Distributor for gm tbi

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babywag
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Re: Distributor for gm tbi

Postby babywag » Tue Jun 05, 2018 8:27 pm

Herk wrote:If the IAC does in fact go all the way to zero "0" with the engine idling, you either still have a vacuum leak or the throttle plates aren't closing all the way. Double check your throttle linkage (unhook from TB when setting idle), and if the idle stop screw has been messed with, back it off a bit. But before you go much farther figure out why the engine was idling so low in the first place. It may be the IAC or it may be the computer. What RPM is it supposed to be idling at? Got a junkyard IAC handy?


The screw isn’t to adjust the idle.
-Tony
'88 GW (aka Babywag) '90 GW (aka JunkBucket) both fuel injected.

ferrum
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Re: Distributor for gm tbi

Postby ferrum » Tue Jun 05, 2018 8:37 pm

Do you have VSS? My current setup doesn’t have VSS and my IAC count hovers around 0. My idle is around 750 rpm.
'76 Cherokee Chief

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babywag
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Re: Distributor for gm tbi

Postby babywag » Wed Jun 06, 2018 8:05 am

ferrum wrote:Do you have VSS? My current setup doesn’t have VSS and my IAC count hovers around 0. My idle is around 750 rpm.


You asking him or me?
IAC counts @ 0 when idling, is problematic.
Either unmetered air still getting in somewhere, or possibly exhaust leak, and ECM is closing IAC all way to attempt to trim AFR but is unable to.

Post a datalog? Or look @ BLM when idling warmed up and IAC count is zero. I forget if Tunerpro datalogs show desired idle speed?

Some GM bins the idle speed is ~550(too low for amc w/ auto) and too low IMHO.

Both mine are ~30-40 IAC counts idling
-Tony
'88 GW (aka Babywag) '90 GW (aka JunkBucket) both fuel injected.

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toothofwar
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Re: Distributor for gm tbi

Postby toothofwar » Wed Jun 06, 2018 9:04 am

Unfortunately I cannot get tuner pro rt to connect with my ecm. Idle is set to 650 from what I can see in winaldl. I have sprayed carb cleaner around the intake and hoses under the hood and no change in idle. I can post a data log from winaldl later today if anyone can make heads or tales from that data.. I set the iac like in bills directions. When I hooked up the iac after and reset the ecm, it wouldn't idle (idle was too low and stalled out) so I ran my screw in just enough to keep it around 600 and reset the tps for now. But the iac count going to 0 and it almost stalling out when setting in gear makes me think I have set it wrong, or my iac is not working properly.

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babywag
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Re: Distributor for gm tbi

Postby babywag » Wed Jun 06, 2018 11:15 am

Again the screw is NOT to set/change idle speed.
ECM does that.

If you’re trying to use it to change idle speed/need to change it to idle properly, something is wrong.
-Tony
'88 GW (aka Babywag) '90 GW (aka JunkBucket) both fuel injected.

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toothofwar
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Re: Distributor for gm tbi

Postby toothofwar » Wed Jun 06, 2018 5:25 pm

Here is the log file from the other day when it went on its first decent drive. About 10 miles or so. This is with the large vacume leak I hadn't fixed yet. I didn't get a log file yesterday when I way tuning the iac again....
20180606_180040_LOG.txt


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Edit. This is the correct file. I uploaded the wrong one. http://cloud.tapatalk.com/s/5b187dd3e9db6/20180603_182905_LOG.txt
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Last edited by toothofwar on Wed Jun 06, 2018 5:25 pm, edited 1 time in total.

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toothofwar
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Re: Distributor for gm tbi

Postby toothofwar » Wed Jun 06, 2018 5:31 pm

Here is the log from tonight. I wanted to get the motor warm so I went up the road a piece and me and my wife cruised to the local gas station. When I got back I let it idle for a few and noticed my iac count was around 50. Not 0 like it was the night before. So I desided to cruise up to the store again ant open it up a little. When I came back I noticed it settles back to around 50..... the tps was normal and everything..... idk. I guess I'm just going to be thankful I had a good drive tonight! Lol.
20180606_180040_LOG.txt


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babywag
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Re: Distributor for gm tbi

Postby babywag » Thu Jun 07, 2018 6:45 am

Geez that thing is probably pig rich? Your AVG BLM is ~105! Waaaay too low.
What is your fuel pressure?
What injectors do you have in there?
Still idling too high, you're 110% sure no vacuum leaks?
-Tony
'88 GW (aka Babywag) '90 GW (aka JunkBucket) both fuel injected.

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toothofwar
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Re: Distributor for gm tbi

Postby toothofwar » Thu Jun 07, 2018 6:57 am

The first post, the edited file, is with the huge vacume leak. But the second one is with no leaks. At least none that I have found. You said it's still idling to high? From what I was seeing it was around 750 to 800 in park and 600 in gear. When I get it to idle any lower it sounds like it's going to stall out. I'll recheck for vac leaks tonight and see if I can find any. From what I can tell from the "seat of my pants" method it feels like it is running better than any carb or motor I have had in this thing yet! But if you say it can be better than I going for it!

Edit
My fuel pressure is around 12.5 to 13. It normally doesn't fluctuate between idle and wot.
Last edited by toothofwar on Thu Jun 07, 2018 6:57 am, edited 1 time in total.

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toothofwar
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Re: Distributor for gm tbi

Postby toothofwar » Thu Jun 07, 2018 6:59 am

Just for a reference, what should my average blm be? Or At least a good target to shoot for.

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babywag
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Re: Distributor for gm tbi

Postby babywag » Thu Jun 07, 2018 7:22 am

toothofwar wrote:Just for a reference, what should my average blm be? Or At least a good target to shoot for.

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128 is target, all this and more than you need to know is documented online. If you plan on tuning it yourself you’ll need to educate yourself some more.

Far as idle speed, from log it’s requesting 675, so anything above (like the log is showing) means something is off.
If everything is working the idle should be 675 regardless of in/out gear.

Idle probably dies out because too much fuel?

If you don’t have the ability to tune yet, and FP regulator has been modified for adjustment?
You can try dropping FP lower. If it’s say 13, try dropping it to 11.


Bill has a decent write-up with pics to modify the FP regulator.
Be sure to have a gasket kit ready if you need to remove the fuel pod to modify. The gasket often tears, and will need to be replaced.
-Tony
'88 GW (aka Babywag) '90 GW (aka JunkBucket) both fuel injected.

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toothofwar
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Re: Distributor for gm tbi

Postby toothofwar » Thu Jun 07, 2018 5:28 pm

Unfortunately I'm not able to do any true tuning. My ultimate goal is to get the sensors as close to correct as possible with the current tune. Once funds free up some more I'll have bill tune me a different ecm specific to my motor setup. I'll try the fuel pressure this weekend.

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toothofwar
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Re: Distributor for gm tbi

Postby toothofwar » Fri Jun 08, 2018 9:53 pm

So a little update. I got to reading back through all of the replys to this and some of the other posts I had. I found where someone asked if I had any vacume OR exhaust leaks. I have been so focused on the vacume leaks, I had forgot about the exhaust leak. The part of the y pipe that the o2 sensor is in has a manifold gasket leak. Someone correct me if I am wrong, but wouldn't that make it run rich? I'll be fixing the leaks and rechecking my logs in the next couple of weeks. But for now, thanks for everyone's help along this journey.

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babywag
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Re: Distributor for gm tbi

Postby babywag » Sun Jun 10, 2018 11:13 am

Yes an exhaust leak will throw off o2 sensor readings, which will throw off fueling.

Everything needs to be correct if you want the system to function properly.
No vacuum leaks, no exhaust leaks, good wiring & connections, good fuel system, etc.
-Tony
'88 GW (aka Babywag) '90 GW (aka JunkBucket) both fuel injected.


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