AlexsZ

Car was acting really odd at low rpms earlier this evening, almost like it was misfiring badly, then the SES light came on...So, i pulled over to hook up the laptop to find out what the dealio is.

The car is idling, laptop is now connected and DTC codes 26, 42 pop up...

26 has to do with EGR, I removed all of mine, did I forget something to disconnect, its been gone for quite a while and this code just now popped up.

42 has to do with my IC circuit...any experience with what it could be. I dont even know what/where the hell it is, but will do a search and find out.

So after calling a friend to hop online, we find out that my 10amp fuse in under the hood was blown (fuse for the fans). So replaced it, and blew it again. So, I'm assuming a wire has become exposed or something?


77(this code came up at the very end of the problems...) ...i read elsewhere that it has to do with the big 'box' relays under the hood, in my box of fuses/relays there. Do they need replacing, or how do I test them to see if they're bad?

Also, a code I've gotten ever since I did my heads/cam swap, is DTC 33, MAP pressure is high-low....I've tried searching to solve it, but have come up with nothing.


Need some help, I'm still searching to find answers, but not really getting any solutions yet.
Search continues....

Injuneer

Step #1: Use a reliable list of codes. You've got a couple of them wrong. I recommend Shoebox's Trouble Code Lists . The alternative would be the one at the end of my ScanMaster writeup.

Using those resources, you would have found:

DTC 26 = Evaporative Emission (EVAP) canister purge solenoid valve circuit.

Nothing to do with EGR... that would be DTC 27. Check the EEC purge solenoid, and wiring thereto.

DTC 77 = Cooling fan relay control circuit.

Makes sense. As you've noted, you have a short somewhere in the fan control circuit and need to find and correct it.

DTC 42 = Ignition Control (IC) circuit (shorted or grounded circuit)

This is the dificult one... there is an extensive list of possible causes. The logic tree for sorting them out is included in the shop manual. Getting a copy of that chart is the best way to approach it.

94formulabz

Did you remove the MAP sensor so that you could get to an intake manifold bolt? If so check that when you reinstalled it you didn't crush the rubber gasket. If not, you may have another small leak somewhere else.

Good luck with that other stuff

-brent

AlexsZ

oKay, i went out...replaced the 10amp fuse in the underhood fuse box for the fans; I reuploaded my programming after I reset the pcm.
Started the car, about 10seconds into it, i get the "DTC 1 open fan failure" ...then, DTC 77 about 20seconds later followed by 26.
**Edit: DTC 26 has the (QDM) error with it, is that pointing to my PCM possibly being bad? I've got another PCM that I could put in it...?**

Did NOT get DTC 42, so would it be safe to say that its the EVAP Purge Circuit thats bad, and not the ignition circuit?

Maybe I should just replace the EVAP soleniod?

AS for the MAP, we did take it off..and the green connector is missing its 'clip' that helps secure it into the sensor, wonder if that could be a sign of it being messed up...

Injuneer

Where are you getting your code info? You need to read my response. QDM = Quad Driver Module.... but that is a 1993 and earlier code. Not used that way in 94 and up. Did you check the EEC solenoid? There should be +12V supplied to it. Check for +12V on the brown wire. Ground the other pin (dark grn/white wire) and it should open, as evidenced by the ability to blow through it.

DTC 33 = Manifold Absolute Pressure (MAP) sensor circuit (signal voltage high, low vacuum)

What is your MAP reading at idle? How big is your cam? Are your valve adjusted correctly?

Yes.... a broken connector can cause problems. Why would you leave it broken... it is one of the most critical sensors on the engine.

AlexsZ

Excuse me...made a mistake, DTC 26 has (ODM) at the end of it, and i'm using LT1 edit communicator tool to get these codes.

I'll check EEC solenoid...to ensure its working properly.

At idle, my MAP is between 66-69kpa...and the pin/connectors arent broken, its the clip that ensures it's to stay in place is what broke off, the connectors/sensor itself arent broken...BUT, could be internally. Its been this way ever since my H/C install, about 3 months ago..and SES light comes on with DTC 33 only if I'm idling, not when I drive. AS soon as I get moving again (if car idled a bit low or whatnot) the SES light will go off.

Also, I'm reading your posts...I just dont know if I'm missing anything. I'm trying to do this step by step, per what your telling me could be the issues, sorry if I missed something. But thanks for taking the time...really!!

Goin back outside....

AlexsZ

OKay, finally went back out and was able to look at the car again and just realized something: The fuel line that runs from the bottom of the EEC solenoid to the carbon canister is plugged, and in the bundle of fuel lines (by the throttle body), is plugged as well.
We did this when we did my heads/cam and we blocked it off thinking it was strictly emissions related...now I see differently.
I'm guessing that the EEC solenoid is now burned up from being improperly connected for about 3 months....?
I have the line, so I'm going to reinstall it and see if that error code goes away.

As for DTC 42, am going to purchase a new ICM and see if that solves that issue.

Injuneer

Your not going to "burn up the solenoid" by simply plugging the lines into and out of it. It could care less whether there is anything flowing through it.

And, since you're OBD-I, the only code that sets for the EEC system is for the solenoid. There is no diagnostic for actual flow or absence of flow, like there is in OBD-II, so reconnecting the lines isn't going to cure anything. It is a problem with the solenoid, or the elctric wiring to the solenoid.

AlexsZ

k...replaced the solenoid, code 26 still gets thrown....time to check the wires from the solenoid to the PCM.