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Where exactly is the Wide Open Throttle sensor?!?!??

3K views 17 replies 7 participants last post by  vmaxaholic 
#1 ·
I have a 93 4.0 that's kicking my ass not wanting to start. Already replaced the starter and starter relay. Now my problem is back...it stalls out, I turn the key and it doesn't turn over. When I jump the relay, it cranks but won't fire up, unless I shoot some carb and choke cleaner in the intake hose. Then it will fire, but won't stay running. I remove the cap on the fuel rail to check for pressure (I hear the pump turning on when I turn the key on) and only a small amount of fuel comes out. I've been reading about the Throttle Position sensor and Wide Open Throttle sensor. Just not sure exactly where they are and what they look like.
 
#3 ·
If you aren't getting any fuel on the rail, either the fuel filter is plugged or iced up, or the fuel pump itself has died. Just cause you can hear it run doesn't mean that its actually doing anything.

I would worry about getting fuel to the motor first, before spending money on a TPS or IAC motor.
 
#4 ·
Ok, what is the IAC motor?? And the fuel filter is brand new as of two weeks ago. This is the second time this has happened. The first time, I diagnosed and replaced the starter and starter relay. No problem, fired right up. Now the relay has shit out again!! I say this because I can jump the 87 pin and 30 pin and it cranks fine, just won't start. I refuse to believe that the fuel pump will sporadically crap out, not when I hear it every time I turn the let on. So effing frustrated!!!!
 
#5 ·
In that pic its posted as an AIS motor, IAC is Idle Air Control.

If you don't have any fuel in the rail, then there has to be a reason for it. Just because you put a new filter in it doesn't mean it didn't get full of water and freeze in 2 weeks. And a fuel pump can have more problems than just not pumping.

There is a micro screen on the end of the pickup tube on the fuel pump, sometimes they get clogged with the gunk in the tank. Inside the tank is a plastic cylinder that the pump sits it to prevent surging when the gas sloshes, I have seen them come off and prevent fuel from getting to the pump.

I would say that you have a fuel related problem, more than a sensor problem.
 
#6 ·
I agree, but I'm trying to dig deeper than maybe the pump has failed on some level. I know that that's possible, but I'm searching for WHY did the pump fail or why is it not getting fuel. Like I said, there is some fuel there, but when I changed the filter and depressed that "valve" on the fuel rail, there seemed to be a lot more pressure at the time. Now, the fuel kind of dribbles out, lacking a lot of force. Could be a line came off the pump, clogged screen or plastic cylinder like you suggest, or perhaps something electronic that is telling the pump not to send fuel. Based on several posts from several threads, I was leaning toward a sensor or something electronic. But truthfully, I am at a total loss. I think I'm gonna let it sit until warmer weather comes, which here in CT will be a couple months at least. Very tired and frustrated with fixing or replacing something new every couple weeks...
 
#7 ·
Tired of fixing something new every couple of weeks? Isn't that the reason that you bought a YJ?

Your Jeep is 21 years old. Things need replaced. They don't live forever without a lot of time and money to put in them. These things are not like the Jeeps of yesteryear. The old willy's could sit in a field for a year (or longer), and the only thing you had to do was dump some gas down the carb and put a battery in it.

You can look into the fuel pump relay and the auto shut down relay, they sit beside each other in the box out by the battery. They are part of the fuel system or priming for start up. If the pump is working, its possible that the fuel pressure regulator is stuck open and not allowing pressure to build for the injectors. (its on the fuel rail).
 
#9 ·
There is no WOT sensor, just the TPS. It handles all the throttle position monitoring duties. A bad IAC or TPS shouldn't keep it from starting or at least trying to start. It might run like total crap & die, but it should at least start & stumble.

Have you checked the fuel psi @ the rail? Fuel pumps do crazy stuff when they give it up. I could tell you all kinds of symptoms mine have done over the years. Just because it kicks on doesn't mean it's pressurizing.
 
#10 ·
I've only been able to kind of "eyeball" the PSI at the fuel rail. Actually, what should it be?? I know that when I replaced the fuel filter a couple weeks ago, I depressurized the system by depressing the valve on the rail, and at the time there was a lot more fuel that came out than there is now. Safe to say it's not getting fuel, but the question is why?? Fuel pump?...maybe. I think I'm gonna try a new relay first since it's cheap. If that doesn't do it, then I'll probably drop the tank, but not until the temps are in the 60's...
 
#13 ·
I need some input...My Jeep is a 2014 Wrangler Unlimited with Manual Trans.

I have been driving it like the brake-in instructions say in the owners manual. But I just hit 1,200 miles yesterday and for the first time I did some brief wide open throttle bursts like the manual says.

I never understood if the manual was recommending doing the wide open throttle around the 500 mile mark or what so I waited a bit longer. It also doesn't say what RPM they recommend getting up to before wide open throttle.

So yesterday I did it six times. three times in 3rd gear at about 1,700 RMP and three times in 5th gear at about 1,700 RPM. My vehicle seemed a bit slow to accelerate and I let up off of WOT at about 2,500 RMP each time.

Each time I did it I got a smell that I can't identify. But it went away immediately after I eased up off wide open throttle. It was not a burning smell I can say that much. I did have my top down so I was wondering if maybe it was extra exhaust coming up from the tail pipe during WOT. My only other though was maybe the clutch was giving off a smell at WOT. So I have two questions

1. Has anyone experienced this or know what the smell is.
2. Should I have done the wide open throttle thing earlier in the brake in period? Is there such a thing as trying to break it in too late and not receiving whatever benefits the wide open throttleing was suppose to give?
 
#14 ·
Take the RPMs up closer to redline and then coast back down. What you are doing is burnishing the rings to seal perfectly. The WOT runs push them out hard against the cylinder crosshatching and when you let off and coast, the high vacuum draws oil up to cool and relube and wash away polishing debris. When you do this, higher exhaust temps will heat up underbody coatings for the first times and outgas and that's what you are smelling. Not to worry.

1200 miles is still low so don't worry about that being too late. Do some more WOT to higher RPM and your good.
 
#15 ·
DREDnot- Thanks for the reply. Good to understand the smell. For the first time I notice my catalytic converter is now discolored from that pretty new look to bluish/copperish color. I think that is the cat converter any way. Mounted to the side of the engine with a sensor sticking out of the top of it? When you say underbody coatings is the cat converter part of smell and what you are referring to? Is that discoloration normal or did I overheat/overstress something by doing WOT at low RPM.
 
#16 ·
Yeah, that's the cat. It's supposed to turn that gold-ish bluish burnt metal color. All sorts of stuff under there getting hot for the first few times. Plastic and paper part number tags, heat shields, insulation, undercoating, sound deadener, corrosion inhibitor, ...not to worry. You're good
 
#18 ·
So, I figured it out!!! I had a ground issue at the relay box under the hood. I cleaned all ground terminals that I could find along with their corresponding connections to either the body or the frame. Their wasn't a proper ground from the fuel pump and starter relays...problem solved.
 
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