V6 (1994-2004) MustangsTechnical discussions on the 3.8L and 3.9L V6 torque monsters Sponsored by Optima Batteries
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strong gas smell at idle
bad gas milage barley seeing 20 with only freeway miles, im getting roughly 13 on city driving.
long crank til start.
And when i get off the gas, and coast, my idle floats around 1000-1200.
Now I thought it was my IAC, but i do not have any issues with a drastic change in idle when i put more acc. loads on the engine. An IAC wouldnt give me bad highway milage would it? Im not at idle.
I suspect a leaky injector, (not fully seating) hence why its so much worse in city driving mpg cause im more stop and go.
I dont have any tools really at my house, I might go pick up a fuel pressure gauge at autozone and see if i get pressure drops at the service port on the rail.
What else could cause my issue?
I also suspect it being an injector because it doesnt have a rough feeling like a miss in every fire, it as if one cylinder is missing at idle, though im not throwing any codes, and the 4 gas anylzer showed no signs of rich condition when i smogged it, though the numbers were read under a load.. so i dont hold much validity to them.
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DO a fuel pressure check/see if it bleeds off after shutdown, if that checks good then do a compression check, if thats good do a cylinder leakdown test, if thats good check for bent pushrods, if those are good do a tune up (that should be 1st anyway). Post back after those are done
Your problems are coming from one of several areas:
I can tell you that there is almost zero chance it's a fuel injector not seated because of the way the fuel rails mount, there are 4 small bolts that hold the rails in place, so unless the thing is bent there is no way for the fuel rails to release enough pressure on the injectors for one to become unseated.
*IAC (yes a bad/faulty IAC will cause a horrible idel)
*Clogged/Faluting EGR Valve or Sensor (if this goes out it can serriously through off the a/f mixture
*Faulty Temp Sensor (if this goes out the engine will run rich as the sensor isn't telling the ecu that the engine is now warm and doesn't need to dump extra fuel into the cylinders)
*Faulty/Dirty MAF Sensor (if the MAF is faulty or dirty this would cause the sensor to send bad or no information to the ECU and the ECU wouldn't know how much fuel to add for the air comming in)
* Unlikely, but Throttle Position Senor could be faulty (this would cause a bad idel, but wouldn't explain the car running rich)
Oh, also, as you figured, a clogged Fuel Pressure Regulator could be to blame as well. Don't bother with Autozone for a meter, I went to mine and the guy looked at me dazed, he didn't know what the hell I wanted, but once I got it through his thick skull, he said they didn't sell them, you might have to go to either advanced auto parts, or another autoparts store, autozone has most things, but I didn't see this one at mine.
If the problem was an egr related one, i would have seen this on the gas anlyzer. Not an egr.
I doubt the iac still, because it is not a horrible idle, its more of a constant one, but you do notice their is a problem with it. It still wouldnt explain my gas milage. They have no play in metering air around that throttle plate once that throttle plate is opened.
Jthorn, I was not talking about the seat to the rail, sorry terminology is gettin across wrong, I was taught that seating with diagnosing an actualy injector meant the needle of the actuator. Meaning its dripping fuel when its not spraying.
A gauge could tell me this If I use it at the service port, but will not tell me which one. You would have to clamp the return, so that you hold pressure from the clamp to the injectors, and if your pressure drops, its not going backwards, cause you clamp it. Meaning its leaking at the actual injectors.
I have not gotten a gauge, about 30-40 bucks at autozone with the ford service valve fitting. They do sell them, somtimes you just have to look for yourself. Or go to a main store. Usually the 24 hour ones around here. I just havnt had the money to pick one up right now. Spending money on gas for school, and I dont have the diagnostic classes anymore so i dont have access to the tools. Im taking a climate control class.
So im stuck with a leaky injector, and another forum gave me the suggestion of the 02 sensors, which are not dead, cause I havnt gotten a code. Maybe going bad, with a very slow response rate, which could explain my mpg, but not my idle.
im have kinda the same issue bad idle, car has a e 303 cam bbk cold air intake edlbrock performer 2 upper and lower intake. SOme time when i come to a light the idle dropps a low or it trys to die out on me if i dont give it a liitle gas. When it does idels it jumps around so check engine light came on yesterday and when it does it idels high above 1k rmp and hen trys to shut off. could this be some of my issues that the guy stated in yours.
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