Evo Engine Temp Sensors - 4 in 8 years?

 Anyone thirsty?  I've got a question I'd like to pose to the
collective experience out there.  Have whatever you choose, 'cause I'm
covering the bill today.

I've been meaning to float this question for awhile now, 'cause it's
been buggin' me.  My fuelie Evo has been going through engine
temperature sensors at a faster rate than I get hair trims.

I've had my bike, a '98 FLTRI, since new and the original engine
temperature sensor lasted about 5 years.  When it started to go
flakey, it drove me nuts for a year, trying to figure out the cause
(engine stuttering, especially in cold temperatures and on the highway
when backing off on the throttle).  Finally got a data-logging device
hooked to it, which revealed the cause, replaced the sensor and things
were good again.

Now, IIRC, that second sensor mighta been a second hand unit.  Not
sure any more...  Anyhow, that one lasted about a year, stuttering
only after a long time on the highway and in cold-ish temps - again,
while backing off on the throttle, mainly.  Didn't seem to get worse
or better, so I headed to Sturgis with things as they were.  By the
time I got there, the bike could hardly run, so I picked up a brand
new sensor at Rapid City (installing it in their parking lot).  Just
about flipped over the price ($101.00 U.S.)  

That was a year ago, August.  Bike ran perfect again, once replacing
the sensor (lucky diagnosis on my part, since the dealers won't help
you during Sturgis week).

Now, a couple of weeks ago during a trip to the Rockies, the dreaded
stuttering (again, especially in cold temps on the highway and mainly
when backing off on the throttle) started again!

Go to the dealer.  By now, I'm pretty familiar with the failing engine
temp sensor indicators, so I price out a new one.  $155.00 Cdn!  Shit,
this is gettin' expensive.

Because it's acting exactly like the problem the engine temp sensors
caused, I didn't even check the ECM trouble codes stored (the temp
sensor never registered before anyway).  But, just yesterday, I went
and checked trouble codes and what do I find?  Code 11, a throttle
position sensor failure!

Dog gone, the behaviour was very similar to the engine temp sensor
failures, but throttle position sensing could cause the same reaction,
I guess.  Maybe it isn't the engine temp sensor after all...  Sure
acts exactly like it though.

So, anyhow, here's what's basically my quandry:  Maybe this is just a
string of bad luck?  Or is this an indicator that something else is
wrong that could be leading to shortened sensor life perhaps?  Anyone
have some hard-earned wisdom to share on this?  Anyone gotta a line on
a cheap supplier of sensors?  I'm goin' through these things like
candies lately.

I should note that I've had periodic troubles codes (for 3 years) of
air temperature sensors throwing fault codes.  Replaced the thing once
and it still does the same thing, but doesn't seem to affect engine
performance at all, so I've taped over the trouble light indicator so
the red bulb doesn't bother me at night.  That was the only code the
bike was throwing for a couple of years.  Doesn't seem to be showing
up anymore though (although it could be buried in the stack under more
numerous Code 11s...).

I know this has been a long question and a lotta background and it's
probably a bit of a chore to read this far so, anyone making it here,
deserves a couple more drinks.  

This problem is something I'd really like to get to the bottom of.  I
put a lot of work into trying to keep my bike running reliably, but
this sensor crap is killin' me.  The bike is starting to get old, I
guess, with 152,000 km (95,000 miles), but I still don't want to part
with it.  Just too attached to it now.

For this latest problem, I guess I'll be picking up a
throttle-position sensor.  Hope that does it.


P.S.  For anyone who needs to look up trouble codes on the road and
can get to an Intenet-connected computer, I've had a page containing
the diagnostics procedure and wiring diagrams at
http://xidos.ca/scripts/personal/Bikes/tech.html  for a few years now.
Have at 'er if you ever need it.

--

Home page: http://xidos.ca/scripts/personal/

 

Cuz, yer confusin' yerself.

The "metal shaving cleaning trick" is for the Vehicle Speed Sensor (VSS),
not the Throttle Position Sensor (TPS).

The TPS's are sealed and you cain't clean shit off'a 'em. I've seen a ton of
'em fail after pressure washing them, mostly on  warm/hot engine and with
either a steam cleaner or a pressure washer. I've not seen too many of 'em
fail from just a plain was on a cold engine (which I HIGHLY recommend doing,
ONLY) but I s'pose it be possible <?shrug?>.

The guys original question was on the CTS, or "Cylinder Temp Sensor", aka ET
sensor (abbreviation for "Engine Temp" Sensor, by OBD-II mandate). The early
CTS's are well known for taking a dump. Redbeard E. had at least one per
trip fail on him when he had his old 96 Evo FLT and IIRC, he had one or two
fail on his 2004 before he dumped it in favor of his new (to him)
Ninety........... 8(?) FLHT/C/U/I.

For some reason, tis a fact of life with the Harley ET sensors. At least on
the Evo's.


Glad I could help,
Preacher - AH #89

 

Wrap the TPS or the Injection Module with a plastic bag and wash away...
can't hurt to keep the MAP sensor dry too.


Preacher - AH 389

 "Road Glidin' Don" lamented...
<snip>

Yeah.  Not sure if it's helpful, though.  Might be helpful words if it makes
people who read this think more completely about FI problems when they show
up.  Not sure if it applies to your case but there might be something in it
for'ya.

A buddy had a late 80s Ford Mustang.  After putting a new intake manifold on
it the thing would buck and chuff whenever he turned left.  Seriously.
Straight, right, no issue, left turn, ca-chug-ca-chug.  He r-and-r'd the
manifold three times and every time he did it ran good for a few weeks then
went right back to chugging on left turns.

Long story short, after blindly swapping every single sensor on the thing he
went to the dealer for a new ECM.  After that didn't work (in the dealer's
lot) he was futiley (sp?) pleading with the dealer to take back the $500
(U.S.) electronic part he'd just purchased.  One of the parts counter guys
asked, "What year is that car?"  The guy disappeared and came back with a
service bulletin on that year's 'stang that said that there was a bad batch
of engine wiring harnesses that had the pins too small.  My buddy mike'd it
up and sho'nuff he had the afflicted harness.  The pins would make contact
in the sockets maybe, maybe not.  Everytime he rNr'd the manifold he moved
the wires and they made contact for a while.  The issue didn't show up until
he first put the manifold on just because of dumb luck on Ford's part.

My point here is that the EMC can claim an error but that claim has some
assumptions with it.  1)  the ECM has to assume that all the circuitry
between it and the sensor are good, 2) it assumes that the sensor has a good
ground, and 3) if the sensor has external power to it then the brain assumes
that the power circuit is good, too.  Oh, and then there's 4), the brain
assumes that IT has proper power and a good ground, as well.

In other words, swapping out your sensor over the years might have "fixed"
the problem because you monkeyed with something and didn't even know it.
Sensor grounding, a corroded splice that you tweaked, something like that.
Something simple.  Check the simple things, even though checking them ain't
always simple to do.

Just my overblown two cents (U.S.).


Thanks, I enjoyed the read.  Not being very knowledgable in Harleys I find
it interesting that the ECM sounds alot like a GM OBD-I from the 80s in the
way that you can query fault codes using the check engine light.  I like
that, it's simple.

 Stingy Bastard wrote:

<snipped a good story about a Ford Mustang>

When I went to GM service school and Ford service school
they both harped on one thing......

Follow the frikkin diagnostic flow charts like a religion.
If you skip a step you WILL replace the ECM, which is
usually the most expensive part in the system.

Don't just read a code that points to a component and
replace that component.....follow the diagnostic steps EXACTLY.

--
Steve Irving (Irv) - BS#237/SLOB#12
http://www.nite.com/bike.html
Under a black flag we shall sail.......