build thread for 2.8 carb to chevy tbi.

[dangerranger83]

Cant view the video on computer or phone, not even trying the other links that your photobucket has.

Try youtube, photobucket has always been iffy.



Posted from my laptop because I can can can.

 

[Lil-Pony]

I know this would be hard to test driving but is the timing staying in timing and it's not retarding/advancing when it's not suppose to?

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Exactly how do those weights on the distributor work? I tied them up like in ricos pictures, but i wasnt able to find a wire as heavy as his.

 

[dangerranger83]

You will have to ask him on that.

If your fuel is consistent, then it's time to look at your ignition. If that turns out, then I'm at a loss.

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[Lil-Pony]

http://youtu.be/5uonK5kjZHY

 

[dangerranger83]

Is the computer suppose to know when you go into gear and that the engine it's taking on the load of the transmission going into gear?

Personally, I'm one of those people that wouldn't worry about that small of an idle fluctuation in gear.

How does it do when the engine and trans is cold and you put it in gear? When I had my 2.8 with the tbi setup on it, hot or cold start, it would idle right on 800rpm. Yes I had a manual buy i also disabled it's ability to be able to control the engines idle by unhooking the ICA and manually setting the idle myself.

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[Lil-Pony]

Thats the issue in the mornings it will kill the engine as shown in the video. I think the auto ecm had a wire for that. But i believe they also controlled the trans servos.

 

[cammeddrz]

there is no way on the gm ecm for it to know it is in gear, the auto trans ecms did have an input for a PRNDL switch, which raised the idle when it was put into gear.

you also don't need to disable the IAC to change the idle, if you google how to change the idle on a gm tbi, about a gazillion results will pop up on how to do it

you disabled the centrifugal weights in the distributor correct? it doesn't matter what you used, if they are immobilized, you are fine

 

[dangerranger83]

I said ica, idle control actuator. Don't know if the gm vehicles had those or not.

If the auto trans on the gm ecm have an input for it to know when it is switching gears and it isn't being used, then use can see why the idle is doing what it does and why it is dying due a sudden increase in load on the engine and consistent load on it.

The struggling to maintain speed sounds like the timing is losing its advance.

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[cammeddrz]

he also may need to just bump the idle up a tiny bit

 

[Lil-Pony]

I said ica, idle control actuator. Don't know if the gm vehicles had those or not.

If the auto trans on the gm ecm have an input for it to know when it is switching gears and it isn't being used, then use can see why the idle is doing what it does and why it is dying due a sudden increase in load on the engine and consistent load on it.

The struggling to maintain speed sounds like the timing is losing its advance.

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So bumped the idle up to 850ish checked the resistance across almost all the wires replaced the iac. Check the map voltage seemed ok to whats described on the chevy forums. Startin to run out of options. My friends diagnostic wouldnt communicate with the ecm. It cant be the est since its not hooked up to the knock sensor. Tho is could be giving a constant knock signal to the ecm. Any suggestions before i start to look in to pining out and auto ecm

 

[dangerranger83]

A knock signal will retard your timing.

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[cammeddrz]

it works the other way around, if the Knock sensor is not hooked up, it will just not send any signal.

both of the rigs I did this on, don't have the K.S. hooked up.

 

[Lil-Pony]

it works the other way around, if the Knock sensor is not hooked up, it will just not send any signal.

both of the rigs I did this on, don't have the K.S. hooked up.

Your correct the est deciphers the ks and decide what is engine noise and whats a knock, when it detects a knock it brings the blk wire to a lower voltage. Telling the ecm to start retarding. Then once the knocking goes away the signal wire goes high again.

 

[cammeddrz]

Rico9 did have an ECM failure on his, and he needed to replace his Junkyard ECM with another one. It was running like crap. but I suspected ECM, so we swapped the ecm from the other one and the problem went away.

but I doubt you have a spare ECM like we did

 

[Lil-Pony]

drove good this morning didnt stall on startup, but once it was warm and i got to school and threw it into park then back into drive it stalled flat on it's face.

going to take it to the mechanic who diagnostic hooked up to last...

were yalls autos or manuals?