Bad Timing Chain? NEED HELP!
Thread Starter
Joined: Apr 2019
Posts: 7
From: CA
Bad Timing Chain? NEED HELP!
I hope someone can help me with the problem I have been dealing with...
So, about a month ago my car started experiencing a rough idle all the sudden right after I got off freeway. Since then it has gotten a little worse; it feels like running weak and it starts weak. Also it sometimes idles really fast as well (it seems like it doesn't want to stop at lights).
it was not that bad as the light never turned on or threw any code, but I took it to a shop for diagnostics.
They found out that it was slightly misfiring. They ran multiple tests including the compression test, and it turned out that all cylinders on the passenger side had lower compression (EQUALLY) than those on the driver's side. They found other stuff too but it's specific only to the passenger side.
Considering issues being only on one side of the engine, they concluded that this rough idle and weak performance are possibly coming from the bad timing chain. They're charging me over $800 and I am not sure if I want to do that, even though I do not think I can do it by myself.
I had misfires early this year, so it has brand new plugs, wires, coilpack, cleaned MAF, and cleaned throttle body.
The head gaskets have been replaced because it blew once, so it could be warped head...... yet there is no indication of that this time.
I would appreciate some insights on what the issue is here!
thank you.
So, about a month ago my car started experiencing a rough idle all the sudden right after I got off freeway. Since then it has gotten a little worse; it feels like running weak and it starts weak. Also it sometimes idles really fast as well (it seems like it doesn't want to stop at lights).
it was not that bad as the light never turned on or threw any code, but I took it to a shop for diagnostics.
They found out that it was slightly misfiring. They ran multiple tests including the compression test, and it turned out that all cylinders on the passenger side had lower compression (EQUALLY) than those on the driver's side. They found other stuff too but it's specific only to the passenger side.
Considering issues being only on one side of the engine, they concluded that this rough idle and weak performance are possibly coming from the bad timing chain. They're charging me over $800 and I am not sure if I want to do that, even though I do not think I can do it by myself.
I had misfires early this year, so it has brand new plugs, wires, coilpack, cleaned MAF, and cleaned throttle body.
The head gaskets have been replaced because it blew once, so it could be warped head...... yet there is no indication of that this time.
I would appreciate some insights on what the issue is here!
thank you.
5th Gear Member
Joined: Jul 2012
Posts: 3,628
From: ohio
If a shop ever used the term " possibly " I would turn around and walk out. I dont want to know what it could possibly be, I want a mechanic to " know " what the problem is.
Anyways, What year car do you have and what engine, it matters. Typically the 3.8l engines use a single timing chain, and I would expect to see low compression across the board if the chain has jumped or stretched out. What exactly were the compression readings?
Low compression on a single bank is inductive of head problems, gasket, or warped head, possibly burnt/dirty valves. But since we know the head gaskets were done recently, I would inspect the heads for proper torque on the head bolts, but before I did anything Id try to track down that vacuum leak thats causing the engine to high idle or check the IAC valve and clean it. Next I would do a seafoam treatment and see if I could clean those valves up, a partially plugged catalytic converter on one bank can cause carbon build up on one bank of valves. Did the shop do a leak down test to determine where the compression is going? Its eather escaping through the intake valves, the exhaust valves or through crank case past the rings , or is it leaking past the head gasket.
Anyways, What year car do you have and what engine, it matters. Typically the 3.8l engines use a single timing chain, and I would expect to see low compression across the board if the chain has jumped or stretched out. What exactly were the compression readings?
Low compression on a single bank is inductive of head problems, gasket, or warped head, possibly burnt/dirty valves. But since we know the head gaskets were done recently, I would inspect the heads for proper torque on the head bolts, but before I did anything Id try to track down that vacuum leak thats causing the engine to high idle or check the IAC valve and clean it. Next I would do a seafoam treatment and see if I could clean those valves up, a partially plugged catalytic converter on one bank can cause carbon build up on one bank of valves. Did the shop do a leak down test to determine where the compression is going? Its eather escaping through the intake valves, the exhaust valves or through crank case past the rings , or is it leaking past the head gasket.
Last edited by dawson1112; Jul 31, 2019 at 06:55 AM.
Thread Starter
Joined: Apr 2019
Posts: 7
From: CA
Thank you for the advice.
The compression reading is actually not bad at all:
#1--175, #2--175, #3--175, #4--180, #5--185, #6--190
Could it be some other cause?
I will ask the mechanic if they did the leak down test.
The compression reading is actually not bad at all:
#1--175, #2--175, #3--175, #4--180, #5--185, #6--190
Could it be some other cause?
I will ask the mechanic if they did the leak down test.
Thread Starter
Joined: Apr 2019
Posts: 7
From: CA
If a shop ever used the term " possibly " I would turn around and walk out. I dont want to know what it could possibly be, I want a mechanic to " know " what the problem is.
Anyways, What year car do you have and what engine, it matters. Typically the 3.8l engines use a single timing chain, and I would expect to see low compression across the board if the chain has jumped or stretched out. What exactly were the compression readings?
Low compression on a single bank is inductive of head problems, gasket, or warped head, possibly burnt/dirty valves. But since we know the head gaskets were done recently, I would inspect the heads for proper torque on the head bolts, but before I did anything Id try to track down that vacuum leak thats causing the engine to high idle or check the IAC valve and clean it. Next I would do a seafoam treatment and see if I could clean those valves up, a partially plugged catalytic converter on one bank can cause carbon build up on one bank of valves. Did the shop do a leak down test to determine where the compression is going? Its eather escaping through the intake valves, the exhaust valves or through crank case past the rings , or is it leaking past the head gasket.
Anyways, What year car do you have and what engine, it matters. Typically the 3.8l engines use a single timing chain, and I would expect to see low compression across the board if the chain has jumped or stretched out. What exactly were the compression readings?
Low compression on a single bank is inductive of head problems, gasket, or warped head, possibly burnt/dirty valves. But since we know the head gaskets were done recently, I would inspect the heads for proper torque on the head bolts, but before I did anything Id try to track down that vacuum leak thats causing the engine to high idle or check the IAC valve and clean it. Next I would do a seafoam treatment and see if I could clean those valves up, a partially plugged catalytic converter on one bank can cause carbon build up on one bank of valves. Did the shop do a leak down test to determine where the compression is going? Its eather escaping through the intake valves, the exhaust valves or through crank case past the rings , or is it leaking past the head gasket.
Thank you for the advice.
The compression reading is actually not bad at all:
#1--175, #2--175, #3--175, #4--180, #5--185, #6--190
Could it be some other cause?
I will ask the mechanic if they did the leak down test.
Gentleman's Relish
Joined: Feb 2005
Posts: 13,189
From: AZ
If a shop ever used the term " possibly " I would turn around and walk out. I dont want to know what it could possibly be, I want a mechanic to " know " what the problem is.
Anyways, What year car do you have and what engine, it matters. Typically the 3.8l engines use a single timing chain, and I would expect to see low compression across the board if the chain has jumped or stretched out. What exactly were the compression readings?
Low compression on a single bank is inductive of head problems, gasket, or warped head, possibly burnt/dirty valves. But since we know the head gaskets were done recently, I would inspect the heads for proper torque on the head bolts, but before I did anything Id try to track down that vacuum leak thats causing the engine to high idle or check the IAC valve and clean it. Next I would do a seafoam treatment and see if I could clean those valves up, a partially plugged catalytic converter on one bank can cause carbon build up on one bank of valves. Did the shop do a leak down test to determine where the compression is going? Its eather escaping through the intake valves, the exhaust valves or through crank case past the rings , or is it leaking past the head gasket.
Anyways, What year car do you have and what engine, it matters. Typically the 3.8l engines use a single timing chain, and I would expect to see low compression across the board if the chain has jumped or stretched out. What exactly were the compression readings?
Low compression on a single bank is inductive of head problems, gasket, or warped head, possibly burnt/dirty valves. But since we know the head gaskets were done recently, I would inspect the heads for proper torque on the head bolts, but before I did anything Id try to track down that vacuum leak thats causing the engine to high idle or check the IAC valve and clean it. Next I would do a seafoam treatment and see if I could clean those valves up, a partially plugged catalytic converter on one bank can cause carbon build up on one bank of valves. Did the shop do a leak down test to determine where the compression is going? Its eather escaping through the intake valves, the exhaust valves or through crank case past the rings , or is it leaking past the head gasket.
Example, When is a P0340 code not a P0340 code (bad camshaft sensor)? When your alternator sine wave is square and causing an interference yet your alternator is working fine unless you put an oscilloscope on it and see the sine wave is bad.
Every other car out there, a P0340 means the sensor is bad. Not on a 05-09 Mustang though....
5th Gear Member
Joined: Jul 2012
Posts: 3,628
From: ohio
The high idle is most common because you have a vacuum leak someplace. That vacuum leak will also cause the engine to run rich, since the computer can only see it between the upstream and down stream 02 sensors. The computer will add fuel to try and get rid of the lean condition, vacuum leaks will make the engine idle really high like you are describing because the computer is unable to control how much air is getting into the intake. Open the hood, start the car and listen for any hissing. Inspect all the vacuum tubing that you can see, if you still dont find it you may need to run some smoke though the intake and watch for where it comes out.
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