Misfire at cylinder 1 & 3 only in idle
02-06-2020, 01:26 AM
#1
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Misfire at cylinder 1 & 3 only in idle Hello I have cadillac escalade 2005 and there is misfire at idle in cylinder 1 & 3. I checked it with tester and other cylinders are fine. It only gives p0300 code. When in high rpm like 3000rpm it runs ok and doesnt misfire (checked with tester).
I tried using my avalanche coils and plugs and plug wires but it didnt change so I took cylinder head off because I thought it is head gasket but I cant see any leak point there... it also did lose coolant but i guess it might be heater core because passenger side of windshield goes in fog everytime i turn off car after longer trip.
So is it really head gasket fault or can it be something else?
And yeah it is LQ9 6.0 vortec
I tried using my avalanche coils and plugs and plug wires but it didnt change so I took cylinder head off because I thought it is head gasket but I cant see any leak point there... it also did lose coolant but i guess it might be heater core because passenger side of windshield goes in fog everytime i turn off car after longer trip.
So is it really head gasket fault or can it be something else?
And yeah it is LQ9 6.0 vortec
02-06-2020, 05:19 PM
#2
Hello I have cadillac escalade 2005 and there is misfire at idle in cylinder 1 & 3. I checked it with tester and other cylinders are fine. It only gives p0300 code. When in high rpm like 3000rpm it runs ok and doesnt misfire (checked with tester).
I tried using my avalanche coils and plugs and plug wires but it didnt change so I took cylinder head off because I thought it is head gasket but I cant see any leak point there... it also did lose coolant but i guess it might be heater core because passenger side of windshield goes in fog everytime i turn off car after longer trip.
So is it really head gasket fault or can it be something else?
And yeah it is LQ9 6.0 vortec
I tried using my avalanche coils and plugs and plug wires but it didnt change so I took cylinder head off because I thought it is head gasket but I cant see any leak point there... it also did lose coolant but i guess it might be heater core because passenger side of windshield goes in fog everytime i turn off car after longer trip.
So is it really head gasket fault or can it be something else?
And yeah it is LQ9 6.0 vortec
not sure what heads are on your truck.
don't mean to scare you, but since you obviously have your heads off, might as well clean them up and check.
02-06-2020, 05:43 PM
#3
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The Castech issue only applies to 706 heads as far as is known.
02-06-2020, 06:22 PM
#4
there have been 799 heads known to crack in that same location.
the TSB was for cracking around the oil drains, oddly enough.
EDIT: i might be mixing up these two issues. Seems like a lot of the heads with cracked cc between the seats don't lose water. the TSB was for castech heads that cracked around the oil drains by the head bolts that did leak water.
the TSB was for cracking around the oil drains, oddly enough.
EDIT: i might be mixing up these two issues. Seems like a lot of the heads with cracked cc between the seats don't lose water. the TSB was for castech heads that cracked around the oil drains by the head bolts that did leak water.
Last edited by dreadpirateroberts; 02-06-2020 at 06:41 PM.
02-06-2020, 06:51 PM
#5
yeah, i just took a quick look at a set of heads i have sitting around, a crack between the valve seats would have to extend upwards at an angle inside the casting for it to meet the cooling jacket. probably not very likely, but remotely possible. i would think you'd have issues with your valve seats before that happened.
sorry for spreading misinfo on the interwebs!
sorry for spreading misinfo on the interwebs!
02-07-2020, 01:18 AM
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I cleaned it but i couldn't find any visible cracks, also turned it upsidedown and poured puddle of brakeclean over valves but they seemed well sealed since it didnt disappear (nether evaporate since its -5 celsius). I also started to think could it be leaky injectors...
02-07-2020, 01:46 AM
#7
I cleaned it but i couldn't find any visible cracks, also turned it upsidedown and poured puddle of brakeclean over valves but they seemed well sealed since it didnt disappear (nether evaporate since its -5 celsius). I also started to think could it be leaky injectors...
you might have done a compression check on the engine before you took the heads off as well. did you get a good look at the plugs for 1 and 3 before you replaced them?
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02-07-2020, 08:10 AM
#9
that could mean coolant WAS getting in the CC somehow... likely you did have a bad head gasket, since those two cylinders are adjacent. cracked head or cyl sleeves are far less likely, but worth checking. could always have the head pressure tested.
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02-13-2020, 04:15 PM
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Loss of coolant is most likely leak in passenger legroom. Carpet is wet.
But now I have changed cylinder 1&3 injectors, spark plugs, coils and plug wires and also changed head gasket and also checked that valves are ok and seal. Couldnt see any or feel any damages in cylinder nor piston. but still i get code p0300 and misfire in cylinder 1&3.
What else i can change? MAF? lambda? vaccuum leak? throttlebody? i think those are so unlike. Does anyone have any ideas?
I also checked that plugs do spark so coil wiring should be ok. I guess I should also check reading from injector wires? What should i get?
But now I have changed cylinder 1&3 injectors, spark plugs, coils and plug wires and also changed head gasket and also checked that valves are ok and seal. Couldnt see any or feel any damages in cylinder nor piston. but still i get code p0300 and misfire in cylinder 1&3.
What else i can change? MAF? lambda? vaccuum leak? throttlebody? i think those are so unlike. Does anyone have any ideas?
I also checked that plugs do spark so coil wiring should be ok. I guess I should also check reading from injector wires? What should i get?
02-13-2020, 06:36 PM
#11
you could use noid lights to test to see if the injector is getting power. if that checks out, swap the injectors around to see if the problem follows them.
did you do a compression test? you could also bypass the heater with a loop at the waterpump and then pressure test the system to make sure the heater core is not the only leak.
sometimes when you pull a head off, some cc's are a little cleaner than others. totally clean and i would be somewhat worried.
are you using the correct heat range plug?
did you do a compression test? you could also bypass the heater with a loop at the waterpump and then pressure test the system to make sure the heater core is not the only leak.
sometimes when you pull a head off, some cc's are a little cleaner than others. totally clean and i would be somewhat worried.
are you using the correct heat range plug?
02-13-2020, 09:56 PM
#12
Loss of coolant is most likely leak in passenger legroom. Carpet is wet.
But now I have changed cylinder 1&3 injectors, spark plugs, coils and plug wires and also changed head gasket and also checked that valves are ok and seal. Couldnt see any or feel any damages in cylinder nor piston. but still i get code p0300 and misfire in cylinder 1&3.
What else i can change? MAF? lambda? vaccuum leak? throttlebody? i think those are so unlike. Does anyone have any ideas?
I also checked that plugs do spark so coil wiring should be ok. I guess I should also check reading from injector wires? What should i get?
But now I have changed cylinder 1&3 injectors, spark plugs, coils and plug wires and also changed head gasket and also checked that valves are ok and seal. Couldnt see any or feel any damages in cylinder nor piston. but still i get code p0300 and misfire in cylinder 1&3.
What else i can change? MAF? lambda? vaccuum leak? throttlebody? i think those are so unlike. Does anyone have any ideas?
I also checked that plugs do spark so coil wiring should be ok. I guess I should also check reading from injector wires? What should i get?
02-17-2020, 06:02 AM
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