SES light flashing, no codes, and a low end miss
05-23-2011, 07:04 PM
#1
Teching In
Thread Starter
iTrader: (5)
Join Date: Oct 2006
Location: Wauconda, IL
Posts: 10
Likes: 0
Received 0 Likes
on
0 Posts
SES light flashing, no codes, and a low end miss I bought this car a couple months ago and when driving it home I noticed the CEL was flashing, but no misfire felt.
Car- 02 camaro ls1, auto, cam and supporting mods, long tubes with cats, 2 front 02 sensors, no rears.
Replaced- Both front 02 sensors (due to codes previously, one for voltage, the other for heater), fuel filter, tr55 plugs gapped at .059
Issue- Flashing SES light while cruising on the highway or at a constant speed, and if it's not on then it will come on if i pass somebody for example, usually goes away after a few seconds, rarely will it still be on when I slow down. I don't believe it's ever come on at idle. I don't feel a misfire at idle, it intermittently misfires under load at lower rpm's when I get on it.
I checked for vacuum leaks around the engine by spraying around the intake (fast 90/90) and idle didn't change and cleaned the throttle body and maf. I also retorqued the intake manifold bolts.
What would a clogged cat do to a car with no rear 02's? At work whenever I have a car with a clogged cat I would have misfires on that bank normally. I'm going to try and delete this weekend if I have time.
I know I should just do a new set of wires, the car currently has msd's, but without a code it's hard to just keep throwing parts at this car. I should have the car retuned as well. Any other ideas guys? I've searched and haven't come across too much. Will a tech2 showing realtime data by the way?
Thanks, Regis
Car- 02 camaro ls1, auto, cam and supporting mods, long tubes with cats, 2 front 02 sensors, no rears.
Replaced- Both front 02 sensors (due to codes previously, one for voltage, the other for heater), fuel filter, tr55 plugs gapped at .059
Issue- Flashing SES light while cruising on the highway or at a constant speed, and if it's not on then it will come on if i pass somebody for example, usually goes away after a few seconds, rarely will it still be on when I slow down. I don't believe it's ever come on at idle. I don't feel a misfire at idle, it intermittently misfires under load at lower rpm's when I get on it.
I checked for vacuum leaks around the engine by spraying around the intake (fast 90/90) and idle didn't change and cleaned the throttle body and maf. I also retorqued the intake manifold bolts.
What would a clogged cat do to a car with no rear 02's? At work whenever I have a car with a clogged cat I would have misfires on that bank normally. I'm going to try and delete this weekend if I have time.
I know I should just do a new set of wires, the car currently has msd's, but without a code it's hard to just keep throwing parts at this car. I should have the car retuned as well. Any other ideas guys? I've searched and haven't come across too much. Will a tech2 showing realtime data by the way?
Thanks, Regis
05-23-2011, 07:46 PM
#2
A flashing engine light is to be understood as a direct indicator for misfiring. If it's just one cylinder misfiring, it's not necessarily detectable, and it also may not set off the light at low frequency. My step father's '89 F-150 has confirmed misfires, but the light doesn't flash all the time. It mostly flashes during high-throttle acceleration, but never when the foot is off the pedal, regardless of whether the vehicle is rolling or still. A live data unit may show you the definitive indicators, but you have to make sure you've got the right unit capable for this detection (they don't go cheap), or else it could mislead you to think nothing's wrong.
The easiest things to eliminate first is to check and replace as many plugs and wires that need replacing. I am, by no means, knowledgeable with the electrical functionality of the engine light/computer and its corresponding sensor ends, but I doubt a problem at the exhaust end would trigger a flashing engine light. The flashing action, itself, is a direct reflection of the intermittence of the problem, where the exhaust would be a continuous flow with concentration moderations fluctuating slower than the speed at which the engine light is flashing.
The easiest things to eliminate first is to check and replace as many plugs and wires that need replacing. I am, by no means, knowledgeable with the electrical functionality of the engine light/computer and its corresponding sensor ends, but I doubt a problem at the exhaust end would trigger a flashing engine light. The flashing action, itself, is a direct reflection of the intermittence of the problem, where the exhaust would be a continuous flow with concentration moderations fluctuating slower than the speed at which the engine light is flashing.
05-23-2011, 08:34 PM
#3
TECH Addict
iTrader: (4)
Join Date: Apr 2010
Location: Longview,TX & Tricitys,WA
Posts: 2,201
Likes: 0
Received 1 Like
on
1 Post
What code is it throwing? I'm assuming the 0300? Ohm test the wires really quick with a multimeter set at the 200 ohm range and it should be around 10-30 ohms or so. Also check them while bent. Pull and check the condition of the plugs too seeing if any one of them shows variance compared to the others
05-23-2011, 09:37 PM
#4
Teching In
Thread Starter
iTrader: (5)
Join Date: Oct 2006
Location: Wauconda, IL
Posts: 10
Likes: 0
Received 0 Likes
on
0 Posts
What code is it throwing? I'm assuming the 0300? Ohm test the wires really quick with a multimeter set at the 200 ohm range and it should be around 10-30 ohms or so. Also check them while bent. Pull and check the condition of the plugs too seeing if any one of them shows variance compared to the others
I don't have any codes. The car has MSD wires on it that came with the car. I'll ohm them out when I get a chance.
06-24-2011, 04:36 PM
#5
Teching In
Thread Starter
iTrader: (5)
Join Date: Oct 2006
Location: Wauconda, IL
Posts: 10
Likes: 0
Received 0 Likes
on
0 Posts
Well it's still acting up.
So far. Both front o2's, fuel filter, plugs, wires have been done.
If i unplug the maf the car runs great and the torque converter locks up which it never has! Has a cel obviously but doesn't flash.
I swapped it with a known good used maf and I still have this issue. Still no codes. Could this be tune related? I can't keep driving it with the maf unplugged obviously.
So far. Both front o2's, fuel filter, plugs, wires have been done.
If i unplug the maf the car runs great and the torque converter locks up which it never has! Has a cel obviously but doesn't flash.
I swapped it with a known good used maf and I still have this issue. Still no codes. Could this be tune related? I can't keep driving it with the maf unplugged obviously.
06-24-2011, 04:51 PM
#6
Well it's still acting up.
So far. Both front o2's, fuel filter, plugs, wires have been done.
If i unplug the maf the car runs great and the torque converter locks up which it never has! Has a cel obviously but doesn't flash.
I swapped it with a known good used maf and I still have this issue. Still no codes. Could this be tune related? I can't keep driving it with the maf unplugged obviously.
So far. Both front o2's, fuel filter, plugs, wires have been done.
If i unplug the maf the car runs great and the torque converter locks up which it never has! Has a cel obviously but doesn't flash.
I swapped it with a known good used maf and I still have this issue. Still no codes. Could this be tune related? I can't keep driving it with the maf unplugged obviously.
Also, have to mention. People have allot of these wierd issues when a plug wire touches any part of the metal exhaust manifold piping.....make sure none of the wires are touching....or can bang up against them while moving.
.
