Power Loss under high load
Thread Starter
Heel & Toe
Joined: Apr 2019
Posts: 15
Likes: 0
Power Loss under high load
Hey guys, Hoping someone can help. I think I have read about every forum on this topic. Under Wot my car pulls great 1st-2nd. About 50% of the time in 3rd and 4th at wot at about 4k Rpms my engine stutters and feels a good power loss. What's weird to me is I can pull fine in those gears in those conditions great and other times it gets the power loss.
if this helps Mods are BBK throttle body, Vortex Rammer CAI, and a programmed tuner tune, These were all done before I owned the car and I do not have the programmer.
I recently have done Plugs/Wires, fuel filter and new CAI filter. Also had to replace both cats due to both being all jacked up. No PCM codes
Any ideas? thanks!!!
if this helps Mods are BBK throttle body, Vortex Rammer CAI, and a programmed tuner tune, These were all done before I owned the car and I do not have the programmer.
I recently have done Plugs/Wires, fuel filter and new CAI filter. Also had to replace both cats due to both being all jacked up. No PCM codes
Any ideas? thanks!!!
Last edited by MurderedLs1; Jan 15, 2020 at 05:37 PM.
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,621
Likes: 4,069
From: Cape Coral, Florida
Without having a scan tool and looking at some data PIDS ( O2's, fuel trims, MAF, MAP, etc...) while the car is under load you'd only be GUESSING !!...can either be fuel related (fuel pump) or a bad or dirty MAF sensor...you can disconnect the MAF sensor and run the car under the load conditions you are having the power loss...doing that will set a check engine light but it's only because of the MAF being disconnected...don't worry about it !!...if no good try cleaning the MAF sensor...also why were your cats replaced ??...say for instance the engine was running rich or you were having some misfiring cylinders and that had "jacked" the cats...if the reason to cause the cats to go bad (the cause) were not rectified the cats will again be "jacked" (the effect) !!...you have to find the root cause !!
Last edited by C5 Diag; Jan 15, 2020 at 05:42 PM.
Thread Starter
Heel & Toe
Joined: Apr 2019
Posts: 15
Likes: 0
I am not sure on the cause of the cats failures, I have cleaned the MAF before, I will go ahead and do it again as well as unplugging it and trying that. Any reason it would be pulling fine in 1st-2nd and occasionally fine in 3rd-4th?
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,621
Likes: 4,069
From: Cape Coral, Florida
It would be more of a "load" issue...under load the PCM sees an increase in airflow (MAF/MAP) and throttle position (TPS) the injector pulse width is increased...i.e. more fuel...like I had said without a scan tool and better yet a scope you'll only be guessing...and that can get expensive !!….and being intermittent it makes it that much harder to diagnose.
Last edited by C5 Diag; Jan 15, 2020 at 06:16 PM.
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,621
Likes: 4,069
From: Cape Coral, Florida
Well first thing if you’ve never had a scan tool it’s not going to tell you what part you have to replace !!...for the money the “Chinese clone” Tech 2 which was GM’s factory scan tool back in the day is pretty decent...it’s bi directional which means you can do things like turn the fuel pump and fans on and off and has some other special functions...can be had on EBay for around $350-400...I have one but don’t use it very often..I use an Autel MS906 which is touchscreen and bi directional and a Snap On Verus D10 which is the same AND has a decent scope feature...it all depends what you want and how much you are willing to spend !!
Last edited by C5 Diag; Jan 15, 2020 at 07:14 PM.
Thread Starter
Heel & Toe
Joined: Apr 2019
Posts: 15
Likes: 0
I had ones that I could run all the parameters hooked into your laptop back when I had mustangs. Im not looking to spend to much just to be able to see all the parameters on this thing and make sure everything is working correctly. Thanks!
Melting Slicks
Joined: Nov 2017
Posts: 2,306
Likes: 747
This is really strange, I experience the same thing frequently. It's not a hard cut off, it feels more like a minor misfire/stumble. Nothing major, I just FEEL it hesitate for a second. Same thing though: fine in lower gears, only happens in 3rd and 4th above 4-5k.
It did it when I was "stock" (K&N intake, shorty headers, Corsa catback, both "stock" tune and ECS mail order tune) and it even does it now that I'm supercharged (new larger in tank fuel pump, new fuel filter/regulator, different injectors, new plugs and wires, new air filter, brand new cats, etc). Stock was using MAF obviously and new tune is speed density, so rules the MAF out.
I gave up because it's not a huge issue or even a real concern.Virtually anything that should logically cause it has been replaced and the tune has been completely changed. Not many possibilities left haha. I just figured it was a normal phenomenon on an LS1 at that point. Are we sure that's not the case?
It did it when I was "stock" (K&N intake, shorty headers, Corsa catback, both "stock" tune and ECS mail order tune) and it even does it now that I'm supercharged (new larger in tank fuel pump, new fuel filter/regulator, different injectors, new plugs and wires, new air filter, brand new cats, etc). Stock was using MAF obviously and new tune is speed density, so rules the MAF out.
I gave up because it's not a huge issue or even a real concern.Virtually anything that should logically cause it has been replaced and the tune has been completely changed. Not many possibilities left haha. I just figured it was a normal phenomenon on an LS1 at that point. Are we sure that's not the case?
Last edited by heggsc5; Jan 16, 2020 at 06:02 PM.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Thread Starter
Heel & Toe
Joined: Apr 2019
Posts: 15
Likes: 0
Well what is really weird to me is it happens about Half the time, some times it pulls great in those gears till redline. Other times I get the "hesitation" or "breaking up" feeling. sometimes I forget about it but right now its been bothering me wanting to get it out at the track when it opens soon.
Acct Suspended APR 2026 by request
Joined: Dec 2010
Posts: 10,367
Likes: 1,272
2020 Corvette of the Year Finalist (performance mods)
C5 of Year Winner (performance mods) 2019
the pcm could also be pulling timing for various reasons programmed into the tune, if you have access to anyone with hptuners or some type of datalogger you can confirm if that is actually the issue
Safety Car
Joined: Feb 1999
Posts: 4,043
Likes: 342
From: Central NJ
Hey guys, Hoping someone can help. I think I have read about every forum on this topic. Under Wot my car pulls great 1st-2nd. About 50% of the time in 3rd and 4th at wot at about 4k Rpms my engine stutters and feels a good power loss. What's weird to me is I can pull fine in those gears in those conditions great and other times it gets the power loss.
if this helps Mods are BBK throttle body, Vortex Rammer CAI, and a programmed tuner tune, These were all done before I owned the car and I do not have the programmer.
I recently have done Plugs/Wires, fuel filter and new CAI filter. Also had to replace both cats due to both being all jacked up. No PCM codes
Any ideas? thanks!!!
if this helps Mods are BBK throttle body, Vortex Rammer CAI, and a programmed tuner tune, These were all done before I owned the car and I do not have the programmer.
I recently have done Plugs/Wires, fuel filter and new CAI filter. Also had to replace both cats due to both being all jacked up. No PCM codes
Any ideas? thanks!!!
Thread Starter
Heel & Toe
Joined: Apr 2019
Posts: 15
Likes: 0
I had a Clutch and other things done when I first got it when I had the Slave give out, the shop re installed the h pipe and the metal exhaust gasket improperly causing it to move and block the exhaust flow. It caused the cat to break apart on inside, and a few months later so did the other side, I'm more then positive that would be the reason for them to break apart on inside. This past weekend I had done a few things to the car, I changed battery since voltage was low when it was sitting, I take apart the Vortex rammer made sure all connections where tight and to unmetered air would get it, I also cleaned the MAF sensor. I checked fuel pressure at idle was at 61psi, wasn't able to check it under load.
This morning on the way to work I would get the "Bucking" / "Hesitation" at about any load and every gear above 1st at about 20% throttle or more..... Which was weird because before it was only at about 4k rpms at wot in 3rd/4th and sometimes 2nd but only at wot. Now it seems to be under any load and every gear
This morning on the way to work I would get the "Bucking" / "Hesitation" at about any load and every gear above 1st at about 20% throttle or more..... Which was weird because before it was only at about 4k rpms at wot in 3rd/4th and sometimes 2nd but only at wot. Now it seems to be under any load and every gear
Acct Suspended APR 2026 by request
Joined: Dec 2010
Posts: 10,367
Likes: 1,272
2020 Corvette of the Year Finalist (performance mods)
C5 of Year Winner (performance mods) 2019
check the plug gap while you are in there... do you know what they were gapped at when you changed them?
Thread Starter
Heel & Toe
Joined: Apr 2019
Posts: 15
Likes: 0
They are all gapped to .55, The local tuner I got a hold of told me this is the plug the go with aswell. Plugs prior were tr55ix and msd wires don't know the gap when they came out.
Went on drive on my lunch right now, car wasn't bucking under normal load like it was this morning but still bucking in high rpm higher load. Ill look up some videos on how to test coil packs, not quite sure how to
Went on drive on my lunch right now, car wasn't bucking under normal load like it was this morning but still bucking in high rpm higher load. Ill look up some videos on how to test coil packs, not quite sure how to