Help! Problems getting blown Vette to perform.
Thread Starter
Pro
Joined: Nov 1999
Posts: 623
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From: Toronto, ON, Canada
Help! Problems getting blown Vette to perform.
I'm hoping everyone can put in their suggestions in. I'm having a hard time figuring out why my Vette won't perform as it should.
My Vette starts coughing, bogs down when I hammer the gas (above 3500rpm). It runs strong if I ease into the power but as soon as the pedal hits the floor (WOT) it's power dies. It feels like I'm running out of fuel but I have all the add-ons, 42lb/hr injectors, Walbro HP FP, Kenne Belle FP BAP controller. I'm also running a Wideband O2 setup to watch A/F ratios. I custom tuned the computer to run 11.5+ or - (tried little richer/leaner doesn't help) and it still runs like crap when WOT.
Just installed a 8-rib ASP pulley setup and hoping this belt isn't slipping. What are the possible problems that can cause this?
My plan is to test the following systematically;
- Check making boost with gauge
- Check fuel pressure under WOT.
- replace plugs and ignition box (box just went bad, now running with Crane coil and stock trigger)
- replace fuel filter (can fuel filter cause problems?)
Anything else? I'm so pissed it doesn't all just work after 15-20hrs (I reinstalled blower 3 times to get it to fit) of installation and wiring for the 8-rib and KB BAP.
My Vette starts coughing, bogs down when I hammer the gas (above 3500rpm). It runs strong if I ease into the power but as soon as the pedal hits the floor (WOT) it's power dies. It feels like I'm running out of fuel but I have all the add-ons, 42lb/hr injectors, Walbro HP FP, Kenne Belle FP BAP controller. I'm also running a Wideband O2 setup to watch A/F ratios. I custom tuned the computer to run 11.5+ or - (tried little richer/leaner doesn't help) and it still runs like crap when WOT.
Just installed a 8-rib ASP pulley setup and hoping this belt isn't slipping. What are the possible problems that can cause this?
My plan is to test the following systematically;
- Check making boost with gauge
- Check fuel pressure under WOT.
- replace plugs and ignition box (box just went bad, now running with Crane coil and stock trigger)
- replace fuel filter (can fuel filter cause problems?)
Anything else? I'm so pissed it doesn't all just work after 15-20hrs (I reinstalled blower 3 times to get it to fit) of installation and wiring for the 8-rib and KB BAP.
Le Mans Master
Joined: Jan 2003
Posts: 8,596
Likes: 19
From: Portland Oregon
The very first thing to do is to get a fuel pressure gauge on the rail to see where the pressure is. It sounds like you are loosing pressure for some reason. Are you still running the auxillary fuel pump that most kits normally have you install in line with the stock fuel pump that is in the tank? And if it is there is the pump running? The reason I ask is because if that second in line pump is not running and you attempt to run the car hard, the factory in tank pump will pump through it and make it run pretty well but as demand rises the inline pump that isn't running will become a restriction.
And as far as the filter goes, it can be a problem if it is clogged up.....most definitely it can be a MAJOR problem if that is the case. When it looses power does it start backfiring? Surging? Misfiring?
And as far as the filter goes, it can be a problem if it is clogged up.....most definitely it can be a MAJOR problem if that is the case. When it looses power does it start backfiring? Surging? Misfiring?
Thread Starter
Pro
Joined: Nov 1999
Posts: 623
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From: Toronto, ON, Canada
Thanks tjwong for the advice.
I have removed the inline Vortech pump and am running solely on the Walbro.
I also have a Cyberdyne Fuel Pressure gauge which I need to install but that should help me determine if I have fueling problems. Crossing my fingers that I don't have a kink in my fuel lines.
The car doesn't back fire, it just feels like it's fallen flat on it's power. Sort of feels like a slipping belt, strong power up to the point of slip and then bog and RPM's flutter as it fights against increase. Almost like someone has pulled major timing out of the car.
I have removed the inline Vortech pump and am running solely on the Walbro.
I also have a Cyberdyne Fuel Pressure gauge which I need to install but that should help me determine if I have fueling problems. Crossing my fingers that I don't have a kink in my fuel lines.
The car doesn't back fire, it just feels like it's fallen flat on it's power. Sort of feels like a slipping belt, strong power up to the point of slip and then bog and RPM's flutter as it fights against increase. Almost like someone has pulled major timing out of the car.
Le Mans Master
Joined: Jan 2003
Posts: 8,596
Likes: 19
From: Portland Oregon
Originally Posted by XTwinTurbo
Thanks tjwong for the advice.
I have removed the inline Vortech pump and am running solely on the Walbro.
I also have a Cyberdyne Fuel Pressure gauge which I need to install but that should help me determine if I have fueling problems. Crossing my fingers that I don't have a kink in my fuel lines.
The car doesn't back fire, it just feels like it's fallen flat on it's power. Sort of feels like a slipping belt, strong power up to the point of slip and then bog and RPM's flutter as it fights against increase. Almost like someone has pulled major timing out of the car.
I have removed the inline Vortech pump and am running solely on the Walbro.
I also have a Cyberdyne Fuel Pressure gauge which I need to install but that should help me determine if I have fueling problems. Crossing my fingers that I don't have a kink in my fuel lines.
The car doesn't back fire, it just feels like it's fallen flat on it's power. Sort of feels like a slipping belt, strong power up to the point of slip and then bog and RPM's flutter as it fights against increase. Almost like someone has pulled major timing out of the car.
Also are you running a boost timing retard mechanism in the ignition system? If you are what amount of boost retard do you have dialed in? It could be that it is set too high. Most systems such as Cranes Hi-6TR and the MSD BTM can allow as much as 21 degrees of boost referenced retard.
Drifting
Joined: Feb 2002
Posts: 1,937
Likes: 2
From: Arvada CO
mmm? i was going to say it could be a fuel pressure regulator diaphram but i dont know if you have somethign like that? i know when i ripped my FPR diaphram it would run good then in WOT it would caugh and fuel would jump from 60-80psi at any given time. So i dont know if the same rules apply?
Race Director
Joined: Feb 2002
Posts: 11,268
Likes: 14
From: Honolulu, HI
I don't think it's a fuel related problem as long as you can see the adjustments to your AF ratio through the Wideband O2 output. If you had fuel delivery problems, it would fatten or lean out and you would see it. That's the beauty of Wideband O2.
I think it could be either a slipping belt (which TJwong told you how to determine,) an ignition problem, or even a slipping clutch.
I was never making 8 psi until my 8 rib conversion, now that I am my car just quits due to a slipping clutch I'm pretty sure because it happens more when I nail it and down shift (sudden RPM change) but when I ease into the throttle and increase the RPM's it doesn't slip as much.
My MSD BTM can pull 3 degrees of timing per 1 psi of boost which @ 8 psi is a total of 24 degrees
Mine is set at 1 degree, what is your set at? Even when I've set mine at full 24 degrees I just felt an overall power loss, it never really "fell on it's face" or quit on me up high in the RPM's.
I think it could be either a slipping belt (which TJwong told you how to determine,) an ignition problem, or even a slipping clutch.
I was never making 8 psi until my 8 rib conversion, now that I am my car just quits due to a slipping clutch I'm pretty sure because it happens more when I nail it and down shift (sudden RPM change) but when I ease into the throttle and increase the RPM's it doesn't slip as much.
My MSD BTM can pull 3 degrees of timing per 1 psi of boost which @ 8 psi is a total of 24 degrees
Mine is set at 1 degree, what is your set at? Even when I've set mine at full 24 degrees I just felt an overall power loss, it never really "fell on it's face" or quit on me up high in the RPM's.
Thread Starter
Pro
Joined: Nov 1999
Posts: 623
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From: Toronto, ON, Canada
All good advice. I'm going to take it one step at a time and knock out all the options as a checklist.
Don't think it's my clutch as I have a MCleod Street Twin installed from last year and I don't see a jump in RPM beyond normal.
May possibly be a bad FP regulator as I'm running a stock regulator (43.5psi on 42lb/hr injectors should be enough fuel). As for timing retard, I'm using LT1Edit on a stock computer to take out 3 to 12 degrees of timing from 3000 - 6000 rpm incrementally. No BTM ignition box.
Will post results of my testing. Thanks
Don't think it's my clutch as I have a MCleod Street Twin installed from last year and I don't see a jump in RPM beyond normal.
May possibly be a bad FP regulator as I'm running a stock regulator (43.5psi on 42lb/hr injectors should be enough fuel). As for timing retard, I'm using LT1Edit on a stock computer to take out 3 to 12 degrees of timing from 3000 - 6000 rpm incrementally. No BTM ignition box.
Will post results of my testing. Thanks
Race Director
Joined: Feb 2002
Posts: 11,268
Likes: 14
From: Honolulu, HI
Originally Posted by XTwinTurbo
Don't think it's my clutch as I have a MCleod Street Twin installed from last year
But I I'm not seeing any increased RPM's when it's slipping either. I always thought I should, but IMO you can still feel a power loss or "fall off" effect without increasing RPM's due to the clutch simply not being able to pull the car any faster. (slight slippage)
Am I wrong? Maybe it isn't my clutch either.
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Melting Slicks
Joined: Jul 2004
Posts: 3,277
Likes: 32
From: Mission Viejo California
Sounds like belt slip. Check your boost guage to see if it flutters and doesn't increase in pressure toward the top of the rpm range. I experienced it before and it does kind of feel like the power fell off because your motor sounds meaner and meaner as the rpm goes up, but you don't get the additional power.