PaveTim

I get a code 43 and the car runs like crap, no power and runs rich. But it seems to eventually go away. I read it could be the knock sensor, spark control module which i have an accel 300, or defective ECM. How would I go about testing these to see which one is the problem. Thank you for any help guys. Oh yeah it is a 1991 Z-28.

Dave Y

????

the ESC module is over near the brake booster, someone else will need to help you with diag

bigals87z28

ok you get code 43?

disconnect the knock sensor
put the ingition in the on position
grab a multimeter and test from the knock sensor wire to a ground it should read between 4-6 volts. if its more or less, read the lower 2

if the voltage is between 4-6 vols
probe the knock sensor terminal and the block you should get a reading of 3300 and 4500 ohms
if its between the two check thde harness and sensor connetor if thats ok remove ecm and be sure the mem-cal is properly seated into the ecm, if the memcal is sat in perfectly... replace the memcal.
If the ohms are not between the two, the knock sensor is bad


IF NOT :the voltage is over 6, the wire from the knock sensor could be to closed to secondary igiition wires or the wires is shorted to voltage or its a fulaty ECM.

IF NOT: voltage is less then 4, the wire is open or shorted to a ground or its a faulty ECM



if none of this works, I give up.

cbmotorsports

iTrader: (1)

You said to be sure the mem-cal is seated properly. What is the mem-cal? Is this the same for a 91 350 tpi? I'm fighting the same thing. Thanks.

david roush

iTrader: (1)

Mem-cal is the 2 wire connectors that plug into the ECM.

cbmotorsports

iTrader: (1)

Thank you! One other thing, I have three connectors on mine. I assume I should on a 91 right?

LnealZ28

No, the MemCal is the "chip", the long blue part that plugs inside the ECM under its access cover. Your '91 will have 3 harness connectors going to the ECM, but they are NOT the MemCal. And there is no ESC module mounted on the firewall on the '91, it's on the MemCal itself, inside the ECM.

MemCal:

mike macedo

I AM HAVING A SIMMALAR PROBLEM ON MY 87 TPI ONLY IT DOSN'T GO AWAY AND MY CAR STALLS WITH THE HEADLIGHTS AND BRAKES AND TURNSIGNALS ON. I HAD REPLACED THE KNOCK SENSOR 3 MONTHS AGO AND MY CAR RAN FINE BUT NOW 43 IS BACK AND I CANT FIGURE IT OUT THIS TIME

cbmotorsports

iTrader: (1)

O.K. found that do not have 4-6 volts on the connector. So you say that should be my problem. I haven't been able to trace that wire up into the loom. Can somebody tell me or give me a diagram of were it goes so I can bypass it. Also, now I'm getting code 34. I haven't touched anthing else. It is a 91 so I do not have a maf sensor so it has to be the map sensor. Like I said I haven't worked on anything else.

cbmotorsports

iTrader: (1)

PLEASE ANYBODY!!!!!!!!!!

87350IROC

iTrader: (2)

sounds like the ecm to me

cbmotorsports

iTrader: (1)

I have two. They both get the same codes, but I am using he same chip.

mike macedo

plugs and wires, and get this a FUEL PUMP RELAY?!?!?!? fixed my car. i tested my plug wires and 1 was bad so i replaced 'em, cleared codes bam 43. new plugs nxt still 43, 1 cold morn car wouldnt start & i didnt hear fuel pump &or relay, replaced relay, started car, no ses light on. now it runs great and no bright yellow light. almost totally unrelated but in a way it is. i would have never thought of that but 1 of the guys @ my shop said he ran into something like that on an old buick. so give that a try, worked 4 me