this is on my fiance's 90 blazer, 4.3 tbi. the idle in gear is too low, and is causing charging system issues. theres no tach, but it sounds like its around 400 rpm in gear. if put into nuetral, it picks the rpms up enough to bring the volts back up to 12.5+. it has a brand new remy alternator, and will be reinspecting the connections tomorrow. she says that it sounds like its going to stall and is shaky. otherwise, the cold idle is fine, it goes up to about 1500 or so.

 

Is the engine light blinking or staying on? Retreive the codes with a paperclip.

 

no check engine light or codes. the iac seems to work correctly at all, it just hot and in gear it idles too low

 

Is the throttle body nice and clean?

 

yes it is. it pretty much started doing this after removing the clogged cat and putting on a low restriction exhaust. at that time i also replaced the battery with a new one. i couldnt imagine that being a major issue as to cause it to idle low. i did check the connections, all clean and tight. i think i will just drill out the plug and turn the screw in a bit

 

How much of the exhaust did you replace? Did you change the "Y" pipe coming from the exhaust manifold? I am just curious if the 02 sensor was changed or eliminated. But I am sure that would throw a code.

 

the y-pie was retained. the cat was removed, 2 90 degree bends installed, and a small glasspack on the exterior of the frame ending just before the rear tire. very low restriction, rather loud and obnoxious (which is how she wanted it to be)

 

just listened to it earlier, but did not have time to diag. the engine was still cold and at high idle. as soon as she put it in reverse, it dropped low and sputtered, then recovered. what are the procedures to checking the timing, and how many degrees should idle be at, about 12?

 

found 2 possible vacuum leaks. repaired them to no correction. so i drilled out and removed that plug and turned the throttle stop up 2 turns. idles a lot better, and mileage has improved. that plug is very easy to remove