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Code 78 APPS Main and Code 79 TPS Main are diagnostic trouble codes (DTCs) that can appear on a 1997 Mitsubishi Pajero.
Code 78 APPS Main: This code indicates that the APPS (Air Pump System) Main relay is not working properly. The APPS relay is responsible for supplying power to the air pump, which is used to control the air-fuel mixture.
Code 79 TPS Main: This code indicates that the TPS (Throttle Position Sensor) Main circuit is not working properly. The TPS sensor is responsible for sending information to the engine control unit (ECU) about the position of the throttle valve.
If either of these codes appears, it is important to have the vehicle diagnosed by a qualified mechanic to determine the cause of the problem. The mechanic may need to test the APPS relay, the TPS sensor, or other components in the fuel system.
Here are some possible causes of Code 78 APPS Main and Code 79 TPS Main:
Faulty APPS relay: The APPS relay may be faulty and not be supplying power to the air pump properly.
Faulty TPS sensor: The TPS sensor may be faulty and not be sending accurate information to the ECU about the position of the throttle valve.
Clogged air filter: A clogged air filter can restrict airflow to the engine and cause the APPS relay to overheat and malfunction.
Low fuel pressure: Low fuel pressure can cause the APPS relay to overheat and malfunction.
Faulty wiring: The wiring to the APPS relay or TPS sensor may be damaged or corroded, causing the codes to appear.
If you are experiencing problems with your 1997 Mitsubishi Pajero and either Code 78 APPS Main or Code 79 TPS Main appears, it is important to have the vehicle diagnosed by a qualified mechanic to determine the cause of the problem and to get it repaired as soon as possible.
Hello, I would have the timing checked first. It sounds like that may be the problem, but if it is not, a plug wire may be loose in the wrong place? Please gather as much information as possible tell me everything including with the plugs, did they remove one wire at a time so as to not put them back in the wrong place? I need to lnow if you have checked things like is it running hot, or rough at speed or just at idle, etc. Let me know okay? Thank You for using FixYa.com!!
This can lead to many things, most of all is because of a bad sensor. There can be a bad sensor somewhere and I strongly suggest that you have the engine scanned. During the diagnostic it will list the trouble codes and by then you'll know what part is in need of replacement.
Although in my own opinion, it can be a possible MAF (mass air flow) sensor issue. If the MAF is faulty there will be vacuum irregularities.
Hope this helps and thank you for using FixYa! Have a good one!
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