Question-------------------------
Followup To
Question -
92 La Baron convertible 3 litre V6 with 170,000 miles. After
solving persistant overheating problems a few years ago it has
run okay since. CURRENT ISSUE: I charged a dead battery
overnight and after disconnecting charger & waiting 20 minutes
my Fluke meter says it held a charge of 12.85, so I decided to
start it - which it did immediately, but it stopped immediately as
I took my foot off the gas peddle. I started it again, revving the
motor a bit this time and had same results. I checked the
battery with the volt meter and it was slowly coming down from
13. 4 - indicating the engine was charging the battery. The La
Baron has not had a stalling history before this specific problem
today.
Answer -
Hi Hawkeye,
It sounds like to get the car to idle you have to provide extra gas via the pedal, but that you can
get it to run for more than a second or so. So that would say that the spark timing signal is
getting to the coil. It also suggests that the spark is sufficient to ignite the mixture. So I would
focus on the mixture modifying sensors or controls as the possible culprits.
Before going on, I might also ask if the dead battery was associated with any unusual running
immediately before that occured? Might there be a short in the system which is dragging down
the operating voltage? You might want to use your ohmmeter function to check the draw on the
battery (remove the + cable and measure the resistance between it and ground both with the
ignition off and the ignition at the run position).
Then I would wonder if the engine controller has noticed a fault which it has stored as a two digit
number in its memory. Try using the ignition key: turn it "on-off-on-off-on" and leave it "on"
(doing this quickly, no longer than 5 seconds). Then watch the 'check engine' light to begin
flashing, then pause, flashing, pause, etc. Count the number of flashes before each pause and
keep track of the numbers. Repeat the readout and verify the counts are correct. Then group
them in pairs in the order that they came out, thus forming two digit numbers. You may notice
that the pause is shorter between the digits of a given number, and longer between the numbers
themselves. Then send me a 'follow-up' question telling me the results of your readout. By the
way, 55 will be the last number (two groups of 5 flashes each) and that is the code for "end of
readout". If you remove the battery cable before doing this readout you will also get a code 12
(power to controller disconnected recently).
I have the troubleshooting manual for the engine and we can look up the possibilities of what is
wrong based upon what fault codes you show.
There is also an essay on fault codes at the site:
http://www.allpar.com/fix/codes.html
which gives the meaning of the code numbers. But then you need to get specific info for what
exactly might be the diagnostic tests or parts to replace to complete the repair.
It is suspicious that you have the discharged battery and then the failure to idle. There may be a
common cause that will reveal itself.
A common 'failure to idle' cause is the MAP sensor vacuum line being cracked so check that
tubing. It should cause a code 13 or 14. The automatic idle control motor can also become faulty
and that sets a code 25. And the coolant temp sensor can be inaccurate which sets a code 22.
Another possibility is a stuck ajar EGR valve. So look at the stem of the valve in the "cage" area to
see if it is moving up and down in response to revving the engine (this will require a helper to rev
the throttle while you observe the grove in the stem for movement). This would not necessarily
set a code because there is no specific sensing of the valve, but rather its electrical solenoid. You
can also try to move the stem manually with the tip of a screw driver applied to the slot to see if
it is free to move.
So if you would try those tests and reflect upon the recent history we may figure this one out.
Roland
THANKS ROLAND - FOR YOUR QUICK RESPONSE. ALMOST TOO MUCH INFO TO DIGEST. BUT
BEFORE I GOT YOUR ANDWER I HAD CHECKED WITH THE 2 MECHANICS I'VE USED OVER THE
YEARS AND THEY BOTH SAID THAT THESE DAYS WITH ALL THE COMPUTER SYSTEMS, CARS THAT
HAVE COMPLETELY DEAD BATTERIES OFTEN LOSE THE MEMORY IN THE ONBOARD COMMPUTERS
AND THAT I SHOULD SIMPLY DRIVE AROUND A BIT - SAY 30 MILES OR SO - AND THAT THE
LABARON'S COMPUTER WILL GET BACK INTO ACTION AND I'M PROBABLY OKAY. BUT BOTH GUYS
SAID I SHOULD HAVE THE BATTERY CHECKED OUT TO DETERMINE THE CAUSE OF THE IT LOSING
IT'S CHARGE IN THE FIRST PLACE. So I'm going to drive it around, see what happens, get the
battery checked and look over your info again - especially if my mechanics ideas don't work... I
do have AAA to tow me back. I'll let yo know how it goes. but please feel free to respond to this
responce if you want. Thanks again... Hawkeye.
AnswerYou are welcome, Hawkeye. My thinking is that the SBEC in a '92 LeBaron is not so sophisticated as to need significant relearning. I think one measurement is needed, having to to with the throttle position sensor (and that may well explain the first die off), but I doubt that is will take 30 miles of driving to stabilize the computer. So I wouldn't keep knocking my head against in the wall waiting for that to happen. There is a learning curve on the transmission module that takes a few upshifts and downshifts but again we have a problem with the engine side here.
I would encourage you to use your Fluke (envy here on my part) to check the resistance that the battery is looking at, as well as to have the battery itself tested at a parts store. It appears to have a taken the recharge. Unless there is a loose connection internal to the battery I don't believe it will prove to be the problem. If it is near the end of its warranty period, then that is a reason to think about getting another one. My batteries tend to quit just about when the warranty expires.
Awaiting further progress reports...
Roland
