thejman92

Hey everyone, I'm hoping to get a little help.

I picked up an 87 trans am with a 305 LG4 Rochester CCC Q-Jet in April and still haven't got it running reliably yet. It had more or less been sitting since 95 when I got it.

I'm having two continuous problems. It idles high all the time, and it wants to die when I give it gas (in gear).

In an attemp to eliminate gas and vacuum related issues here's what I've done so far: inspected vacuum lines, replaced the three vacuum diaphragm purge valves, ripped out the intake manifold and replaced the gaskets, sent the carb away to be profesionally rebuilt and adjusted, replaced the alternator (it powers the electronic choke), replaced the mechanical fuel pump and filter, and checked the fuel line going to and from the pump and vapor canister. Oh and also through on a new cap and rotor for the distributor.

Any thoughts on what it could be? Ignition? Computer? Bad wiring? One of the previous owners had an after market security and sound system installed. And the other attempted to remove the security system with only about 50% success. Keep in mind also, who knows if mice could have chewed something.

Thanks!

usetaboost

iTrader: (1)

Sounds like my 85 regal I can't figure out. I've done about everything you have done. Even disconnected and plugged the port on the egr. Starts fine, idles high and acts like it doesn't want to kick down. Replaced that goofy stepper motor off another carb. I've swapped about everything and still the same. Even busted out the converter. Hope you get it resolved. My next step is to pull the cap, rotor, and module and swap it out with known good.

five7kid

iTrader: (14)

First thing is to set the base timing with a timing light. Nothing will be right if the timing isn't right.

Next, is the SES light on? If so, have you checked the codes?

Is the choke light on?

High idle is almost always something keeping the throttle blades open, whether that is the choke high-idle mechanism, a gasket in the way of the throttle blades, or a bad throttle cable. Check the choke mechanism first, including the thermostat. You mentioned replacing the alternator because it has to be working for the choke to open (which is true), but did you observe the choke not fully opening? Did it start working after you replaced the alternator?

Idle speed is adjusted on the car, both high idle and curb idle. Even a "professional" rebuilder can't do that off of the car.

usetaboost

iTrader: (1)

Check the front vacuum break and see if it holds. Found one bad on mine and seemed to make a bit of difference.

usetaboost

iTrader: (1)

Why did you close my thread? It may not be a third gen, but news flash, a dualjet is the primary side of the quadrajet and they operate the same way the v8 feedback quadrajets do. That's why the 4 barrel intake and 4 barrel feedback quadrajet is a DIRECT swap.

Sorry don't mean to booger up your thread jman92. Have you checked to see if you got a good fuel stream squirting in the carb when you blip the throttle? Try unhooking the egr and capping off the port on the valve and the carb. Also check your vacuum breaks and make sure the aren't leaking. May be a good idea to get a vacuum reading also.