Thanks to The Dan for a simple header.
For the past two years, I would get an occasional code 9 (blinking FI indicator), with no discernible change in performance, usually the code 9 would be gone the next day.
Recently I've started getting a code 9 daily, accompanied with:
The Honda shop manual states that a code 9, indicates a malfunction of the IAT (intake air temperature) sensor, however a number of posts here on ST-Owners suggest checking the vacuum hoses, and plastic tee's nestled within the throttle body assembly.
Here's what I've done to date, with no consistent improvement:
For the past two years, I would get an occasional code 9 (blinking FI indicator), with no discernible change in performance, usually the code 9 would be gone the next day.
Recently I've started getting a code 9 daily, accompanied with:
- Poorly running engine (symptoms suggest fuel starvation).
- Surging at speed (steady throttle).
- Idling at 1500 rpm (was 1000 rpm).
- Fuel economy has dropped off to180 miles per tank (was 280 miles per tank).
The Honda shop manual states that a code 9, indicates a malfunction of the IAT (intake air temperature) sensor, however a number of posts here on ST-Owners suggest checking the vacuum hoses, and plastic tee's nestled within the throttle body assembly.
Here's what I've done to date, with no consistent improvement:
- Replace spark-plugs. No change in engine performance.
- Adjusted valves. No change in engine performance.
- Run Sea-Foam through the system. Initially, better engine performance, then back to poor performance, and a code 9.
- Replace IAT sensor. No change in engine performance.
- Complete diagnostic check (Honda manual pages 5-24 & 5-25). Resistance, supply voltage, and signal voltage are all in spec.
- Replace ignition coils, spark-plug wires, spark-plug caps (broke an insulator during spark-plug replacement). No change in engine performance.
- Replaced fuel-pump assembly. Initially, better engine performance, then back to poor performance, and a code 9.
- Inspected all vacuum lines, and tees. All are clean as a whistle.
- Inspected fuel pressure regulator. It appears okay, diaphragm holds a vacuum (need to get a replacement, and swap out).
- Inspected fuel line (pressure side). It appears okay, and flows fuel easily
- The spark-plugs at 80,000 miles were probably fine, though due for replacement.
- The valves can go for a long time before requiring adjustment.
- Sea-Foam may or may not be useful.
- The original IAT sensor is probably fine.
- The original ignition coils, and wires are probably fine.
- A torn rubber spark-plug cap does leak voltage.
- The original fuel-pump assembly is probably fine.
- That I'm amassing quite the inventory of spare parts.
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