LT1 to LS swap don't stay running
06-27-2014, 07:39 PM
#1
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LT1 to LS swap don't stay running K, guys I have an issue and need some help.
This is a 93 T/A converted to a LQ4 408 with a cable driven TB an a 411 PCM.
I also have a "Ebay" 92MM TB.
Car is also tuned as Speed Density.
I have an issue and I hope someone can shed some light on it.
I have fuel @ 56lbs constant, I have spark in all cylinders but it don't stay running.
I have tracked it down to the IAC.
With my SnapOn brick I can see that the IAC is holding @ 310 with no change at all and I even bought a new one and it does the same thing.
TPS is @ .51 @ 0.0 closed and 4.28 @ WOT...........I did play with it up to .65 @ 0.0 and had my best results @ .55
MAP voltage is 2.26 KPA 53 BARO 60 @ rest
What led me to a bad IAC or so I thought was when I removed it from the TB but left it plugged in but stuck a pen in the hole that had a grip on it and had my
wife start the car and it ran as long as I could keep the pen in the right spot.
With some research I found that 310 is what an unasigned port will do to the IAC, not sure if this true or even the issue.
I'm lost!
Any help would be great
This is a 93 T/A converted to a LQ4 408 with a cable driven TB an a 411 PCM.
I also have a "Ebay" 92MM TB.
Car is also tuned as Speed Density.
I have an issue and I hope someone can shed some light on it.
I have fuel @ 56lbs constant, I have spark in all cylinders but it don't stay running.
I have tracked it down to the IAC.
With my SnapOn brick I can see that the IAC is holding @ 310 with no change at all and I even bought a new one and it does the same thing.
TPS is @ .51 @ 0.0 closed and 4.28 @ WOT...........I did play with it up to .65 @ 0.0 and had my best results @ .55
MAP voltage is 2.26 KPA 53 BARO 60 @ rest
What led me to a bad IAC or so I thought was when I removed it from the TB but left it plugged in but stuck a pen in the hole that had a grip on it and had my
wife start the car and it ran as long as I could keep the pen in the right spot.
With some research I found that 310 is what an unasigned port will do to the IAC, not sure if this true or even the issue.
I'm lost!
Any help would be great
Last edited by Phantom383; 06-27-2014 at 08:08 PM.
06-28-2014, 01:58 PM
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Just heard from my tunner and he says the car should still run with a bad IAC but with mine reading 310 is that commanding the car to dump extra fuel??
Things are not making sense to me.
And Merv, I have asked him to look at it so we will see what he says.
Things are not making sense to me.
And Merv, I have asked him to look at it so we will see what he says.
06-29-2014, 07:55 AM
#7
I see your fuel pressure was tested at 56, it needs to be 58. I know this seems minor, but believe it or not it can make a difference.
What pump and or filter setup did you use?
What pump and or filter setup did you use?
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06-29-2014, 09:05 AM
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It's a Walbro 255 with a Vett filter and primes @ 60
Running -6AN line, running SVO Green Top 42lb injectors (LT1 EV1 style)
Is it possible I have an air leak that is causing poor pressure??
Running -6AN line, running SVO Green Top 42lb injectors (LT1 EV1 style)
Is it possible I have an air leak that is causing poor pressure??
Last edited by Phantom383; 06-29-2014 at 09:13 AM.
06-29-2014, 10:38 AM
#9
What king of tuning has been done? Remember, if the injectors arent tuned for it will dump fuel and lose pressure. The green tops are actually 49-50LBS at 58 psi.
Bill
Bill
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LSX, LTX Stand alone swap harnesses. S10 LSX conversion PLUG AND PLAY harnesses, 24x conversion PLUG AND PLAY harnesses. LT1 to LSX PLUG AND PLAY Harnesses.
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06-29-2014, 03:18 PM
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I had the PCM back 2 times for changes already.
He knows what injectors I'm using and told me that they would have to be tuned for 48's or so.
I did check my MAP to make sure I didn't get an LS3 and it's not so I'm good there.
I don't have any tuning software but I do have a SnapOn brick that I can read some things with.
06-30-2014, 04:32 PM
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Not a mail order tune, I actually dropped the PCM off, give him a list of mods and then pick it back up.
People make mistakes, I just want to see some ownership and help in figuring things out.
People make mistakes, I just want to see some ownership and help in figuring things out.
07-03-2014, 06:48 AM
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Well over the past few days I have come up with nothing new 
Car fires and then dies so I'll have to wait till I go get the car tuned cause I believe it has something to do with the IAC and the 310 limit I'm seeing.
Heck, the SnapOn brick don't even show movement at all so that tells me the PCM can't see the IAC either.
Car fires and then dies so I'll have to wait till I go get the car tuned cause I believe it has something to do with the IAC and the 310 limit I'm seeing.
Heck, the SnapOn brick don't even show movement at all so that tells me the PCM can't see the IAC either.
07-03-2014, 08:33 AM
#16
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You didn't mention the harness. Is it new or reworked? Can you keep it running by giving it throttle? If so then it's either iac related or tune. If not then it's probably fuel related since you said it runs on starting fluid.
07-03-2014, 01:14 PM
#18
TECH Regular
I would make sure the iac is wired correctly. Did the PCM come from a drive by cable application? Make sure it's the correct PCM and correct operating system for a dbc application.