Author Topic: LS376/515 swap in a '78 Trans Am  (Read 2778 times)

Nexus

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Re: LS376/515 swap in a '78 Trans Am
« Reply #80 on: April 27, 2019, 10:54:09 AM »
I'm just caught up from when you posted the video clip...does it ever sound smooth.....right on...won't be too long now!!!!
Charlie

79 Esprit but like many, it will be a T/A clone
(18 years and counting but still have her)

skisix38off

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Re: LS376/515 swap in a '78 Trans Am
« Reply #81 on: April 30, 2019, 07:01:20 AM »
I'm just caught up from when you posted the video clip...does it ever sound smooth.....right on...won't be too long now!!!!

Yes, It's run enough now that it settles in at around 1100 rpm idle and has a nice snappy sound to it!

skisix38off

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Re: LS376/515 swap in a '78 Trans Am
« Reply #82 on: April 30, 2019, 07:08:32 AM »
So, a couple posts ago I said that it was getting too hot after running for a while.  It heats up like it doesn't have coolant in it.  I did replace the lower radiator hose and now I believe that's not choking flow.  It still ran hot and I never saw anything circulating in the radiator and thought the tstat might be stuck closed.  Then I removed the Tstat and ran it again, this time it got hot just as before only it took a few more minutes to get hot.  Again, no circulation in the radiator. 

A bad water pump?
Is there some priming sequence I should have followed?

Updated71

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Re: LS376/515 swap in a '78 Trans Am
« Reply #83 on: May 01, 2019, 05:30:05 PM »
Could it be an air pocket?
The surgeon general never said nuthin' 'bout smokin' the competition!

skisix38off

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Re: LS376/515 swap in a '78 Trans Am
« Reply #84 on: May 10, 2019, 07:22:02 AM »
A brief update...  I replaced the water pump with one that I got from a good friend and after removing the Tstat again, that seems to allow it to run for extended periods of time while staying around 200F.  While this was going on I got to noticing that the Holley system doesn't seem to go into Closed loop mode.  It starts quickly and then idles for around 20 sec at 850-1000 rpm and then it slowly picks up rpm until it goes to 1500-1700 rpm and stays there.  The A/F says it's running at 11.5 and the learn % is 0.  I went back through the handheld to make sure I have learning clicked to "on" and 100%. I have the CTS set to 150 and both the coolant enable and rpm enable are set to "on".


Re: LS376/515 swap in a '78 Trans Am
« Reply #84 on: May 10, 2019, 07:22:02 AM »

skisix38off

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Re: LS376/515 swap in a '78 Trans Am
« Reply #85 on: May 13, 2019, 06:51:01 AM »
In my quest to get the engine to run in closed loop mode I poked around until it no longer starts again.  I thought for a bit that maybe I was having fuel pump problems but, no the fuel pump is working just fine.  It does start if I pour a bit of fuel manually down the TB, so the injectors aren't firing!
OMG- when does this BS stop? 

I know a lot of people have great experiences with their Holley EFI systems, I clearly am not in that category!  And I am not blaming all my woes on the Holley, every new part on this update has had one problem or another.

Vent paused for now...

FormTA

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Re: LS376/515 swap in a '78 Trans Am
« Reply #86 on: May 13, 2019, 08:13:31 AM »
Wow, sorry the hear you are having all these issues with the swap. Kind of makes me glad I used the lame stock 1998 ecm with my LS swap. Good luck, I hope it is an easy fix for you.
79 Trans am 301 (work in progress) LS swap n progress
79 Formula 301 (Work in progress)
67 RS Camaro (Work in progress)
See the recurring theme???

skisix38off

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Re: LS376/515 swap in a '78 Trans Am
« Reply #87 on: May 14, 2019, 06:59:19 AM »
Wow, sorry the hear you are having all these issues with the swap. Kind of makes me glad I used the lame stock 1998 ecm with my LS swap. Good luck, I hope it is an easy fix for you.

I normally go the route you went Form, this time I wanted things to work the very first time and not have the regular trouble I have trying to get some used parts to work with other used parts.  Turns out, at least this time, that the new parts don't go together any better then the used parts.  I guess if this issue isn't a relay or some inexpensive part store piece, I can send it back to Holley and they will take care of it - that just means that it's on blocks for that much longer!

ryeguy2006a

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Re: LS376/515 swap in a '78 Trans Am
« Reply #88 on: May 17, 2019, 11:15:56 AM »
I'll trade you straight up for all my stock EFI stuff for your Holley stuff :cool:

Did you make sure that the IAC was within the 2-10 range? If not, you will need to adjust the throttle air blade position until you reach that range. It sounds to me like you are possibly either running out of the range for the IAC, or you are potentially running low on fuel pressure. Do you have a way to log your fuel pressure? And was it set to 58 PSI?

My Dad's Chevelle was doing the same thing with the idle that wouldn't go below 1300-1500 and it ended up being a combination of those two things. Also, the ECU won't go into closed loop until it's running within the parameters of your tune. So like my dad's for example wasn't learning since it wasn't getting hot enough. We had to fix that before it would learn.

Hope that helps.
« Last Edit: May 17, 2019, 11:18:26 AM by ryeguy2006a »

1976 Trans Am LS1, 6 speed, C5 12.8" Brakes, LS1 rear 12" brakes, 17" Aluminum Rims, and much more...SOLD
My Build: http://transamcountry.com/community/index.php?topic=24465.0

New project: 1968 Camaro with 6?.?0?  5.3 w/ Z06 cam/T56
http://transamcountry.com/community/index.php?topic=74591.0

ryeguy2006a

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Re: LS376/515 swap in a '78 Trans Am
« Reply #89 on: May 17, 2019, 12:10:44 PM »
Oh and I re-read one of your earlier posts and this makes sense now. If you have a trapped air pocket, your temp sensor may be reading incorrectly and causing the ECU not to go into closed loop. I would try raising the front of your car up 12" or so and opening one of the front steam vents. That may help to relieve the pocket. You could also open the other 3 until antifreeze comes out to help with bleeding the system. What's nice is some of the earlier LS motors came with a 4 corner steam port that tied them all together and you can route them back into the radiator. That way it basically purges itself.

1976 Trans Am LS1, 6 speed, C5 12.8" Brakes, LS1 rear 12" brakes, 17" Aluminum Rims, and much more...SOLD
My Build: http://transamcountry.com/community/index.php?topic=24465.0

New project: 1968 Camaro with 6?.?0?  5.3 w/ Z06 cam/T56
http://transamcountry.com/community/index.php?topic=74591.0

skisix38off

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Re: LS376/515 swap in a '78 Trans Am
« Reply #90 on: May 21, 2019, 07:31:59 AM »
I'll trade you straight up for all my stock EFI stuff for your Holley stuff :cool:

Did you make sure that the IAC was within the 2-10 range? If not, you will need to adjust the throttle air blade position until you reach that range. It sounds to me like you are possibly either running out of the range for the IAC, or you are potentially running low on fuel pressure. Do you have a way to log your fuel pressure? And was it set to 58 PSI?

My Dad's Chevelle was doing the same thing with the idle that wouldn't go below 1300-1500 and it ended up being a combination of those two things. Also, the ECU won't go into closed loop until it's running within the parameters of your tune. So like my dad's for example wasn't learning since it wasn't getting hot enough. We had to fix that before it would learn.

Hope that helps.

I'll keep trying with this Holley stuff- Thanks tho!
The TPS is 0, and I thought that was the issue but, Ill go back to see the IAC value.  Fuel pressure is set to 42-44 psi which is what says in the manual..

ryeguy2006a

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Re: LS376/515 swap in a '78 Trans Am
« Reply #91 on: May 21, 2019, 09:47:28 AM »
I was kidding about swapping ECU's haha.

But you are right, on the 43 psi. I forget that you are running the terminator throttlebody on the LS engine. Keep me posted as we are having a little trouble with my dad's system too. He opted to swap from the large cap HEI to the small cap and when he did it's running terrible now... Trying to diagnose what is wrong with it to cause this issue.

1976 Trans Am LS1, 6 speed, C5 12.8" Brakes, LS1 rear 12" brakes, 17" Aluminum Rims, and much more...SOLD
My Build: http://transamcountry.com/community/index.php?topic=24465.0

New project: 1968 Camaro with 6?.?0?  5.3 w/ Z06 cam/T56
http://transamcountry.com/community/index.php?topic=74591.0

Re: LS376/515 swap in a '78 Trans Am
« Reply #91 on: May 21, 2019, 09:47:28 AM »
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