alex
05-28-2001, 04:07 PM
I have an interesting situation that I can't diagnose.
My 85 GW runs great most of the time, but after I apply wide open throttle or near WOT and accelerate to about 45 MPH then step on the brake and stop (like at a traffic light) my engine begins to run incredibly rough and will die 8 out of 10 times.
If I pull off the road and wait 2 to 3 minutes the idle will return to normal and all is well as if nothing had ever been wrong.
In attempting to diagnose this I have attached a vacuum gauge to my manfold and recorded the readings. At normal idle I get about 21.5 inches (not bad for a 16 year old motor with 123,000 miles). After the WOT and stop I get about 14 inches. Wait 2 to 3 mintues and the manifold pressure snaps to 21.5 and the idle instantly returns to normal.
I have adjusted my mixture using the vacuum gauge, it's about 1.75 turns out. All this takes place with the vehicle warm, so I don't think the choke is the culprit. Although when I start off with a cold motor I do get severe hesitation at about 1500 RPM. Don't know if it's related.
I have gone through my vacuum lines fairly carefully and verified that all look good (most are new), my PCV valve is only a couple of months old and rattles when I shake it.
Anyone got any brilliant ideas?
Thanks in advance, Alex
My 85 GW runs great most of the time, but after I apply wide open throttle or near WOT and accelerate to about 45 MPH then step on the brake and stop (like at a traffic light) my engine begins to run incredibly rough and will die 8 out of 10 times.
If I pull off the road and wait 2 to 3 minutes the idle will return to normal and all is well as if nothing had ever been wrong.
In attempting to diagnose this I have attached a vacuum gauge to my manfold and recorded the readings. At normal idle I get about 21.5 inches (not bad for a 16 year old motor with 123,000 miles). After the WOT and stop I get about 14 inches. Wait 2 to 3 mintues and the manifold pressure snaps to 21.5 and the idle instantly returns to normal.
I have adjusted my mixture using the vacuum gauge, it's about 1.75 turns out. All this takes place with the vehicle warm, so I don't think the choke is the culprit. Although when I start off with a cold motor I do get severe hesitation at about 1500 RPM. Don't know if it's related.
I have gone through my vacuum lines fairly carefully and verified that all look good (most are new), my PCV valve is only a couple of months old and rattles when I shake it.
Anyone got any brilliant ideas?
Thanks in advance, Alex