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1990 Ls400 Misfiring


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ok well after i was coming back from a work trip 450miles

my car started to shake and misfiring

so i looked and seen my wires need replacing so new oem installed

new plugs installed NGK (driver side coil had a crack I seen so I replaced )

my car is still missing and i tested each plug cyl 5 i can unplug and nothing changes but if i unplug any other plug car get worst

what could i look at new and i got code 14 for ignitor 1.... (is ign1 by shock tower or by air box ))

Thanks

Anthony

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ok well after i was coming back from a work trip 450miles

my car started to shake and misfiring

so i looked and seen my wires need replacing so new oem installed

new plugs installed NGK (driver side coil had a crack I seen so I replaced )

my car is still missing and i tested each plug cyl 5 i can unplug and nothing changes but if i unplug any other plug car get worst

what could i look at new and i got code 14 for ignitor 1.... (is ign1 by shock tower or by air box ))

Thanks

Anthony

Hi According to the lexus workshop manual the igniters are grouped together adjacent to the shock spring tower the leads from coil no 1 feed ignitor no 1 and coil no1 is adjacent to the a/c compressor .trouble shooting instructions dictate a new ignitor if logic chain flow chart fails but as your code as dictated ignitor thats where I would start.

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Get one of your old plug wires and a sparkplug and connect to that spot on the rotor. Start car and hold plug against metal chassis somewhere.

Outcome 1: Sparkplug is sparking. Either your plug wire is bad or the plug is bad (fouled).

Outcome 2: Sparkplug isn't sparking. Assuming the other cylinders on this rotor are firing (you need to check that). Then something must be fouled in the rotor/cap combination.

It is common to lose a bank of 4 cylinders on these cars due to failure of one of the coils. Are you sure it isn't you've lost the whole bank and not just cylinder 5?

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ok this morning i got in car car started perfect and didnt misfire till i got to my work i turn off and turn back on and it was misfiring

it was after it was heated up

would CAM SENSORS be going bad aka heat senstive now making my car misfire.....

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would CAM SENSORS be going bad aka heat sensitive now making my car misfire.....

I think you are reaching for far too complicated a scenario. These cars are famous for ignition coils going bad. They become intermittent which might explain why the problem is elusive.

You say it is only cylinder 5 but I'm less sure. Losing one cylinder at idle wouldn't make the car dramatically change. Losing 4 would.

A coil is pretty cheap I'd put a new one in where you see problems. If you want to invest a little time of your own just swap the existing coils from left to right and see if the problem moves to the other bank. Then you'd have more confidence to go out an get a new coil if proven so.

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no codes and none stored on ecu

today my car started perfectlly and didnt misfire i drove to work and as soon as i pulled in it started misfiring ... no check light

do you think cam or crank sensors are going bad .... i was reading that cam or crank sensor can become heat sencitive

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You need to determine whether No 5 cylinder has a spark or not, pulling off the plug lead and it making no difference could be due to other reasons not necessarily just a missing spark.

Have you actually made sure there is a spark arriving at No 5 cylinder by removing the lead from the plug,fitting a known good plug into the lead,grounding the plug body and then getting someone to crank the engine overwhile you look to see if a spark is being produced.

The other possible causes of a misfire on one cylinder is a faulty fuel injector for that cylinder (swop it with another one and see if the fault moves confirming a faulty injector) also check the injector wiring as well is it trapped or damaged?

Lastly and the most unlikely is a lack of cylinder compression on No5, unlikely but not impossible!

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ok my injector is working my plug is wet every time i pulled it out and it got a week spark when car running but when it was running good in am i fire normal and no misfire only when motor heats up it start misfiring when motor is dead cold it runs perfect..

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