Question about 1988 Nissan Pathfinder
Check throtle position sensor behind the TBI. Run mode 4 in the computer diagnostic checks to see what codes is giving.
By the way, if any of the sensors give a code, don't spend money replacing them. They are all inter related. If one fails you will get codes for the others also. What you really need to do is above suggestion and then trace the circuits for continuity. Am assuming you know how to run ECM codes in the computer. Eliminate codes one at a time, and re-run mode 4, until all codes have been eliminated.
If code 55 is in the computer. Replace the whole TBI. After 20 years of use, they appear to corrode inside. But try the below first in the interest of saving money.
You might want to remove the TBI. Don't disturb the pre heater underneath the TBI if is stuck to it.
Take choke cleaner (Pep Boys or Autozone) Carb and Choke Cleaner in yellow can. There is an opening in the pre heater for the Air Flow Sensor, liberally spray it with the plastic little nozzle attached to the can and ensure all the gook in the passage way is clean, spray until no more junk comes out. Remove mass air flow sensor from TBI before doing this. You don't want to damage it. Spray the passage way from MAFS side also. While you have the TBI off, look at the port for EGR VALVE see if its clogged up with Carbon. Clean them out you can remove the carbon by scraping with a phillips head or bladed screwdriver. Two holes leading to the EGR Valve. They are about 1/2 inch in diameter round holes. Flush with the carb cleaner. If you really want to do ir right, remove the EGR Valve, clean it also and check to make sure its working. If NG replace it. Your EGR valve might be getting stuck due to carbon in the open position thus letting to much air into the intake manifold thus cunking out. Or the EGR has a leak. Check with vacuum pump by attaching VP to EGR. It should hold steady with 20 - 30 vacuum on the EGR. If it does not hold, throw it away and buy a new one.
You mentioned you replaced the MAFS. Remove it again and look in the element. Is it Wet or Dry?
It should be dry. Don't touch it. If its wet, then your air passages are clogged in the TBI. While you have the TBI out, spray all the vacuum fittings with the carb cleaner ensure they are free of blockage. Replace everything back carefully. Your truck should idle at 850 rpms if its standard and 700 if its auto. + or - 50 rpms. 850 is ideal. Let me know what happens after all of that.
Last but not least. Check the hose to the PCV Valve, ensure is not cracked, if damage, replace the hose and replace the PCV Valve. Ensure all vacuum hoses have no leaks and are correctly routed, especially the EGR valve one. From the manifold connect hose to center vacuum port or bottom port on the Solenoid Cut off Valve. Connect port B (Middle one to the EGR Valve.) Connect Port A (top one) to the Air Filter Canister. With the car on there should be continuity between port C and and B. You can check that with the vacuum pump. Gun the engine and see if you get a momentarily reading on the gauge if yes the port is good. If NO the Cut off Solenoid is NG. Find a working one in junk shop they are $100 bucks at the dealer. (highway robbery) If you are in PA go to Harry's U pull it. 5 bucks, each take the vacuum pump so you can check it before buying. The suffer from corrosion in the ports. Hope this solves your problem. Good Luck!
Posted on Oct 29, 2008
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Posted on Jan 02, 2017
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Oct 30, 2015 | Cars & Trucks
ENGINE HESITATES WHILE ACCELERATION
LOSS OF ACCELERATION
can be fuel pressure issue or it's the problem with accelerator pedal or its
clogged filters causing there.
are many other possibilities. I suggest you to go through the list of help
links mentioned below, these will help you to confirm where the actual fault
These details will help.
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