Im getting code 42 every once and. a while when i get it my car doesn't run the best and when i restart it once its still there and the second time its gone. I have a 87 2.5 and from what i can see it does not have a distributor but a ignition coil. Ive tried to look but no one really has a 87 2.5 it seems like so its hard to find stuff. Thanks

quote Originally posted by 16austin16: Ive tried to look but no one really has a 87 2.5 it seems like so its hard to find stuff. Thanks

Lots of people have an 87 2.5. Are your spark plug wires old? Cleaning the ignition connectors may help too.

Code 42 refers to an electrical fault in the EST (electronic spark timing) circuit. The first thing to do would be to check the electrical connectors on the ignition module (the regular wires, not the spark plug wires). Make sure the contacts are clean. Also, check to make sure the PROM chip in the ECM is fully seated. Electronic chips can sometimes "walk" out of their sockets over time. And make sure the ECM electrical plugs are snug.

If you have a multimeter and some time, here's a more in-depth article on troubleshooting a Code 42. It talks about a distributer, but the DIS in your Fiero works very similar.

http://www.fieros.de/en/v6help/code42.html

1. See my Cave, DIS Ignition, Ground "Myth" notes and 87-88 DIS Duke ECM

2. Clean/fix all grounds bolted to engine/trans. DIS brick uses grounds here to ground the PIM and part of ECM. Coat wire ends and hardware w/ silicon or Brake grease to keep water out.
Unbolt C500 and pull/plug connector a few time to make sure all pins get good contact. Don't clean it. Grease is OE to keep water out. DIS brick power goes thru here.

3. Missing/iffy DIS parts can cause a "fake" DTC 42.
Example: Missing shield can cause problems and even destroy the PIM and Coil(s).

4. If not sure of age/condition then Replace plugs and spark plug wires because can cause above and more and make iffy/bad coil(s).
Caution: DIS hates some types of plugs. read above links.
I use Autolite APP666 "Double Platinum" plugs. Has a bit of platinum and 5 year warranty but Mainly because have Nickle coating to prevent rust on the nut part.
see also https://www.fiero.nl/forum/F.../HTML/140795.html#p6 new plugs.

Caution: Do Not try to take apart DIS brick and other similar plugs. They are metripak pull to seat type and easy damage w/o proper tools. See my Cave, Wire Service

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

[This message has been edited by theogre (edited 01-18-2018).]