MrPi

I have had some idle issues recently I think it is because of lack of vacuum on the EGR valve I get code 43.

I don't know where to start to find this lack of vacuum issue. Or if this is even the cause. I have removed the vacuum line and felt no pull with my finger. Would this cause the EGR not to open and cause a high idle? (900-1200)

DanielRicany

Code 43 is electronic spark timing code.

Check to make sure that your EST wire is plugged in, and then make sure that your base timing is set to 6* BTDC, the EST wire needs to be unplugged to set timing properly.

There is a diagnosis that I have, I can maybe post it for you tomorrow if you send me a PM and remind me.

vetteoz

Stating the year of your car helps when asking for advice
Many changes over 12 years and one size does not fit all

Read whichever applies for your year
http://www.chevythunder.com/maf_esc_module_code_43.htm
http://www.chevythunder.com/esc_map_code_43.htm

No
EGR doesn't operate at idle

Cliff Harris

The vacuum to the EGR valve is "ported". It is only there when the throttle blades are not in the idle position. They must be partially or fully opened.

MrPi

It is an 85 sorry I always forget to specify. The car was set to 4 without it plugged in. I set it to 6 and it still is idling high I replaced the EST tonight and it seemed to stay lower longer. But eventually went to 1100. I recently put in new spark plugs (and wires) that were longer on the insulator side (same threads) and triple checked all the wires were all snapped on correctly.

Cliff Harris

The ECM controls the idle speed by adjusting the position of the IAC. Take the throttle body off, remove the IAC and clean everything.

Event the best ECM can't compensate for a vacuum leak -- which causes high idle.