Jeremyzincv6

Now I have a 2002 v6 mustang. And by no means am I super car savvy. So My engine does this thing sometimes where my rpms go up and down at idle almost as if my car is going to die and it did once but that had fixed an issue... My exhaust is a lot less toned than when i got it installed.. Now last time when my rpms were doing this, my engine died, and then i turned it back on and my exhaust was loud again, lasted a week and now it's doing the same thing... what could this be? Are these linked or are they separate.

PNYXPRESS

possibly a blockage in the exhaust, low fuel pressure, low voltage to coil/plugs, IAC dirty/clogged....

What did you have installed with your exhaust?
how soon after getting exhaust work did the problem start?
when was the last time the fuel filter was changed?
when was the last time the plugs were changed?
how old is the battery?
how dirty is the air filter?

Chromeshadow

You can usually tell if you have a clogged exhaust with a $15 vacuum gauge in 15 minutes or less.
http://www.secondchancegarage.com/public/186.cfm

scenario 14 shows the reading for clogged exhaust

Matthew954

I had a similar issue with my 04 V6. My coworkers had suggested mixing a bottle of Gumout fuel injection cleaner to a tank of 93 octane gas. Mine cleared up as the treated gas ran through the system.

TfcCDR

You also might try doing a Seafoam treatment. Can't hurt, anyhow.

Jeremyzincv6

Well, the exhaust is just welded on, I've had it taken back its custom with some glasspacks. The quietness just stared but there's always been a hissing sound coming from the pipes. After my car warms up there's like a snake sounding hiss that comes from the tips. I have a CAI could that be why with the really cold air? Fuel filter idk.. The rest is good plugs battery air filter

PNYXPRESS

Custom how? Just a muffler, duals from after the cats, cats on back, or full exhaust including headers? Is there a CEL?

Check your IAC for buildup causing a blockage.

jthorn9

I would have your IAC sensor checked out first. When the IAC sensor starts to fail your idle will become erratic and the car can sometimes stall out at idle.

Another area to check would be the EGR sensor and valve. Same things are prone to happening when these go out.

Lastly, if those two check out, I'd check the OBDII sensors. While unlikely, when the OBDII sensors go out, weird things can occur with idle.

If all that checks out, then your issue lies with either the MAF sensor, AIT sensor, or a faulty injector(s).

PNYXPRESS

We don't have tps we still have a throttle cable.


It may possibly be the IAC valve gummed up

jthorn9

Touche' lol, that's what I meant lol.