1989 GT manual with a/c ECU Computer

[yellow3800]

my 89gt threw a computer [confirmed, by good knock-sensor circuit] and code 43.

I need a computer with a/c and for manual trans.

don't need the chip... but hey, these are so old, I may buy in bulk, so whatever right!

andy
amckevitz@yahoo.com <---best
865-771-5310 <---2nd best

[Cliff8928]

The A/C, engine and trans are all determined by the PROM (chip).

What you need is a '7730 ECM which can be found in any V6 87-93 and in some 87-88 2.0 models among a plethora of other cars.

[yellow3800]

So I bought a computer - problem

Code: Select all

.  knock signal voltage is 1.5v-1.9v [1.5v at idle] sluggishly running...  

I'm ready to buy a chip, because

circuit wires okay
computer board replaced 2x
knock sensor okay
crankshaft sensor okay
ignition module replaced okay
coils okay
plugs and wires okay

Andy
amckevitz@yahoo.com

[Cliff8928]

You don't happen to have a scanner to read the knock retard from the ECM, do you?

I had a code a long time ago and the knock sensor appeared fine, but replacing it cured all.

Either way...

Open circuit voltage at the knock sensor harness should be roughly 5v.

Resistance between knock sensor and engine block should be 3300-4500Ω

[yellow3800]

I'm getting 1.5v on the knock sensor signal and the resistance on the sensor checks properly [your values correct]. circuit is not shorted to gnd, or open - wires check fine and harness is in great shape. the diagnostic tree says to replace the chip. when the car starts, its immediately fumbling around like its on 5 cylinders or less... thats how rough.

no I don't have a scanner to see the timing... [do they make handheld ones for that?] I always thought those were the $50k monster machines.

I have 3 computer boards and one mem-cal. all boards give me the 1.5v reading.

[wicked-irocz]

I have $110 into my scanner setup IIRC.

[yellow3800]

I'd love to see all that aftermarket tubo stuff you have. wow, that is one thing I haven't conquered yet - and rebuilding transmissions, but have no desire to do that, but hey, I will given the opportunity.

UPDATE: I have 3 computers of svc no 1227730 and have found the knock sensor ref. voltage to match the diag. tree. of 5v when sensor unplugged and 2.5v with it plugged in.

this is correct, and the code 43 prevails. The diag tree says bad mem-cal.

my chip is labeled APWF and has 2492 at the bottom. I don't know what to do from here... must call international autoparts or an aftermarket chip supplier or something.

too bad this car is my daily driver! its barely worth it! lol

[Cliff8928]

I looked up your MEM-CAL ID and it's the second revision (of 4) for the 89 2.8 MT.

The MEM-CAL I have in my GT (ARCN) looks to be a service replacement to correct the problem in this bulletin

OCCASIONAL ENGINE STALL DIAGNOSTIC/NEW SERVICE MEMCAL #89-276-6E - (10/16/1989)

THIS BULLETIN HAS BEEN REVISED TO UPDATE THE PART NUMBER FOR THE 1988 A STE MODEL.

SOME CUSTOMERS DRIVING THE FOLLOWING CARS;

- 1988 J-CAR WITH A 2.8L ENGINE (VIN CODE W) - 1989 A/J/L/W MODELS WITH A 2.8L ENGINE (VIN CODE W) - 1988 "A" ALL-WHEEL-DRIVE MODEL WITH A 3.1L ENGINE (VIN CODE T)

MAY COMMENT CONCERNING ANY OF THE FOLLOWING:

A COLD START STALL, A TIP-IN HESITATION, OR A DECEL STALL

IF A CUSTOMER COMMENT CONCERNING AN OCCASIONAL ENGINE STALL OR A DRIVE HESITATION IS RECEIVED, THEN COMPLETE THE FOLLOWING:

1. PERFORM DIAGNOSTIC CHECKS, PER SECTION 6E OF THE SERVICE MANUAL AND REPLACE ANY DEFECTIVE COMPONENTS.

PROCEED TO STEP #2 ONLY IF DIAGNOSTIC CHECKS UNCOVER NO CAUSE FOR THE CUSTOMER COMMENTS.

2. INSTALL A NEW MEMCAL, WHICH MAY BE OBTAINED FROM GMSPO (REFERENCE THE ATTACHED SERVICE PART NUMBER CHART).

IMPORTANT: THE FOLLOWING PROCEDURE MUST BE COMPLETED WHEN REMOVING AND INSTALLING A 60 DEGREE V6 ENGINE CONTROL MODULE (ECM) MEMCAL (REFERENCE CORPORATE BULLETIN #836540 AND #836540R).
BUICK BULLETIN # 89-6E-2 DATED 11-15-88 CHEVROLET BULLETIN # 89-41-6E DATED 12-16-88 PONTIAC BULLETIN # 89-6-9A DATED 12-07-88 OLDSMOBILE BULLETIN # 89-T-16 DATED 12-07-88 GM CANADA BULLETIN # 89-628-102 DATED 12-15-88

A). DISCONNECT THE BATTERY.

B). REMOVE CURRENT MEMCAL AND INSTALL A NEW SERVICE MEMCAL.

C). RESTORE THE BATTERY POWER AND PLACE AIR CONDITIONING CONTROLS (IF EQUIPPED) IN THE "OFF" POSITION.

D). FIRMLY APPLY THE PARKING BRAKE AND BLOCK THE DRIVE WHEELS. START THE ENGINE, AND SHIFT THE TRANSAXLE TO "DRIVE" FOR AUTOMATICS OR "NEUTRAL" FOR MANUALS.

E). ALLOW THE ENGINE TO RUN UNTIL THE ENGINE COOLING FAN HAS CYCLED ONCE, OR A MAXIMUM OF 10 MINUTES.

F). TURN THE IGNITION KEY TO THE "OFF" POSITION FOR AT LEAST 5 SECONDS.

G). START THE ENGINE, AND SHIFT THE TRANSAXLE TO "DRIVE" FOR AUTOMATICS OR "NEUTRAL" FOR MANUALS.

H). ALLOW ENGINE TO RUN FOR AT LEAST 5 MINUTES.