Hard starting / PO420
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From: Woodstock, GA
Hard starting / PO420 The PO420 has been set for the past month or so. Just in the last day, it's become hard to start. This morning I had the same issue and turned off the key and back on to prime and it started. It's also been stumbling when I come to a stop frequently.
I'm planning to replace the plugs and the fuel filter this weekend; I haven't check the fuel pressure.
I was going to install the downstream O2 into a spark-plug anti-fouler as opposed to replacing the cat.
Anything else I should be looking at?
I'm planning to replace the plugs and the fuel filter this weekend; I haven't check the fuel pressure.
I was going to install the downstream O2 into a spark-plug anti-fouler as opposed to replacing the cat.
Anything else I should be looking at?
Joined: Nov 2001
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From: Schiller Park, ILL Member: #317
P0420/P0430 wouldn't have anything directly to do with the hard starting condition which has developed a month later.
P0420/P0430 simply indicate that tailpipe emissions have climbed above a minimum threshold (i.e. the cat(s) is(are) not adequately scrubbing the exhaust). These codes can and do happen even when the engine is running perfectly but the cats have just been removed/hollowed out or failed (coatings worn off of substrate being most typical). This is usually a non-issue unless you have an emissions test to pass.
If you've more recently developed hard starting and stumbling, beyond doing the tune-up mentioned above, I would most certainly suggest checking fuel pressure (also check for retention of pressure after shut-down; check valve failure might be the reason for hard starting/additional priming needed even if pressure is generally OK when running).
P0420/P0430 simply indicate that tailpipe emissions have climbed above a minimum threshold (i.e. the cat(s) is(are) not adequately scrubbing the exhaust). These codes can and do happen even when the engine is running perfectly but the cats have just been removed/hollowed out or failed (coatings worn off of substrate being most typical). This is usually a non-issue unless you have an emissions test to pass.
If you've more recently developed hard starting and stumbling, beyond doing the tune-up mentioned above, I would most certainly suggest checking fuel pressure (also check for retention of pressure after shut-down; check valve failure might be the reason for hard starting/additional priming needed even if pressure is generally OK when running).
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From: Woodstock, GA
Thanks for the response. I didn't think the inefficiency code had anything to do with the hard start/stumble. I've actually reset it a couple of times and it'll go several hundred miles before setting the CEL. Interestingly, after yesterday morning I've had no issues with the starting/stumbling. I'll break out the fuel pressure gauge and see what's up. Might as well slap a set of plugs in there ..... it will be it's 4th set; I generally change them every 100k.
Thanks for the response. I didn't think the inefficiency code had anything to do with the hard start/stumble. I've actually reset it a couple of times and it'll go several hundred miles before setting the CEL. Interestingly, after yesterday morning I've had no issues with the starting/stumbling. I'll break out the fuel pressure gauge and see what's up. Might as well slap a set of plugs in there ..... it will be it's 4th set; I generally change them every 100k.
You have 400k miles on your car? Damn.
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From: Woodstock, GA
Absolutely.
When I bought her 17 years ago, I had no idea that she'd be daily driven for so many years, but I have the philosophy that when something breaks, you fix it.So 3 10 bolts (don't hate), full suspension, 3 water pumps, a radiator, AC compressor (that lasted over 300k), motor mounts, oil pump, timing chain, 2 4L60es, 4 alternators later, she still runs strong as hell; best car I've ever owned; certainly my favorite of 4 f-bodies.
When I bought her 17 years ago, I had no idea that she'd be daily driven for so many years, but I have the philosophy that when something breaks, you fix it.So 3 10 bolts (don't hate), full suspension, 3 water pumps, a radiator, AC compressor (that lasted over 300k), motor mounts, oil pump, timing chain, 2 4L60es, 4 alternators later, she still runs strong as hell; best car I've ever owned; certainly my favorite of 4 f-bodies.
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Sounds like the cats are clogged. Start it up and have someone floor it while you have your hand by the tail pipe. See if it changes the flow drastically. If it doesn't it could be the cats. But definitely change the fuel filter first.
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Verdad Gallardo Joined: Nov 2001
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From: Schiller Park, ILL Member: #317
Doesn't sound like a clogged converter to me based on the details of the issue so far. That's not the sort of problem which would typically be intermittent, and if it was clogged bad enough to cause hard starting and stumbling at idle then the engine likely wouldn't even be able to rev to higher rpms.
Thread Starter
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Joined: Nov 2011
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From: Woodstock, GA
Doesn't sound like a clogged converter to me based on the details of the issue so far. That's not the sort of problem which would typically be intermittent, and if it was clogged bad enough to cause hard starting and stumbling at idle then the engine likely wouldn't even be able to rev to higher rpms.