1990 LS 400 bad miss issue
10-02-13, 03:20 PM
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1990 LS 400 bad miss issue
Heello all, Im a newbie here and decided to regester to see if you guys can help me troubleshoot this issue. I have a 90 LS400 with 186k miles on it, that was parked for about 3 years. I would start it occationally and no issue, ran fine. then recently it wouldnt start at all, found out it was a bad fuel pump, so I replaced that and then it did start, but now it misses really bad, will barely idle, and if you drive it you have to keep your foot on the gas and brake to keep it from dying out. feels like its running only half cylinders. I also noticed one of the coils arcing so I replaced both of them, still no improvement. im thinking bad wires/plugs? but im wondering how this could happen from simply sitting?
Any ideas?
Much thanks,
Shan
Any ideas?
Much thanks,
Shan
10-02-13, 03:42 PM
#2
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When you changed the coils did you remove any of the plug wires and maybe put them back on wrong? If you still have original wires (possible) you could have broke a wire when you removed them. I would change plugs and wires. Probably needs them anyway from sitting so long. Yes, they can get bad from sitting for long periods.
10-02-13, 03:45 PM
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When you changed the coils did you remove any of the plug wires and maybe put them back on wrong? If you still have original wires (possible) you could have broke a wire when you removed them. I would change plugs and wires. Probably needs them anyway from sitting so long. Yes, they can get bad from sitting for long periods.
so they possibly need a good bleeding?
10-02-13, 04:01 PM
#4
Lexus Champion
this could be many things, but first lets go on the wire/coil arcing theory:
you want to run the car outside in a dark area at night and generally you will be able to see any arcing
you can also take a spray bottle with water and squirt the coil area as well as the area along where the wires run, from one end to the other, as listen for any change in engine sound or rpm
if that doesn't locate the problem, then please download the ECU diagnostic codes, following this easy tutorial and then post the codes you come up with here, I would then clear the codes and then redump them after driving the car again.
this bad running could be many things, such as a bad AFM sensor, bad Engine Coolant Temp Sensor or even failing ECU capacitors as well as some other possibilities such as timing belt jumped one tooth - the codes will tell us more!
what does really stiff mean as far as brakes?
you want to run the car outside in a dark area at night and generally you will be able to see any arcing
you can also take a spray bottle with water and squirt the coil area as well as the area along where the wires run, from one end to the other, as listen for any change in engine sound or rpm
if that doesn't locate the problem, then please download the ECU diagnostic codes, following this easy tutorial and then post the codes you come up with here, I would then clear the codes and then redump them after driving the car again.
this bad running could be many things, such as a bad AFM sensor, bad Engine Coolant Temp Sensor or even failing ECU capacitors as well as some other possibilities such as timing belt jumped one tooth - the codes will tell us more!
Also the brakes seem really stiff so they possibly need a good bleeding?
10-02-13, 04:49 PM
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this could be many things, but first lets go on the wire/coil arcing theory:
you want to run the car outside in a dark area at night and generally you will be able to see any arcing
you can also take a spray bottle with water and squirt the coil area as well as the area along where the wires run, from one end to the other, as listen for any change in engine sound or rpm
if that doesn't locate the problem, then please download the ECU diagnostic codes, following this easy tutorial and then post the codes you come up with here, I would then clear the codes and then redump them after driving the car again.
this bad running could be many things, such as a bad AFM sensor, bad Engine Coolant Temp Sensor or even failing ECU capacitors as well as some other possibilities such as timing belt jumped one tooth - the codes will tell us more!
what does really stiff mean as far as brakes?
you want to run the car outside in a dark area at night and generally you will be able to see any arcing
you can also take a spray bottle with water and squirt the coil area as well as the area along where the wires run, from one end to the other, as listen for any change in engine sound or rpm
if that doesn't locate the problem, then please download the ECU diagnostic codes, following this easy tutorial and then post the codes you come up with here, I would then clear the codes and then redump them after driving the car again.
this bad running could be many things, such as a bad AFM sensor, bad Engine Coolant Temp Sensor or even failing ECU capacitors as well as some other possibilities such as timing belt jumped one tooth - the codes will tell us more!
what does really stiff mean as far as brakes?
Shan
10-02-13, 05:48 PM
#6
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Pedal goes down a 1/3 of the way and then gets really hard, checked the booster and it holds vac. so no issue really there. I doubt the timing belts slipped because the car was sitting. another curious issue was the presence of 3 blown fuses including the main one at one point. what I dont get is the car was just sitting how can that happen? also the airbag light is on. thinking maybe another bad fuse or relay somewhere. though my bet is on the ignition components because of me having a similar issue on my old 5.0 mustang when 2 plugs died...
Shan
Shan
10-02-13, 06:24 PM
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another thing, the cars tach and temp gauge dont work. the temp gauge starts out at half way and makes it look like its over heating when its at normal op temp and the tach needle barely moves. I have another instrument cluster as I suspect the control board may be at fault, it did this for years even when the car was my DD... what say ye?
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10-02-13, 06:57 PM
#8
Lexus Champion
when a LS400 or any car sits for a long time, it is especially hard on the capacitors, which are already 24 years old anyway, so the chances of them failing in a very old car that has sat a long time is quite high
your cluster board and your ECU are both filled with these electrolytic capacitors
if it was my car, the first four things I would do:
● replace single wire gauge temperature sender ($15) with genuine Toyota part so I know what the real temperature of the engine is
● replace the engine coolant temperature sensor ($54) with the real Toyota one (sits right next to gauge sensor above, both are right behind passenger side coil) so that the ECU knows what the real temperature of the engine is
● replace ECU capacitors (which controls most of the systems that could cause all of these symptoms)
● replace cluster capacitors
the nice thing about all of these jobs is that they all will need to be done soon anyway, so no real wasted expense or effort, and this has a high probability of fixing most everything!
your cluster board and your ECU are both filled with these electrolytic capacitors
if it was my car, the first four things I would do:
● replace single wire gauge temperature sender ($15) with genuine Toyota part so I know what the real temperature of the engine is
● replace the engine coolant temperature sensor ($54) with the real Toyota one (sits right next to gauge sensor above, both are right behind passenger side coil) so that the ECU knows what the real temperature of the engine is
● replace ECU capacitors (which controls most of the systems that could cause all of these symptoms)
● replace cluster capacitors
the nice thing about all of these jobs is that they all will need to be done soon anyway, so no real wasted expense or effort, and this has a high probability of fixing most everything!
10-03-13, 10:59 AM
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How hard is it to recap the ECM? is there away to test it to see if that is indeed the issue?
when a LS400 or any car sits for a long time, it is especially hard on the capacitors, which are already 24 years old anyway, so the chances of them failing in a very old car that has sat a long time is quite high
your cluster board and your ECU are both filled with these electrolytic capacitors
if it was my car, the first four things I would do:
● replace single wire gauge temperature sender ($15) with genuine Toyota part so I know what the real temperature of the engine is
● replace the engine coolant temperature sensor ($54) with the real Toyota one (sits right next to gauge sensor above, both are right behind passenger side coil) so that the ECU knows what the real temperature of the engine is
● replace ECU capacitors (which controls most of the systems that could cause all of these symptoms)
● replace cluster capacitors
the nice thing about all of these jobs is that they all will need to be done soon anyway, so no real wasted expense or effort, and this has a high probability of fixing most everything!
your cluster board and your ECU are both filled with these electrolytic capacitors
if it was my car, the first four things I would do:
● replace single wire gauge temperature sender ($15) with genuine Toyota part so I know what the real temperature of the engine is
● replace the engine coolant temperature sensor ($54) with the real Toyota one (sits right next to gauge sensor above, both are right behind passenger side coil) so that the ECU knows what the real temperature of the engine is
● replace ECU capacitors (which controls most of the systems that could cause all of these symptoms)
● replace cluster capacitors
the nice thing about all of these jobs is that they all will need to be done soon anyway, so no real wasted expense or effort, and this has a high probability of fixing most everything!
10-03-13, 11:38 AM
#10
Lexus Champion
Recapping the ECU is 6 hours of microsurgery, to do it right - a lot depends on the kind of person you are and whether you are a good solderer, or at least willing to practice on some junk computer motherboards for a while in order to develop these skills - are you the kind of person who has the patience to build a model? -a tinkerer of small things? - the guy who could repair a fine clock with a bit of training? - or fix the insides or a tiny laptop or cell phone, if not, then you need to find an old school microelectronics type guy, like an electronics geek that prototypes his own circuits. - you need Steve Wozniack when he was 20 - lol
The places who "rebuild" ECU's seem to do a horrible hack job - To do the job right, they're supposed to be using a very rare and hard to find type of capacitor, that is only available from Japan, it is low-ESR, high reliability, high temperature, high ripple rejection, long life type from only a couple of companies that make them, out of hundreds of capacitor makers. But ECU rebuilders are not interested in locating these capacitors or paying for them, so they use generic Chinese junk caps of the wrong type, and often even the wrong value as a couple of the small sizes are really elusive. There is also a huge problem with counterfeit capacitors, even guys who fix these and are trying to do right, end up ordering their capacitors from ebay, and they end up with fakes, when they should have ordered from the manufacturer's authorized distributor ONLY.
Yes! - there are two ways, sometimes there is visible leakage, as shown here and there is also Yamae's ripple test
The places who "rebuild" ECU's seem to do a horrible hack job - To do the job right, they're supposed to be using a very rare and hard to find type of capacitor, that is only available from Japan, it is low-ESR, high reliability, high temperature, high ripple rejection, long life type from only a couple of companies that make them, out of hundreds of capacitor makers. But ECU rebuilders are not interested in locating these capacitors or paying for them, so they use generic Chinese junk caps of the wrong type, and often even the wrong value as a couple of the small sizes are really elusive. There is also a huge problem with counterfeit capacitors, even guys who fix these and are trying to do right, end up ordering their capacitors from ebay, and they end up with fakes, when they should have ordered from the manufacturer's authorized distributor ONLY.
is there away to test it to see if that is indeed the issue?
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