A decrease in acceleration or just me..
Thread Starter
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
A decrease in acceleration or just me..
Took the 86 for a 20 mile drive today and every thing seemed fine. Stopped at the post office and started the car back up and something didn't seem right. It idles fine and does good cruising. I put my foot through the floor board while cruising and there was no power. The engine revved like it should but there was not much acceleration like it should be. Either that or I've been driving the 92 with about 120 more HP. 
My fan comes at 200* and was on when I parked. The temp usually drops down to 180* fairly quickly, but stayed around 195* after 5 minutes of ideling. It is pretty damn hot down here (100*). Seems like I could hear a rattling at the mufflers, but the exhaust felt free. The cat is suppost to be hollow from what the previous owner told me, but I haven't checked. I need to check the fuel pressure and the cat.
My fan comes at 200* and was on when I parked. The temp usually drops down to 180* fairly quickly, but stayed around 195* after 5 minutes of ideling. It is pretty damn hot down here (100*). Seems like I could hear a rattling at the mufflers, but the exhaust felt free. The cat is suppost to be hollow from what the previous owner told me, but I haven't checked. I need to check the fuel pressure and the cat.
Team Owner
Joined: Sep 2001
Posts: 62,160
Likes: 1,733
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
May need just a tuneup, or hook it to a scanner and see if its getting knock counts. Easy in the kind of heat we have right now.
A plugged cat would cause the same, but wouldnt come all-of-the-sudden like that.
A plugged cat would cause the same, but wouldnt come all-of-the-sudden like that.
Thread Starter
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
The car seemed to run better than it ever has when the engine temp was 120-180*. The engine seemed smooth and peppy. I even turned the tires a few times. It was after I shut it down and restarted it, that is seemed to have lost it's pep.
It very well could have some engine knocks. I couldn't hear them due to the exhaust note. I got a little concerned that something just wasn't right. I stuck my foot into it and the engine revved up but it just didn't feel like before. Hell, it could be a prob with the tranny slipping.
The car hasn't been driven in the last 2 months or more. I've started it 1-2 times a week and let it idle til the fan comes on. I did a tune up last year when I had all the problems with it. It's been driven less than 500 miles since then.
When I get some time, I will investigate a little more. I can scan it and see what's going on.
It very well could have some engine knocks. I couldn't hear them due to the exhaust note. I got a little concerned that something just wasn't right. I stuck my foot into it and the engine revved up but it just didn't feel like before. Hell, it could be a prob with the tranny slipping.
The car hasn't been driven in the last 2 months or more. I've started it 1-2 times a week and let it idle til the fan comes on. I did a tune up last year when I had all the problems with it. It's been driven less than 500 miles since then.
When I get some time, I will investigate a little more. I can scan it and see what's going on.
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,063
From: altered state
St. Jude Donor '05
The car will always feel stronger at lower temps. Once heat soak sets in it seems theres a loss of power to some degree. I have seen this on the dyno and on time slips...
Personally I like to keep em running a little on the cool side for that reason. Not TOO cool though.
Personally I like to keep em running a little on the cool side for that reason. Not TOO cool though.
Thread Starter
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
The car will always feel stronger at lower temps. Once heat soak sets in it seems theres a loss of power to some degree. I have seen this on the dyno and on time slips...
Personally I like to keep em running a little on the cool side for that reason. Not TOO cool though.
Personally I like to keep em running a little on the cool side for that reason. Not TOO cool though.
But in this case it was a lot more obvious that something was wrong. I went straight home with it. Nothing about the car changed other than the loss of, what I thought, was good acceleration before. 
Race Director
Joined: Dec 2002
Posts: 13,348
Likes: 233
From: SCMR Rat Pack'r Charter Member..Great Bend KS
The infamous butt-dyno is notoriously inaccurate.
Take it out again at about 2AM, and see how she runs.
Larry
code5coupe
__________
not easily impressed....
Take it out again at about 2AM, and see how she runs.
Larry
code5coupe
__________
not easily impressed....
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
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
I just went to start it up and it won't start unless I coach the accelerator pedal. It won't idle on it's own and it sounds wierd while it's running. Not any knocking or chattering noises...just like it's not getting enough air, fuel, or spark. I don't have enough time now or today to diagnose it. Figure what ever I find will be the cause of yesterdays event. 
Team Owner
Joined: Jun 2001
Posts: 26,196
Likes: 0
From: Orlando FL
St. Jude Donor '08-'09
Does your car still have pre-cats? If so, it may have blew its load into the pipes somewhere and clogged it up.
This happened to me twice (once after each pre-cat broke down inside the exhaust pipes). I had total loss of power, but idled and revved just fine. I had the same rattling sound you described in your first post too.
Luckily I still had my main cat in, which the pre-cat crap had clogged up in the front of the main cat and I was able to just dump it out. Worse case you now have crap in your mufflers that will be a biotch to get out.
BTW: this was an instantaneous change both times to me and not a gradual one... worked one day all day, then when I started it up that evening the problem was there. I dumped the crap trapped in the cat out and was fine again 100%. A few months later the other pre-cat went and SAME EXACT scenario.
This happened to me twice (once after each pre-cat broke down inside the exhaust pipes). I had total loss of power, but idled and revved just fine. I had the same rattling sound you described in your first post too.
Luckily I still had my main cat in, which the pre-cat crap had clogged up in the front of the main cat and I was able to just dump it out. Worse case you now have crap in your mufflers that will be a biotch to get out.
BTW: this was an instantaneous change both times to me and not a gradual one... worked one day all day, then when I started it up that evening the problem was there. I dumped the crap trapped in the cat out and was fine again 100%. A few months later the other pre-cat went and SAME EXACT scenario.
Last edited by GIJoe; Aug 15, 2007 at 01:50 PM.
Team Owner
Joined: Jul 2003
Posts: 24,650
Likes: 8
My Main cat busted and a chunk flew back into the front of the rear Y, and nearly completely clogged it up. Wouldnt Idle right, wouldnt rev past about 3000.
Decided it was a good time to gut the cat. Best decision I EVER made.
Decided it was a good time to gut the cat. Best decision I EVER made.
Team Owner
Joined: Aug 1999
Posts: 24,017
Likes: 634
St. Jude Donor '10
I just went to start it up and it won't start unless I coach the accelerator pedal. It won't idle on it's own and it sounds wierd while it's running. Not any knocking or chattering noises...just like it's not getting enough air, fuel, or spark. I don't have enough time now or today to diagnose it. Figure what ever I find will be the cause of yesterdays event.
I too would consider the slower acceleration of the car to be the record breaking temps everyone is experiencing right now.
Thread Starter
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
The fuel filter and serviced injectors were installed in Feb this year. Agreed on flooring the accelerator pedal to shut off the injectors (clear flood mode), but didn't help. No vac leaks, I have searched over them extensivly in Feb.
There is definately a problem now that it will not run on it's own. Last time it did this the battery was low. I have a charger on it and will try it again tomorrow.
There is definately a problem now that it will not run on it's own. Last time it did this the battery was low. I have a charger on it and will try it again tomorrow.
Thread Starter
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
It will start up, if I giggle the accelerator pedal...but soon quits. I will figure it out sooner or later. I have a spare chip and ECM I can install, as I just had this chip tuned that is in the car now and it was the first time out with it. I haven't checked for good spark or really much of anything right now. The car mostly just sits, so I'm in no hurry. I've got two other vettes I can drive.
