fritz84
New Member
- Joined
- Nov 17, 2019
- Messages
- 12
- Reaction score
- 0
- Points
- 1
- Location
- Maryland
- Vehicle Year
- 1994
- Make / Model
- Ford Ranger XLT
- Transmission
- Automatic
Recently purchased a 1994 Ranger w/2.3 and auto trans. The truck has ~130K miles on the original engine and a recently rebuilt A4LD trans. I just had the timing belt (and thermostat/water pump) replaced. In addition to basic tune up (new OE plugs and wires, air filter, fuel filter) and oil change type maintenance, I have been attempting to track down the source of rough idle/shaking issue that remains elusive. I have searched for and read through threads reporting similar issues and have thrown a number of parts at the truck to no avail, they include: MAF senor, TPS, coolant temp sensor, IAC valve, PCV, and upstream O2 sensor. Where relevant I tried first cleaning the items in this list before replacing, but no formal testing. They were all original parts so I figured no harm in replacing them, even though possibly not necessary. The check engine light is not on nor was I able to get any recoverable problem codes using an OBD1 scanner. This truck did not come with a EGR valve (determined based on looking for it and confirming with reference to vin). I (and a couple of mechanics) have looked for vacuum leaks and only one small one was found and addressed. There is no doubt the throttle plate adjustor screw has been monkeyed with previously, and I adjusted it again following the protocol described in one of these forums (maybe the Explorer/Ranger site), where you are advised to back it out to the point where the engine just barely remains running with the IAC unplugged. While the truck didn’t come with a tach from the factory I have since wired one up using the dedicated wires from the instrument cluster. I have read where the rpm’s should be around 750 at idle (with the IAC plugged in) once the engine is warm. I’m not sure if the aftermarket tach I have is reading true (AutoMeter 2306) but it functions and provides some frame of reference. So, after adjusting the throttle plate screw and plugging in the IAC the rpm’s definitely jump up as expected and suggesting it is working as it should, at least more or less. On a cold start the rpm’s jump up to maybe 1500 initially but then falling very quickly to 1000 until the engine reaches operating temp by which time rpm’s settle at 500 and the rough idle and engine shaking/apparently low idle condition is evident. The vibrations are most noticeable in the steering wheel, but also extend to the dash. The condition is most noticeable with the transmission in drive with the vehicle stopped compared to when in park, but not dramatically so. Standing outside of the truck while it is running you don’t sense the carriage is shaking, although the sound of an irregular/low idle is evident. The engine does not threaten to stall, and these symptoms pretty much go away (or are masked) when driving. I have reset the computer following all of the major adjustments in order to let the system ‘re-learn’ the air/fuel mix information, as seems to be recommended. The engine and transmission mounts are in good condition, having all been replaced recently. Finally, I’ll just mention that the exhaust system is original, as best I can tell, and it looks like it could stand to be replaced, though is not blown out by any means. If I can’t figure this out with your help I’ll have to search for a mechanic who is more familiar with these engines etc than I have encountered so far. I appreciate any relevant suggestions/experience you might be able to share…