***92 SC400 only firing on half its cylinders***
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***92 SC400 only firing on half its cylinders***
this is my first post if its in the wrong location i apologize, been a member for 6 years and the information on these forums has been incredible and helped me out tremendously but i have a problem i cant solve...
heres the situation, ill give all the info i can
one day i got into my car it would crank but wouldnt turn over, eventually it did but idle was low and as soon as i put it into reverse to back out of my driveway it would die, eventually it wouldnt turn over at all
i took it to a shop to be diagnosed ultimately as im sure youre thinking i was told to get new plugs and drivers side ignition coil. I towed the car home to do it myself since they were trying to rape me on labor.
Changed out the plugs, ignition coil and battery, the engine was flooded as well so i took the old plugs out and let the engine sit for a couple days to essentially air out. put new plugs in and started her up, didnt start, i got angry and yelled haha. I tried a few more times and she eventually started up but i had the same problem i did initially low idle and extreme power loss. I let the car run for a little bit to see if it would correct itself since she had been sitting for weeks without starting. I took one of the plugs out to test for spark and wasnt getting a spark. As im testing for a spark i noticed loud random pops and white smoke coming from the spark plug hole i assume its just excess gas/oil burning out since it was flooded. I shut the engine off after a few "pops" just in case. I thought maybe its the wires or distributor caps....i swapped the distributor caps to test them and they were fine. I did find a my distributor rotor from the passenger side (side that wasnt firing) was broke to pieces. EUREKA this must be the problem. I changed the distributor rotor out and started her up.
SAME PROBLEM. The passenger side cylinders arent firing and by that i mean the cylinders coming from the passenger side distributor 2, 3, 5, 8 (i think but dont quote me on it).
anyways im getting a spark to all four plugs but still the loss of power and low idle. I also saw white smoke coming up from the passenger side behind the engine.
long story short ive checked and my wires, plugs, dist caps, dist rotors, and ignition coils are all fine and still only half the cylinders are firing......im really at a loss as to what to do next. even though its only firing on four cylinders its a nice smooth idle all be it low and she starts right up no problem.
on a side note and not sure if it matters but ill put it in here, the speakers inside the car went out and my battery seems to be draining pretty quickly. again doubt it has anything to do with why im not getting full ignition but who knows.
if anyone can help id be forever greatful.
heres the situation, ill give all the info i can
one day i got into my car it would crank but wouldnt turn over, eventually it did but idle was low and as soon as i put it into reverse to back out of my driveway it would die, eventually it wouldnt turn over at all
i took it to a shop to be diagnosed ultimately as im sure youre thinking i was told to get new plugs and drivers side ignition coil. I towed the car home to do it myself since they were trying to rape me on labor.
Changed out the plugs, ignition coil and battery, the engine was flooded as well so i took the old plugs out and let the engine sit for a couple days to essentially air out. put new plugs in and started her up, didnt start, i got angry and yelled haha. I tried a few more times and she eventually started up but i had the same problem i did initially low idle and extreme power loss. I let the car run for a little bit to see if it would correct itself since she had been sitting for weeks without starting. I took one of the plugs out to test for spark and wasnt getting a spark. As im testing for a spark i noticed loud random pops and white smoke coming from the spark plug hole i assume its just excess gas/oil burning out since it was flooded. I shut the engine off after a few "pops" just in case. I thought maybe its the wires or distributor caps....i swapped the distributor caps to test them and they were fine. I did find a my distributor rotor from the passenger side (side that wasnt firing) was broke to pieces. EUREKA this must be the problem. I changed the distributor rotor out and started her up.
SAME PROBLEM. The passenger side cylinders arent firing and by that i mean the cylinders coming from the passenger side distributor 2, 3, 5, 8 (i think but dont quote me on it).
anyways im getting a spark to all four plugs but still the loss of power and low idle. I also saw white smoke coming up from the passenger side behind the engine.
long story short ive checked and my wires, plugs, dist caps, dist rotors, and ignition coils are all fine and still only half the cylinders are firing......im really at a loss as to what to do next. even though its only firing on four cylinders its a nice smooth idle all be it low and she starts right up no problem.
on a side note and not sure if it matters but ill put it in here, the speakers inside the car went out and my battery seems to be draining pretty quickly. again doubt it has anything to do with why im not getting full ignition but who knows.
if anyone can help id be forever greatful.
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Well my CEL light is still coming on and everything else is fine so as far as I know the ecu is ok. I'm finding fuel mixture on the plugs for the cylinders not firing.
I'm not a mechanic and everything I know is from these forums. Is there a way to check compression and the fuel injectors without a specialized tool? I'm just baffled by this issue.
I'm not a mechanic and everything I know is from these forums. Is there a way to check compression and the fuel injectors without a specialized tool? I'm just baffled by this issue.
#5
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If you have gone through the ignition components, and have a problem on multiple cylinders, most of the time it has been found to be the ecu having leaky capacitors. you can save alot of time and energy as well as money spent on replacing parts by opening up your ecu and taking a look yourself.
The capacitors that leak on all these ecu's almost always affect the injectors.
If you are getting spark, but it doesn't seem to fire off most likely the ecu is just dumping fuel on those cylinders.
we have seen the exact problem on here a few times now. the chances of 4 injectors failing wide open at the same time is very unlikely.
when you first start it up it wont be so bad, but soon after the ecxess fuel will wash out the spark and then the cylinder begins to fill, adding more resistance to the engine turning over, and dumping raw gas into the exhaust manifold (sometimes goes back into the intake which is always fun).
what cel codes are you triggering? If you cannot pull the codes, thats another strong indication of a bad ecu.
The capacitors that leak on all these ecu's almost always affect the injectors.
If you are getting spark, but it doesn't seem to fire off most likely the ecu is just dumping fuel on those cylinders.
we have seen the exact problem on here a few times now. the chances of 4 injectors failing wide open at the same time is very unlikely.
when you first start it up it wont be so bad, but soon after the ecxess fuel will wash out the spark and then the cylinder begins to fill, adding more resistance to the engine turning over, and dumping raw gas into the exhaust manifold (sometimes goes back into the intake which is always fun).
what cel codes are you triggering? If you cannot pull the codes, thats another strong indication of a bad ecu.
Last edited by Ali SC3; 08-14-12 at 01:31 PM.
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I havnt ran for codes lately but at the shop my friend said the car was communicating with the diagnostic computer but wouldn't throw codes. When all this started it didn't throw codes either. Did the diagnostic bypass and te cel just flashed non stop every half a second or so. Again no codes. So maybe I've misled myself and need to replace the ecu.
Will a visual inspection suffice to determine if it's bad? Is there a sure way to test the ecu and know for certain if it needs to be replaced? I'm in college and don't have money to waste :/
Will a visual inspection suffice to determine if it's bad? Is there a sure way to test the ecu and know for certain if it needs to be replaced? I'm in college and don't have money to waste :/
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#8
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oh i thought the CEL was on all the time, but you are just saying that it works and there are no codes, thats a good sign.
the only way to know for sure is to swap with a known working ecu, or you have to pry open the ecu and visually check it for leaking capacitors, if they are leaking they are pretty obvious, can't miss it.
the only way to know for sure is to swap with a known working ecu, or you have to pry open the ecu and visually check it for leaking capacitors, if they are leaking they are pretty obvious, can't miss it.
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K I'll check tomorrow. But no it's not on all the time. Comes on when key is at start position then goes off. Which it it's definitely something I'll check out. Thanks. And any other suggestions are always welcome.
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Just in case anyone has this problem.
It was all my fault. I took the car to my friends shop to have him look at it. Even as a master tech it took him almost 2 hours to figure out what was going wrong. Turns out
!!!!i put the distributor rotor on "backwards". Basically it was firing but not in the correct timing since it was reversed. You would think a piece like that would have the screws in a position where you could only put it on one way.
Anyways she runs like a dream now. And I feel a little stupid ad it cost me 100$ to figure it out but hey better than a 200$ ecu or sitting there throwing money at the engine for nothing.
Mystery solved
Thanks to everyone that responded appreciated the recommendations ad advice.
It was all my fault. I took the car to my friends shop to have him look at it. Even as a master tech it took him almost 2 hours to figure out what was going wrong. Turns out
!!!!i put the distributor rotor on "backwards". Basically it was firing but not in the correct timing since it was reversed. You would think a piece like that would have the screws in a position where you could only put it on one way.
Anyways she runs like a dream now. And I feel a little stupid ad it cost me 100$ to figure it out but hey better than a 200$ ecu or sitting there throwing money at the engine for nothing.
Mystery solved
Thanks to everyone that responded appreciated the recommendations ad advice.
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