88 2.8 Fiero Knock sensor install

[Cidacious]

The ECM is 1227170 stock 88 Fiero V6 computer with custom prom. I have read a few hints that you can add a knock sensor to this engine by running wires to ECM and buying the proper knock sensor and installing. Does anyone know how this is done and what to buy?

[robertisaar]

assuming it's even enabled in the mask?

IMO, it would be easier to run an ECM that has always been meant to play nice with a knock sensor, like a 1227730 or 1227727. and you won't be stuck with the godawful 160 baud datastream either.

[Cidacious]

Yeah, it is definitely in the mask. The tuner messed with those values and assumed the physical sensor was there, but it, in fact is not included from the factory. I don't want to have to change the computer because I just spent $370 for dyno/tune time. If I change the computer they will probably have to start over and re-type all the values to a new mask/definition combo, sensors etc. I have a spare 3.4DOHC computer I may be able to mess with... A different computer may have a different harness pin-out too right?

[robertisaar]

from what i'm reading.... that ECM uses the same basic circuit board as the 1985 TPI V8 motors.... and those used external knock modules that had a knock sensor hooked to it, filtered it's signal, and then sent a signal on pin B7 whenever there was knock.... now, i can't find any V6 motors that used even remotely the same PCB AND used a knock module.... so i'm not sure if the filtering would be correct at all. in 1985 they were still flat-tappet motors, but the bores are way wrong. of there was an application that had a bore similar to the 2.8, i can see it working....

the 7170 is specific to the fiero 86-88 2.8, but the ECMs it shares a lot in common with are the 1226869(85 fiero 2., 1226870(85-86 LB6 and LB8 2.8s and 85 5.0 and 5.7 TPI motors) and the 1227302(86-89 LB8 and 86 LB6 2.8s)...

CHANGE OF INFO: the 85 F-car 2.8 with MPFI also used a knock module and sent a signal on pin B7. that should solve your problems.

[Joseph Upson]

I can't recall an ESC module on my old 2.8 F body but I remember the MASS Airflow Sensor that you would need for that ECM mask. There shouldn't be that much work in switching to the 85 Fiero ECM, they could copy and paste the values from the tables they changed as the data should be pretty much the same everywhere else as long as the cars the masks are from are similar. I started tuning with both the 24 and 24A code and even between the auto and manual trans I don't recall seeing an awful lot of difference in the tables. I'm not sure a knock sensor will work with the later 170 Fiero ECM as the code was incomplete for boost so they may have left that logic out also. There was a 2bar MAP switch in the constants but no supporting 2 Bar spark table from what I recall.

[BillS]

IIRC, only the first year of the Fiero V6 had an ECM capable of dealing with a knock sensor input. You should be able to find one fairly easily (I can dig up the number if you need it - the Miller Woods turbo kit routinely swapped out for this part when the customer wanted to add a knock sensor).