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ECMlink Major Crack in JMFab Exhaust Manifold!

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tdykes1234

Proven Member
70
0
Feb 12, 2013
Columbus, Indiana
I may be putting this inthe wrong forum so feel free to move it if need be. The issue that I'm experiencing is that I can not go full throttle or build over 15psi on my hx40. I've had someone who is an engineer for cummins and a fellow dsmer look at my logs (which I'm unable to post) and he 100% believes that this exhaust leak is the cause of the issue. He mentioned that my mafraw value was too high for the gm/rev that the engine was seeing at that point and this was being caused by the exhaust leak pulling in fresh air and throwing off the o2 sensor. I would like to also mention that I'm running a downpipe right out the front bumper so he said that's why its so sensitive to the readings that it is getting. I'm going to post the data at least from that point so you guys can get an understanding of what we are looking at. I know that an exhaust leak, especially a big one like this, will slow spool and cause a rich/lean condition at idle/cruise while in closed loop. It shouldn't affect the car at WOT in open loop though should it? It shouldn't prevent me from being able to go WOT and actually build past 15psi? And can it truly affect the maf readings in any way, shap,e or form? I'd appreciate the help here because id like to be able to make just one pull on this car without it breaking a part!!!

Car Mods:
6-Bolt Swap Fresh Rebuild (185 on all cylinders)
Dual Fuel Pumps 450intank/350inline
1800cc Injectors
Aeromotive FPR (43.5psi)
Aeromotive Fuel Rail
6an Feed/6an Return
E85
JMFab Exhaust Manifold
Holset HX40
FMIC (No Boost Leaks)
S90 74mm TB
Crower Springs/Retainers
Crower 280 Cams
Aires 9:2 Pistons
Pauter XBeam Rods (HD Pins)
1.3mm Cometic HG
All ARP Hardware

EcmLink Readings:
RPM - 5,656
ThrotPos - 52%
TPSVolts - 2.90
Battery - 14.1v
BoostEst - 13.5psi
AirflowPerRev - 2.17gm/rev
Airflow - 204.5gm/s
MAFRaw - 2419.3Hz
AFRatioEst - 10.0:1
AEMInlineUEGO - 18.0:1
LTFT HI - 0.0%
LTFT LO - -2.7%
CombinedFT - -2.1%
InjDuty - 38.7%
Closed Loop - 0
IdleSw - 0
CoolTemp - 182F
 
A hole and in your exhaust manifold definitely affects the turbos ability to build boost. Not really the best idea to keep going WOT with a leak of your mani either. Where is the leak? Do you have pictures? Could just have someone weld it for you.
 
I'm taking it off the car today and sending it back to JMFab for repairs. I'll post pictures later today.
 
This picture shows the readings when it starts to break up
 

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Yea not really surprising your having trouble building boost, with a crack it’s like a second wastage dumping exhaust gas. Basically the turbo can’t spin as fast because that crack is redirecting exhaust letting it escape before your turbine.
 
It’s too lean in that picture 18 afr. Full log would help. Your leak must be huge to cause 18 afr reading.
I'm unable to actually post a log because the laptop I'm using doesn't have a wifi card. And the crack is absolutely huge. One runner is completely separated from the flange at the weld. It's cracked all the through and all the way around. That's why I'm sending it back. Did you notice though that AFRest was pig rich though? Shouldn't those be close to each other?
 
Damn I didnt even notice that, looks like it progressively leans out throughout the pull too. I wonder what the actual boost is. @tdykes1234 how do you monitor boost? A gauge and BoostEst?
Yes, I have an autometer boost gauge and then used BoostEst in the log just so you guys could see that. I can go past 15psi and I cant go WOT without it breaking up.
 
Last edited:
I'm unable to actually post a log because the laptop I'm using doesn't have a wifi card. And the crack is absolutely huge. One runner is completely separated from the flange at the weld. It's cracked all the through and all the way around. That's why I'm sending it back. Did you notice though that AFRest was pig rich though? Shouldn't those be close to each other?

That’s the target afr at that load. You were above 60% throttle and probably in boost so it will target a richer afr. You can track it on the maxoct table
 
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