Hello,

I have a 89 suburban,5.7,400t, I know it is not an F body but I am hoping someone here can help me with burning a chip.

I use tuner pro, and an autoprom, and i understand most of the scalars and tables. Problem is noting seems to lower my IAC steps correctly.

My engine is always about 850 rpm in neutral (IAC 11). 550 in gear (IAC 33)
when i go from gear to neutral the it takes forever for the IAC steps to extend. the motor revs to 1300 and 30 seconds late it finally comes to rest.

Anyway, I read this post,

http://www.diy-efi.org/gmecm/papers/747iac.txt

It has a lot of info, and i follow the steps,, but i must be missing something,

One thing,, when i am logging, the reading says i am always in park, even when i place it in gear, not sure if i have a bad wire or switch, or if in 89 it did not communicate this info, there are parameters in the bin for park/neutral.

Any help would be great,
Thank you,
Chris

 

Having the P/N input to the ECM will help with this. Otherwise the IAC bump won't occur when changing into or out of gear. Being that it always shows park, that means that the P/N input to the ECM is always grounded (pin B10, ORG/BLK). Open is for in-drive.

When in P/N there is little idle speed control. Basically a low and a high limit, that's about it.

RBob.

 

I also notice I am not getting any readings from my speed sensor. It is always zero MPH.

The 1227747 ECM should be accepting an monitoring mph? for 1989?
Again, I apologize, this is a suburban, not an F body but i think the TBI talent at this site is more than at my truck forum.

I attached my bin file if anyone wants to see a crazy mess? DO NOT USE IT. I have read it 3 times now and verified, I am not sure how the truck runs with it let alone smoothly but it does.

I am modifying a downloaded bin for a 5.7 now. If someone can direct me to a bone stock 5.7 , auto, bin that is good as a start it would be a great help.

THanks again,
Chris

 

The speed sensor needs to be working correctly for proper IAC operation. The computer has different IAC settings for when the car is moving as opposed to when it's running and stationary.

 

I just realized that maybe i have the wrong deifnition for my tunerpro. My original mask ID is 4F not $42. using 4F all of my scalars and tables, look correct but there are no r IAC parameters to adjust. (delay,filter) when i load a $42 xdf my data log does not have speed anywhere to be found. Now i have a TPS % of 28 at an idle and 210 wot. (buttt the voltage is correct) .57 idle

I am ready to drive this truck to a junk yard soon,

Chris

 

I think someone changed your ECM as the 1989 Suburban 5.7L turbo 400 came with 1228747 ECM? $4F

Same year range Suburban, which I own a 1990 came with 1227747 $42 and 700R4 trans.

There's a guy working on changing the ECM from 8747 to 7747 using an auto bin with TCC diabled but I don't know how the turbo 400 KickDown is being applied or what changes are needed in bin to do this?

$4F 1228747 light duty is ALDL file A58.ds which is identical to A33.ds The ADX file for data logging in TunerPro is identical to $42 1227747 except for name of one byte changed and it does have a knock sensor.

$4F 1228747 HD is simalar based on A108.ds ALDL file but no knock sensor. All files needed for TunerPro $4F XDF, ADX and many bins light duty and heavy duty. All those TunerPro files $4F LD. ADX which yours should be, is well advanced and some bins can be found here:
http://www.gearhead-efi.com/Fuel-Inj...Information-4F

Now if it is 1227747 $42 the TunerPro files I have a nice set with a lot of work including data tracing set up so ADX and XDF work as a set, and bins are here:
http://www.gearhead-efi.com/Fuel-Inj...Information-42

Since your using an AutoProm to burn chip it must be 27SF512 (cause AutoProm won't do stock chips) did you set the offsets correctly?

 

The bin you uploaded is $4F and when using difference tool in TunerPro it is identical to stock AKWA...

 

Eaglemark,
Thank you for the links, Having the $4f file sure makes things easier. (what a mess before).
I still can not adjust IAC delay, i see no parameters for delay or filters. Can you guide me to a link for adding an entry that may correct this.

My biggest issue I have,and what started me on this quest, is when i put the truck in gear, the IAC steps increase, but when i come out of gear the engine revs to 1200 and takes 20+seconds to get back to an idle. Is there a delay parameter for the IAC using 4f. with $42 thee was a multitude of settings for the IAC.

thanks,
Chris

 

You would need a $4F commented hac which I think I have to include things in XDF.

But RBob pointed out above this is probaly do to your Park/neutral drive switch. Which manual does not have in 1227747. Guessing same in 1228747...

But if motor is stock and your using an auto bin on auto car it should really be fine as is? Manual bins have many changes to IAC logic...

Then it could be a difference in wiring on 1227787 and your using a 1227747 so need to check all wiring from old ECM is correct to new ECM...

 

Hello again,

I officially quit, I using the adx and xdf files from the link you posted. I have verified the butterflies are closing. (set the idle with the iac closed and adjusted the torx screw) and my truck will not go below 875-900 rpm. I can almost live with that but when i come from gear (500 rpm and 60+IAC steps) the motor revs to 1200 and hangs for 15? seconds before making it way down to 875.
If anyone knows what parameters need to be changed to stop the IAC delay for a $4f 7787 ecm please shed some light for me.

in the latest def. files i do not see any parameters to change as i did when using the wrong $42 def.

I would gladly take a call from anyone and post the results so it may help future readers.

Thanks,
Chris

 

On a stock chip?

You have a vacuum leak, your not going to be able to tune that out. You just proved it above.

 

eaglemark,

I ran a test again setting the IAC to zero by grounding a&b and the truck will idle below 500, I tried adjust the idle screw up to 700 rpm and also and also lower. I have made adjustments to the parameters and table in tuner pro , and the truck will idle lower until;

I put it in gear, the iac step increase, and when i return to park, it is if the idle logic learns???and overides any imputs i make. For instance if i was idling at 750 in park at 20 steps, i put it in gear and the iac increases to 40 to maintain the 550 setting in the table. when i return to park the iac steps will never return to 20, maybe to 30 but never to 20. And then the truck idles at 875. it will never go below 875, ever.

If anyone knows if this is just an issue with this model year, or knows how to fix this , please reply, I would love to speak to someone who can trouble shoot this thing over the phone. I must be missing a parameter and i just do not understand this thing. All help is appreciated. Idling around town between 875 and 1000 rpm is getting really old.

Thank you,
Chris
702-874-49 seven zero

 

Still sounds like a vacuum leak?

Was the motor totally warmed up when you closed the IAC?

Did you set RPM to 100 RPM below what is programmed in bin for Closed Loop Idle?

Was the motor in closed loop?

There are differant idle settings when an engine is warming up.

 

Hello again,

I logged some data today and the data says i never am in a closed loop and always in park.

I can change a few parameters and lower my idle to 700 in park but as soon as i put it in gear, it will add IAC steps and never go back to 700.

If you have tuner pro i attached a zip file with my bin, adx, xdf and my data log.

If any one wants to mess with it and send it back i would love to see if someone can fix my idle problem, or find the parameter that is not allowing closed loop??

Thank you,
Chris