Excessive fuel consumption, backfire on decelleration, and rough idle
I have put a new exhaust system in, put a new exhaust manifold gasket in, o2 sensor in, and made sure i dont have any exhaust leaks. i cant get over 72 mph on the highway. haynes manual doesnt help narrow down problems. anyone got any advice??
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Re: excessive fuel consumption, backfire on...
Put a vacuum guage on the intake I hope its an automatic one foot on the brake and one on the gas in drive slowly accelarate if the vacuum falls to or near O as you accelerate you have a restricted exhaust,
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MOST LIKELY A BAD O2 SENSOR...Potential causes of an P0160 code include: Holes in exhaust near post cat o2 sensor Bad Bank 2, position 2, o2 sensor Wiring problem, melted harness, broken connectors, etc. Bad PCM
There are two kinds of backfires, one is produced from the engine air intake and the other is produced from the tail pipe of the exhaust system. The cause for a backfire condition can vary depending on the malfunction of a particular system. Some backfires can be extreme enough to cause damage to related components. Anytime a backfire is observed immediately diagnose and repair as needed. If the engine is running rough it can produce a backfire. A backfire occurs when there is an imbalance in the air to fuel ratio required for your vehicle to operate properly. If the fuel mixture is too lean (not enough fuel) you may have a backfire in the intake manifold gasket, or too rich (too much fuel) you may get a backfire out of the exhaust system. It is important to observe the location of the backfire.
Sometimes if the throttle has been dirty for a while the engine will have been running rich due to lack of air intake. When this happens the O2 sensor on the exhaust manifold gets covered in soot and as a result is no longer able to measure oxygen levels in the exhaust accurately. If the O2 sensor sends a low voltage signal to the ECU (high level of oxygen in exhaust) the ECU tries to compensate by increasing injection times and this further enriches the intake mix. The end result is a lumpy idle and heavy fuel consumption. You may not yet have a check engine light but it might be a good idea to have your diagnostics scanned for any stored error codes. Failing that remove the O2 sensor and check it's condition if it's black with soot then you will know what is now causing it. Either change it or, since you have nothing to lose, use a plumbers burner to heat the O2 tip to red hot to burn off residues. Hope this gives you some avenues to think about.
1. P0173 O2 Sensor System - Lambda Controller at the Limit (Bank 2P0170 O2 Sensor System - Lambda Controller at the Limit (Bank 1Visually/physically inspect for air leakage in intake/exhaust system as following items.
Vacuum hoses for splits, kinks and improper connections.
Throttle body gasket.
Gasket between intake manifold and cylinder head.
Seals between intake manifold and fuel injectors.
Exhaust system between HO2S and Three way catalyst for air leakage.2.Visually/physically inspect the restriction in intake/exhaust system as following items.
Air cleaner filter element for excessive dirt or for any foreign objects.
Throttle body inlet for damage or for any foreign objects.
Throttle bore, throttle plate and the IAC passages for chocking and for any foreign objects.
Restricted exhaust system.
Not to worry. Run the engine up to operating temp before jumping to conclusions and let the heat burn off any excess oil. A leaf will not do any damage.Do not let the engine overheat while idling and if the oil light comes on switch off immediately. The smoke from the exhaust is oil deposited by oily assembly hands just burning off. It should dissipate after about 15 minutes at most.(or 5 miles' drive)