OK, got a memcal from Jason, working fine except I can't get the IAC counts down to 40. Set the timing to around 6 BTDC, set idle on 383 to 580 RPM and got about 16 in.hg. but can not get the counts down no matter what I do.
Here's the Autoxray file;

101 >>>>>>>>>> Vehicle Scan Report <<<<<<<<<<
Trouble Codes No Trouble Codes Found Vehicle Data
PROM ID 5801
Coolant Temp 181.4°F
Start Up Coolant Temp 161.1°F
Throttle Sensor 0.52 Volts
Throttle Angle 0%
Engine RPM 947
Vehicle Speed 0 MPH
Oxygen Sensor 700 mVolts
O2 Cross Counts 105
Block Learn 122
BLK LRN Cell 4
Integrator 133
Idle Air Mtr Pos 160 steps
Desired Idle 950 RPM
MAP Sensor 2.46 Volts
Manifold Air Tmp 68.0°F
EGR Duty Cycle 0.0%
CCP Duty Cycle 0.0%
Battery Voltage 12.0 Volts
Fuel Pump Sense 12.1 volts
Learned Idle Pos 40 steps
Oil Temp -38.6°F
Spark Advance 21.3°
Knock Sensor 2
Knock Retard 0°
Injector Pulse 2.5 mS
Engine Run Time 307 seconds A/C
Not Requested A/C Forced Off No
Battery Voltage High : No
Shift Light Off
TCC Status Not Locked
Park/Neutral Not Detected
Fan Number 1 On
A/C Clutch Disabled
Oxygen Sensor Ready
Fuel Cut Off Disabled
CCP Purge Off
Air Divert Solenoid On
Air Switch Solenoid Off
Learn Control Enabled
Rich Lean Flag Rich
Loop Status Closed
Capture Data

I have onboard A/F ratio, it's say slight rich most of the time.

I've isolated all vacuum taps and checked PCV.

Have went through the setup procedure for IAC and TPS multiple times and it still goes high counts.

It doesn't seem to be running too bad, a plug visual check did not show fouling problems.

Have swapped the IAC motor out and no change.

Could I have a vacuum leak? I have to admit it was very tough getting the timing down to 6 BTDC without dying.

I've checked the IAC motor resistance it's OK.

The wiring between the 7730 and IAC is correct.

Anyone got and idea of whats happening?

Thanks.

 

OK, here's another scan. The IAC is down to 48 counts but idle is too high, must be my chip programmed idle? The vacuum is at 17 in.hg with this scan and steady as a rock. I slowly added vacuum taps, air divert, EGR, Purge Can, nothing brought the vacuum down so I must be dealing with something on the memcal. Jason must be out of town right now or something.

101 >>>>>>>>>> Vehicle Scan Report <<<<<<<<<< Trouble Codes No Trouble Codes Found
Vehicle Data PROM ID 5801
Coolant Temp 189.5°F
Start Up Coolant Temp 58.5°F
Throttle Sensor 0.58 Volts
Throttle Angle 0%
Engine RPM 909
Vehicle Speed 0 MPH
Oxygen Sensor 696 mVolts
O2 Cross Counts 167
Block Learn 126
BLK LRN Cell 4
Integrator 126
Idle Air Mtr Pos 48 steps
Desired Idle 912 RPM
MAP Sensor 2.62 Volts
Manifold Air Tmp 64.4°F
EGR Duty Cycle 0.0%
CCP Duty Cycle 0.0%
Battery Voltage 12.1 Volts
Fuel Pump Sense 12.2 volts
Learned Idle Pos 40 steps
Oil Temp -38.6°F
Spark Advance 26.2°
Knock Sensor 9
Knock Retard 0°
Injector Pulse 2.7 mS
Engine Run Time 1197 seconds
A/C Not Requested
A/C Forced Off No
Battery Voltage High : No
Shift Light Off
TCC Status Not Locked
Park/Neutral Not Detected
Fan Number 1 On
A/C Clutch Disabled
Oxygen Sensor Ready
Fuel Cut Off Disabled
CCP Purge Off
Air Divert Solenoid On
Air Switch Solenoid Off
Learn Control Enabled
Rich Lean Flag Rich
Loop Status Closed
Capture Data

This is with 45 psi Fuel Press set with vacuum disconnected (I'm running FMS #24 Inj). The A/F indication off my onboard gage indicates slightly rich.

Do you guys see a problem other than maybe memcal RPM setpoint?

Thanks for the help!

Mark

 

So I take it you want it to idle at a lower rpm? Yes it has to be reprogrammed in the prom-look at the desired idle; it's in the 900's. That is the value that will be changed. There is also idle speed adders for park/nuetral etc. that will change it. The second scan looks fine-iac at 48. And your blm and int is 126 at idle-128 is "perfect", I'd take 126 as plenty good.
As for the A/F indicator you mentioned-if it's not a wide band-don't get hung up looking at it. It is just like a "standard" O2 sensor; good for a rich lean switch above and below 14.7:1 and thats about it.
The first scan-I'd have just cracked open the TB blades a little more to take the iac counts down. Since you have a 383 the "by the book" method of adjusting the min. idle won't work too well....Just adjust the tb blades until the iac count is about 30 to 40.

 

Thanks drive it, good input, BTW does your headers glow red on your engine during operation? I'm running much hotter than stock of course, but the TPIS headers run cherry red under no light and even in light they have a red tinge. Is this normal for strokers?

 

Uhh, noooo, I wouldn't call the headers glowing normal!!! Mine do get hot-but they don't glow! I remember some folk having that problem but I don't remember their solutions.
Are the tpis headers coated?

 

OK, here's my 2 cents. Been doing a lot of reading on this and if I find the link I will post it. But basically, what I've read is that on the aftermarket TB's there is a hole missing in the IAC circuit that is in the factory TB. Check the picture. Don't know the size, you need to get it from your original TB. But this hole needs to be there especially for bigger cams. Opening the TB blades won't cut it because the bigger cam causes reversion in the intake and causes baddly split BLMs at idle. So, you want the blades as closed as possible and use the IAC to control idle air. To do this and keep IAC down you have to drill this hole.

Also, there is another problem with some aftermarket TB's, namely BBKs, not sure about the Holley 58. I have a Holley 52 and don't have this problem, but anyway. The problem is that the IAC circuit needs to be isolated and on the BBK there are two notches that lead from the TB blade openings to the IAC. These need to be blocked off.

Again, if I find the link I will post it. Hope this helps...


Found it. There is lots of good programming stuff on this page, plus his car is really cool! http://para.noid.org/~lj/




[Modified by 95Aqua, 1:40 PM 3/13/2002]

 

Yes there coated, it really surprized me that they would run that hot, again, this is with the lights off in my garage. Under normal light its not that noticable.

Thanks Aqua, someone else said something about drilling a hole in the throttle plates. They are definately cracked open now to keep IAC counts down. It makes sense though. I have a stock TB but I never noticed a hole, I'll check it again. Anybody got a guess what size the hole should be or is it just trial and error (hopefully not ) :rolleyes: .

Thanks guys.


[Modified by Mark84_L383, 12:54 PM 3/13/2002]

 

Hmmmm, I'll have to take a close look at my tb next time it's off; I've got the BBK. As for the drilling of a hole-if you have too rad of a cam that could help-same as with drilling a small hole in the blades of a carb. What's your cam specs? If it's mild enough to pass smog it shouldn't need it.

 

Comp Cams 218/224 .492/.502 112 Roller with Crane Gold 1.5RR's, not really radical. What have you got?


[Modified by Mark84_L383, 11:13 AM 3/14/2002]

 

My cam specs are 222/226 at .050 with .494 lift with 1.6's on a 114 lsa installed at 110. With your specs you shouldn't have to worry about drilling any holes in the blades. Also you certainly shouldn't have any problems at all passing smog. I'm considering a larger cam, but right now I'm having fun (NOT) bolting on a SR!

 

I hear that! Man what a pain. Hope your right about the smog I'm due this month!