david roush

iTrader: (1)

I know it's the electronic spark timing , but what causes it and what do i check for to fix it ???? Any help on this one ???? I already did a search that yielded nothing.

Morley

Depends on the year, knock sensor, prom, ESC...

david roush

iTrader: (1)

Well the car is a 92' ...motor is a 350 crate motor and the tuned port set up is off an 89' IROC. If you think prom morley, you might be right .I know the prom is not really the right prom for my car because it came out of a automatic and mine is a 5 spd. I have an issue with the shift light because of it and the torque converter being absent. Just didn't know the prom problem would flash me a 42.

Morley

Prom might be defective, or ignition module or the ESC. On the speed density cars the prom handled the knock sensor, which is tied to spark control, or was it the ignition module... either way ...
Oh and it could be the knock sensor itself, do you have the one for the 90-92 TPI?

david roush

iTrader: (1)

Yea...i changed knock sensors when i put the 350 in. Although Auto Zone tells me a 92 305 tbi and a 350 tpi has the same part number for the knock sensor. And i am running MAF not speed density.Everything was working okay until i did the tpi swap.

Morley

Wow, you've got a real conglomerate of parts there. First thing, if you are running the MAF computer, you have the wrong knock sensor in there, you need an 87-89.

You have an incompatilibity issue with the knock sensor and ESC. You need the ESC for the MAF cars and definately need the Knock sensor to match. The code you are getting is probably the one I got while running the 305 sensor. It is a failure of the knock sensor self test routine. I put in the proper 350 K/S and it has disappeared for 2 years and counting.

91gta_tpi

My GTA read the same code, but nothing was actually wrong with it so I just reset the comp on it, just unhook your battery for about 5 min, and hook it back up and it will be cleared, as long as you are for sure nothing is really wrong with it.

8Mike9

Not to contradict the above advice, but all KS issues I've dealt with came from code 43's, not 42's.

What I have noticed regarding 42's, is that any solution was due to either the connector (EST bypass) was faulty, or wiring issues. (my only "experience" with 42's have come from readnig here on the TPI Forum)

In fact, my Helms doesn't mention anything about the KS, in regards to troubleshooting the "42"...besides wiring, it lists the fault as ECM or ignition module.

Hope this helps.


Edit:

It also mentions that if the Memcal isn't fully seated, could result in a code 42.

Jproz1167

iTrader: (3)

a faulty magnetic pickup coil will also trigger code 42, they run pretty crappy though when this is the problem

david roush

iTrader: (1)

Well the car definitly isn't running crappy. Motor sounds smooth and with the TPI set up on i can be in like second gear rolling about 30 mph and if i stomp on it the rear wheels break loose. Auto Zone gave me a print out on code 42 today and what to do to try and fix it and it mentions nothing about the knock sensor. The code i am getting is a soft code (check engine light isn't on, but i still get the code when i check the diagnostic plug) I think the first thing i am going to do is what 91 gta suggested and take the battery cable off for 5 minutes and try that first, seems the most logical, easy and less costly right now.

Dan8289gta

The pickup coil can cause a 42? I am having issues with code 42 right now and my car runs ok at idle or low rpms but runs like sh*t over 30 mph it doesnt advance timing so when you stomp on it it backfires and sputters, i took it to the shop because i was fed up with messing with it after two weeks and after 2 hours of supposed "diagnostic time" swapping parts i just replaced they said it is the computer but they dont sound sure and they want 58.00 to install one...lmfao....and if i install it myself and its not the problem oops now i have 2 ecms. Its really pissing me off to pay them to trial and error fix it , i could have done that myself ya know. They even told me my car has no esc module. So much for paying "profesionals" to do it right. would have been better off leaving it at home and buying a keg of beer to drink until it was fixed. ....Sorrry jut needed to vent a little

david roush

iTrader: (1)

Dan...try checking out the wires in the pigtail that hooks in the back of the distributor. There should was 2 pigtails (i think they both connect from the coil but not sure)that went into mine, the one pigtail that had 4 wires going into it had a bad prong inside , when i was pushing the pigtail in, it was pushing one or a few of the prong connectors out. I bought a new pigtail, soldered it, put in a msd 6a ignition box in and i was good to go. Make sure you check it first cause that little pigtail was $38.00. Just something for you to check.

Dan8289gta

cool ill take a look tonight thanks