Join Date: May 2014
Location: San Andreas Fault Zone
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Re: Ammonia smell?
No, the production of ammonia is a "side reaction" taking place during the normal operation of current generation catalytic converters. NH3 production appears to be enhanced by the use of low-sulfur fuel (which you have no direct control over), and by rich fuel-air mixtures, which can be triggered by a multitude of problems with an engine's fuel-feedback mixture control system.
So, the following can be contributors to rich operation:
1. Dirty mass airflow sensor;
2. Dirty/inaccurate intake air temperature sensor;
3. Inaccurate coolant temperature sensor;
4. Defective coolant thermostat;
5. Leaky fuel injectors;
6. Inaccurate fuel/air sensor;
7. Inaccurate oxygen sensor;
8. Vacuum leak;
9. Exhaust system leak;
You can get a better idea of what is going on by connecting a monitor to the OBD-II diagnostic port and determnining what the engine's ECU thinks it is seeing as far as fuel-air ratio, and look at the long-term and short-term fuel trim values.