How to tell if someone put too large injectors into a stock 5.0???

I have been trying to figure out for the life of me why my 95 mustang 5.0 has been idling so rough and extremely rich. The only conclusion I can come up with is that someone installed too large injectors into it.

When I purchased the car the kids said it had a "CAM" in it. Well the engine is stock and shows no signs of ever been tampered with. So, I did what some of you suggested, I took off the throttle body, cleaned it and the sensors thoroughly. I replaced all the gaskets fired it back up and a very mild change at best.

The car has a very hefty idle, it sounds like it has a large cam. But, the very rich smell of fuel at idle and the fact the car does not have anymore power than stock tells me other wise.

Is there a way to tell by looking at the injectors which #PSI they are?
The check engine light has not come on, and I am pretty much stuck at what to do next.

Any advice??
 
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well they look yellow from a glance........could that be a faded orange lol

I will go out again in the morning and double check.

Thanks guys for the response....any other ideas to why I am having a rough idle and it running so rich??

Thanks for the responses
 
do you know what it has for a cam? May be to big for it not having anything else done to it or it could just need a tune b/c the cam is causing havoc w/ the ECU. If you smell fuel then its probably running rich.
 
It does not appear to have a cam. There is not indications of the timing chain ever being removed. Everything looks pretty stock including the water pump.
I have a buddy has as 92 stang which has a F303 cam and my stang has a much greater lopier idle than his does.

I am beginning to wonder I do not have some sticky injectors or something. I grabbed a new fuel filter today and will make an attempt at changing that out this coming weekend.
 
...the very rich smell of fuel at idle and the fact the car does not have anymore power than stock tells me other wise.

Well, I won't try to decipher if you do or don't have a cam, but I will
say that rich mixture = slow car. So even if your car does have
a performance cam, you will never see any performance with the
engine running as rich as you describe.

Someone who is 5.0 HO tech saavy will have to give you details, but
there is also the possibility that someone cranked the fuel pressure
up too high. That is another way to get more fuel to the engine without
going to bigger injectors.
 
I didn't know if HO regulators were adjustable or not...

On my F150 5.0 (non-HO), I did the 'free mod' of taking a socket
and hammer to the non-adjustable regulator while I had a gauge
hooked up. If you aren't familiar, you just put the socket over the
hookup for the vacuum line on the regulator, then gently hit it
with the hammer, denting it, until the gauge reads the pressure
you want. Gotta do it slow, it is permanent and it is not good to
have too much pressure. I did mine because headers and ORP
caused me some detonation from being slightly lean. I bumped
it up 4 or 5 psi.

However, you can go too far.
So I thought maybe the same mod could be possible for the HO.
Thus the possibility that a PO went too far with it.
 
Wow....I appreciate the responses....
Well I just purchased this car about a month ago. I live in the good ole state of Washington and we have more snow here than anyone knows what to do with. I can not even get into my garage at the moment due to the snow birms around my house.
I have not been driving the car much, just seen it on craigslist and could not resist.
Anyways......I only a code reader for OBDII vehicles. It is possible it is throwing codes, the check engine light has not come on.....yet. The fuel pressure regulator looks original and dent free. I dont think it has been tampered with. Do these ever go bad, or get faulty?
This is the first EFI mustang 302 I have worked on. I just sold a 99 Dakota R/T 370RWHP because it was absolutely worthless to in this wonderful weather we have. I did all the mods to the truck and a few vehicles before hand.
Is it possible that the O2 sensors could be effecting the idle and mixture this badly? I know there is a leak that the doughnut behind the header on one side.

I do not have any grand plans for this car until late this year. I was looking at doing a 306 or stroker engine. Until then I was just looking to put a few miles on it as is.

I guess I can start back by the fuel pump and work forward replacing what I can.

Thanks for the help and ideas
 
I know a huge vacuum leak will cause a super rough idle. Not sure if it'll be rich or not. My car "seems" to be running really rich, but without cats and the fact that I have exhaust leaks is probably why I'm smelling it more right now. I don't have a CE light either.

To the original poster, when you turn the key to "ON" before you start it, does your check engine light come on then? Just wanting to make sure the seller didn't pluck the bulb out before he put it up for sale!

Anyway, clean the mass air meter, which is in the big black air box. You can clean it with carb cleaner and a cue tip, or use alchohol. Then check the engine for vacuum leaks.

Also, just because it doen't look tampered with doesn't always mean it wasn't opened up. I put a cam in a Fox once and after a few months of driving it, it all looked nice and cruddy once again!
 
Well I could not get my R/T out of my driveway. It is 2 wheel drive with a posi rearend. I was kinda the laughing stock of the neighborhood....smoking the tires trying to get out of my driveway. I did ok once I got moving....but most of the time I could not even get out. I miss that truck, but it was time to move to something new.

The mustang will not be driven in the snow. Its more of a toy/summer car.

There very well could be a cam in this car. It is possible that it could have been installed a while ago. It is beyond me why someone would with everything else being stock.
I am going to pull the plugs today to see whats going on with them. The injectors are 19# so unless they are stuck I do not think the problem is there.

Yes the check engine light does come on when turning over the key.....lol This was one of the first things I looked for when buying the car.
Does anyone know if stock 4.6 injectors will work on this. I believe the are 19# as well. They just look a lot slimmer.

Thanks
 
Pull a plug that'll be a good indicator of the fuel.... I would want to see what vac it at idle and is it steady or jumpy. Have you test the fuel pressure yet??
Pulled any codes to help you out??

Sounds like you have to run thru the normal trouble shooting stuff....:(
 
I didn't know if HO regulators were adjustable or not...

On my F150 5.0 (non-HO), I did the 'free mod' of taking a socket
and hammer to the non-adjustable regulator while I had a gauge
hooked up. If you aren't familiar, you just put the socket over the
hookup for the vacuum line on the regulator, then gently hit it
with the hammer, denting it, until the gauge reads the pressure
you want. Gotta do it slow, it is permanent and it is not good to
have too much pressure. I did mine because headers and ORP
caused me some detonation from being slightly lean. I bumped
it up 4 or 5 psi.

However, you can go too far.
So I thought maybe the same mod could be possible for the HO.
Thus the possibility that a PO went too far with it.


From what I've read it makes no difference where you set the F/P on these cars because the computer will compensate and basically nullify the adjustment.