I'm using a temp gun to shoot the header right as it's coming out of the port. All other cylinders are 500 deg or so, #5 is 193-250 degrees. The car has an intermittent stumble/miss at idle, but runs good otherwise during normal driving. I've done a search and found one thread that mentioned that a valve spring could be broken, but what else could it be? I've changed plugs twice, and I've checked the resistance across the terminals on the coil. I've also check the resistance of the 10mm wires. They all read around 3.5k ohms, except for the one on the #1 cylinder which was 1k ohms higher...but it's temps are in normal range like the others. Has anyone experienced this?
#5 Cylinder 300 degrees Cooler
- Thread starter peterkin
- Start date
greeneyegi
Well-Known Member
- Joined
- Feb 21, 2010
is the plug wet?does it look like its been firing?
greeneyegi
Well-Known Member
- Joined
- Feb 21, 2010
i would do a compression check on that bank of cylinders
it will tell you if its a broken spring.
it will tell you if its a broken spring.
- Joined
- May 28, 2001
Flat cam??
jhanson1750
just a 10th quicker
- Joined
- Apr 24, 2005
X2 on compression check and then pull the valve cover to check rocker movement.
I ran into this same problem before,
are you measuring "at idle"?
try bringing the rpm up to 2500 for 60 sec or more, and read them again.
I think what you are experiencing is poor distribution at low air flow.
I had checked cam, coils, wires, springs, inj, inj wires, etc, etc, nothing gave me a reason.
on the dyno (at rpm) all were within 20 degrees, so I stopped worrying about it,
are you measuring "at idle"?
try bringing the rpm up to 2500 for 60 sec or more, and read them again.
I think what you are experiencing is poor distribution at low air flow.
I had checked cam, coils, wires, springs, inj, inj wires, etc, etc, nothing gave me a reason.
on the dyno (at rpm) all were within 20 degrees, so I stopped worrying about it,
Changed all of the valve springs between last night and this morning, and none were broken and the cam lobes are fine measuring the rocker travel. I let the car idle while I moved my GN over to the other bay and put it on dollies. It's still sputtering intermittently at idle, so that hasn't changed. I think I'll check the grounds on the back of the engine another day. I took the car out for a drive and it pulls great, so that miss doesn't seem to affect it during normal driving.
greeneyegi
Well-Known Member
- Joined
- Feb 21, 2010
have you tried pulling that wire off the cylinder while at idle?see if its same temp and idles the same.
it seems like the 200degrees might be radiant heat fom the rest of headers.
what about an ohm test on coil.i had a coil that seemed to run fine but once i learned how to test one,mine was bad.took away my low idle miss.
just spitballing here
it seems like the 200degrees might be radiant heat fom the rest of headers.
what about an ohm test on coil.i had a coil that seemed to run fine but once i learned how to test one,mine was bad.took away my low idle miss.
just spitballing here
Powertechn2
Member
- Joined
- Feb 3, 2014
sub'd x2
We just got back from visiting family for Easter, so I apologize for the late reply.
I have tried pulling the wire while running and it just runs crappy, but I didn't measure temperature. One of the things that I had not tried, which was suggested here, was checking the #5 temp above idle against the rest of the cylinders. I have ohmed all of the wires and both coils that I have with there being some variance in resistance, but nothing that would cause an issue. I forget what the actual resistance across the coils were, but they were all within the same range. The wires were all around 3.5k ohms, except the wire on the #1 cylinder, which was 1k ohms higher I believe. Like I said, I'll get out there and tinker some more today. Maybe having a full four days away from the car will start the investigative juices flowing again.
Thanks for all of the replies and I hope that the suggestions in this thread are helping others as well. larry33ck and Powertechn2, what are you experiencing?
Well I just did a injector change. 83- 120's . And now I have a miss at load. I temped my headers too and I have four cylinders At 450-550 and two 1&5 at 150deg.
I think my situation has to be the injectors because I have swapped hot plugs for cold with know change. But I also swapped injectors to 1&3. The temp did change but not much.
My injectors are suppose to be cleaned and flowed fresh so I'm lost at what it could be. I guess I going to have to send them out and have them done so I know.
I think my situation has to be the injectors because I have swapped hot plugs for cold with know change. But I also swapped injectors to 1&3. The temp did change but not much.
My injectors are suppose to be cleaned and flowed fresh so I'm lost at what it could be. I guess I going to have to send them out and have them done so I know.
greeneyegi
Well-Known Member
- Joined
- Feb 21, 2010
any update?
I never found what it was. I spun a bearing in the car just driving normally down 95 South to the track to watch some racing last Friday. I had honestly got tired of chasing it and wanted to just enjoy the car and drive it! I'm in the process of unbuttoning this motor and prepping one that I have on the stand to go in the car. I can't wait to flip this thing over and see what the carnage will look like. I apologize for leaving this thread hanging and I hope that those of you that are chasing issues can figure out what they are.
