Auto or manual trans? First guess on code 27 is a corroded harness
for the injector circuit. The injectors are fed a constant +12v and
are pulsed by the ecm grounding out the injectors. Not 100% on obd-I,
but on my 96 the injector circuit splices for the +12v were on top of
the engine in the harness bundle that wraps around the intake. My
splices were fuzzy and green when I had some stumbling issues when
cold. I cleaned the splices and soldered them up. That solved my
issues immediately. Check a fsm for the splice location and check
them out.
WiLieR
On 9/12/07, rws <rwsam2002@yahoo.com> wrote:
>
> 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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