Please Help!Most probable cause for Code 42?

[Mustang 1]

Please help!What is the most probable cause for code 42?This is the only code that I have.I am right now checking all connections to the module,ecm,etcThe car runs great for awhile then the check engine light comes on and the car runs like s*#%!Sometimes I can shut the ignition off and then restart and the light goes off and the car runs fine!Sometimes the light will go off by itself when cruising!Any ides?Thanks in advance!

 

[Mustang 1]

Posible causes and Questions..
1.BYPASS line is open or grounded-Wher is this line and how to identify?
2.EST line is open or grounded-Same Question as above.
3.PROM or CALPAK not seated properly-Remove and reinstall-What to look for?
4.Poor connection between ignition module and ecm-Where to check?
5.Poor routing of EST harness-Example?
6.Poor ignition wires EMI induced ignition noise-I have Taylor Pro Race 409 Ignition wires,but I do have some ignition nosie in the radio.
7.Faulty ignition module-Remove and have tested?Like at Autozone?
8.Faulty ECM-How to check?

All help will be greatly appreciated-The Grand Rod Run is in Pigeon Forge this evening.I wanted to participate,but not running lik this.Also,when this happens,the take acts weird.It shows about 2000 rpm at idle even though the idle is normal at 1000.Seems to be connected.What triggers the tach as far as the ignition or sensors go?Thanks gain!

 

[bruce]

Originally posted by Mustang 1
Posible causes and Questions..

6.Poor ignition wires EMI induced ignition noise-I have Taylor Pro Race 409 Ignition wires,but I do have some ignition nosie in the radio.

Try a different set of wires, and then a new chip.
Those are the two quick and easy tries to fix it.

 

[Mustang 1]

Back again! I have been playing with this car for over a week now! I still get code 42. It also seems like the BstC Boost Commander sometimes des not operate properly. There are splices with like piggy back connecter right next to the ecu. This connections seem kinda suspect to me. Is there a possibility with a bad splice there causing this to happen? I got a member here to send the directions to me for install the BstC and it says that the red wire connects to the ecm ignition power feed which i a pink/black wire. Is it a possibility that a poor splice here throw this code? Also, the other night on the way home the active light on the boost commander seemed much dimmer than usual and now is brighter-could this be a bad connection here also? Judt thought some of you may have some ideas. Thanks in advance!

 

[Mustang 1]

I keep leaning towards a problem with the chip,so I just ordered two that are specified for my combo from PTE (Joe Lubrant).He seems like a great guy and I am looking forward to trieing his chips!

 

[TurboBob]

Are you using Direct Scan?

It will cause this sometimes if it picks up noise.

The solution is a shielded ribbon cable or at least a shorter cable.

The same thing can cause popping at WOT....

Bob

 

[Mustang 1]

Thanks Bob for your reply! I do not have a direct scan. I do have a BstC Boost Commander. I do get some interference through the radio from my Taylor wires. The BstC is mounted directly above the radio and spliced in the ecm with piggyback splices. This seems to be an iffy connection at best! I am going to solder the splices and double check and insulate.This problem could also be related to the chip, so I just ordered 2 new ones from Joe Lubrant for my combo. I like to tinker with my car - jus not everyday! Thanks

 

[87 we4 gray t]

check tps voltage and the grond wire coming from the ecu(blk wire on the edge of the plug). problem i had.

 

[Sinful6]

I am looking to buy a BSTC for testing if you ever decide to sell yours...

As for you problem, I would just change the coil and such... see how it runs then.



-DC

 

[cyabye]

I had the same problem with my 85. Some days the car would run fine and other days, the check engine light would come on and the car would start running rough and misfiring. I scanned the computer and came up with code 42. It ended up being a loose ground on the pass side fender. When I first got my new 87 T, it also had code 42. Ended up being a bad ECM. Providing that you dont have wiring harness problems, and have checked and cleaned the grounds, code 42 usually indicates a bad module, ecm, or both.

 

[Mustang 1]

Back again! I just replaced the chip. I double checked everything! The ground on the fender I was able to turn a little tighter. The ground on thefirewall I was unable to really tighten. It appears to have been over tightened at some time. I think it is a self taping bolt actuall into the sheet metal.Would a bolt wit slightly larger threads fix this?Also could this cause the code 42.If it by chance is the ecm how do you check?Just replace with a known good one? One of the possible causes said something about a bybass wire - what and where? Thanks again for all your help!