ZCAM875

iTrader: (2)

Hey everybody hows it going? I have just recently purchase my first LS1 Fbody. I am having a bit of a problem with it. I am not at wits end with it yet but don't know quite as much as I would like to about the LS1 and the tunning/PCM parameters and such. I am a automotive technician and work for GM powertrain engineering so please dont treat me like a moron in your responses, as I have seen some people do on here. The problem that I first encountered with the car was it had a check engine light on, so I scanned it and found a P0332 rear knock sensor code, no big deal. Then after several weeks of driving the car we had our first big rain storm of the season here in Michigan. During this storm the car obviously got wet, however its seems to have an alergy to water, as it started to misfire. The misfire would last maybe 10 minutes or so and then clear up. The mil also flashed during the misfire indicating cat damage. So I got around to rescanning it and found that it still had the knock code but also had a P0300 misfire code and a P0152 Bank 2 sensor 1 high voltage. I looked at the data stream and found that the voltage was not switching and was staying at 1105mv. I was also showing a incementing misfire on all cylinders on bank 2. I am thinking that the PCM saw the misfires and the high voltage for to long and then went into a limp type mode, but am unsure of this. The vehicle has LT's and Offroad Y. Homemade O2 extensions(not by me) and O2 simulators for the rear. So last night I got a new O2 and went to install I found that the people who had put the exhaust on that had done the extensions just used regular butt connectors with no heat shrink or tape or anything, they just rapped the harness in tape. I found heavy corrosion on one of the wires and the other didnt look to healthy. I tried to solder new wires in for the extensions but the wire on the O2 is not normal copper strand wire, so I used heat shrink butt connectors and then taped them and taped the harness. Installed it and cleared the codes, test drove to evaluate repair, seemed ok for the moment. I got the hose and sprayed down the exhaust/ O2's to see if I could induce the same fault. The misfire returned and set the mil off. Hooked up Genysis scan tool (what I have been using this hole process) and found the knock code, the misfire code, and now P0132 Bank1 sensor 1 high voltage. Damn thing is doing the same thing but on the other side now. I am going to put another O2 on the left bank and redo the extensions tomorrow to see if this fixes the condition. If condition still exists anyone have any ideas on why it is occuring or why it switched sides? Additonaly the car has a predator programer, lid, smooth bellows, slp maf, and 160 stat. I guess if you guys wanna wait to post for me to replace the other O2 thats cool. I would like some input on why you think it might have switched sides though. What are the most likely causes for the knock sensor code on these cars. I know that water collects in the valley cover and rusts the knock sensors but other than that, what are somethings that you guys have run into? I checked the resistance on them and they are 99.7K ohms which according to GM Service Info are with in spec. I havent checked to see if there is any AC output from them while tapping on the block, that is my next step.

Any help is greatly appreciated.
Nick

98Z28CobraKiller

iTrader: (17)

Nick,

Buy a WB02 and Hptuners or EFIlive. Then take the stock o2's and throw them in the garbage. Tune the car in open loop (regardless of whether or not you are keeping the MAF). I have found that as soon as an o2 fails the car will go super rich and run like ***. Can't really diagnose until you have either a good o2 or no o2's and the car is in open loop.

marc a

iTrader: (1)

So will removing the O2 sensors automatically put the PCM in Open Loop and keep it there??

Another question . . . my conversion does not at this point have a speed sensor. How will that effect the PCM since the A/F mixture & timing is determined by using either the crank sensor or the cam sensor (can't rememner which) and not the speed sensor?

Thanks a ton.

2000c-5

Something to keep in mind. O2s have to vent to outside air. The O2s that we use vent through the wire itself. If the wire has been cut and spliced, this vent could accept water in to it or it could be sealed, not allowing the vent to work.

Borrowed this from a Google search:

"Capillary pore" oxygen sensor designs include a narrow diameter tube through which oxygen diffuses into the sensor. Oxygen is drawn into the sensor by capillary action in much the same way that water or fluid is drawn up into the fibers of a paper towel. While capillary pore sensors are not influenced by changes in pressure, care must be taken that the sensor design includes a moisture barrier in order to prevent the pore from being plugged with water or other fluids.


The O2 sensor compares the oxygen content of the exhaust with that of the outside air. Based on the difference between the two readings, the sensor sends a voltage signal to the on-board computer. Typically, O2 sensor voltage ranges between 0 and 1 volt. If the O2 sensor senses the fuel mixture is too rich, the voltage signal should be approximately .9 volt; a lean mixture results in an O2 sensor voltage near .2 volt. The O2 sensor signal "switches" between these rich and lean conditions many times a second, allowing the onboard computer to respond accordingly. A faulty oxygen sensor may not switch properly between rich and lean. Common symptoms that can indicate O2 sensor failure include surging and/or hesitation, a noticeable decline in fuel economy, increased tailpipe emissions and premature failure of the catalytic converter.

Doc

iTrader: (9)

Never cut or splice O2 sensor wires-see the factory manual. The sensors are putting out millivolt values that will be inherrently changed by the butt connector or solder splicing that is caused by the thermocouple (two dissimilar metal junction) effect. In short, replace the wires. If the previous owner made an attempt like this most likely there are some other trouble spots in the wire looms around those headers (melted) that is causing the rest of your problems.

ZCAM875

iTrader: (2)

Thanks for the input guys. I Purchased another O2 yesterday and rewired it. I just found out about the vent through the wires that 2000c-5 is talking about. Unfortunately I had already cut and spliced the right bank and did the same with the left. That must be why there are extensions to purchase, they are kinda expensive though. With both new O2's in and rewired using heatshrink butt connectors car seems fine. The O2's are switching properly and no misfiring as of yet. I guess if I have this probelm again(which I probably will, based on the info provided by Doc) I will maybe buy some wideband O2's and the extensions or build my own using weather head connectors. The only thing that confuses me from what 98Z28CobraKiller about tunning it in open loop is that when the car was defaulting to open loop to get rid of the misfire, the car seemed to lack power and was not as responsive (the misfire was not present in open loop). So I am wondering why it seems to lack power and how does tunning it in open loop make it run better/give it more power? I would consider getting HP tuners or EFI live but I am affraid I would screw something up and blow the car up. Can I get more power out of the car doing a custom tune verses the predator that I have now? If so approximately how much power gain would I get? Does anybody know of some good tuners in Michigan. Also does anybody have input on the knock sensor problem (your experiences with the fualt code). I picked up two new knock sensors yesterday have yet to install them. I havent performed the AC voltage output test yet I am planning on doing that today. When I was working at a dealership I had a few trucks come in that had knock codes and it was found that they needed to be replaced. There was also a bulletin on the trucks (don't know about cars) about water getting into the cavity where the sensors are and creating corrosion causeing a bad ground. Any input is appreciated.

Thanks Nick

Doc

iTrader: (9)

Nick,
If I was in your shoes I would take the sensors back and get some of the Vette rear O2's for your car. They are longer, the only alternative is the extentions. Besides that, almost all of the questions you are asking can be found in the stickies. Not to be a jerk but, really you can find alot in there. If this is your only vehicle, DD, I would find a good local tuner and sell the predator. A good tuner will have no problem going through all of your questions and concerns as he/ she tunes your vehicle. If they "don't have time" to explain to you what they are doing they are either, full of crap or incredibly narrow minded.

In short, a properly tuned vehicle with one of the two major tuning suites with a wideband O2 sensor will out perform the Predator or any other "canned CARTOON."

I would suggest going into your regional forums and start asking where folks around your parts are getting the most satisfaction and then interview the possible tuners yourself.

Good luck.