problem after converting to 1g cas help video included

[Reedup6911]

So I converted to a 1g black top Cas today and it's a first start up since rebuild any thoughts on how to fix? https://www.youtube.com/watch?v=l-7DN2UyMnY&feature=youtube_gdata_player

https://www.youtube.com/watch?v=l-7DN2UyMnY&feature=youtube_gdata_player

 

[NHerron]

I want to clarify first if you don't mind

This is a fresh rebuild and during that rebuild you converted to a 1g cas? Is this the stock engine (95') with the stock (95') ecu? Your not using DSMlink or anything are you?

If you don't have any type of aftermarket engine managment system you must make a signal inverter for the CAS to work correctly just because the 1g cas puts out a different (inverted) signal than what the 95 ecu expects. OR another method is to swap injector wires around and spark plug wires. It will still start either way but will run differently.
Easy link:
RRE Instructions

As to your video I don't know if the CAS would be fully responsible there. But before any assumptions, is this a first start on a brand new engine or has the engine been running fine up until the CAS swap?

 

[Reedup6911]

We got a different bottom end and had it rebuilt,the head is still original, we dropped the motor in and it wouldn't start so people here on dsm tuners recommend I convert to a 1g Cas so I followed the diagrams on ree write up.also the 95 ecu that came with my car was shot so I'm running a 97 ecu I bought from a friend.

Also forgot to answer your question this is the very first start up ever it didn't run before so this is first start up after rebuild

 

[NHerron]

Ok I see then, nevermind about all the inverting stuff since it's a 97 ecu.

Did you set ignition base timing since it's now adjustable? Can you test the IAC motor? What about the MAF? Has that been modified at all? Sorry man, I don't know the most likely cause but there's lots of surging threads. Make sure your BOV isn't opening during idle, which will let unmetered air in, just tighten it more so it stays shut. You should have the BOV recirculated BTW unless running speed density or a GM MAF otherwise you run pig rich between shifts...

Also do a boost leak test since vacuum leaks can cause surging. Unrelated, but we chased a vacuum leak on our suburban, ended up being the intake manifold gasket leaking causing a surge like that.

 

[Reedup6911]

Lol honestly I'm new to these cars and I'm no machanic so I'm teaching myself so sorry in advance if I ask alot of questions.how do I set ignition base timing?what's a iac motor?and maf hasn't been modded at all.I was told a long time ago to recirculate the bov so I'll do that next I appreciate the help and knowledge,

Also on another note since I have the 1g cas am I still going to use the same firing order 4-1-2-3?

 

[mchustle]

If your running the 97 ecu, you keep the firing order 4123. Base ignition is set by grounding the timing connector, which on my 95 gst is a brown plug on the firewall behind the intake mani. Just clip a wire onto the metal prong inside the plug, hook the other side of the wire to the negative of the battery,and start it up. Then use a timing light to set the timing by loosing the 2 bolts on the Cas and adjust it while looking at the lower timing cover with the light, there is a line etched into the under drive pulley and lines on the cover. There is a video on YouTube that you can watch that shows which line is 5* which is what you want. Now since your not running a upper timing cover the just incase your not running a lower timing cover, since you wouldn't have the marks to line up if your not running a lower, you will have to use the gears. This is a little more tricky but still doable. You have to follow the same steps to get it into timing mode but then you need an adjustable timing light. Set the adjustable timing light to 5* and point it at the cam gears an adjust until the timing marks in the cam gears line up when the light flashes.

 

[Reedup6911]

Awesome thank you I was actually watching videos on YouTube how to do it before reading your post thx will work on this in the morning

 

[NHerron]

The IAC motor controls how much air bypasses the throttle plate during idle. So if you turn on the ac it causes a slightly bigger load to be put on the engine therefore needs more air and fuel to keep the idle up and the car doesn't die.

Anyway you probably have the brown style iac which the specs are around 30 ohms (28-32). There is 4 separate sets of coil windings which need to be checked and the way you do that is with a DVOM on the resistance AKA ohm setting. There might be a symbol which looks like a horse shoe pointing down on the DVOM too. This IAC is located on the throttle body right below the intake elbow. You will see a 6wire connector, unplug the connector and move it out the way.

This is a video I found on youtube a while ago...
DSM ISC motor testing & Replacement - YouTube

 

[Reedup6911]

Thank you guys for the help and info I'd be lost without this site and people like you guys kick ass