Engine speed flair when clutch depressed

[GMC Truck]

I have a 1984 truck converted to TBI with 7747 ecm and i'm needing some help finding out what to change in TunerPro software to adjust my problem.
Problem: Engine at full operating temp crusing around town (low speed) rolling up to light and step on clutch the engine revs to 1300 and then comes down to idle slowly.
This rpm flair is a pain. I have the abilty to burn my own chips and i'm using TunerPro software on a 7747 ECM with $42 XDF. What am I looking for to make the changes?? Thanks

 

[dave w]

Check these setting with the settings you have. Maybe something is different? Maybe you do not a VSS? I think the VSS resets the IAC at 35MPH?

dave w

 

[GMC Truck]

Check these setting with the settings you have. Maybe something is different? Maybe you do not a VSS? I think the VSS resets the IAC at 35MPH?

dave w

I do have the VSS on the back of the cluster and it looks like my settings are real close to those, but how about your IAC to coolant temp chart? Most of my upper temp settings are at 24. Could that be too high? My idle is at 650 with 12 iac counts, could it be jumping up to the 24 count setting when I step on the clutch?? Where did you get your XDF file, mine dont look like yours?? BTW my EGR is disabled because my manifold dont have the provision for it.

 

[dave w]

I read the chip information (.bin file) from an actual chip using a Burn2 from Moates.net. I found the ECM / Chip in a salvage yard, so I'm fairly positive the application (88 GMC 5.7 Manual Trans) is correct. I was thinking maybe a .bin from a manual trans application could help?

I have an AutoXray scanner. Maybe you can get a scanner to help see what the IAC is doing when the engine speed flairs?

dave w

 

[GMC Truck]

I have a BIN file for a manual shift as well (ASDW) and thats exactly what my IAC page looks like. I changed the settings everywhere on that chart where there is a "24" I reduced to "9" like on the 454 BIN files. I'll try that to see if i'm on the right track??? I think my XDF file is diffrent that yours? I dont have a page for "target idle RPM vs coolant" ? Where did you get your XDF file for Tuner Pro? I got mine from the Tuner Pro web site....

 

[dave w]

I downloaded the $42.xdf from moates.net.

https://www.moates.net/files.php

I think maybe you will need to register with moates to download?

dave w

 

[GMC Truck]

I have a BIN file for a manual shift as well (ASDW) and thats exactly what my IAC page looks like. I changed the settings everywhere on that chart where there is a "24" I reduced to "9" like on the 454 BIN files. I'll try that to see if i'm on the right track??? I think my XDF file is diffrent that yours? I dont have a page for "target idle RPM vs coolant" ? Where did you get your XDF file for Tuner Pro? I got mine from the Tuner Pro web site....

It seems that changing the "24" iac counts to "9" counts helped the flairing of the idle speed but now it kinda wants to stall when letting out on the clutch. I think i'll try and split the diffrence and burn again. I have a setting called "IAC vs P/S stall" Does anybody know what that is for???

 

[dave w]

It seems that changing the "24" iac counts to "9" counts helped the flairing of the idle speed but now it kinda wants to stall when letting out on the clutch. I think i'll try and split the diffrence and burn again. I have a setting called "IAC vs P/S stall" Does anybody know what that is for???

There is a Power Steering Switch for several TBI applications. When the power steering is in full lock, the ECM will adjust the RPM to prevent a stall.
dave w

 

[GMC Truck]

There is a Power Steering Switch for several TBI applications. When the power steering is in full lock, the ECM will adjust the RPM to prevent a stall.
dave w

Ok, that makes sense. I got the XDF file from Moates and it turns out that the one from the Tuner Pro site has way more info. It may be useless info as i'm still learning what they all mean or change. BTW thanks for all your help it has helped me a bunch!

 

[dave w]

Try TunerCat http://www.tunercat.com/ The downloads are fully functioning versions of the software that can be used for evaluation for a period of 30 days without registration.

The compare .bins function of TunerCat is very nice!

 

[GMC Truck]

I looked at TunerCat but decided to stick with TunerPro.