Stalling after starting?

2004 HONDA CIVIC
175,000 MILES • 1.7L • 4 CYL • 2WD • AUTOMATIC
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NETDALE10
My car will start every time but sputters and dies immediately after it srarts. Smells like sulfur sometimes. Have codes P0171 P0134, P2A00 I have replaced the Oxygen sensor.
Jul 7, 2025 at 7:19 PM
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JACOBANDNICKOLAS
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Hi,

Two of the codes are specific to oxygen sensors. The one that has my attention is the P0171. That code indicates a lean fuel mixture. Have you checked to make sure there are no engine vacuum leaks? If not, start there. Here is a link that explains how to check.

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

If you cannot find one, the next thing would be to check the fuel pump pressure. It can be too low or too weak to run the vehicle. I attached the directions and manufacturer's specifications below.

Let me know if this helps or if you have questions.

Take care,

joe

See pics below.
Jul 7, 2025 at 9:33 PM
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NETDALE10
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Thank you for such a quick response. I am checking for leaks right now. I do have a leaky plug on the end of the cam shaft cover. Oil is leaking there. Is it possible that this is the problem? I have to wait a few days until the new one arrives. I just find it hard to believe that this problem is caused by a leak somewhere. The car always starts. But sputters and dies as soon as the car starts. If I try to rev it up, the RPMs go up but sputters and shuts off.

Also measured the fuel pressure. It is a steady 45psi.
Jul 11, 2025 at 10:53 AM
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NETDALE10
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I am confused. I don’t see any response here. Only see some other comments supposedly related to my issue.
Thank you
Jul 11, 2025 at 11:15 AM
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STRAILER
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Sorry for the delay, the fuel pressure is good, it seems like you have a large vacuum leak. This is why the oxygen sensor cant respond and the PCM is dumping fuel into the engine.

P0171 - System Too Lean (Bank 1)
P0134 - O2 Sensor Circuit No Activity Detected (Bank 1 Sensor 1)
P2A00 - O2 Sensor Range/Performance (Bank 1 Sensor 1)

Here is what you need to do to find the leak:

https://www.youtube.com/watch?v=LRKWV4Are5c&t

The leak detector is like $62.00 on Amazon.

https://amzn.to/3InmPwo

Let us know what you find.
Jul 11, 2025 at 11:45 AM
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NETDALE10
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why is the engine is getting too much gas if the code says it’s running lean.

Also I should mention that I believe that the head gasket is bad. The car will overheat if at low speed or idling too long. Have to put about a pint of water in it every time I make a trip.
Jul 11, 2025 at 11:54 AM
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STRAILER
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So if the long term trim says it is lean, then the short term trim will try and richen the mixture. This is why you smell the cats over working themselves. It can be a bad fuel injector as well that, is why we need to run the tests I presented to see what the problem is, there is no "one" answer to this problem, we must run some tests. If you remove the spark plugs and look at them it can tell us if a particular cylinder is causing the problem. You can upload an image of the plugs so I can see. I hope this helps.
Jul 12, 2025 at 9:00 AM
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NETDALE10
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Here are the the pictures:
Jul 12, 2025 at 9:38 AM
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STRAILER
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Yep, now we know it is not one cylinder causing it. There is a fuel vapor line I need you to check that goes to the engine, it should not have fuel in it. Here is the location so you can check it out. Thanks for the images. Check out the images (below).

Jul 12, 2025 at 9:58 AM
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NETDALE10
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I believe that this is the line you are referring too. It looks like a return line for the fuel. It is dry inside.
Jul 12, 2025 at 10:10 AM
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STRAILER
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Low vacuum can cause this issue as well, if the exhaust system is clogged ie: clogged catalytic converter it will cause this issue. Did the engine have good power before all of this started?
Jul 12, 2025 at 10:20 AM
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NETDALE10
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Yes. Plus that was my very first check. I unbolted the exhaust manifold from the engine and stuck my leaf blower I. The tail pipe. No blockage at all. To be sure I even tried to start the car. No difference
Jul 12, 2025 at 10:23 AM
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NETDALE10
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I’m wondering if the fuel injection is the problem. The car does try to accelerate when I press the gas petal. But stutters and stalls. It just seems like it isn’t getting gas into the engine. I haven’t figured out an easy way to check them. I have order a good scanner so I can monitor the signals going to the injectors without me having to put my frequency Fluke meter on the actual wires that are hard to get to.
Jul 12, 2025 at 10:34 AM
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STRAILER
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It sounds like it can be a weak fuel pump or the camshaft timing has jumped. Here is the camshaft marks so you can check it. Check out the images (below).

Jul 12, 2025 at 6:28 PM
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NETDALE10
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Thank you I’ll check it tomorrow. I checked the fuel pressure. It is a steady 45psi.
Jul 12, 2025 at 6:33 PM
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STRAILER
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Okay, yep I would check the timing of the camshaft. Have a good Sunday!
Jul 13, 2025 at 11:57 AM
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NETDALE10
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It took me some time to check it. It is about maybe 1 tooth off.
Jul 25, 2025 at 4:15 AM
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STRAILER
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One tooth off is enough to cause low engine vacuum which will cause the ECM to give the engine excessive fuel. I would install a new timing belt.
Jul 25, 2025 at 9:46 AM
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NETDALE10
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The timing is now dead on. No difference in running. But I installed a new Upstream O2 sensor and got some interesting numbers:

now that I’ve replace the O2 sensor. I think these number made further indicate a vacuum leak:

At about 1500 rpm (throttle position 17.5%:

Manifold Absolute pressure 85.4 kpa
O2 Sensor bank 1 S1 .781 lambda

It looks like we never pull much of a vacuum and the engine actually runs rich.
Jul 26, 2025 at 11:59 AM
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STRAILER
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Hmm, does the car have a catalytic converter on it? It may be clogged, please go over these guides to help us see what it going on.

https://www.2carpros.com/articles/why-an-automotive-engine-will-run-rich

and

https://www.2carpros.com/articles/how-to-test-a-catalytic-converter

Please go over these guides and get back to us.
Jul 27, 2025 at 10:47 AM
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NETDALE10
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That was the first thing I checked. I disconnected the exhaust manifold and tried to run the car. I also blew air from a leaf blower. It is fine. I am convinced that the head gasket that I know is bad it the root cause. I am trying to test the engine compression. It is not easy to test on a Honda. I need an extension pipe to reach down to where the plug goes
Jul 27, 2025 at 10:53 AM
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STRAILER
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Yep, you can be correct, test the compression and inspect the plug plugs as they are removed which can help tell you which cylinder is having the issue. These guides can help

https://www.2carpros.com/articles/how-to-test-engine-compression

and

https://www.2carpros.com/articles/head-gasket-blown-test

Please go over these guides and get back to us.
Jul 27, 2025 at 11:01 AM
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NETDALE10
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So I’m back with the head cylinder pressure readings on my 2004 Honda Civic EX

They are as follows:


#1 cylinder 175 psi
#2 cylinder 220psi
#3 cylinder 195psi
#4 cylinder 195 psi

Now I need to add something interesting and points to the obvious.

Water sprayed out of cylinder #2
Jul 28, 2025 at 12:16 PM
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STRAILER
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The compression readings are good, but you mentioned coolant shooting out of the #2 spark plug hole, this is a sign the head gasket is blown. FYI.
Jul 28, 2025 at 12:51 PM
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NETDALE10
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Of course. I have started the removal process

Thank You
Jul 28, 2025 at 12:55 PM
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STRAILER
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Sounds good, please post a new question if you need help with the head gasket.
Jul 28, 2025 at 1:33 PM
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