1997 jeep grand cherokee runs rich after long trips
4.0 liter 179,000 has new plugs,wires,map sensor, 2 new oxegen sensors. i cleaned thotle body. runs great around town. long runs it gets a code po171 lean cond. some black smoke from exhaust. shakes at idle. when cooled runs grat again and after i clear the code po171. can one of the bosch parts be bad, what else can it be motor is otherwise strong.
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You replace sparkplugs,plug wire,tps,map,cap and rotor.Thats good,If the vehicle runs and you come to a stop and it stalls,That is the IAC (Idle air control) you say it ran fine for a week now its acting up, Service the IAC or get it replaced.
you need to check the fuel pressure,and did you mean you replaced the distributor or just the rotor because inside the distributor is a pickup plate that some times causes this also 02 sensor can cause this.is your check engine light on if so go to chain auto parts store they usually read your codes for free.
Have you checked the coolant temp sensor. They also have something called a MAP(manifold absolute pressure) sensor that could be causing this issue. This sensor will have a 4 pin connector and 1 vacuum line going to it. Should be on the firewall, just behind the engine.
If the ignition turns on and dies while driving, you might have a clogged idle air control valve. The valve is located in the throtle body, just below the air intake hose. Locate the idle air control valve, un plug the connector, unscrew it (you will need star screw driver) and next clean it using an electronic contact cleaner spray, I use 3M for that. Next, make sure all cleaning liquid inside is gone (it evaporates quickly) and re assemble it. This should solve your problem once for all.
A slight hesitation after engine shut off due to engine running rich meaning not meeting golden air:gas ratio of 14.6:1 so fuel residue in chamber continue to burn for the last moment.
The same rich fuel problem that was why you had to let gas off during acceleration.
Check out the O2 sensor
Check out MAP sensor