3400 Swap start up errors

[Kaiju Senso]

Finally got my Fiero swap started the other weekend with a 3400 out of an Equinox (basically a 3500 from the outside). It'll start if you give it a bit of throttle but won't just turn the key and idle like a normal car. Any thoughts on what to check? Run with a 98 monte carlo OBDII PCM with matching fuel rail. Here's a video of it trying to start.

http://www.youtube.com/watch?v=w8QMqJ0qE4k&feature=player_embedded

[Azrael]

Could be a bad/stuck idle air control valve. Did the PCM+fuel rail/injectors come from a known running car?

[Kaiju Senso]

No, I do not know first hand if the car they came out of was in running condition. They were purchased over the internet from a tuning company half a state away. The PCM had VATS removed and was tuned for a manual transmission, could it be the idle wasn't set right to account for not having the automatic?

How stiff is the IAC supposed to be? Should it spring back when compressed? (about a quarter inch) because mine didn't. It could be worn out but I haven't seen a new one to compare it to. It definitely had some carbon build up from the EGR (now removed but throwing a code) but I tried to clean it off when I cleaned out the throttle body.

Come to think of it, I'm not even 100% sure the fuel rail was from a 98 monte because the injector wiring harness was different, thus I got one from the local Pull A Part to match the plugs on the 98 Monte harness I disassembled. The fuel in and return lines were similar though (not the long 3400 ones from a grand am for sure).

Either way if you give it throttle it'll start and the less throttle you give the lower it'll idle down to about 650 where I'm just barely touching the throttle and it'll hunt for idle intently. Let off completely and it straight dies. Waiting now for my exhaust to come back from getting modifications before I can finish hooking up the necessities to give it a test drive.

[pocket-rocket]

An IAC should stay where you put it if actuating it by hand. I'm not sure how familiar you are with stepper motors, but that's how the IAC operates.

[SappySE107]

What throttle body are you using? Is the IAC passage on the back of it connected to the main bore?

[Kaiju Senso]

Throttle Body is from a 2001 Alero LA1


and @pocket-rocket, thanks, wasn't sure if it was just stuck from the carbon buildup and no clue how it works.

Oh and the TPS was reading about 0.57 volts with no throttle (if it is of any help)

[SappySE107]

Yup, the IAC passage probably doesn't go anywhere on the new intake manifold. Notch it between that square and the main bore and it will probably idle fine.

[Kaiju Senso]

Oh the upper intake is from a Venture (smooth top, now realize it has the worst flow so will be looking for a 3500 upper) The Equinox upper intake just looks way to tall to clear the Fiero decklid.

[Kaiju Senso]

Thanks for the insight. I just wanted to post some pictures for everyone to see and understand if they didn't know there was a difference.



Notice the different IAC port openings.



Chevy Venture upper intake.



Olds Alero upper intake.

I wouldn't have even looked into this without your help Sappy, thank you!!

[pocket-rocket]

I didn't even think of it. We had to deal with this same thing on the 96 Achieva 3400 swap we did, too...

[SappySE107]

That is why I knew:P