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Need help with diagnosing a high idle

Old 07-01-2015, 10:57 AM
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Default Need help with diagnosing a high idle

I have HP tuners and today is the first day I can actually fire the engine and use it.

I'm getting a high 1600 idle at cold start, I figured out how to do a real time scan so could someone help me out and see if there is something out of wack that could be causing this high idle?

I checked for vacuum leaks and replaced the intake gaskets with no change

My PCM is supposed to have a 2004 express Van tune, modified to work with my 2004 5.3 truck engine modified to DBC. The PCM is from a 2004 express Van and base tune done by lt1swap.com

Here are the details on the motor

Stock 5.3 Cast iron block from a 2004 Silverado, with all stock sensors that came on this engine

modified 2004 harness that came with this engine

2004 Express Van PCM with the correct wiring added for the cable throttle body

LS1 intake with the stock DBC throttle body, Map and 350 injectors

Custom Air intake with the MAF from the 5.3 truck engine

Rear O2 delete
Old 07-01-2015, 10:58 AM
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Here's a quick scan of the running engine while I was trying to figure out HPtuners
Attached Files
File Type: hpl
scan 1.hpl (14.4 KB, 56 views)
Old 07-01-2015, 10:59 AM
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If pulling the bin file will help to see what's going on, I can do that too...just forgive my ignorance as I am literally learning this stuff today lol
Old 07-01-2015, 11:19 AM
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I'm using a TPS sensor for a 2004 express Van on a LS1 throttle body. I know the sensors are different between those models but would it mount the same on either one?

Here's my engine info BTW
Attached Files
File Type: hpt
My PCM Scan.hpt (516.2 KB, 55 views)
Old 07-01-2015, 12:15 PM
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Do you have a PCV system hooked up. The truck PCV system is not directly compatible with a LS1 intake. Did you modify it to work with the car intake? Do you have a full exhaust system hooked up? At around 30 seconds into the scan the passenger side O2 starts indicating that bank 2 is extremely lean. A log of it fully warmed up would be better. It hasn't gone or tried to go into closed loop in the log you posted.
Old 07-01-2015, 12:23 PM
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I have a set of LS1 valve covers and a LS1 PVC hose assembly on the LS1 intake. I hooked the PVC up per the stock diagram that's floating around on the web, but I know that's correct.

Just as a test I removed my IAC and turned the key, it pulled the pintle all the way in and never moved from that point.

I took some tape and blocked the hole in the IAC mount on the throttle body, started the car up. Which if it was installed it would be all the way opened..which equals high idle

It idles a little rough, but leveled out smooth and quiet...that's what I am trying to get lol

I replaced the o-ring on the IAC and put it back on the throttle body... started the car....back up to 1600 rpm idle again

I don't have a full exhaust under it yet btw...just mufflers attached to the downpipes past the o2 sensors.

So know I need to determine if it's a bad IAC valve, wiring or computer settings
Old 07-01-2015, 12:31 PM
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I'll put some antifreeze in the motor and get a longer reading (to warm up) in a little bit.

How long of a scan should I do? Maybe 5 minutes?

I can get a new IAC locally for around $100, but I didn't want to get one if I didn't need it.

Thanks again
Old 07-01-2015, 12:49 PM
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Add the IAC pid to the table display so you can see the IAC counts.
Old 07-01-2015, 01:00 PM
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ok, will do

I grabbed this scan and got it to operating temps. Again I am learning this, but it feels good to start making some headway

Thanks for the help, I'll get another scan with IAC pid in a few minutes
Attached Files
File Type: hpl
scan 2.hpl (37.5 KB, 53 views)
Old 07-01-2015, 01:18 PM
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I'm not seeing a option for IAC in my PID list. I went to engine > and nothing there

Am I missing something? I opened a new table before going to insert it.

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Old 07-01-2015, 01:24 PM
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well crap, the copy of HP tuners on my laptop is tied to my computer..so is there a reason the idle drop down isn't there?

I installed a copy of VCM scanner on my desktop and I have that list. It's not tied to anything yet



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Old 07-01-2015, 01:25 PM
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could it be possible that the IAC functions weren't enabled when I had the PCM tuned? The whole reason I bought this HP tuners was to be able to see what's going on with my tune and make sure there isn't anything out of the ordinary with it
Old 07-01-2015, 01:30 PM
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Should be an idle tab between general and airflow. Try using this config.
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File Type: cfg
Default Imperial_1All.cfg (2.5 KB, 52 views)
Old 07-01-2015, 01:39 PM
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Here is what I've found. Looking at Alldata to try and get the wiring pin outs for a IAC on a 04 Express van, Alldata shows that vehicle to be a DBW vehicle with a TAC module. Looking at your tune file the ETC option has been turned off in the General>System Options tab. I just downloaded a 04 Express van file from the HPT repository and it has the ETC enabled in the tune. What I'm not sure of is if you deselect the ETC option in the System Option table that it makes the OS a DBC OS. Judging by your problems I would guess not.
Old 07-01-2015, 01:52 PM
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Thanks, I scanned for a few minutes..I don't like to run the car with this kind of RPM for very long

Looks like the count was at 0 most of the time. NOt sure what that means
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File Type: hpl
scan 3 (IAC).hpl (21.6 KB, 62 views)
Old 07-01-2015, 01:58 PM
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Originally Posted by 2xLS1
Here is what I've found. Looking at Alldata to try and get the wiring pin outs for a IAC on a 04 Express van, Alldata shows that vehicle to be a DBW vehicle with a TAC module. Looking at your tune file the ETC option has been turned off in the General>System Options tab. I just downloaded a 04 Express van file from the HPT repository and it has the ETC enabled in the tune. What I'm not sure of is if you deselect the ETC option in the System Option table that it makes the OS a DBC OS. Judging by your problems I would guess not.
I'm not sure. I basically picked up an PCM based on what was suggested on lt1swap.com that had the correct internals for the stepper motor for DBC.

http://www.lt1swap.com/cable_conversion.htm

I did the pin-outs as suggested for the TPS and IAC and even used the correct wire.

I sent the PCM to him to get the tune based on either GTO or express Van DBC to reflect my engine and mods done around it
Old 07-01-2015, 02:01 PM
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But if electronic throttle control was disabled, shouldn't there be something present for the TPS and IAC sensors?
Old 07-01-2015, 02:05 PM
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Doca scsn and see what the vehicle speed sensor is showing. Anything over 0 will do exactly what you described, we went through this on my little brothers truck before we hooked up the speed sensor then again because the wiring was too close to the spark plug wires and was getting interference.
Old 07-01-2015, 02:22 PM
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Thanks, I'll do that
Old 07-01-2015, 02:25 PM
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Looking at the IAC table on this spreadsheet it starts at around 203, then goes to 315 at one point, then drops to zero for a bit

Then slowly picks up from 20 or so until around 183 before I shut the car off

Is this normal? Or anything out of wack
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File Type: csv
scan 3 (IAC).csv (56.4 KB, 35 views)

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