Coolant Temp Sensor would be the first to check. Without actually knowing
what the readings are...it's just speculation.
- Bernd
(DC Lead Tech)
-----Original Message-----
From: rws [mailto:rwsam2002@yahoo.com]
Sent: Wednesday, September 12, 2007 12:27 PM
To: dakota-truck@dakota-truck.net
Subject: DML: Cold Starts causes Check Engine Light + LIMP mode
Hi,
I just joined DML and this is my first post.
We have a '94 5.2L MPI Dakota SLT 4X4 @ 162K miles.
When it sits for days or just overnight and when
starting in the morning or when cold (60oF) it goes to
LIMP mode and the Check Engine light turns on. LIMP
mode is something set by the ECU or SMEC or single
module Engine Control. After driving it till
temperature is up, about 15 minutes, I restart the
engine and the problem is gone. During the day @ 70oF
or higher, it can be restarted and the problem doesn't
re-appear.
About 11k miles ago we did the CA Smog test only thing
and it got low numbers on all three pollutants. It
passed then, but now that the Check Engine light comes
on, I'm sure it will not pass.
I'm wondering what sensor(s) could be intermittent or
malfunctioning that gives the wrong temperature
condition. I'm looking at the O2 sensor since it has a
heater and is a 4-wire unit, the ECT Eng Coolant Temp
sensor, the Air Intake sensor -- what else should I
test? The O2 Sensor is not tool old < 20k miles, the
other two are original or 160k miles old. Coolant has
been flushed at 15k -20k intervals.
What is the best way to test for an intermittent
sensor? I have a heat gun and was thinking of using
it to stress test along with a DVM.
Someone told me to replace the Distributor's Pickup
Coil, that they are a problem. I don't know why, but
that doesn't make sense to me. Are they temperature
sensitive or do they wear out w/o failing?
Btw, It has 2 codes 12 and 27. Seems to never go away.
I know what the codes mean but don't understand how to
test.
For 12 I cleaned and reconnected all the primary
voltage wires and connections.
For 27 I have no idea how to test MPIs or FIs for
output or the ECU, if it is not getting injector's
signal. Someone told me they had the same code and had
to replace the ECU. If that's the case, what's the
best replacement value ECU?
Thanks for any help/advice.
socalrws
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