1FZFE rough idle, stumbles, stalls...
- Thread starter woody
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- #22
no pun intended, but one of the disconnected O2 connectors off the harness was Gum'd badly (mud, it appears)...not sure what was wedged in there, but it's a possible short point...
so, some electrical cleaner (ie: lots) and reconnecting the O2's (one needing a zip-tie since the connector refuses to clip) and it's idling right now....need to do a test drive, but will address that later this afternoon...have an appointment at 2p to head to now....
yet another of the dozens of reasons IH8MUD
so, some electrical cleaner (ie: lots) and reconnecting the O2's (one needing a zip-tie since the connector refuses to clip) and it's idling right now....need to do a test drive, but will address that later this afternoon...have an appointment at 2p to head to now....
yet another of the dozens of reasons IH8MUD
you have to have at least the front O2 sensor working for the ECU to calculate fuel trim. With out it you will be in limp mode if I'm not mistaken.
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- #24
well, I put on 400ish miles with NO O2's connected....
either way, I just did a test spin, and it ran great and didn't toss any codes....will be doing some more road time with it over the next few days to be sure, but it's looking good...
Gona log with ScanXL on the laptop too, will help monitor anything if it DOES pop up...
either way, I just did a test spin, and it ran great and didn't toss any codes....will be doing some more road time with it over the next few days to be sure, but it's looking good...
Gona log with ScanXL on the laptop too, will help monitor anything if it DOES pop up...
lets say this is a highway blast for the most part. In that case the ECU would be in open loop and not adjusting anything. The problem would arise when you slowed down and was stop and go. Now you are in closed loop.
Just one explanation, but you really do need those things.
Hi guys I have been trying to follow this thread , because I am dealing with a similar problem though not as extreme as yours but frustrating non the less. 1995 FZJ80 intermittent cut out at all speeds and stalling at stops only when I have my coffee cup is in my hand, replaced the pump and filter (pain in the ass) no change ,I was going to pull the o2 sensors just to check there condition,, It is hard to tell if it is a fuel delivery or electrical problem. But I don't know all the terms you guys are using ...I will do my best to follow ,, but if you replace a sensor please clarify which one it is so I can follow thanks so much.
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- #28
Did NOT replace a sensor, just reconnected them and cleaned the connection points.
Do you have a scantool to monitor everything? I use ScanXL from Palmer Performance on my laptop and it allows me to record while driving...that might allow you to see what sensor makes a drastic change.
And, have you checked the intake hose, between the air cleaner and the throttle body? Mine rotted/tore a few years back, and a few Robbie-approved wraps of duct tape fixed it on that trip...some very sporadic issues on that one.
Do you have a scantool to monitor everything? I use ScanXL from Palmer Performance on my laptop and it allows me to record while driving...that might allow you to see what sensor makes a drastic change.
And, have you checked the intake hose, between the air cleaner and the throttle body? Mine rotted/tore a few years back, and a few Robbie-approved wraps of duct tape fixed it on that trip...some very sporadic issues on that one.
How come when you write ECU it doesn't have a link like some of the other terms used. I not sure what a ECU is please help a brother out (I promise I will not slow you down on the trail)
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- #30
@Ken, the O2's were just never reconnected after replacing the motor/trans/case and installing a new engine harness...mostly because they were tossing codes constantly with the old motor and I 'assumed' they would do the same with the replacement, so I opted to not plug in...
obviously, given the circumstances, not one of my brightest ideas...
obviously, given the circumstances, not one of my brightest ideas...
thanks for the info (very informative) and I hope all works out well for this issue and I will be checking out a lot of little things this weekend. and following this thead.thanks again
X2..on the intake hose. If you have not done so check that. Mine did the same thing and could not figure out what the problem was. The crack on the intake hose was hard to see because it was on the groove area.
It won't go into limp in, but it won't go into closed loop.
so what is the meaning of limp in ? and what is open and closed loop all about ? if you don't mind training someone that really wants to learn. thanks
Oh and to update my issues, I found a very small leak in the heater hose above number 6 and evidence of a puddle around the spark plug seal pulled it and dried up what little moisture I could see, tighten up the clamp on the hose and now it runs fine . new code though a knock sensor is broken I might have broke it when I did the fuel filter.
The finer details have been up for debate but,
Closed loop is where the ECU adjusts fuel trim according to the readings from the front O2 sensor.
Open loop is where the ability to adjust the fuel trim is beyond the ECU's ability so it runs with a constant value instead of adjusting it.
Limp mode is where the ECU has determined a sensor fault and runs a pre determined set of variables which usually means a rich condition allowing the driver to "limp"home without damaging the engine.
This might be a long shot and not the absolute answer but seems to be a couple of valid theories.
In the 95-97 models there are two O2 sensors inline with each other, one in front of the cats and the other after versus the 93-94 models where each sensor monitors three cylinders before the cats. With the 95-97 models the ECU is going to be programmed to make at least some before/after comparisons between the two sensors to make sure the cats are performing properly.
If both sensors were unplugged there would be no differences (?) and possibly no big effect on engine performance, i.e. the engine stays running. Next you travel in mud and water and one connector gets stuffed with dirt and water, shorting the heating circuit and sensor circuits which might allow some miscellaneous signals to be sent back to the ECU. The ECU then tries to adjust fuel/air which stalls the engine.
The O2 sensors are heated sensors and it takes ~30 seconds to get the sensor up to temperature. The ECU may ignore the output of the O2 sensor for this period of time which would explain the successful restart and failing after the short period again.
In the 95-97 models there are two O2 sensors inline with each other, one in front of the cats and the other after versus the 93-94 models where each sensor monitors three cylinders before the cats. With the 95-97 models the ECU is going to be programmed to make at least some before/after comparisons between the two sensors to make sure the cats are performing properly.
If both sensors were unplugged there would be no differences (?) and possibly no big effect on engine performance, i.e. the engine stays running. Next you travel in mud and water and one connector gets stuffed with dirt and water, shorting the heating circuit and sensor circuits which might allow some miscellaneous signals to be sent back to the ECU. The ECU then tries to adjust fuel/air which stalls the engine.
The O2 sensors are heated sensors and it takes ~30 seconds to get the sensor up to temperature. The ECU may ignore the output of the O2 sensor for this period of time which would explain the successful restart and failing after the short period again.