Powertrain data codes available in another module,, this will take some
research, also it is possible your pcm system is obd1 and I believe the 3.4
is obd11, some some components may not be compatible, did you install the
entire engine or the long block and is this a GM replacement engine or from
a scrap yard, lots of info missing here.
P1640 is the QDM "A" driver error. Got that on my '95 a couple of years ago.
Related symptoms are: TCC inoperative, Full-time vapor purge (high/rough
idle), cooling fan 2 always on, oil level light always on. There's a whole
flow chart to follow in diagnosing it. For me I just disconnected the PCM,
coated the connectors in dielectric grease and reconnected. Haven't had that
code back since.
Shep - FYI, the '95 3.4L DOCH is OBDI, but not in the traditional sense.
Through '94 and '95, most GMs (as far as I believe) are this ALDL8192 OBD.
On F-bodies and other LT1 engine vehicles I believe it goes all the way back
to '91. They give P codes like OBDII does.
The replace engine was a 3.4 Doch v-6 and was replaced with the same engine
bought used at a junk yard.The pcm and prom were replaced also nut did not
replace all the sensors or electronics.Have kept replaced engine with
blown hwaed gasket in case I need senors or elctronics off it.Have kept
original trans.Re-checked every thing pluged in. Car does not idle rough
and I only get ck engine light when load is applied.When car is idling
heat sensor will move pass mid-mark but fan turns on and heat indicator
will back to normal range.If car is at idle and AC is on heat indicator
stays at normal range?
Other questions need to be asnwered along with Shep's:
Was the original engine a 3.4?
Is it a 3400 or a 3.4 DOHC?
When you replaced the engine did you replace the PCM or PROM with the
Did you just replace the long/short block, or everything including all
sensors and electronics?
Is the engine new/used/rebuilt?
Did you keep your original trans or replace it as well?
Did your car happen to originally come with a 3100 mated to a 3T40 (i think
that's the 3-speed) trans and you replace the engine and PCM with the engine
and PCM from a 3.4L DOHC that was originally mated to a 4T60-E?
When you replaced the engine did you double check that you plugged
Good info Steve, the trans on the 95 Lumina was only the 4t60e. How are you
doing with your car? Lots of open issues with this post on the swap, not
unusual though. You could expect a quad driver problem on a mis- matched
swap with the pcm trying to command components it wasn't designed to
F'in car. Getting worse. The "bucking" is really bad now at highway speeds.
The motor mounts seem worn but not broken. Something I did notice last
night, it's the first time I've driven in the dark in months, the headlights
and dome light flicker. When the engine feels like it "comes to life" the
light stop flickering and glow brighter. Odd.
Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here.
All logos and trade names are the property of their respective owners.