I've got a 2000 V8 LS that didn't run and I've been picking everyones brain trying to get her running again.............Now I got the car running but the motor resonds very sluggishly.......I changed the plugs, the coils and it fired up but would stall and pop to a stop.....would only run for about 15 seconds.......someone out there mentioned possible bad cats so I did the quick and dirty and pulled the o2 sensors......now the motor runs, still sluggishly but it idles.....however there is still a backfire I can hear in the intake........could it be a completely plugged cat? I did pull a few Black spark plugs from the passanger side of the motor. I'm thinking of dropping the exhaust off the manifolds and see what happens next.
can clogged cat cause backfire through the intake?
- Thread starter JOEMACH
- Start date
joegr
Dedicated LVC Member
Broken record here: Did you do the compression tests? If so, what were the results?
If you pulled the O2 sensors, there should not be enough restriction to force any sort of backfire. What's the vacuum reading on the intake? Is it steady?
I'm still betting on a valve/valve-timing problem.
If you pulled the O2 sensors, there should not be enough restriction to force any sort of backfire. What's the vacuum reading on the intake? Is it steady?
I'm still betting on a valve/valve-timing problem.
LS210SAM
New LVC Member
Has anyone figured out this problem im going crazy trying to figure out why my lincoln ls is popping thru the intake.
I have a 2001 ls v8
I took off the 02 sensors before cats and its higher idle but still backfires through intake
I have a 2001 ls v8
I took off the 02 sensors before cats and its higher idle but still backfires through intake
1LoudLS
Dedicated LVC Member
When my cats completely clogged up, it just choked out the engine after a few seconds. it never backfired.
if your just getting a backfire through the intake, I'd say the above comment is the most likely cause of your problem. if it also chokes out when the 02 sensors are in, then my money is on you having both problems.
if your just getting a backfire through the intake, I'd say the above comment is the most likely cause of your problem. if it also chokes out when the 02 sensors are in, then my money is on you having both problems.
backfiring thru the intake...how could that be, Hmmmm...
cylinder leak down test. place timing mark at zero with number one jug at TDC. pressurize cylinder number one with shop air. listen at the open throttle. if the air is blowing out of the intake when the valves to number one cylinder are supposed to be closed, it means the valves to number one cylinder are not closed. what, you ask , could cause that? a bent valve, a bad valve seat, a bad camshaft, slipped timing chain, any combination or all of the above or any of the above.
Quick and dirty troubleshoot is to pull the valve cover off and inspect the number one valve train with the engine at TDC 0deg and number one on the compression stroke. you should see the valves completely closed. if not, QED.
cylinder leak down test. place timing mark at zero with number one jug at TDC. pressurize cylinder number one with shop air. listen at the open throttle. if the air is blowing out of the intake when the valves to number one cylinder are supposed to be closed, it means the valves to number one cylinder are not closed. what, you ask , could cause that? a bent valve, a bad valve seat, a bad camshaft, slipped timing chain, any combination or all of the above or any of the above.
Quick and dirty troubleshoot is to pull the valve cover off and inspect the number one valve train with the engine at TDC 0deg and number one on the compression stroke. you should see the valves completely closed. if not, QED.