Favor needed -- temp gun reading of exhaust pipe at idle

[Fiatdude]

Battling my 2989 -- -- 3/4 temps are at about 250-260*F about 4/5" from head (each pipe is within 10* of each other) and 1/2 are above 500*F -- need to know which side is in the ball park and which one I need to tear apart LOL

Pretty sure it is going to be 1/2 out of whack, but won't to make sure before I start ripping and tearing -- no easy task on my POS

engine 8-28-14.jpg

[FJCamper]

Hi Fiatdude,

When we do exhaust temp reads, we're usually looking for the coldest readings (representing inefficiency), but in your case you have one side over twice as hot at idle, which tends to too lean.

Don't take anything apart until you have done all the usual intake or exhaust leak tests. That's just a light spray of your favorite test liquid over all joints and seals. It can be messy, but it finds the hard-to-see leaks.

I'd replace the 1-2 side head exhaust gaskets if a spray on the intake plumbing doesn't work.

At our last LeMons race we had our carb's crossover tube brass fitting between manifolds loosen by a half turn and it leaned one side out enough to burn the electrodes right off both spark plugs. The point is, the loosening was so minimal we could not see the half turn. A mechanic felt the fitting move when he touched it.

Now, if there are no leaks, you've got a lean mix problem on the 1-2 side. Not being familiar with your fuel delivery system, I can't say if you have a bad injector, bad info controlling the injector, or what.

Do the easy stuff first. If that works, it makes you look very smart.

FJC

PS: You have your plug wire connectors set up like we used to run them, 914 connectors to make them easy to handle. Be forewarned of the engine ever torques sideways, the close proximity of the 914 connector and the sheet metal will snap the plug conector right off. Takes only a very few degrees. We have all kinds of engine and tranny hold downs and it still tries to rotate around its axis sometimes.

[andy198712]

both sides of injectors working fine too?

[Fiatdude]

I'm kind of scratching my head on this -- because of such a big cross-over (intake) pipe, I thought that a small intake leak would have a small effect on the tune --- will check into it today -- I'm running batch fire both on the injectors and spark -- the fuel loops from pump to 4-3-1-2 to regulator -- I played with richening up 2,4 to see if would make a difference, 4 defiantly got fatter but no so much 2 -- -- going to pull 1,2 injectors and see if there might be an issue of them being clogged for some reason -- might try replacing the screens in them too,,, have to remember if I installed any screens in them to begin with LOL -- they are at a 'low' point in the fuel line right before the by-pass regulator ----- I've had so many issues with clogged injectors,,, they are my first guess right now. I've got several sets of injectors so I might just swap in a set of 160# and pull the 100's and see if that solves the issue -- I also bought 5 gallons of methanol, might even try that BUHAHAHAHA ---

thanks for the input guys

[andy198712]

Hopefuly its an easy fix bud!

setting up a meth lab?!!?!?

[Piledriver]

An even slightly tight valve will also do what you see at idle.
Easy way to find even tiny leaks (OK ~easy to do on a fully sealed up system like yours)

Stuff a potato or tennis ball or rubber plug on the tailpipe.

Get a large PVC cap for the TB inlet hose... drill and pop a $1 valve stem in it.
Hit it with ~5 PSI of compressed air, and spray every joint liberally with soapy water.
(dishwashing liquid suds up nice)

This is the setup for finding boost leaks, but it works really dandy for finding all sorts of leaks, with the engine not running it is almost too easy, even works on exhaust gaskets.

Less interesting and somewhat more involved than spray and pray, but is likely the best method short of a smoke machine.

[Fiatdude]

Thanks Pile --- will get the pieces I need to do that today

[Piledriver]

If you have a mechanical low range pressure gauge, you can stick that in the cap as well.
I have a 15 psi gauge I added, used it to find boost leaks on my TDi.
(it has no overlap on the cam so it doesn't even need the potato)