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I got a 1998 dodge ram auto with the 318 that I bought back in january. Every since i bought it, its had the same problem but has progressivly gotten worse. When I first drive my truck in the morning (when the engine is cool) it seems to have a bit of a rough idle but not bad. when I start going down the road it has a nasty missfire for a second right when I start accelerating but comes out of it quickly. After i get up to about 20 mph +/- after it shifts into second, it almost feels like im hitting the brakes and the eninge sounds like its loading up. Itll start popping and surging untill i let off the gas or stomp on it. I tried it with the A/C on one morning to see if it would act differently and it makes it much worse. The extra load on the engine loads it down even more and quicker (before it shifts into second) but once it comes out of it it drives fine untill i drive it later in the day when the engine has cooled down a little bit.
It also seems to have no power off the line. I know that the 318 isnt all that muscular but when I first bought it I had no problem getting the tires loose and now it has a hard time breaking loose even on gravel unless I stomp on it. once the rpms climb to about 2800 the engine seems to catch and it starts pulling pretty good. im also getting terrible gas milage (around 8-9 highway) I know these trucks are gas hogs but i have a 96 ram with the 360 and was getting around 12 highway.
Another problem it seems to have is loading up at an idle. Once i start it and let it idle for a little bit it starts to bog down, chug and idle really rough.
I know these trucks are notorious for blowing lower intake pan gaskets but it doesnt seem to have all the same symptoms like oil consumption. when I first bought the truck i pulled an o2 sensor code but havent scanned it recently. also, it sounds like I have a pretty nasty vacuum leak. It almost sounds like a turbo on my engine. I know that needs to be fixed but im not sure if the vacuum leak would cause those problem to happen at only those times.
I cleaned the throttle plates up, new cap, new rotor, wires look new, not sure about plugs.
any advice or ideas are appreciated
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I owned a dodge pu of that vintage,poor hp and 9-13 mpg I hated that truck.
Looking forward to the live data.I pulled 1 stored code: P0138- O2 circuit high voltage bank 1 sensor 2 (which is the sensor behind the cat)
I pulled 2 pending codes: P0141- O2 sensor heater circuit bank 1 sensor 2 AND P0308- Missfire detected on cyl #8
working on getting the live data. I’ll try to get screen shots and post them.
these are the o2 and fuel trim reading holding at around 2200. o2 bank 1 sensor 2 holds at 1 volt constantly
these are the o2 and fuel trim readings at idle. o2 sensor bank 1 sensor 2 reads 1v constant during this test also. both test were done when the engine was at OT but when i first started the truck i checked the o2 voltage on bank 1 sensor 2 and when the engine was cold it was at 1v also.
just checked vacuum. it holds steady at about 18 inches. but once it starts bogging down the vacuum drops to around 5-7 inches. My guess is because the engine is idling so rough, it cant build vacuum when it bogs. As soon as i give it a bit of gas it snaps out of it and holds at about 18 inches again. still not sure where the whistle is coming from or if its even related to vacuum.
I just tried to check for any vacuum leaks using a propane torch but didnt find anything. I went over all the lines I could see and the intake but no change in idle.
[quote=”sam_priem” post=63929]I pulled 1 stored code: P0138- O2 circuit high voltage bank 1 sensor 2 (which is the sensor behind the cat)
I pulled 2 pending codes: P0141- O2 sensor heater circuit bank 1 sensor 2 AND P0308- Missfire detected on cyl #8
working on getting the live data. I’ll try to get screen shots and post them.[/quote]
I would check the heater circuit on the upstream o2. P0141
also check the fuse.sounds like the heater circuit is gone.
change the sensor if faulty.bank 1 sensor 2 is the downstream sensor behind the cat. I’ll probly wind up replacing it since its hold at 1v constant with a heater circuit code and see what that does.
just ordered a new o2 sensor. I’ll update as soon as i get it hooked up. Just for future reference if anyone reads this in the future, never use bosch O2 sensors in dodge trucks. In my experiance (6+ years) working with dodge trucks, they reject bosch sensors. NTK is the best brand for dodge trucks.
I have not found that Bosch sensors work on most anything that did not come from Germany to begin with. Longshot on your issues-isolate the power brake booster from engine vacuum and notice any changes in your conditions. Had the booster be the cause of driveability issues in the past on many different brands. Does not always show up in brake pedal feel or braking performance. Cheap try!
update: I put in the new o2 sensor but no luck. It still acts the same. Runs rich, no low end power, Bad mpgs, loading up cold, rough idle, its all still there. I reset the computer after i put it in have and given it 2 days to relearn but theres been no change. I’ll check for codes tomarow and read the live data again to make sure the o2 and fuel trim are working properly with the new sensor. I might pull the front o2 and check back pressure to make sure the cat isnt clogged. Not sure where else to go with this. Any more advice is appreciated.
Just read the live data and codes. I pulled 1 code for the idle air control system but i doubt it has anything to do with my problem especially since it just appeared. the o2 codes are gone and the voltage is moving up and down like normal. fuel trim looks ok, but the long term fuel trim at 2000 rpms shows the truck running a bit lean (ltft stays at about 11% while stft goes up and down like normal, no more than +/- 5%). Checked for vacuum leaks and did not find anything so im still thinking about the cat being partially plugged. that would explain the loss of power also. at an idle (while at OT) the ltft stays at about +2% while the stft stays mostly above 0% but no more than +5%. If anyone would like me to post the live graphs i can. I saved the log files so if theres something else that i should look for, i can go back and check. Any help is appreciated.
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