So this is a bit of a long shot, but I'm just getting started with diagnosing an newly arisen engine problem. I thought maybe the 2 things might be related.
I had a 4hr drive home after a trail run Monday. There is one 4 mile climb on I-70 to get up over the continental divide. The truck was pulling hard and had just down shifted to 2nd pulling about 4000 RPM when it started dropping out or stuttering on me. I let off the gas and it mostly went away but it did do it once or twice more before the climb was done.
Following that was a long stretch of downhill driving where there's not much engine load so nothing seemed to be amiss.
Once I got back on flat land it would miss or stutter occasionally under steady state driving. Then when I got to the areas with frequent stop lights I discovered it was idling rough. It is a constant miss or hiccup. It idles fine, doesn't try to die, but it has a miss. Almost like one cylinder isn't firing. You can hear and feel it as the RPM revs up until basically the RPMs are high enough to kind of mask the miss.
The odd thing is when the truck started doing this, I tried to connect my phone with the ALDL cable using the ALDLdroid app. It has worked fine for over a year now, but now it won't receive data from the ECU. It connects to the ECU and then says "waiting for data from ECU".
So in looking at what might be causing my engine miss, is there something that could be causing both the miss and the ALDL not to receive data from the ECU?
I'm still planning to try and use my laptop to connect to the ALDL cable/ECU just to make sure it's not a glitch with the app or my USB to phone adapter.
I did some initial quick checks to make sure there aren't any burnt plug wires and also check the injectors.
Tonight I'm going to pull the plugs to check for a fouled plug. I also think I may have noticed the ground wire between engine block and firewall is missing, which is odd because I know it was there in the past.
But like I mentioned, I thought it was an interesting coincidence the engine started running rough and the ALDLdroid app wasn't receiving ECU data.
Engine info:
I had a 4hr drive home after a trail run Monday. There is one 4 mile climb on I-70 to get up over the continental divide. The truck was pulling hard and had just down shifted to 2nd pulling about 4000 RPM when it started dropping out or stuttering on me. I let off the gas and it mostly went away but it did do it once or twice more before the climb was done.
Following that was a long stretch of downhill driving where there's not much engine load so nothing seemed to be amiss.
Once I got back on flat land it would miss or stutter occasionally under steady state driving. Then when I got to the areas with frequent stop lights I discovered it was idling rough. It is a constant miss or hiccup. It idles fine, doesn't try to die, but it has a miss. Almost like one cylinder isn't firing. You can hear and feel it as the RPM revs up until basically the RPMs are high enough to kind of mask the miss.
The odd thing is when the truck started doing this, I tried to connect my phone with the ALDL cable using the ALDLdroid app. It has worked fine for over a year now, but now it won't receive data from the ECU. It connects to the ECU and then says "waiting for data from ECU".
So in looking at what might be causing my engine miss, is there something that could be causing both the miss and the ALDL not to receive data from the ECU?
I'm still planning to try and use my laptop to connect to the ALDL cable/ECU just to make sure it's not a glitch with the app or my USB to phone adapter.
I did some initial quick checks to make sure there aren't any burnt plug wires and also check the injectors.
Tonight I'm going to pull the plugs to check for a fouled plug. I also think I may have noticed the ground wire between engine block and firewall is missing, which is odd because I know it was there in the past.
But like I mentioned, I thought it was an interesting coincidence the engine started running rough and the ALDLdroid app wasn't receiving ECU data.
Engine info:
- 89 TBI 350
- New AC Delco cap and rotor 200 miles ago
- New NGK spark plugs 200 miles ago
- New Taylor plug wires 200 miles ago
- Set timing 5°BTDC 200 miles ago (after finding the previous owner set timing with the timing plug connected)
- Oil changed 200 miles ago
- Rebuilt throttle body 200 miles ago
- 250000 miles + on the engine
- About due for new fuel filter
- It has dual fuel tanks, each tank has a new Delphi pump; same symptoms regardless of tank and fuel level.
