motopsycho650
Active Member
- Joined
- February 20, 2009
- Messages
- 84
- Reaction score
- 1
- City, State
- Denver, CO
- Year, Model & Trim Level
- 1994 XLT
Hi, I'm new to this forum, but I am having issues with my '92 XLT.
About a week ago, I went to start my Explorer in the morning, and it sounded like it was running on 4-5 cylinders, Very Rough. After warm-up the rough running improved a little, but I could feel power cutting in & out while going down the road. The last weird symptom was, while sitting at a stop light for about 30 seconds, the RPM's would drop from the normal 700ish to below 500. Then it would cough a few times, and eventually return to normal RPM's, although still rough. Oh, and there is no Check Engine Light.
First thing I did was changed the fuel filter, and pulled the plugs. All the spark plugs were very black and rich looking. I cleaned them, checked the gaps, and put them back. I also sprayed out the Mass Airflow Sensor with carb cleaner, and disconnected the battery to clear the computer. Some of this helped a little, but not enough. It is still running rough cold or warm.
So, I found this forum, and was looking at different posts about a 4.0L running rich. I read one that said to check my thermostat, since the computer could be keeping the truck choked, trying to warm it up. Well, that was right, my thermostat was broken. Replaced it, started it up again, and again next to no change in running. While I was driving around, warming it up, I finally got a check engine light.
Came back home and pulled the codes from the computer. All I got was a 172 - Oxygen Sensor Reporting "Lean" code from the stored memory. So, I changed out the O2 Sensor. While I did that, I did a good inspection for vacuum lines, all of which look okay & dry. I also reset the computer again.
The O2 Sensor did make a change while it runs, but did not fix the problem entirely. Now, running cold is still rough. When it warms up, and is moving, it becomes a very rhythmic miss fire. The power is steadier, not cutting in & out like it was before, but still only 75% of normal. While sitting at a stop light, I still get the RPM drop after 30 seconds or so of sitting & idling.
I have two guesses left, but since I don't have much money to waste, I thought I'd ask you guys. 1st. The EGR Valve. This makes sense to me with the RPM Drop at stop lights, but how much does this have to do with fuel mixture? 2nd. The MAF Sensor. I did a test, and while the engine was running, I disconnected the MAF. There was no change in the way the engine ran with the MAF either connected or disconnected. The CEL did come on when I un-plugged the MAF, and turned back off as soon as I plugged it back in.
What does anyone think?? If you have any questions about my long story here, please ask... I appreciate anyone trying to help...
About a week ago, I went to start my Explorer in the morning, and it sounded like it was running on 4-5 cylinders, Very Rough. After warm-up the rough running improved a little, but I could feel power cutting in & out while going down the road. The last weird symptom was, while sitting at a stop light for about 30 seconds, the RPM's would drop from the normal 700ish to below 500. Then it would cough a few times, and eventually return to normal RPM's, although still rough. Oh, and there is no Check Engine Light.
First thing I did was changed the fuel filter, and pulled the plugs. All the spark plugs were very black and rich looking. I cleaned them, checked the gaps, and put them back. I also sprayed out the Mass Airflow Sensor with carb cleaner, and disconnected the battery to clear the computer. Some of this helped a little, but not enough. It is still running rough cold or warm.
So, I found this forum, and was looking at different posts about a 4.0L running rich. I read one that said to check my thermostat, since the computer could be keeping the truck choked, trying to warm it up. Well, that was right, my thermostat was broken. Replaced it, started it up again, and again next to no change in running. While I was driving around, warming it up, I finally got a check engine light.
Came back home and pulled the codes from the computer. All I got was a 172 - Oxygen Sensor Reporting "Lean" code from the stored memory. So, I changed out the O2 Sensor. While I did that, I did a good inspection for vacuum lines, all of which look okay & dry. I also reset the computer again.
The O2 Sensor did make a change while it runs, but did not fix the problem entirely. Now, running cold is still rough. When it warms up, and is moving, it becomes a very rhythmic miss fire. The power is steadier, not cutting in & out like it was before, but still only 75% of normal. While sitting at a stop light, I still get the RPM drop after 30 seconds or so of sitting & idling.
I have two guesses left, but since I don't have much money to waste, I thought I'd ask you guys. 1st. The EGR Valve. This makes sense to me with the RPM Drop at stop lights, but how much does this have to do with fuel mixture? 2nd. The MAF Sensor. I did a test, and while the engine was running, I disconnected the MAF. There was no change in the way the engine ran with the MAF either connected or disconnected. The CEL did come on when I un-plugged the MAF, and turned back off as soon as I plugged it back in.
What does anyone think?? If you have any questions about my long story here, please ask... I appreciate anyone trying to help...