HI im wondering if someone can help me.
I have just purchased a 85 iroc with the 305 TPI motor.
Everything is stock except for the smog removal.
When i picked the car up it starts hunting on startup and running very rich, so when you drive it it bunny hops until you give it some throttle because the revs are going up and down.
I have changed the IAC valve hoping it was that but its still bad on startup but if you rev it a bit it runs alot better and doesnt run rich but still doesnt sound quite right.
The previous owner has serviced the car which i have checked but will replace the fuel filter anyway
Any ideas?

 

hows thr egr

 

Is there anyway to check the EGR valve?

 

Im not sure but will have to double check when i see the car again tomorrow, wont the egr be disconnected if the smog/air stuff has been ripped off? will this cause a problem?

 

There are many things that can cause a hunting idle. Leaky injector, ignition problem, leaking EGR, vacuum leak, and the list goes on. You really need someone with a scanner and some skills to see what's happening.

 

I have replaced all the hoses as there were some vacuum leaks, ignition system is fine tested it all the way through, its definatly a fuel problem.
If the egr has been disconected can this cause a problem? Does it need to be connected or removed if the air system is gone?

 

If the EGR disconnected and closed tight, it won't effect idle.

 

check your Throttle Positioning Sensor if your car if equipped with one. The TPS can be checked with an Amp reader voltmeter tool. I had this problem on my fuel injected iroc z

 

Checked egr today,its disconected but someone has just put some glue in the tube where the vacuum pipe goes on, (is that good enough?). The pipe work is still there which goes to something next to the distributer? Will check the TPS tomorrow. Seemed to be worse this morning sounding like not running on all cylinders and shaking badly when revs applied.

 

Doesn't matter if the valve is plugged, as long as the vacuum line to the EGR solenoid is. You might want to just plug it back in. It doesn't hurt performance any, makes it less susceptible to pinging, and lowers NoX emissions. Something else to consider is the distributor. The pickup coils and ignition modules fail pretty frequently. They too can make it miss badly at lower RPMs.

 

Ok thanks, got some things i can check out, the vacuum line to the egr solenoid is open at the moment, Also car started to backfire today on tickover?

 

Put a new bulb in the service light as previous owner had removed it and got code 33 which i think is mass air flow sensor? can i fit one off a 86 tpi car just to see if its the problem or are they differnet on a 85?

 

I'm pretty sure '85 was a one year sensor.

 

Ok, replaced the fuel filter and spark plugs today doesnt miss anymore but still hunting. Does the IAC need to be setup like in the technical guide? as my rev counter is shot and with it hunting i cant get a accurate rpm to set it up.
Also seems to run ok when warmed very slightly, then when cooled down and re-started it starts hunting again. any ideas?

 

Check that the TPS is at .54 volts at idle. Ohm your injectors when they are cold, and again at operating temperature. Make sure the vacuum lines are all connected and in good condition. Check that the egr valve moves freely up and down. Check the spark plugs and the wires. If you mist the plug wires with water and start the engine in the dark, you will be able to see cross-sparking if the wires are bad. Post your results after checking these things.