- Thread starter
- #21
I also pulled the EFI fuse this evening. Took it for a drive with a couple of stops to shutdown, restart.
No change.
No change.
93 FZJ80 - Advanced timing now have rough idle (2 Viewers)
- Thread starter mudgudgeon
- Start date
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- Thread starter
- #22
Got any more details on this?
My understanding is that idle speed is controlled by the EFI
No OBDII on my truck. I'm not aware of a scanner that works with a 93?
Sorry, I ignored both your year and the history of OBDII coming into reality.
The "idle cable" i mentioned isn't really an idle cable. There are two cables (well, three maybe if you count the one going into the tranny) side by side on the throttle body. One is accelerator and one is cruise control, I believe. Anyway, I couldn't get my idle above 400 one day - it was rough and felt like it wanted to stall if I took my foot off the gas. There was no reason for the behavior (no recent work, confident of no vacuum leak), and I was heading somewhere, so I popped the hood. I adjusted the cable pulleys by hand while looking around to keep it idling. With no signs of any issue, I decided to simply adjust the throttle cable to get the rpms up. I ride an old '74 Honda CB350, so adjusting cables - and idle screws on carb engines - isn't uncommon to me. I was alone, so I recorded with my phone which cable moved when I went back into the cab and hit the gas. The one that moved was the one I adjusted (as this was the accelerator). I set it so it wouldn't fall back below 600rpm -I also noticed it was set to its loosest before, so possible the nut had loosened over time. Never saw the issue again (on that drive or thereafter), and rig always ran good and found the 650 idle range within a day. While the EFI or ECM or whatever the computer system is that controls idle does manage the idle, the cables can also impact it (at least in my experience). If you cranked them to their tightest and set your idle rpm to ~2,000 (or whatever it would be) I'm unsure if the computer could "manage" it down to 650.
Again, I don't think this will work in your case as you don't seem to be experiencing a random low/stalling idle.
The "idle cable" i mentioned isn't really an idle cable. There are two cables (well, three maybe if you count the one going into the tranny) side by side on the throttle body. One is accelerator and one is cruise control, I believe. Anyway, I couldn't get my idle above 400 one day - it was rough and felt like it wanted to stall if I took my foot off the gas. There was no reason for the behavior (no recent work, confident of no vacuum leak), and I was heading somewhere, so I popped the hood. I adjusted the cable pulleys by hand while looking around to keep it idling. With no signs of any issue, I decided to simply adjust the throttle cable to get the rpms up. I ride an old '74 Honda CB350, so adjusting cables - and idle screws on carb engines - isn't uncommon to me. I was alone, so I recorded with my phone which cable moved when I went back into the cab and hit the gas. The one that moved was the one I adjusted (as this was the accelerator). I set it so it wouldn't fall back below 600rpm -I also noticed it was set to its loosest before, so possible the nut had loosened over time. Never saw the issue again (on that drive or thereafter), and rig always ran good and found the 650 idle range within a day. While the EFI or ECM or whatever the computer system is that controls idle does manage the idle, the cables can also impact it (at least in my experience). If you cranked them to their tightest and set your idle rpm to ~2,000 (or whatever it would be) I'm unsure if the computer could "manage" it down to 650.
Again, I don't think this will work in your case as you don't seem to be experiencing a random low/stalling idle.
- Thread starter
- #24
Coming back to this in case it helps someone else.
This vehicle blew out the head gasket at the front of pot #1.
Finally got out all buttoned up and running lay night after revisiting the head gasket.
While it was apart, I checked all injectors. Changed ALL vacuum lines, replaced the harness connectors on all injectors (some where in poor shape), changed the rubber crossover pipe from air cleaner, changed the PCV grommet and hoses
So, I suspect for me, the head gasket was the problem, but potentially vacuum related.
Some hoses were past the use by date for sure. Could well have been a vacuum leak. I particularly suspect the PCV hose and grommet may have been leaking.
This vehicle blew out the head gasket at the front of pot #1.
Finally got out all buttoned up and running lay night after revisiting the head gasket.
While it was apart, I checked all injectors. Changed ALL vacuum lines, replaced the harness connectors on all injectors (some where in poor shape), changed the rubber crossover pipe from air cleaner, changed the PCV grommet and hoses
So, I suspect for me, the head gasket was the problem, but potentially vacuum related.
Some hoses were past the use by date for sure. Could well have been a vacuum leak. I particularly suspect the PCV hose and grommet may have been leaking.
How did you “check” injectors. Flow rate balancing is a good idea if you went that far.
- Thread starter
- #26
Yeah, check is a word used loosely there I guess.
Checked they were clean. Checked the solenoids fired when 12 volts was applied.
They are certainly still an unknown quantity.
With everything else fresh, and harness checked, if I still had a miss, the injectors would still be on the suspect list
