erratic idle on my '89
Thread Starter
Intermediate
Joined: Dec 2004
Posts: 38
Likes: 0
erratic idle on my '89
I had the front of the engine torn down to change the water pump so I decided to clean things up a bit. I removed the air pump system, the egr, installed headers, removed the cat, installed new injectors (24lb-I was told that this was the stock size by a mechanic). The car ran like a bat out of hell for two weeks; now it just runs like hell. It starts fine but after it warms up the idle hunts between 500 and 1200 rpm. It also is running very rich and has set a code 44. Any info would be most helpful. Thanks.
Burning Brakes
Joined: Dec 2000
Posts: 1,161
Likes: 0
From: Orangeburg, NY
You might want to check the IAC and throttle body for carbon build-up. Because the injectors are 24#, the fuel pressure may have to be adjusted.
Disconnect the battery, and clean the air intake along with the IAC ports. I found it easy to use wome q-tips and a rag.
Disconnect the battery, and clean the air intake along with the IAC ports. I found it easy to use wome q-tips and a rag.
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,063
From: altered state
St. Jude Donor '05
Wouldnt bother with the APFR just yet. Code 44 is EGR, no?
If your EGR isnt working properly tha car will act like it has a vacuum leak and describe the symptoms you have.
If your EGR isnt working properly tha car will act like it has a vacuum leak and describe the symptoms you have.
Last edited by cv67; Dec 31, 2007 at 11:30 AM.
Pro
Joined: Nov 2006
Posts: 638
Likes: 0
From: Plano TX
I would think with all that work you had done to it that you should be thinking about getting a chip burned for it.
Also, check for vacuum leaks. Could be as simple as a vacuum line is loose or cracked. Do you have the FSM? If not, you should get it and check out the Symptoms area. It'll list out many difference checks related to troubleshooting unstable idle.
Also, check for vacuum leaks. Could be as simple as a vacuum line is loose or cracked. Do you have the FSM? If not, you should get it and check out the Symptoms area. It'll list out many difference checks related to troubleshooting unstable idle.
Le Mans Master
Joined: Jun 2006
Posts: 5,642
Likes: 5
From: One day you're a Comet...the next day you're dust... Arkansas
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Thread Starter
Intermediate
Joined: Dec 2004
Posts: 38
Likes: 0
partially fixed
I changed out the O2 sensor and now she purrs like a kitten. However, the vette is still running very rich. The old O2 sensor was caked in black soot and that was only after running it for 2 weeks. Do you think having a new chip burned with the changes would make the difference?
Thanks in advance.
Thanks in advance.
6th Gear
Joined: Jan 2009
Posts: 6
Likes: 0
From: Deltona Florida
OK now I am feeling the pain.
Before I built my L98 I had no issues....Now with a ZZ9 cam,rocker ratio changes and intake with the runners and manifold along with a 52mm body and level 3 prom all @ TPIS I have an eratic idle.
Saw a few posts about plugs and Mass air sensors so I will change out the modified Mass air for the granitelli one I have as well as my old plugs but have found no leaks on the vacum lines.
I am not running any air pumps or egr and have not done so for over a year.,...no codes. Radiator not pressurizesd nor anything in the oil so I think the block and heads are mute.
once its well warmed up she idles fine and runs like snot but initially its a pain like going back in time for that eratic up and down idle if only for a short spell.
Even thought of a stall for the auto but was advised by TPIS that I should not need one.
Any one elese experienceing this sort of fun?
Regards
Mark
Before I built my L98 I had no issues....Now with a ZZ9 cam,rocker ratio changes and intake with the runners and manifold along with a 52mm body and level 3 prom all @ TPIS I have an eratic idle.
Saw a few posts about plugs and Mass air sensors so I will change out the modified Mass air for the granitelli one I have as well as my old plugs but have found no leaks on the vacum lines.
I am not running any air pumps or egr and have not done so for over a year.,...no codes. Radiator not pressurizesd nor anything in the oil so I think the block and heads are mute.
once its well warmed up she idles fine and runs like snot but initially its a pain like going back in time for that eratic up and down idle if only for a short spell.
Even thought of a stall for the auto but was advised by TPIS that I should not need one.
Any one elese experienceing this sort of fun?
Regards
Mark
