Had the CEL come on again today on the 96 Mystique six . Code P0174,
bank 2 lean.
I checked the long term fuel trims on bank 1 and bank 2.
At idle both are at 25. At 2000RPM I had about 17 on 2 and 7 on 1. I
checked the PCV elbow hose and everything looks good - and would
likely affect both banks?
Anything else to check before I pull the manifold (nasty job) and
replace the gaskets??
No, the O2 sensors are both counting just fine. If I did not have the
discrepency between long-term fuel trims between banks I'd say mabee
an intermittent O2 failure, but when the O2s are all clocking properly
I still have that trim discrepency -----
Seems to me one bank is keeping the injectors open a lot longer than the
other. So why would the O2 sensors read the same? Pull the plugs and see if
bank 2 is rich, if it is it's the O2 sensor giving false info to the ECM.
Final mixture is the same - so the plugs burn the same. Problem is,
the computer needs to richen one bank (longer pulse width) to maintain
that mixture. This is due to unmeasured air getting into the one bank.
I'm just trying to make sure there is no other way for this to happen
other than a leaky manifold gasket/seal.
The PCV system is a common problem, with the rubber elbow splitting.
However, this would affect both banks, giving both P0171 and P0174.
I'm only getting P0174, and upon checking the PCV system,everything
Any other good ideas before I call the dealer and find out haw badly
the gaskets are going to hurt my wallet? In two weeks the car will be
driven by my daughter from Waterloo Ontario to Morden Manitoba and
back for a friend's wedding - and I want it right before it leaves -
don't need the CEL coming on in the middle of no-where, miles from
home with 4 young ladies on board.
Ok, at least your still thinking. Now if it had a vacuum leak and the ECM
upped the fuel to compensate, why is it not idling a lot faster? Think about
that for a while:) Why not just switch the O2 sensors?
Very simple answer to both questions. The idle is not faster because
the idle control valve closes to maintain the engine speed. It is
designed to do that. If it had a REAL bad leak, the idle control would
NOT be able to compensate, and the O2 sensors WOULD indicate a lean
running bank. At this point the computer has increased the fuel
injection pulse width beyond a programmed (and relatively small)
amount and has corrected the mixture to the point the O2 sensor sees
it as OK.
As for why not change the O2 sensors - because they are (relatively)
expensive, not REAL easy to change, and I KNOW it will not solve the
problem. 36 years experience tells me that.
At this point the engine is still running fine - and passed the
Ontario Driveclean test just last week (2 weeks after the light first
came on, and 10 days before it came on this time)
The light comes on if, on 2 CONSECUTIVE run cycles, with the vehicle
at cruise speed for 3.4 minutes, the long term adaptive fuel trim
richens the mixture by more than (something in the range of) 18%, more
At this point it is not a serious issue, EXCEPT the car will be doing
a 4300 Km round trip over the weekend 2 weeks from now - and I will
not be with it to look after any problems. I don't need it breaking
down somewhere between Waterloo Ontario and Morden Manitoba. I've been
broken down in Flint Michigan before on a long weekend - and believe
me it's no fun. For my daughter and her friends it would be a lot
worse than a minor inconvenience - and finding a competent mechanic to
work on a Mystique is not a trivial problem either - even under the
best of conditions.
On Sun, 19 Jun 2005 23:44:52 -0400, firstname.lastname@example.org
Further to breaking down in Flint - was labour day weekend 4 years
ago, taking said daughter to University in Winnipeg for her first
year. I had been in West Africa for a month, andknowing I had worn
U-Joints in the Aerostar, had it taken into the shop to have them
replaced. I got home a week before leaving for Winnipeg, and felt
something was not right with the U-Joints, so back to the shop for the
mechanic to double-check his work.Late friday afternoon of the labour
day weekend,just outside of Flint, with my daughter at the wheel, one
bearing cup on the rear U-Joint "left the building". The truck felt
like it was about 8 inches off the road.
We got towed into Flint - and could not find a shop who could look at
it before Tuesday. Had the tow truck operator drop me in a parts store
parking lot. I bought a new U-joint, a hammer, vice, and the only set
of metric wrenches in the place (a short chinese set) and crawled
under the truck. Could not get the bolts holding the joint to the yoke
loose - bent the wrench into a "C" shape. Found a local chap with
wrenches willing to help and still could not get them loose, so we
knocked the joint apart ON THE TRUCK and replaced the 2 bearing cups
that press into the shaft end holding the vice on my chest. We made
sure the clips were in perfectly and continued on our way. Total delay
something like 6 hours - half of which was waiting for the tow truck.
If my daughter was alone with the truck, it would have been Thursday
before she got to school. If it was a problem with the Mysique, it may
have been October.
On Mon, 20 Jun 2005 15:08:43 -0400, email@example.com
Well,the $156 wasn't the end of it.
That was only ONE upper and ONE lower gasket (needs 2 of each) and one
injector seal (needs 6). Total came out to about $235 in parts. The
lower gasket was blown in 4 places (3 on bank 2, 1 on bank 1) I put
new plugs intoo, while I had the manifold off. A lot easier that way,
but almost $50 more for the plugs.
The secondary throttle assembly (runner control) was badly carboned
but otherwise everything (gaskets NOT included) looked pretty good.
With any luck no more CEL and code P0174
Started about 2pm - finished about 7:30 with a short rain break and a
trip to each of the 2 Ford Stores in town to get the missing parts.
A little over 400km on it since re-assembly - and no CEL. It was
coming on after 2 or 3 5km runs previously.
The bottom gaskets were both visibly bad - with all 3 "secondaries" on
bank 2 sucked in, as well as one primary, and one secondary on bank 1.
I set the stops on the IRC so the butterflies cannot close completely
- my theory is high vacuum on decel with the butterflies closed
contributed to the failure.
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