LM7 Swap Incredibly Rich
LM7 Swap Incredibly Rich Hoping somebody can shed some light:
I'm having an issue with my car running incredibly rich. Eye burning, spraying fuel out the exhaust rich...
I swapped a 2001 LM7 into my Chevelle two years ago. I ran it for a year with the truck intake manifold, accessories, harness, and PCM. Ran perfectly fine without a single hiccup for the couple thousand miles I put on it. Running the corvette FPR, getting 58 psi at the rail.
The next winter I installed an LS6 intake manifold/fuel rail/injectors with corvette accessories and PSI conversion harness with red/blue PCM tuned by PSI conversions. My main goal was just to clean the look up under the hood, but didn't go as well as planned. The car now runs incredibly rich AFTER it has warmed up to ~160F coolant temp. The car will run perfectly fine up until that point.
This is essentially a stock LM7 with what is supposed to be a stock tune w/ VATS removed, rear 02's removed, etc. I don't currently have access to any scanners to see whats going on behind the scenes. I swapped all the sensors to fit the psi harness so I'm not missing anything that I know of. The IAT/MAF/TPS are the same that were on the car previously.
I know this post is pretty vague, but I'm happy to answer any questions/test/measure whatever regarding my set-up to help pinpoint the issue.
I'm having an issue with my car running incredibly rich. Eye burning, spraying fuel out the exhaust rich...
I swapped a 2001 LM7 into my Chevelle two years ago. I ran it for a year with the truck intake manifold, accessories, harness, and PCM. Ran perfectly fine without a single hiccup for the couple thousand miles I put on it. Running the corvette FPR, getting 58 psi at the rail.
The next winter I installed an LS6 intake manifold/fuel rail/injectors with corvette accessories and PSI conversion harness with red/blue PCM tuned by PSI conversions. My main goal was just to clean the look up under the hood, but didn't go as well as planned. The car now runs incredibly rich AFTER it has warmed up to ~160F coolant temp. The car will run perfectly fine up until that point.
This is essentially a stock LM7 with what is supposed to be a stock tune w/ VATS removed, rear 02's removed, etc. I don't currently have access to any scanners to see whats going on behind the scenes. I swapped all the sensors to fit the psi harness so I'm not missing anything that I know of. The IAT/MAF/TPS are the same that were on the car previously.
I know this post is pretty vague, but I'm happy to answer any questions/test/measure whatever regarding my set-up to help pinpoint the issue.
I have a set that I can try, just need to buy the EV1/EV6 adapter.
PSI conversions should have tuned the pcm to account for the different flow rates between injectors.
Any idea why it would run fine at the lower operating temperature? I assume closed vs open loop, but if the injector flow rate is whats messing it up I would have thought it'd be off in both open and closed loop?
PSI conversions should have tuned the pcm to account for the different flow rates between injectors.
Any idea why it would run fine at the lower operating temperature? I assume closed vs open loop, but if the injector flow rate is whats messing it up I would have thought it'd be off in both open and closed loop?
I am not discounting this, and I will look into it, but are there any other possibilities that could be causing this?
TECH Resident
Joined: Jun 2011
Posts: 936
Likes: 472
Hoping somebody can shed some light:
I swapped a 2001 LM7 into my Chevelle two years ago. I ran it for a year with the truck intake manifold, accessories, harness, and PCM. Ran perfectly fine without a single hiccup for the couple thousand miles I put on it. Running the corvette FPR, getting 58 psi at the rail.
I swapped a 2001 LM7 into my Chevelle two years ago. I ran it for a year with the truck intake manifold, accessories, harness, and PCM. Ran perfectly fine without a single hiccup for the couple thousand miles I put on it. Running the corvette FPR, getting 58 psi at the rail.
When is it running rich?
Prior I ran the corvette FPR with the truck intake & return-less truck fuel rail/truck injectors and it ran fine.
It runs rich at idle through ~2,200-2,500 rpms. It seems to smooth out some at above 2,500 rpm and 50%+ throttle, but I can feel that it is still stumbling some.
Trending Topics
TECH Resident
Joined: Jun 2011
Posts: 936
Likes: 472
I have the stock LS1/LS6 fuel rail w/ the corvette FPR.
Prior I ran the corvette FPR with the truck intake & return-less truck fuel rail/truck injectors and it ran fine.
It runs rich at idle through ~2,200-2,500 rpms. It seems to smooth out some at above 2,500 rpm and 50%+ throttle, but I can feel that it is still stumbling some.
Prior I ran the corvette FPR with the truck intake & return-less truck fuel rail/truck injectors and it ran fine.
It runs rich at idle through ~2,200-2,500 rpms. It seems to smooth out some at above 2,500 rpm and 50%+ throttle, but I can feel that it is still stumbling some.
When you converted to returnless, you have 58psi regardless of vacuum. This increased the fuel flow at idle by 10% (regardless of the injector size) from what the engine had stock. The bigger the injector, the more off the fuel would be (total flow rate-wise). So if the new injectors are rated for higher flow rate, they will be off even more in terms of pph delivery.
How it's behaving is consistent with converting to returnless without adjusting the type of system in the calibration. The heavier the throttle, the closer to the correct expected pressure delta across the injectors it will be. It starts out rich @ idle and part throttle, leaning out as load goes up, until it's correct.
Also need to ensure they updated the injector characterization data (low pulse correction). If the correct data hasn't been put in for the injectors, it will throw off your idle and light throttle even more.
Last edited by 68Formula; Mar 12, 2020 at 08:13 PM.
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
Gas Monkey Built a 6-Wheel Ferrari Testarossa With a Corvette LT4 Engine
Verdad Gallardo
7 Most Reliable High-Performance Engines GM Has Ever Built
Verdad Gallardo
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin
Verdad Gallardo
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo