So here’s a brief (but long) summary of my latest repair journey (codes 113, 221 and 232).
My Bentley list’s them as fault in fuel injector and rich/lean mixture at idle, but it took me awhile to find the real problem. The Journey Begins: Several years ago -150k removed the air box thermostat and blocked the air return duct. 3 months ago - 200k service, including clean AMM, throttle body, flame trap, breather box, idle air valve, replaced throttle body gasket and some of the vacuum hoses. Just recently while driving the check engine light came on (codes 231 and 221). Car started and ran fine, smooth idle, maybe a little high for about 1-2 seconds at start up, then drops to about normal. Gas mileage is about 20-21 mpg; E-10 Gas, Half town at 35, half I-95 at 85. Checked all vacuum hoses and replaced a few more (some were loose or cracked at the intake manifold nipples and down at the charcoal canister). Also found I had previously knocked the vacuum canister hose off while cleaning leaves (duh), so that was reconnected. Also checked the intake hose from AMM to TB. Cleared codes but they came back. Next checked the FPR hose and looked like some fuel was present on the nipple at the TB, so replaced that. Still threw codes, but now 113 and 232. Next went to O2 sensor, did all the Bentley tests, but I didn’t know how to interpret the readings correctly (I misread the fluctuation as a fault, I was expecting a more steady reading, so I replaced that too). Started motor, O2 sensor went through the warm up period of about 45 seconds (0.4 to 0.5V), then the voltage starts bouncing around; 1 secs at 0.59 – 0.65V, then 2-3 secs of low voltage reading, repeat.. I thought that meant a bad sensor (Duh), but a new 02 sensor at 210k probably isn’t a total waste of $). If I disconnected a vacuum hose the voltage dropped, then when I reconnected it when up to 0.8V then settled back to previous. If I disconnect the 02 wire, the ECU voltage is zero. BTW - disconnected AMM, that made the idle rough. Then checked the plugs. Boot 2 was loose (I must not have snapped it on right). Plug 4 looked a teeny bit wet. All plugs not fouled, looked good. All injectors are delivering fuel (unplugged each to check change in idle). Next unplugged and cleaned the contacts of each injector, all measured16 ohms. Disconnected battery and cleaned the 2 computer grounds to the manifold. Also removed the ECU connector and cleaned with electrical cleaner spray, blew dry w/ canned air. Removed the two ground loops and cleaned those contacts, then reconnected everything carefully. The strap from the valve cover to the fire wall was repaired at 200k. Cleaned neg battery terminal. It then ran fine for about a week then threw the 221,231 code. Now in doing some of this work and reading codes I discovered by accident (wouldn’t hold voltage overnight) the battery had a bad cell, so that was replaced. So then I finally decided to swapped out the AMM with a good one from the Mrs. Brick and low and behold her brick immediately threw the 121 AMM code (women’s intuition?)…. So replaced the AMM w/a rebuilt Bosch from FCP and problem solved, for now…. So I’m not sure what really happened, but I think it may have been a conspiracy…. Hopefully this saga will help others in their quest, or at least be a source of mirth and entertainment