High searching Idle

[jss06c6]

where are you seeing the table you're referring to? may need to add this to my XDF.. I'm using $AFA for my '91. AXFK...

[S.hafsmo]

Just to mention it, my idle drops 50 rpm (750 to 700) if I plug the bore to the primary blade (IAC obviously still at 0). I'm assuming the air to the remaining 50 RPM are leaking around the secondary blades. These throttle bodies are not the best design.

Primary blade:

[jss06c6]

Hot engine..

Idles smoothly at 750 rpm
MAP rock steady at 34 kPa
MAT 44 C, 111 F
Coolant temp 93 C, 199 F

[jss06c6]

Originally Posted by S.hafsmo

Just to mention it, my idle drops 50 rpm (750 to 700) if I plug the bore to the primary blade (IAC obviously still at 0). I'm assuming the air to the remaining 50 RPM are leaking around the secondary blades. These throttle bodies are not the best design.

Primary blade:

Yep, checked my primary when I had the TB out. It was pretty dirty, so cleaned it up a bit with brake cleaner.. Didn't have quite as much daylight around it as I see in your picture.. Secondary blades had virtually NO light showing around them.. I feel like I'm chasing a rabbit here for which there is no real symptom.. The engine idles well, never stalls when I come to a stop and pulls like crazy all the way to 7500 (no courage to go higher than this!).

[XfireZ51]

Originally Posted by jss06c6

where are you seeing the table you're referring to? may need to add this to my XDF.. I'm using $AFA for my '91. AXFK...

I think you are using the wrong .xdf for AXFK. When I use AFA on that bin, the cylinder volume is 114. I read AXFK correctly using $AF.

[jss06c6]

Cylinder volume reads right on mine.. Marc may have swapped to another BIN..

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[XfireZ51]

Originally Posted by jss06c6

Cylinder volume reads right on mine.. Marc may have swapped to another BIN..

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I use BRXB for the $AFA Mask. GM changed the Broadcast code for the correct calibration depending on whether it was for the original Mask or if it was for the updated Mask. So $AF would use the AXFK cal, while $AFA would use BRXB for the 91s. As another example, the 92 $D0 bin is AZZC, while the updated $D0A uses BPPA.
Actually, I do think that Mark uses the latter version of the Mask for his cals. No real reason to use the earlier version. As I look at both 91 stock bins, they did play a bit with the IAC and then changed it in the 92. But it shouldn't affect the idle portion.

[jss06c6]

Thanks!

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[XfireZ51]

BTW, Hans tells me his stock 90 idled at 750rpm w 6-14 IAC counts.

[Vette73]

Couldn't help but read this entire thread on engine idle......One question I have is, how accurate is the tachometers on these cars? I have a 91.....

Mine idles at between 900-1,000 rpm...Motor is fully ported with full exhaust and intake cams...

Even when my car was stock it seemed to favor anywhere from 850-950 usually..

I do notice at times when I pop it into neutral coming to a stop, it may take 5-10 seconds for the idle to " settle in" at around 900-1,000....

Forgive the ignorance , new bee here still learning...👍

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