Ok guys, I really need your help big time. I know this is really long, but I will GREATLY appreciate any help you fellas are able to give me. I have a few problems, but the main one being a massive loss of mileage that I will explain below:

I’m at a severe loss of mileage here. I would go so far as to say that I’m getting no more than 10mpg, if that. This is ridiculous. It used to get 18, but then out of nowhere, it started getting worse and worse…it’s not like I even did anything to the engine, it just started getting bad. Now, when I speed up a little bit and then come down to an idle at a light or something, I smell gasoline…it’s pretty potent too. Now, I did all the obvious testing already…I checked underneath the car while it was off, running, revving, idling, and nothing was leaking. I checked the fuel lines, and all fuel lines are intact. The parts of the fuel tank that I can see are fine. Also, I am not getting a check engine light at all, and I just replaced the O2 sensor about 4 months ago. I do not think it is the EGR because of the lack of the check engine light, and the idle is still smooth. I CANNOT FIND OUT WHERE THIS GAS IS COMING FROM! But it is killing my mileage. I did a throttle body bypass mod a few months ago, but, however I never got around to plugging up the coolant inlets that were bypassed. Could this be contributing to it?

I have attached a few pictures, in hopes of maybe narrowing down the problem

-One is of some oil that has made its way up to underneath the plenum…I don’t know how or why it got there. Any ideas?




-Another one is of my fuel pressure gauge which jumps between 50-60psi continuously.




-Another one is of the passenger side valve cover and a valve that has no hose going to it…where should this hose be going to?




-I took off the AIR Diverter Valve when I installed my headers and never put it back…I figured it was useless with the lack of the AIR lines. There is now air coming out of what I detached this from (from the smog pump maybe?) Is this posing a problem?




-And last is the MAP sensor that is just loosely lying on the passenger valve cover…where should this be fastened to?




With that knowledge, does ANYONE have any idea what could be wrong? If not, could you give me what you predict could cause a loss in mileage/gas leak in order of likely-to-occur first? Please help me out here, I'm a freshman at Rutgers University in NJ, and the money that I have to spend on gas is really putting me at a loss here.


Thank you all so much
_Clark

 

Well, don't know if I can tell you what's going on, but hopefully I can help you narrow it down a bit.

First off, I'd think it's extremely unlikely that the 'coolant bypass mod' is contributing to your problem one way or the other - lots of people have done it (myself included) with no ill effects.

Second, you did manage to raise my eyebrows a bit when you said that your MAP sensor is disconnected - that could be a big factor in the problems you're having. Unfortunately, my car uses MAF, so I can't tell you how to hook it back up.

Next up is the "the passenger side valve cover and a valve that has no hose going to it" - that looks a lot like your PCV valve (although my PCV is on the driver's side ). If that valve is coming from the rear part of the valve cover, then you're probably supposed to have a hose that runs from that valve up to the pass. side of the throttle body - it should attach to the top "nipple" on the TB on the right side, just behind the Throttle Position Sensor. (Hopefully that'll get you started...)

Finally, we come to what I suspect is the biggest culprit - the "fuel pressure gauge which jumps between 50-60psi continuously". That tells me that either the diaphragm in the fuel pressure regulator (FPR) is torn/broken (most likely), or that something else is so wrong that the ECM is going nuts trying to correct for it.

Best advice I can give you is to get all of the sensors, vacuum hoses & wires connected to their proper locations (& also check for vacuum leaks/cracked vacuum lines, etc.), & see how much that helps you out. If you're still having problems, you might have to open up your FPR to see if the diaphragm is leaking - but that's probably a good "last resort" idea...

I hope that helps you at least a bit - and I wanted to give you a for writing a pretty decent description of the problems/symptoms you're seeing. I'll bet that someone here will be able to give you better help than I have!

 

Hey V8, thank you for your response. I did a little research and found out that it ISNT the PCV valve, but its the CCV valve, and you are correct, it DOES connect to the top inlet on the throttle body. I'll start there tomorrow and then work from there. So far, from what I can tell without moving anything around is that the vacuum lines are all intact and in good shape (well, other than the hose to the CCV, lol). I am kind of skeptical about the FPR guage in the first place, it's always seemed to jump around alot before this issue, I just never really realized it until now.

As for the MAP sensor, it is connected, it's just not bolted down securely to anything...its being held up by the valve cover and vacuum lines it's attached to.

I am starting to lean towards FPR, and from what I gather, they aren't the most friendly components in the world on these thirdgens. But would a bad FPR throw a check engine light at me? Seems to me like it would.


Thanks again to anyone that is able to help me out with my situation.

_Clark

 

fuel pressure regulator will NOT throw a code on its own, it is purely mechanical, and your fuel pressure is too high, that MIGHT set a code, but not always
check the regulator vac line for fuel

 

I think the hoses from both valve covers are part of the positive crankcase ventilation (PCV) system. I don't think that this is the source of your problem, but its a good (and cheap) idea to remedy this problem as soon as possible. The fuel pressure thing however is a much bigger deal. If you fuel pressure is indeed running between 50 and 60 PSI then you are running rich and thats your problem. Stock fuel pressure should be between 38-43 PSI but with some mods your car can support UP TO about 50 PSI from an adjustable regulator but I don't think it is a good idea to be any higher, especially without a computer tune. From what you are saying, I don't think you have an adjustable FPR so I would first check the FPR vacuum line and if its good, get an FPR rebuild kit or just get a new one, preferably adjustable.

 

from what i'm reading it definately sounds like the fuel pressure regulator
50-60psi is waaay too high

the map sensor is secured to the cowl, at least thats where it is on my car

 

Yeah, I am mostly leaning towards the FPR here. I fixed the missing line to the CCV valve, and took a trip down to the beach and back. I used a little less than half a tank for a 80 mile trip, but I still smell gasoline at idle, so I don't think that was the remedy. I'm off college for thanksgiving break 5 days, so I'll look into the FPR then. I should be fine with just a stock one from autozone right?

Thanks so much guys.

 

watch out, high fuel pressure can also come from a restricted return line............

 

Okay, the plenum is coming off next week to check the FPR. Is there anything specific that I should see or look for that says "Hey, this Regulator is messed up, get a new one."? Like, will I notice if it needs to be replaced?

Also, do you know where I could find a diagram for a fuel system for my car? I want to be able to find the return line and look into it, as Dave89Iroc suggested, incase the FPR is still okay.

 

Take the vacuum line off of the FPR when the car is at idle and see if gas comes out of the regulator. Sometimes if the diaphram is bad it'll push fuel out that little line.

just my $.02

 

Biggest thing I've seen/heard of WRT the FPR is the rubber diaphragm being torn - and generally, that's pretty easy to see once you've got it apart.

Google is your friend!

(BTW, glad to help earlier!)