How to avoid Code 42 after a plenum pull
 

To date I’ve done more plenum pulls than I can count and other than a blown INJ1 fuse or a finicky coolant fill I’ve never run into any issues with codes when finished. Recently in doing one for a friend we ended up with a code 42 when it was all buttoned up. Very irritating. After running some diagnostics, specifically the FSM diagnostic tree for code 42, we determined that the most likely issue was a bent pin at the main DIS module connector. This means pulling the plenum again. Which also means draining and later refilling coolant. Some searches on the forum revealed that this is not an uncommon issue because of the awkward access to the main DIS connector for reassembly. It doesn’t take much for even a slight misalignment to cause a bent connector pin. That’s what we found, a bent pin.

It occurred to me that if I added one step to the reassembly process I could assure no code 42 and the associated work of a second plenum pull and coolant drain/refill. Its simple. (Note, you will need a Tech1 or code reader of some type.)
When you get to the point where the plenum is on (not bolted down) and all the DIS connectors are in place, stop. Now connect all the other electronic connectors that came off in the process, if only temporarily. The MAT sensor, Idle Air Motor, the Throttle Position Sensor and the MAP Sensor. If you disconnected your battery, reconnect it. At this point simply turn the ignition on. (Don’t turn the engine over!) Your code reader will now tell you if there are any codes. A code 42 will instantaneously come on if it’s there. If there is no code 42 your good to go. If you do find a code 42 clear it, cycle the ignition off and back on (don’t turn the engine over). If the code comes back you likely have a bent DIS connector pin. You can now more easily go back and check the connector pins. You just saved yourself a full second plenum pull.
H
:cheers:

Re: How to avoid Code 42 after a plenum pull
 

Block TB Coolant at Injector Housing if you want to make it super easy to remove the Plenum :thumbsup:

See .........1995 LT5 SPECIFIC TOP END REBUILD TRICKS in signature.

Re: How to avoid Code 42 after a plenum pull
 

Very true, I have mine done, but most people don’t do it.
H
:cheers:

Re: How to avoid Code 42 after a plenum pull
 

I removed the two MAP Sensor Bolts (those two bolts are now Allen head) one time making it very easy to disconnect MAP Vacuum and the MAP electrical connector (then removing the MAP bracket and sensor completely). This then made it considerably easier to disconnect/connect the DIS connector with 1/4 inch socket and a 1/4 inch socket wrench with 4 inch extension.

I then connected the MAP electrical plug to the MAP sensor before connecting the MAP bracket with MAP sensor to the Plenum after Plenum is installed which was very easy.

I have never bent a connector pin in the DIS (DIM) but that definitely can happen and worthy of your checking procedure :thumbsup:

This is a 95' Plenum......

https://cimg2.ibsrv.net/gimg/www.cor...2798d4b7c3.jpg

Re: How to avoid Code 42 after a plenum pull
 

Mine had a code 16 with a bent pin. See post #25

Got my car at a pretty good deal due to this a few miscellaneous issues.

http://www.zr1.net/forum/showthread.php?t=29346&page=3

Re: How to avoid Code 42 after a plenum pull
 

That’s true, it depends on which pin you bend.
H
:cheers:

Re: How to avoid Code 42 after a plenum pull
 

It's been a while since I did a plenum pull. I have a slight vacuum leak that could be the plenum gaskets. Hoping it's not the injector housing gaskets. I guess I can't getaway with just slipping in new plenum gaskets or can I. Just drain a bit of coolant and remove the bolts to the plenum. Raise the plenum a bit and prop it up just enough to install the new gaskets on the top of the injector housing and then bolt the plenum back up.

Marc ported the heads ,injector housing, and plenum. There are no secondary's anymore, or secondary actuators all that stuff is history. Anybody have a view of a LT5 with the secondary delete? With the plenum pulled that is.

Re: How to avoid Code 42 after a plenum pull
 

Here’s a shot of mine with the plenum off. I’m running without secondaries as well.
H
:cheers:

https://farm66.staticflickr.com/6553...b7811ec5_c.jpg

Re: How to avoid Code 42 after a plenum pull
 

Now you need Phil's Modified Fuel Pressure Regulator :thumbsup:

The most unique feature of the LT5 is the Full Power Key...........
....But.......I admit on one ZR1 I have also eliminated Secondaries :D

Looks like you blocked TB Coolant.......
......but your Plenum Gasket is backward :D:D

Re: How to avoid Code 42 after a plenum pull
 

What are Y'all doing to hold the gasket in place when putting the plenum back on?

I had a buddy help me a while back who is a former pro-motor cycle racer. He used hair-spray. I never heard of such a thing put it worked!