1990 Isuzu Trooper Follow up of Mr Wiesel/ Tpoic ID254584 F

  • 2 POSTS

Computer problem
1990 Isuzu Trooper 6 cyl Four Wheel Drive Manual 180k miles

COPY of first interchange between ****

Computer problem
1990 Isuzu Trooper 6 cyl Four Wheel Drive Manual 177000 miles

my car wouldn't run and I verified ALL the vital signs

a repair place verified all vital signs (compression, timing, fuel pressure, spark, fuel delivery, and much more even as I"

they said they could not communicate to the compute, that it must be sending out garbage

they ordered MINE rebuilt ($300)

after they got it back I noticed (as I spyed) that it still would not run.

then they figured it out, PLUGGED converter
seriously plugged

started right up


the computer lights almost always flashes slow
sometimes fast on startup

if I go 75MPH it stays on
if I let off the gas on a good decell it goes off

as soon as I touch the gas pedal, even the minutest
it goes to slow blink.

(they said it means "lean")

i get worst mileage than I did before (17) - now I get 15MPG!

and no matter what sensors I unplug, for days !(MAP, TPS, Oxygen etc) I get no computer codes

it does its 12 three times and does it again 12 three times in continuous loop with no report

they "the shop" are giving me a run-around that I have to wait days, days, for computer sensor reporting

and last they said I must replace the catalytic convertor else the whole system won't work right.

(hey, the O2 sensor is BEFORE the convertor)

PLEASE help me
the car feels like it runs great
i did advance the timing a bit after getting it back

i have been monitoring this for two weekd now
i have even substituted "new" sensors when I've bench checked then already (you know, volts and ohms, I'm an E.E.)

THANKS and I will pay more for the solution to this. I am so tired of chasing - guess I shopud have went to the dealer.

Please answer each concern you see in this letter

Carlton Lovejoy

Posted at Sat Oct 11, 2008 5:46 pm
By James R. Weizel, Have Donated

Plugged convertor won't keep a car from starting.
Question; If the convertor was, as you say, "seriously plugged", how did the shop unplug it? If it was seriuosly plugged, you would have so much back pressure the motor would barely come above an idle without fighting itself. And now they want you to replace it. Hmmmmmm.
Computer; The computer, if it's working correctly, should log a trouble code in memory at the same instant the light comes on. Can you scan the "rebuilt computer" and get any stored codes? Even after you disconnect a sensor? If not, I would have to say your computer is defective. Please advise, this will be interesting.


NEW MATERIAL HERE (the "advise" you asked for

interpretation correction:

the shop "gutted" the convertor, this DID make the car run - fact and yes, how it "had" barely run above idle (would and wouldn't) just as you said, was eliminated.

yes I have had sensors unplugged for days (map, oxy, etc and NO REPORT)

matter of fact, the computer is in diagnostic mode
with simply the key IGN "on" flashing the 12 code
continuously. The way it worked before the shop sent it out to illinois was right, the Check Engine Light just comes on once and goes out.

I have replaced the catalytic convertor and my mileage is up 2 MPG, the car likes the backpressure!

Please just confirm to me that the computer is bad based on what I have told you. I still believe another
MPG or two is in place when the computer is made right, my personal belief is that the mixture is a little rich due to the computer in some kind of loop.

Please comment


Do you
have the same problem?
Tuesday, October 14th, 2008 AT 10:56 PM

1 Reply

  • 2,424 POSTS

Now let me get this straight. Was it your old computer that flashed "12" all the time, or is it the rebuilt?
Was it the old computer that you couldn't log a code into by driving with a sensor unplugged, or the rebuilt one? If any of the above traits apply to your "rebuilt" unit, it is definitly bad. Your response came through all scrambled, so I had trouble understanding what you were trying to say.

Was this
Wednesday, October 15th, 2008 AT 2:56 AM

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