My son has a 1989 Delta 88 3.8 L V6 140 Kmiles. Had problems getting it
started. Adjusted the Throttle position sensor and it starts OK (with the
MAP sensor unplugged). If MAP sensor is plugged in it will die (this is a
replacement MAP sensor known to be good).
Idles OK but on the road test it sputters and lopes (?) and almost wants to
run right. Have to goose the accelerator pedal to pull away from a complete
stop or else it will die.
A little history:
Checked fuel pump and fuel filter OK.
Changed the air intake temperature sensor a couple of months ago because it
was way off temperature.
Checked the coolant temperature sensor OK (3.6 VDC at about 160 DegF).
Changed the spark plugs and has new wires.
Cleaned the carbon from intake manifold a while back - it may be carboned
again - haven't checked recently.
No sign of vacuum leak or head gasket problem.
The Haynes manual shows the MAP sensor has Gray, Green/Black and Black wires
to it. My son's car has Pink/Black, Black/White and Yellow wires. The
voltages are pink/black to Black/White 12.3 VDC (ignition on and while
running). Yellow to Black/white if 5 VDC ignition on and pulsing when
running (0.5VDC and 0.7VAC on my multimeter - I don't have a scope). The
MAP sensor has the part #AFH50M-02A embossed on it.
Couldn't find the crank sensor to test it.
Should I recheck any of the above items? Any hints would be appreciated.
Thanks for the suggestion.....
Checked the codes according to what we found on the internet. No codes
register. Not sure it's done right.
Beginning to suspect the electronic control module. Will do more
I think this one is the same as my '84 3.8 with a different MAF setup. You
should check/change the dist. cap rotor and coil pack as these are cheap,
and you probably don't have a scope to check them properly. If that
do it, (which I am guessing it won't) check the cam timing in relation to
the crank. I am
guessing the timing chain/belt/whatever has slipped. Since the MAP/MAF
is known good, when it is unplugged the engine goes to the factory preset
the timing is retarded, when it's plugged in the timing is advanced to the
place, which puts it too far out and the engine dies.
But, if that checks OK, then you need to review the MAF/MAP again. (I
this is the MAF not the MAP and your post just labeled it wrong) How do you
know it's good? I can tell you this on my 84, the engine ran rough due to a
MAF. I diagnosed it and replaced the MAF with a rebuilt one, and it still
crap. I gave up and took it to a professional mechanic and HE diagnosed the
damn thing by substituting with a good MAF he had on the bench. I told him
a rebuild replacement (new ones are $300+ on that engine) and he went
rebuilds before the 3rd one he got was good. I don't know what problem it
that the rebuilders have with these devices but they apparently do.
say I was rather pissed off at the place that sold me the first rebuillt
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.