Car54

My neighbor and friend comes over several weeks ago and says his '96 LT1 check engine light came on. He says he went to Autozone and found these codes: P0300, P0151, P0154, P0171, P0174. We first cleared the codes and drove it. The only code that came on immediately was P0151. We changed the bank 2 sensor 1 Oxygen sensor even though it had been changed about 1 year ago. The next code that came back was P0174. We did the poor mans vacuum line test....turned the propane bottle on....starting just above the battery. We noticed that the idle went up so we started looking for bad vacuum hoses and found that the hose running from the cruise control through the big rubber grommet in the firewall was questionable. After several attempts in vain to get the hose to turn loose of the grommet, we managed to dislodge the grommet completely from the firewall. Then with lots of WD40 we installed a new hose and with more WD40 on grommet it went back into the firewall. Fired the car up and drove it. You are right....we still got codes. This time we got P0171 and P0174. So we looked for more vacuum hose issues. We found the vacuum line (fresh air hose) running from the airbridge to the optispark was broken. We then spent the next 4 hours trying to figure out a way to connect a new hose to the Opti without dismantling the front of the engine. The hose was reattached only after we got another neighbor (with much smaller hands) to come help us. After about an hour he managed to get the new hose attached to the opti. We were happy campers. We fired it up and after about 8 miles....you guessed it. Codes P0171 and P0174 came back. We had taken the MAF off and inspected it earlier in this process and it looked clean so we were not expecting it to be an issue. Just in case we bought some MAF cleaner and liberally sprayed the inside of the MAF and connector, dryed it out and reinstalled it. We are up to 110 miles and counting and no new codes. We are indeed happy campers. The moral to this story is that even if the MAF does not look dirty after 140k miles, it probably is. Was that the only problem that was causing all the codes? Hard to believe that the two vacuum lines we replaced were not also contributing factors but who knows. Through out this process I kept checking the forum to find helpful hints so I am posting here to help the next person.

thanks

bill