I took it to Autozone and it gave the codes p0171 and p0174. I did use a lucas gas addittive hoping it would help..no luck. If it is the 02 sensors, Where are they located and how difficult to rplace?
It only has 42k miles on it.
Thanks to anyone who can help.
This maybe due to an intake gasket leaking vacuum and causing a lean air-fuel mixture. Check for a vacuum leak where the lower intake plenum meets the cylinder heads. Separating the upper and lower intake manifold is not necessary. These gaskets are plastic and metal. The plastic gasket cracks causing a vacuum leak. This is an unmetered air leak and may cause fuel trim codes like PO171 and Po174 to set. There is an updated gaskets to repair the problem from Isuzu. These codes are for a lean fuel condition, not bad O2 sensors. Do you also have a rough idle?
Ewashmidas is exactly right. I have replaced the intake manifold gasket 4 times in a 1999 Trooper. Only last repair did I learn there is a TSB from Isuzu specifying 13 ft lbs of torque on bolts vs previous specified 18 lbs. Over tightening the bolts appears to be what is cracking the plastic gasket.
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yes, very rough idle
I have almost the same problem. Idles rough then dies. It's fine as long as I don't come to a complete stop for too long... check engine light is flashing as I'm driving. I cleaned the EGR and now I'm replacing the pcv valve and intake manifold gaskets. I also heard replacing the Air Mass Meter may help.
when you get a P0171 & P0174 the PCM is compensating for a lean condition , correcting the desired fuel/ratio by increasing the injector time , once the correction of fuel trim has exceeded the parameter of normal operation these codes will set to inform you there is a problem , several things can cause this , not knowing the actual fuel trims in the PCM's freeze frame data , we will have to do some assuming , which is not the best plan . vacuum leaks would be the first to eliminate , broke vacuum lines , stuck egr valve , leaking intake manifold gasket , etc. , second reasonable possibility is fuel volume and pressure , ( how old is the fuel filter ? ) , if you can verify there are no vacuum leaks and you do not have a clogged fuel filter , you can try moving on to the next stage of assumming ... start throwing parts at the vehicle , or maybe have it diagnosed by a professional .
J5
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