whitesol

So the wife has an 01 max with 200K+ on it. The dreaded P0430 code has been popping up and all my research lead me to buy the warpspeed y-pipe. Gutted the front cat, installed the y-pipe and attempted to install the antifoulers on both downstream o2 sensors. Due to where the warpspeed y-pipe has the bung located for rear downstream o2 I could not use the anit-fouler there (as the o2 sensor would come into contact with the trans pan) but was able to use one on the front bank. Finished all this up a few weeks ago, and the P0430 is still popping up. I initially figured the ECU had to be reset to sort of clear the memory it had when the (presumably clogged) pre-cats were still in place. So disconnected the battery long enough to reset the ECU and the P0430 pops back up within a few miles of driving. Contacted warpspeed who basically said this shouldnt happen and it should go away with a few hundred miles. Its been more than a few weeks, more than a few hundred miles, more than few full tanks of gas and the SES light is still popping up with just a few miles of driving after clearing it. Fuel economy is definitely taking a hit as well. She filled up today and got a little over 17 MPG. She can recall seeing 20-23 MPG easily in the past.

What am I missing here and what else could the problem potentially be?

DennisMik

iTrader: (2)

P030 is for bank 2 of the engine. Bank 2 is the one by the radiator. Since this is to one you gutted, I am assuming you have the anti-fouler on this one.

But your reference to the gas mileage being down points to the upstream O2 sensor. This is the one right after the exhaust manifold. You might consider changing it.

whitesol

Correct. I assumed I'd get the code for bank 1 where I could not install the anti-fouler.

But would a faulty upstream 02 sensor return the same P0430 code and not a different code entirely?

DennisMik

iTrader: (2)

A bad bank 2 upstream sensor should give one of several codes, but P0430 isn't one of them. Some are 032, 052, 150, 151, 152, 153, 154, 155, 1163, 1164, 1168. However, the DTC codes don't always accurately reflect what is going on. An example of something where the codes don't work correctly is the MAF. 99% of the time you don't get a code for a bad MAF, you have to go with your gut. That's what I'm doing with the O2 sensor, going by the poor gas mileage.

MadMax SE

I was getting horrible gas mileage and I had the p430 code. Soon after I had a maf code pop up. I replaced the maf sensor and both codes are gone now.

whitesol

man I hate just throwing parts at a problem without knowing if they're really bad. But, I guess changing that upstream 02 and possibly the MAF is where I'll have to start.

Anyway to test the MAF before replacing? Particular voltage that can be read off it perhaps?

MadMax SE

It's supposed to read how much air passes it to give a reading. Unless you can simulate constant airflow on a bench or something your just better off buying one.

whitesol

so here we are months later and the P0430 code still randomly pops up. I did replace the MAF and that upstream O2 sensor. The SES no longer comes on after only a few miles; but it is still happening. Fuel economy is slightly better but still not great (dont have the exact numbers since its not my daily driver). What am I missing?!

maxiiiboy

There are quite a few other potential reasons. From the the FSM, pg. EC-427:

• Warm-up three way catalyst
• Exhaust tube
• Intake air leaks
• Injectors
• Injector leaks
• Spark plug

I would focus on air leaks and malfunctioning injectors.

whitesol

Intake leak is simple enough to check. Any simple way to test injectors?

maxiiiboy

Try this stuff from youtube:

maximatech12

Just pull the rail clip in injectors reconnect battery and turn ignition to on ->NOT START!
This will pressurize the system then simply look for fuel dripping from injector nozzle.
That's a way to test for a leaky one.

maximatech12

Another way is pull the plugs after a drive and see which ones are wet.
If it's leaky it will keep spraying fuel after car is shut off.
Personally I'd just get all new ones that way you can rule it out.

SubwayVQ

That's throwing money away.

whitesol

When we're saying a leaking injector we do mean a bad injector and not just a bad o-ring or something simple like that right?

Thanks I'll check those out.

Gotcha. So key on should pressurize the system and in theory no fuel should be seen from the injectors yet. If I see fuel I've found the bad injector.

Makes sense; but if there also happened to be something wrong with the ignition system I might also see a washed out plug right? definitely not looking to simply toss any more money at a 16 year old car with 200+K on it lol! I already feel like I wasted the $ on the warpspeed y pipe and the effort involved there. But if you're generous and have the $500-$600 laying around for me I'll give it a shot!

Agreed! With that mentality I may as well give up and just go buy a new car lol.