2018 Intake Manifold with IMRC into a 2016 GT - please please help!!!

[NJMike50]

Hello, I swapped out my stock intake manifold for a brand new 2018 manifold with IMRC lockouts. I researched and watched many videos of the swap and followed the instructions to the letter. Long story short, I installed the 2018, flashed the new Lund tune for the manifold, started the car and.....

It turned over once, idled horribly and then died.....tried several times - same thing. I finally gave up and turned it over to my mechanic who has tested everything and sees no issues with the TB, vacuum lines, fuel system - nothing. No matter what we try, the car will not turn over and idle....

From what I saw this should be an easy swap out, but it has been anything but. Does anyone know what I may have missed, or what else I should check on?

I'm desperate at this point...anyone out there....please HELP!

Sponsored

 

[Need4SpeedMotors]

When I installed the 18 manifold on my car and had it tuned by lund they told me to remove and lockout the imrc's. They turn them off in the tune I think. The imrc could be closed shut and that's why the car is acting weird. I would double check with lund on that. Im almost positive that is what it is.

 

[NJMike50]

They're removed and I have LMR lockouts installed...it's a brand new 2018 manifold. I swapped out the OEM throttle body too....not using the one that came on the 2018. Also swapped over the 2018 fuel injectors since they are brand new as well....

 

[Torinate]

Not sure - but are the 18 injectors the same size as the 15-17? May want to try the originals and see what happens!

 

[EFI]

Did you check with your tuner? This sounds like a tune issue rather than hardware related.

That would have been my first call after ensuring everything was installed correctly and there were not obvious vacuum leaks.

 

[NJMike50]

So here's another twist...when I swapped the 2018 manifold in, I used the 2018 injectors too. They are brand new so I figured why not, they're compatible....well, now I'm seeing that the 2018 injuctors are smaller than the 15-17 (28 lbs vs. 34 lbs). Stupid question, but could this be the issue all along??

 

[NJMike50]

So here's another twist...when I swapped the 2018 manifold in, I used the 2018 injectors too. They are brand new so I figured why not, they're compatible....well, now I'm seeing that the 2018 injuctors are smaller than the 15-17 (28 lbs vs. 34 lbs). Stupid question, but could this be the issue all along??

Update: My shop just called and thankfully I found this forum and was able to figure out the issue with the injectors. They swapped my original '16 injectors and the car fired right up! So, moral of the story, newer doesn't necessarily mean bigger, or the same even. The manifold on the 18's is a big HP adder, but not if you use the 18's injectors, as they are much smaller than the previous gen's. Lesson learned.....hopefully this helps someone else down the road, since I've never seen anything posted about it when people are swapping their intake manifolds over to the better flowing 2018.....cheers!

 

[NGOT8R]

I’m still surprised you didn’t have to get with Lund and have them turn off the IMRCs in your tunes. They did it for me when I locked mine out. Cost was $150.

 

[NJMike50]

I’m still surprised you didn’t have to get with Lund and have them turn off the IMRCs in your tunes. They did it for me when I locked mine out. Cost was $150.

I should have replied earlier. The new tune includes the IMRC lockouts since they are no longer part of the mani. Same here - $150 for the new tune.

Did you notice a difference in power with the 2018 mani?

 

[NGOT8R]

I should have replied earlier. The new tune includes the IMRC lockouts since they are no longer part of the mani. Same here - $150 for the new tune.

Did you notice a difference in power with the 2018 mani?

My intake manifold is actually a GT350 manifold. I can’t say that I noticed a difference at all since locking them out. I only removed all of that crap from my IM to declutter the area and make it easy to access the two top transmission bolts to drop the tranny and do clutch changes when necessary.

 

[ice445]

Update: My shop just called and thankfully I found this forum and was able to figure out the issue with the injectors. They swapped my original '16 injectors and the car fired right up! So, moral of the story, newer doesn't necessarily mean bigger, or the same even. The manifold on the 18's is a big HP adder, but not if you use the 18's injectors, as they are much smaller than the previous gen's. Lesson learned.....hopefully this helps someone else down the road, since I've never seen anything posted about it when people are swapping their intake manifolds over to the better flowing 2018.....cheers!

That's because gen 3 actually has 16 injectors. Half the system is direct injection, so the port injectors don't need to have the same flow numbers as gen 2 which has only that.

Sponsored