egt gauge problems

[eclipsed at 3am]

is there any reason a mechanical egt gauge would be pointing to 6, when im at 5500+ rpms and accelerating hard?

usually it would be at like 11-12. last night, it seems to be running ok, just stays low all the time. sometimes it actually seemed to be higher when i was going slower, unless i was just imaging things.

when my car is at idle and even sometimes when im cruising, the egt needle bounces around a lot. i mean REALLY bounces, it would bounce from 6 to 10 repetedly at like a million mph. could that have to do with vibrations in the exhaust?

also, what does an egt gauge actually consist of? the guy who had the car before me put it in, so i never saw it. I know there is the power wires for the light, but is there like a vaccuum wire or anything, or like one big sensor wire?

[david-b]

It should be one big wire. EGT is basically a thermometer in the exhaust. Nothing too advance. But I see that is mechanical, so actually I'm not too sure then. I would think it would just be a wire tho.

[Blackcrow64]

Yeah, its pretty much a thermometer. One signal wire to the gauge and all the gauge needs is a power and a ground... Are you sure you have it all tuned correctly? It should run hotter the harder your driving it, not the easier you drive it.

[eclipsed at 3am]

yeah everything is tuned fine, and the gauge was usually at the right spots before. one day out of the blue it just had this one problem of the needle vibrating raipidly between 6 to 10. no changes in drivability at all. and now last night, it just wouldnt go up very high. still drove fine though.

i think that the rapid needle has to do with something i fixed. 2 months ago i got a new exhaust manifold. when i was putting it on, i noticed that it was very loose where the downpipe connects to the actual exhaust pipe. the bolts were the locking kind, but there wasnt enough spacers in between, and so i guess it loosened up over time. i put some more spacers in there and tightened it up, and now everything seemed to run a bit quieter. i dont know if that has to do with the egt or not, but the problem happened about that time. the egt probe is connected to the exhaust about 6 inches below the spot where the two pipes (downpipe and exhaust) connect.

[Blackcrow64]

The EGT probe is supposed to be off of cylinder 1 in the exhaust manifold you realize.

[eclipsed at 3am]

Originally Posted by Blackcrow64

The EGT probe is supposed to be off of cylinder 1 in the exhaust manifold you realize.

um....wow.

well its not lol. is there a major cooling difference between the exhaust manifold and the exhaust piping?

also, i have the evo 3 exhaust manifold, and there is a small hex bolt right by cylinder one, i think. its the far drivers side of the manifold. i thought it was for an external wastegate. could it be for an egt?

[david-b]

Sorry to hi-jack the thread, but I'm going to be getting an EGT probe for my car. I know N/Ts really don't need it, but I want good tuning. I was going to place mine b4 the cat. Is that good, or do I need it closer to the header?

[Blackcrow64]

Originally Posted by eclipsed at 3am

well its not lol. is there a major cooling difference between the exhaust manifold and the exhaust piping?

Yes, theres a huge difference. It is supposed to be metering the temperature off of cylinder 1. Not the combined temperature of all 4 cylinders and then however much heat it loses between there and where you have your EGT probe.

Originally Posted by eclipsed at 3am

also, i have the evo 3 exhaust manifold, and there is a small hex bolt right by cylinder one, i think. its the far drivers side of the manifold. i thought it was for an external wastegate. could it be for an egt?

That is indeed for it. It should thread right in there.

Originally Posted by david-b

Sorry to hi-jack the thread, but I'm going to be getting an EGT probe for my car. I know N/Ts really don't need it, but I want good tuning. I was going to place mine b4 the cat. Is that good, or do I need it closer to the header?

The closer to the header it is the more accurate it will be. Also, like I said before, you should be metering the temperature from cylinder 1 instead of the combination of all 4 cylinders.


**EDIT**
If you guys have ever looked up close at pulling tractors, they have an EGT probe and gauge for every cylinder in their headers... Like I said before, its all a tuning issue and getting an accurate reading. If you put the probe too far downstream then your gonna be thinking its running cool enough that you can lean it out some more. In reality though it will really be beyond meltdown temps and you will be replacing all the valves in your motor.

[eclipsed at 3am]

[quote=Blackcrow64]Yes, theres a huge difference. It is supposed to be metering the temperature off of cylinder 1. Not the combined temperature of all 4 cylinders and then however much heat it loses between there and where you have your EGT probe.

ok then, blackcrow thanks for the info. also, i dont think the manifold would vibrate around as much as the exhaust pipes, so that would probably be good.

[Blackcrow64]

Originally Posted by eclipsed at 3am

ok then, blackcrow thanks for the info. also, i dont think the manifold would vibrate around as much as the exhaust pipes, so that would probably be good.

Yeah the manifold is a lot more sturdy than the downpipe is. lol

I'm just a big ball of useless information like this. lol

[eclipsed at 3am]

Originally Posted by Blackcrow64

Yeah the manifold is a lot more sturdy than the downpipe is. lol

I'm just a big ball of useless information like this. lol

excellent. could you tell me why my idle is funky?

[Blackcrow64]

Originally Posted by eclipsed at 3am

excellent. could you tell me why my idle is funky?

Well whats wrong with it? Does it surge or is it high/low?

[eclipsed at 3am]

Originally Posted by Blackcrow64

Well whats wrong with it? Does it surge or is it high/low?

my answer would have to be D, all of the above. and the needle is constantly moving, sometimes just cycling a few hundred rpms, sometimes a lot more. it never has a nice steady idle. ive tried adjusting the tps, ive checked the ohms on the iac, i adjusted the throttle cable. i have no idea what it could be. but i dont want to jack my own thread though. ill touch on it another time.

unless you have a magical answer?

[Blackcrow64]

Originally Posted by eclipsed at 3am

my answer would have to be D, all of the above. and the needle is constantly moving, sometimes just cycling a few hundred rpms, sometimes a lot more. it never has a nice steady idle. ive tried adjusting the tps, ive checked the ohms on the iac, i adjusted the throttle cable. i have no idea what it could be. but i dont want to jack my own thread though. ill touch on it another time.

unless you have a magical answer?

Ok, I was gonna say it sounds like the IAC is going bad but I can't say that in 100% confidence.

[eclipsed at 3am]

the ohms should be like 32 right? 28-32 i think. the ohms on mine actually were about 48-50. when i asked someone about it, they said that a good working iac would say about 50 ohms, and older used iac should be about 27-32. do you know anything about that?

also, when your car was running, did it idle perfect? or, have you ever seen a perfectly idling dsm?

my dad's sportage, my stepmom's elantra, buddy's civic, another buddy's audi, my sister's accord, the idle doesnt move at all. not a single milimeter. even when the ac turns on, or the cooling fan, or anything. my idle is all whacky all the time.