vadergator

i have a 97 jeep GCL 4.0L 2WD ( IN-LINE motor ) . the vehicle does not have a EGR sensor, knock sensor , or MAF sensor. my understanding is that the MAP sensor also does the job of the EGR on my vehicle. correct me if i'm wrong. this is my problem. the vehicle has symptoms that are listed under MAF ( mass airflow ) , EGR , knock , and speed sensors. i'll be specific. it has a very rough idle. fuel is disappearing quickly without any fuel leaks. the grass on the ground is turning black from the exhaust pipe ( something invisible to the naked eye is coming out of the exhaust , but, it is not oil. i put a rag on the ground and it started getting black dots on it. has no smell to it. i revved the rpms up to close to 6000 rpms, and a big cloud of black smoke come out of the tailpipe. this has happened only once ). the jeep runs strong ( with a rough idle ) while in park. put the vehicle in reverse or drive, the motor runs weak, like it's going to stall. give it some gas, and it strengthens up. i just drove it for about 5 minutes and it had a strong smell of exhaust or something else. this all started after i changed my valve cover and throttle body gaskets. i cleaned my throttle body and the MAP, IAC , and TPS sensors. throttle body cleaner for the TB, and electronic / contact cleaner on the sensors and their connectors. i cleaned all electrical connectors and applied dielectric grease. i did this to the O2 sensors as well. i had to go back and clean the O2 sensors of the grease because it threw a DTC code of PO171 ( O2 sensor 1 Bank 1 ). the fuel was running too lean. this was not doing this before i cleaned / greased the connectors. my vehicle had been hard to start in the mornings and after the engine had cooled off, prior to return trips. once the motor warmed up, it usually ran great. on rare occasions it would stall a few miles down the road, but crank right back up. i did not have a rough idle before all this either. the motor lopes like a muscle body car from the 70's. sounds good, but it's not right.i am burning half of a quarter tank of gas just driving three miles or less. transmission works great. when i first started the motor after all the maintenance, it idled great for 10 minutes before i left the driveway. a few miles down the road, i noticed the loping sound and the rough idle. drove 4 miles like that with no problem. 3 hours later, it fired up and stalled. crunk back up and i had to nurse the gas until the motor warmed up. drove it home 5 miles and turned it off. 7 hours later, the motor just turned over without firng up. next day, fired right up with the rough idle. i have changed my coolant temp sensor, crankshaft position sensor, cam position pick-up / relay sensor, distributor cap and rotor, coil , plugs and wires, both O2 sensors 6 months ago, battery , and put in a new catylic converter and muffler. the gaskets and temp sensor are the only new parts. i also added 2 grounds to the jeep. there was no stud on the dipstick with a ground. there was no thin ground on the back of the cylinder head to the firewall either. nothing to the firewall. i put one from the fuel rail bolt to the firewall. i put one on the negative battery bolt to a radiator support in front of it. i cleaned all the fuses and relays and the power distribution center with electronic cleaner. again, other than cold start stalling, the jeep ran like a charm. is there any suggestions on what this could be. no loose wiring harness or connector problems with moving wires. fuel pressure checked out with a 49 rating ( must be between a 44 - 54 ) and have good fuel system and relays. electrical charging system checked out great also. it's got to be a sensor i would believe. problem is , which one. because like i said, some symptoms are like sensors i do not have. appreciate any assistance ya'll can throw my way.

dave1123

I don't know because I've never had one off, but is it possible you put the throttle body gasket on wrong thus blocking a sensing port? None of my repair manuals show the bottom of the throttle body or the gasket.

Good catch on the grease on the 02 plug. The weak electrical signals from the sensor can be blocked by it.

After you get it running right. Take it on a road trip to clean the carbon out of the converter.