74 manifold swap issues!!

so the other day i installed the 74 manifold with the stock 72 egr tube and tb.now when i start the car i revs high than goes down(does not rev high for more than a sec) if i put it in n it idles like i have a cam in it ( mind u when i had the stock mani in the a/f gauge read 14.9-15.2 at most!) anyways now it running at lik 16.9 to --- at idle. it threw the cel but i didnt read it i just assumed it was either the egr or vacuum so i checked every thing and unpluged the batt to reset the ecu and it still running like idling like shit! so can someone give some help please!!!!!!!! not sure if im making sense

This is what I referenced for info on FB

https://www.thegalantcenter.org/showthread.php?t=45356

It probably would have been a good idea to scan for the code in order to pinpoint exactly where the issue is. You might want to double check all vacuum routing to make sure everything is going where it needs.

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Originally Posted by keith6110

This is what I referenced for info on FB

https://www.thegalantcenter.org/showthread.php?t=45356

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Hey Keith I like how you referenced my thread lol N I'm still having my egr issue. FML!!! lol

It sounds like you have a big vacuum leak, but the AFRs dont support that. It should be reading richer.

Did you swap over the Diamante TB too, or you already ran that with the stock manifold?

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Originally Posted by mko

It sounds like you have a big vacuum leak, but the AFRs dont support that. It should be reading richer.

Did you swap over the Diamante TB too, or you already ran that with the stock manifold?

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well i just read the cel and it said im runnig too lean!! im thinking i might need another tune!!

the only thing i swaped was the manifold everything else is from the 72

did you swap the lower portion of the manifold?

or is there one?

the lower manifold stays the same. I'm assuming he left that much alone. I'm having a real hard time thinking of what happened. There has to be something that isn't quite right. I never seen any cel's with the Diamante plenum when I had the 3.0 and still not with my 3.8 too.

my buddy did the Diamante manifold swap, and his engine would cut out at about 5k RPM. I don't know if this could be similar to that. He ended up swapping back to the Galant manifold since he had so many problems with the other.

I have been talking with Marlon on this the last few days and this is probably a vac leak somewhere. He has a TB spacer on it which I suggested he remove and put the TB back on, also has a couple bolts that apprently snapped which could cause a vac leak on the lower-upper manifold flange.

The reason this is running lean is because the engine is pulling in un-metered air (vac leak after MAF), so it is still injecting same amount of fuel for "X" amount of air at idle or any other RPM, but more air is entering the combustion chamber via a vac leak somewhere.

so i installed manifold gasket and tb gasket plus i followed the fsm for the vacum lines.now now the car idles like i have some big cames and if at stop light it almost stall and driving at night the headlights flicker if stoped

raise the idle a bit and see how it acts

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Originally Posted by galant1983

so i installed manifold gasket and tb gasket plus i followed the fsm for the vacum lines.now now the car idles like i have some big cames and if at stop light it almost stall and driving at night the headlights flicker if stoped

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No reason to mess with idle speed (nor without doing it within the ECU at that)...again this manifold swap is nothing but simply bolt and go type modification

Did you remove your TB spacer, as well as fix the two broken manifold bolts? Are the gasket surfaces cleaned 100% before new gaskets are on, and are new gaskets being used?

Next thing is check for vac leaks around the manifold flanges and TB flange. This swap is definitely not something that causes issues for people so something else is happening here.

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Originally Posted by SPD_FRK

No reason to mess with idle speed (nor without doing it within the ECU at that)...again this manifold swap is nothing but simply bolt and go type modification

Did you remove your TB spacer, as well as fix the two broken manifold bolts? Are the gasket surfaces cleaned 100% before new gaskets are on, and are new gaskets being used?

Next thing is check for vac leaks around the manifold flanges and TB flange. This swap is definitely not something that causes issues for people so something else is happening here.

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yes i have removed the broken bolts and cleaned the surfaces of the mani and tb.i also did the vac lines accord to the fsm. here is a video of how the exhaust/idle sounds like http://www.youtube.com/watch?v=lyfeAQtPhy4

after you did everything you did allow the car to idle for 10-15 min befor touching the gas right the ecu needs to recalibrate after the ecu memory is lost other wise you will have probs it was the same way when we put my nephews system in his 3g eclipse it was dark and cold so we hooked up the battery and went for a drive to warm the car up and it kept wanting to stall got home reset the ecu and let it run for a bit and was fine

ive tryed everything i just think the swap is trash!! i mean if its a popular swap why are there no how to's??? i know someone on here has an idea or has ran into this problem

if you think the swap is trash, go back to the 6g72 plenum. No offense here but there has to be some kind of mistake causing this. It's really not hard to do for anybody with hands-on automotive experience. In fact, I found it quite simple. I could have written a how-to, but when I'm working on something, it's a little annoying to stop and take pictures and write notes, and honestly, it doesn't really require enough modification to really need a how-to.

I did my 74 plenum and TB swap and have had no issues from any kind, and I did it like year and half back. I have no EGR, rear bracket or coolant lines. The only issue I note sometimes is on very hot days (93-96ish degrees) my idle rpms have a tendency to low to around 550-600 rpm and get back to normal (700-850), but that's maybe because I disconnected the coolant lines... I dunno really. Oh, I have never touched or adjusted the TB screw.

I forgot... never have had a CEL from the swap.

I do!!!!!!