Mechanics

P0306 P0174 PROBLEMS...?

1999 Ford Ranger

Engine Performance problem
1999 Ford Ranger 6 cyl Two Wheel Drive Automatic

My Check Engine light came on 2 weeks ago and I did a scan, p0306 and p0174. I relize 306 is misfire cylinder 6 and 174 is a lean code but im lost where to go now. I have replaced the coil, spark plugs, wires, DFPE sensor, egr valve, Replaced injector 6, Cleaned MAF and I am still getting these codes. I am absolutely stuck now and need a guide on what to do next or what possiblities would cause these codes, and are they related some how? Also I have been getting the p0306 for awhile now but the 174 started to come when I added my new Cold Air Intake, and yes I have tested for leaks and there are none PLEASE HELP ME! Thanks!
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Doner8749
April 8, 2008.



My 1999 Ford Ranger had the same problem, I was getting the same codes. It was driving me crazy. It wanted to skip and jump on acceleration. Then one day I remember that I replace the plugs with pre gapped plugs, so I decide to check the plugs gaps. They were set wrong from the factory they were set at .065 when the book calls for.055. Cure all my problems after resetting them to right gap.

Tiny
Cookie1
Apr 9, 2008.
I do not believe it is the gap settng considering I have tried three different types of spark plugs. The Plugs I have now are LSG Brisks, which you cannot set the gap if you look at the design. Which they are gapped to.44 permenantly. Please help?

Tiny
Doner8749
Apr 9, 2008.
First of all, get rid of those plugs and install the Motorcraft's that it calls for. Sounds like it may have sucked the intake gasket on the #6 cylinder.

Tiny
Jack42
Apr 10, 2008.
I agree with Jack. The P0174 code is the key. It registers lean on bank 2 which is the bank that cyl 6 is on. If it was a plug issue, that would cause an incomplete burn in fuel which would register a rich code. Lean codes are almost always attributed to intake concerns. And with the misfire code, I would bet on the intake gasket.

Tiny
Flexy5
Apr 10, 2008.
I just picked up a new intake gasket set and will let you know if its clears it. Also I have noticed that the light is only triggered on cold starts. When the engines warm or if its later in the day it does not come on. Hope it clears : )

Tiny
Doner8749
Apr 10, 2008.
So I purchased a gasket set from Fel-pro, and took the truck into the shop. They Replaced The Intake Gasket and 100 kilometers later the light p0306 light comes on still. The p0171 code cleared, the mechanic said it was because of my oiled air filter wasover oiled and the MAF was dirty, cleaned it up and hasnt returned. But now im stuck, Ive Also replaced the Spark Plugs with Autolite OEM plugs, Wires, new Coil, Intake Gasket, Fuel Filter and the problem still persists. Any other ideas?

Thanks Alot!

David Doner

Tiny
Doner8749
Apr 21, 2008.
Do you know if they replaced the uppers, lowers or both on the intake? If it's not an intake problem, then it only leaves the injector and valve issues. Also, is this a 3.0 or 4.0? That might be helpful knowledge for further diag.

Tiny
Flexy5
Apr 21, 2008.
Yes they replaced both the upper and lower intake, also the idle air control gasket, The injector has already been replaced with a new one, code came up again, swapped it with one of the other working ones and sure enough the code came up again. It Is a 3.0 Litre

Tiny
Doner8749
Apr 21, 2008.
If we have considered all the obvious, then we are left with the obscure. You may want to consider the possibility of a sticking valve. Does the vehicle run rough at all? The other possibility os poor compression when cold.

Tiny
Flexy5
Apr 23, 2008.
I took my truck into the shop and they think that it might have been a leaking injector since spark plug 6 was brown and the rest were not, but im not so sure since it is a brand new injector. They ran a high concentrate injector cleaner and cleared the code with there scantool. They tested all of the gaskets and they were fine, does that seem right?

Tiny
Doner8749
May 3, 2008.
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