the motor so the engine can warm up. Once the engine is hot, the gel inside hardens and the fan spins at the same speed as the engine.

it wont cause your engine to bog out, but your engines fan will sound like a turbine if its gone bad. also makes your engine work harder

yea you will know when it's the fan clutch. Mine went out on my 2.3L. Engine was basically an airplane at that point and wouldnt rev out very quick. Tons of noise from fan constantly spinning

Wonder what your problems are?

2Ghetto threw a code and had a few hiccups last trip. I'm wondering if mine is dirty air filter orMAF or what.

I also know my 2.3L had some hesitation issues before and had to replace the ECT sensor. (engine coolant temp sensor)

Whenever you guys figure it out please post back so if I run into the same problem.. you did allt he hard work for me. LOL

okay ust making sure and checking things off my checklist. haha and im tryin to figure it out. it started running a little better now that ive done a few things to it but its not gone. still doesnt run right