Help!!! Help!!! Help!!!

[paul13_1]

I have a 1997 k/1500 ext.cab z-71. I first started having trouble in early september with my truck dying when I would be backing up. It would also cut in and out while in OD. Not all the time just every once in a while not even everytime I drove it. Then as gas prices were on the rise I decidied too change dist. cap, rotor, wires, plugs, and new fuel filter. And also cleaned K&N filter to get better milage. I put AC delco parts back in and a wix filter. My old fuel filter was completely stopped up. You couldnt even blow through it. After all this took place the cutting in and out became more serious but still just every once and a while. It does not do it while idiling or when its in gear and you are holding on brake. Any how the service engine light started coming on. The first time it was scanned it was a MAPP sensor under & over voltage code. I was waiting for my repair man to get me in to take a look at it the S.E.L. came on again. This time its a TWC Efficiency Low Bank 1 & 2 PO 430A code. Does anyone have any idea's? I have talked to several mechaincs and everyone tells me something different. Has Anyone experienced anything like this? I have read where some people are getting these codes and they just change their O2 sensor but I was wondering if theres trucks were doing the cutting in and out and backfiring? I have 170,000 miles on it. ANY HELP WOULD BE VERY MUCH APPRETIATED!!!! THANKS

[Bullet[BS]]

Originally Posted by paul13_1

I was wondering if theres trucks were doing the cutting in and out and backfiring? I have 170,000 miles on it. ANY HELP WOULD BE VERY MUCH APPRETIATED!!!! THANKS

If it is backfiring then it is either a timing issue or a ignition issue. First look at your coil if there are white marks on the outside of it then it needs replaced! Either way your need someone with a Scanner to check deeper, and properly diagnos it. That way you can either pay them to fix it and get a warranty or repair it yourself after you pay to get it properly diagnosed. Best of luck let me know how it turns out.

[tom3]

Truck ever had the fuel pump replaced? It's due.

[paul13_1]

Originally Posted by tom3

Truck ever had the fuel pump replaced? It's due.

Yes I am now on the 3rd fuel pump.

[SpitAndDirt]

Cutting out and backfiring? P 0430 code? I think you need to head to the muffler shop and see if they will test your catilytic converters for blockage. I replaced my muffler at 164,000 and chunks of catylist fell out. The pieces that fell were all melted and stopped up. I think that years of neglect of the basic fuel management and ignition components will do that. I also get that code from time to time because its saying that my cats are no longer in spec for emmisions efficiency. I know I need to replace mine, but at least I know they are flowing freely now. Clogged cats will KILL gas mileage. I get around 20 to 22 mpg on the highway in my 96 z71. Good luck. -Chris

[SpitAndDirt]

Oh and don't simply just change your O2 sensors, apparently they are still working. You have 4 of them. Two pre-catylist(upstream) and two post catylist sensors(downstream). If you have never replaced the upstream sensors in the time you have owned it and it has more than 100,000 miles. I would replace them. The upstream are directly responsible for gas efficiency, because they monitor how rich or lean the engine is running and tell the computer to adjust the amount of fuel being injected to compensate. However, the down stream sensors dont take nearly the abuse. I am still running my original downstream sensors because they are still producing an output voltage to the computer. No voltage output would signal a bad sensor and a different code would be set.

[paul13_1]

Originally Posted by SpitAndDirt

Cutting out and backfiring? P 0430 code? I think you need to head to the muffler shop and see if they will test your catilytic converters for blockage. I replaced my muffler at 164,000 and chunks of catylist fell out. The pieces that fell were all melted and stopped up. I think that years of neglect of the basic fuel management and ignition components will do that. I also get that code from time to time because its saying that my cats are no longer in spec for emmisions efficiency. I know I need to replace mine, but at least I know they are flowing freely now. Clogged cats will KILL gas mileage. I get around 20 to 22 mpg on the highway in my 96 z71. Good luck. -Chris

Thanks for the info chris my gas milage is running around 13-14 around town i dont drive it anywhere else hardly. I did fail to mention that i have a few exhaust leaks on my exhaust system. I was wondering if the down stream o2 sensors might be getting clean air through the exhaust systems and telling the computer that the air was good and clean and it was putting more fuel to the engine? Thats what info I have translated from other things i have found on that code. I have thought about dumping the catalytic converter and putting a flowmaster muffler in and just dumping the pipe off at the rear end. what do you all think? Will the S.E.L. still come on? Or do i need to just replace the convertor and put new exhaust on? Thanks for all the help and info guys!!!

[SpitAndDirt]

Your about to tackle an entirely different animal.....everyone has a different opinion on cats or no cats. Personally I want to put cats back on. I run a 50 series Flowmaster dual in/dual out setup. I like the sound because it doesn't get loud inside the truck on long trips unless I want it too. It has plenty of bark for everyone to hear outside. I hate cab resonance because I like to hear myself think. That and I have had my fill of glass packs from my earlier driving years. I don't have to impress the girls anymore.


You can save some money and have turn downs after the muffler, that's okay. I just perfer to have them exit out the back because I hate exhaust residue all under my truck. It's corrosive to paint, exhaust residue that it. And you can't get to all of it. Fix your leaks, then have the cat's tested. Then decide what you would like to do. -Chris