P0430 Code, help please

Alright, so here's what's been goin' on.
I'm new here, first time posting. I have been on this site a lot looking at threads for similiar problems I've been having. However, I am stumped. With searching all over the internet I can't find something concrete. By the way, Merry Christmas!

My 2000 5.3 Silverado has been through a lot, as I'm sure everyone else's trucks have been. I have put a lot of money back into it to get it running like new. And for the most part it does. Though I have always had this hestitation problem. From a dead stop to flooring the pedal, it stumbles and hestitates for a second or two, then it takes off.

This isn't the first time, but again it threw a P0430 code, and that's the only code it threw. I have relatively new cats on it (less than 2 years old), 2/4 new o2 sensors, new fuel pump, new pressure regulator, new fuel filter, new spark plugs, new spark plug wires (AC Delco mind you, oem), new pcv, etc.

I have a small leak between the headers and the y-pipe on the driver side, where they bolt together. Perhaps this could be the problem? I doubt it, it doesn't seem like that would cause my hestitation. Anyways, I have not checked for vacuum leaks and the cats should not be bad.

If anyone could possibly shed some light on what I could do to fix my sputtering problem? It'd be awesome! Thank you so much.
The search for the code turns up

<LI itxtvisited="1">The catalytic converter is no longer functioning properly <LI itxtvisited="1">An oxygen sensor is not reading (functioning) properly <LI itxtvisited="1">There is an exhaust leak
Perhaps its an o2 sensor, or an exhaust leak or both. However, the search says :

'You will likely not notice any drivability problems, although there may be symptoms such as a (http://www.obd-codes.com/p0430#) rough/hard idle when cold.'

My idle is completely fine when cold or hot, purrs just like a kitty ha! I'm just stumped and I'd really like to get it fixed. Thanks

I guess you missed the no exhaust leaks allowed posting.

with an exhaust leak the timing gets thrown back , then the engine runs with poor economy and can Foul up the cat converters...

after you fix the leak and IF this continues, you then remove the upstream O2 sensor one at a time ,and with the hole open see if the engine has more power and no hesitation !

if the engine runs better with the upstream O2 sensor hole open the cat is usually the cause.

p0430 is cat converter performance sucks.

merry xmas .......


with no other codes fuel pressure check is also required ..53-62psi with engine turned off should hold at these pressures..rapid drop off is usually the fuel pump..

the plugs must be the ac iridium plugs, this engine is very picky about plugs.

if you had a dtc lean code checking for intake manifold leaks is required.

If you wash your engine or used carb cleaner on it you could have gasket/knock sensor issues for sure.

Welcome to the AF forum and a Merry Christmas to you also.

As said, an exhaust leak could very well cause this code. What happens is that the cam overlap (EX closing/IN opening) on each stroke causes a lower pressure in the exhaust system. Basically this exhaust leak allows outside ambient air to enter the exhaust stream and send an air/fuel signal to the O2 sensor that is not right.

So, I suggest you fix that exhaust leak and see what happens. It may be that you have 2 separate issues but start there 1st.

Hope you will post back on your progress.

Well thanks a lot. I suppose I just had to have the push in the right direction. I will definitely post the result when I get this fixed.

On account of it being freezing and snowing outside I don't expect to get on the ground any time soon.

Thanks!

alrigt so I ended up replacing the gasket in my exhaust. The leak stopped but the hesitation problem continued. Not knowing what it could be I ohmed out my ignition coils. All of which one had a reading half of all of the others. I replaced it and hoped te problem would be solved. But no, it seems as though the problem hasn't changed for the most part.

does anyone have any ideas as to what else it could be?

alrigt so I ended up replacing the gasket in my exhaust. The leak stopped but the hesitation problem continued. Not knowing what it could be I ohmed out my ignition coils. All of which one had a reading half of all of the others. I replaced it and hoped te problem would be solved. But no, it seems as though the problem hasn't changed for the most part.

does anyone have any ideas as to what else it could be?

After any and all repairs the code should be cleared and vechical drove to check if the problem is fixed.
Was the exhaust leak and bad coil on the same bank as the code?

As to what can cause a cat code it is going to be a big long post.:rofl:

Most cat codes are caused by engine running rich or not running right or cheap replacement cats.




http://www.batauto.com/articles/catfailure/

DTC P0420, P0421, and P0430 & P0431: Check Possible Cause Of Misfire DTC P0420 and P0421 indicate bank one catalyst system efficiency is minimum requirement. DTC P0430 and P0430 indicate bank 2-catalyst system efficiency is minimum requirement. Possible causes are as follows: Use of leaded fuel. Oil contamination. Cylinder misfire. Fuel pressure too high. HO2S sensor improperly connected. Damaged exhaust system component. Faulty ECT sensor. Faulty HO2S. Ensure ignition timing is correct. Retrieve all Continuous Memory DTCs. If misfire code is not present, go to next step. If misfire code is present, isolate cylinder and repair as necessary. Check HO2S Monitor DTCs If DTCs P0136, P0138, P0140, P0141, P0156, P0158, P0160, or P0161 were present in step 1), service as necessary before continuing. If none of these codes are present in step 1), go to next step. Check ECT Sensor DTCs If DTCs P0117, P0118, P0125 or P1117 were present in step 1), service as necessary before continuing. If none of these codes are present in step 1), go to next step. If any codes except P0420, P0421, P0430 and/or P0430 were present in step 1), service as necessary before continuing. If no codes except P0420 and/or P0430 were present in step 1), go to next step. Check Rear HO2S Wiring Harness Turn ignition off. Ensure HO2S wiring harness is correctly routed and connectors are tight. Repair or replace as necessary. If wiring harness and connectors are okay, go to next step. Check Fuel Pressure Turn ignition off. Release fuel pressure. Install fuel pressure gauge. Start engine and allow to idle. Note fuel pressure gauge reading. Increase engine speed to 2500 RPM and maintain for one minute. For fuel pressure specifications, see FUEL PRESSURE SPECIFICATIONS article. If fuel pressure is as specified, go to next step. If fuel pressure is not as specified, go to CIRCUIT TEST HC. Check For Exhaust System Leaks If exhaust system leaks, it may cause catalyst monitor efficiency test to fail. Inspect exhaust system for cracks, loose connections or punctures. Repair or replace as necessary. If exhaust system is okay, go to next step. Check For Exhaust System Restrictions Inspect exhaust system for collapsed areas, dents or excessive bending. Repair or replace as necessary. If exhaust system is okay, go to next step. Check Manifold Vacuum Install tachometer. Connect vacuum gauge to intake manifold vacuum source. Start engine and raise engine speed to 2000 RPM. Manifold vacuum should rise to more than 16 in. Hg. If manifold vacuum is okay, go to next step. If manifold vacuum is low, go to step 11). Leave tachometer and vacuum gauge connected. Start engine and raise engine speed to 2000 RPM. On a non- restricted system, manifold vacuum should quickly rise to normal range as increased RPM is maintained. On a restricted system, manifold vacuum will slowly rise to normal range as increased RPM is maintained. If manifold vacuum is okay, no indication of exhaust leak or restriction has been detected and testing is complete. If manifold vacuum is low or slow to respond, go to next step. Leave tachometer and vacuum gauge connected. Remove exhaust pipe from exhaust manifold. Start engine and raise engine speed to 2000 RPM. If manifold vacuum is now okay, fault is downstream from exhaust manifold. Reconnect exhaust pipe to exhaust manifold and go to next step. If manifold vacuum is still low or slow to respond, fault is in exhaust manifold or intake manifold gasket. Repair or replace as necessary and repeat QUICK TEST. Leave tachometer and vacuum gauge connected. Disconnect muffler/tailpipe assembly from rear of catalytic converter. Start engine and raise engine speed to 2000 RPM. If manifold vacuum is now okay, fault is in muffler/tailpipe assembly. Repair or replace as necessary and test-drive vehicle to verify elimination of symptom. If manifold vacuum is still not okay, fault is in catalytic converter. Repair or replace as necessary. Check tailpipe/muffler assembly for debris from catalytic converter. Test drive vehicle to verify elimination of symptom.

alrigt so I ended up replacing the gasket in my exhaust. The leak stopped but the hesitation problem continued. Not knowing what it could be I ohmed out my ignition coils. All of which one had a reading half of all of the others. I replaced it and hoped te problem would be solved. But no, it seems as though the problem hasn't changed for the most part.

does anyone have any ideas as to what else it could be?

as I stated in post reply #2 " after you fix the leak and IF this continues, you then remove the upstream O2 sensor one at a time ,and with the hole open see if the engine has more power and no hesitation ! "

with the operation of this engine with these exhaust manifold leaks the converters may get damaged..

with your engine issue , I would not be surprised to have you state these converters are restricting the exhaust...another issue can be the muffler is restricting the exhaust because the converters are breaking up..

the exhaust manifold gasket may have blown out from the pressure..

since you fixed this leak I would expect the engine to run worse if the exhaust is plugged up..

So it ended up being the catalytic converters.
About 20,000 miles ago I replaced the stock cats with walker direct fit cats with the y-pipe.
Unfortunately for me I didn't file for the 50,000 mile warranty. I found the paper to sign up for it but I would suppose it'd be too late to send it in then get a new cat set up.

So I'm going to buy a new y-pipe set up in the future sometime, I'd like to get the ypipe assembly that came on the truck originally. Or does anyone have any recommendations on what to get? Magnaflow?

Thanks for the help.

So it ended up being the catalytic converters.
About 20,000 miles ago I replaced the stock cats with walker direct fit cats with the y-pipe.
Unfortunately for me I didn't file for the 50,000 mile warranty. I found the paper to sign up for it but I would suppose it'd be too late to send it in then get a new cat set up.

So I'm going to buy a new y-pipe set up in the future sometime, I'd like to get the ypipe assembly that came on the truck originally. Or does anyone have any recommendations on what to get? Magnaflow?

Thanks for the help.

why give up on the warrantee ? you got your papers ?, call them up !

thanks for posting back with your issue corrections.

So it ended up being the catalytic converters.
About 20,000 miles ago I replaced the stock cats with walker direct fit cats with the y-pipe.
Unfortunately for me I didn't file for the 50,000 mile warranty. I found the paper to sign up for it but I would suppose it'd be too late to send it in then get a new cat set up.

So I'm going to buy a new y-pipe set up in the future sometime, I'd like to get the ypipe assembly that came on the truck originally. Or does anyone have any recommendations on what to get? Magnaflow?

Thanks for the help.

Weird. I have a set of OE replacement cats, unknown manufacturer (Walker, Magnaflow sell the same replacement sets) an have had zero issues other than a heat shield being in the way. Maybe they weren't installed correctly.

You cannot buy the y-pipe. The two cats slip in together at the center of the y and it has a clamp band on it to hold the two together. Essentlially, each cat has half of the y-pipe.

I'd suggest LPP , Ebay (they have some cheap 2xx.xx long tubes), or OBX Longtube headers, an Off-road y-pipe (just google it, I think you'll find it), and a PCM tune to elminate the rear O2 sensors (they don't do anything anyways except monitor emissions.)

Weird. I have a set of OE replacement cats, unknown manufacturer (Walker, Magnaflow sell the same replacement sets) an have had zero issues other than a heat shield being in the way. Maybe they weren't installed correctly.

You cannot buy the y-pipe. The two cats slip in together at the center of the y and it has a clamp band on it to hold the two together. Essentlially, each cat has half of the y-pipe.

I'd suggest LPP , Ebay (they have some cheap 2xx.xx long tubes), or OBX Longtube headers, an Off-road y-pipe (just google it, I think you'll find it), and a PCM tune to elminate the rear O2 sensors (they don't do anything anyways except monitor emissions.)

when you operate this engine with an exhaust leak the engine management goes wacky...the the converters get damaged..

when replacing converters you must be sure the O2 sensors and other fuel mixture controls are working correctly ..if not ////don't matter what converters you buy ..

Alright so the problems fixed. About 30,000 miles ago I changed my spark plugs to the NGK .060 whatevers. I decided to change my spark plugs to the AC Delco .040 Iridium plugs. Those are what GM calls for. No more rough acceleration or anything like that. Gas MPG has increased. I highly recommend only using the AC Delco Iridium plugs.

Alright so the problems fixed. About 30,000 miles ago I changed my spark plugs to the NGK .060 whatevers. I decided to change my spark plugs to the AC Delco .040 Iridium plugs. Those are what GM calls for. No more rough acceleration or anything like that. Gas MPG has increased. I highly recommend only using the AC Delco Iridium plugs.

the ngk is .040 on the gap ..you installed the wrong plugs. also the 430 code only would not indicate a plug ONLY as your cause for this..I would suspect one of the plugs had a cracked ceramic. as a possible cause with the only 430 code.

with the ac delco 41-110 this is gapped to .o4o...also if you check or change this gap you must know what your doing or you WILL damage the very fragile tip !

good luck and always use caution when selecting replacement parts.

Agree with jcat. There is no way plugs caused 430 code. Any way just fixed this code on my truck about 5-6 months ago. Same symptoms as you listed. Replaced all 4 sensors and put some Eastern cats in and it was brand new truck. Turns out pass side cat wasn't flowing at all. Sensors didn't have anything to do with it necessarily but they were due (100k)
BTW my two cents on plugs is use OEM unless you have some crazy mods/run higher temps/ race(on a track). If you get the right ones= no need to fool with gaps = pain + worry free