Misfire and Knocking: Fuel Injectors? - Ranger-Forums - The Ultimate Ford Ranger Resource

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Old 05-11-2015
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Join Date: May 2015
Posts: 2
Misfire and Knocking: Fuel Injectors?

I'm posting here and the 3.0 forums, in hopes of a few replies...

Alright, so I'll start off with saying that I'm still a big novice when it comes to vehicle repairs, but I've been looking over online tutorials and and making things happen. I need some advice from the experts here.

I've got a 1999 V6 3.0 with 135,000 miles on it. I'm having some bad misfires in cylinder 3 and had a shop take a look at it. They've told me it's a bad fuel injector. They also said I should buy one online, get the better deal.

Now, I've been browsing but I have a few questions. One, I'm not sure if there is a difference and I haven't heard any differences until now, but out of curiosity, is there a gas only version of the 1999 automatic V6 3.0 4x4? I'm seeing a lot of Flex Fuel models, but only O'Reilly's sells "Gas" model fuel injectors. After some research into my truck, it seems as though it may be a Flex Fuel, "Ethanol or Unleaded Gas Only" is printed on the inside of my fuel door. If I'm only putting in regular unleaded gas into the truck, no Ethanol fuels up here in AK, does it really matter what fuel injector I buy?

I've done a lot of work on my truck, including spark plugs and redoing my hubs. Is the injector something easily replaced, or should I have my shop do it? If I replace one fuel injector should I just replace them all? Is there really much difference for the average driver in fuel injectors? I tow a small trailer at times but don't really go for a lot of after market modifications.

Any information would be helpful, I've been scouring the web, but now just need to ask the questions and figure it out.
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Old 05-11-2015
Join Date: Apr 2015
Location: brantford ontario
Posts: 32
try cleaning the mass air flow meter with brake clean. just make sure its completely dry before pluging it back in. worked on my 94 ex 4.0l. had the same problem.
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Old 05-11-2015
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Join Date: Jan 2014
Location: Vancouver, BC
Posts: 7,595
Look on the Driver's Door label, back of door, for your VIN, or on the dash board plate, seen thru windshield.
The 8th digit of the VIN number will be the engine code
U is a gas only 3.0l
V is a Flex Fuel 3.0l

Yes you need to get the correct injector, V engine needed a larger injector because E-85, ethanol, higher air:fuel mix, so computer needs to add much more fuel.

Mis-matched injector will give computer and you all sorts of grief, lol

Pinging/knocking is not uncommon with the 3.0l, they tend to build up carbon if not maintained, allowed to run rich too long.
Add some Seafoam in the gas tank.

Check EGR system, EGR cools cylinders under load so it prevents pining/knocking.
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Old 05-12-2015
Join Date: Nov 2014
Location: Niagara, ON
Posts: 44
Seafoam is AWESOME stuff, especially in non-ethanol gasoline, QB. I'd do (No, I DO, once a year) the full treatment, as seen on YouTube - crankcase, gas tank AND intake, then change your oil.

Originally Posted by RonD View Post
Check EGR system, EGR cools cylinders under load so it prevents pining/knocking.
RonD, I've never understood how Hot exhaust gasses "cool" the intake air stream...especially with the upper intake being heated. (yes, this is a discussion for it's own thread...sorry, OP)

I've done the Hot Water Bypass and seen a mileage increase...I'll bet I'd see a similar one with an EGR defeat. EGR is a factory designed dynamic vacuum leak...both of which they eliminated with no other major changes in MY2002...Hmmm...

And yes, I know that's "messing with my emissions system," but if I'm more fuel efficient, am I not less of a polluter? Especially if I'm not throwing codes? Around here in Onterrible, we have similar Clean Air testing requirement to BC called DriveClean - codes is all they look at for passing. They used to test tailpipe emissions (still do for diesel trucks), but engines in the past 20 or so years have been SO cleaned up that it's become moot, expensive and time consuming.

Again, apologies to the OP, QB, for hijacking the thread...
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Old 05-12-2015
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Join Date: Jan 2014
Location: Vancouver, BC
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Our atmosphere is 78% Nitrogen and 21% oxygen, 1% trace gases

When air is sucked into the intake there is far more nitrogen than oxygen, 57 parts more, lol.

Nitrogen and oxygen don't react with each normally, obviously.
But at extremely high temps they will combine to make NOx - nitric oxide, the higher the temp the greater the production of NOx.
Ever hear of "acid rain"...........NOx from engines was a major contributor to that, Sulfur Dioxide from coal burning as well.

There is no way to run an internal combustion engine without producing some NOx.
But to limit the production you need to keep the cylinder's combustion temperature as low as possible while still providing a full burn in the cylinder.

When an engine is under load the cylinder temp will rise, and so will NOx production.
While exhaust gases are hot they are not as hot as combustion temps, the temp drops pretty fast as the gases expand and push the piston down, so on the exhaust stroke they are cooled off well below any NOx production levels.

Exhaust gases are basically inert, they don't add power and they don't take away power when added to intake air, the inert gases just absorb heat during combustion to lower the overall temp.

EGR valve is not used at idle and it is not used at full throttle, which is why some engines will ping at full throttle, you back off the gas pedal slightly and pinging stops because EGR valve opened.
Hotter cylinder temps do give you more power, but that also melts pistons and valves, lol.
So there is a balance of NOx production vs power.

EGR system don't "rob power" in any real sense for daily driving, it adds to engine life and reduces NOx production, plus and plus.

Running an engine with high combustion temps will give better MPG, i.e. running lean gives better MPG and higher temps.
But you are producing more NOx, so..................using less gas to make more pollutants, lol

Last edited by RonD; 05-12-2015 at 12:16 PM.
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Old 05-12-2015
Join Date: Nov 2014
Location: Niagara, ON
Posts: 44
So what you're saying, Your Guru-ness, is that the warmer air (compared to Intake air temp) from the exhaust lowers the combustion temps to non-engine melting heat range, which conveniently prevents NOx formation? Under 1600 degrees F, if wiki is to be trusted:
NOx - Wikipedia, the free encyclopedia

That makes more sense now. Especially when you consider relative quantities. OK, EGR stays undefeated.

Thank you, once again.
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