Infrared temp gun - tuning tool?

So I've got this 1995 Mustang that is new to me as of a couple weeks ago, and I've started slogging through the deferred sustenance (thanks previous owner!) and all four plugs came out light tan to white. Lean running here. Now I was going to try and figure out a way to clean the new plugs I'm putting in so I can just pull them, read, adjust fuel pressure, and put them back in for another couple tanks full of gas. Rinse and repeat.

Only now I'm seeing how cheap some infra-red temp guns are on Amazon.com (there's one for $23 with free shipping, as an example) and I'm wondering if one of these would be accurate enough to use to check header temps for a rich/lean condition. How do I know what temp the exhaust manifolds should be after driving? Is this really just something to tell cylinder to cylinder deviations and not something to check overall tune?

If this isn't a great idea and reading the plugs makes more sense, is there an easy way to clean plus to re-read without compressed air? Like, say, contact cleaner and a brush up with some 400 grit and paper? Thoughts? I think this thing just needs a fuel filter (going on tonight or soon after) but if it needs more help I'd like to really know I've fixed the issue.

Does it run correctly on the ECU- as in closed loop with the O2 sensors?

Unless you run hard most of the time, it will be running stoich- or closely around there. Modern plugs will show virtually no signs of running rich.

Also, to answer your question, if it IS running on the O2 sensor, you'll have a tough time measuring differences between the cylinders. And the O2 sensor will probably be right, assuming it's not throwing a code or two.

I had an EXCELLENT Fluke infrared camera at work. It would take a picture with temperatures shown in various colors. It was amazing, but also a few grand.

You can clean the plugs with carburetor cleaner and a wire brush. They will air dry almost immediately. I seem to recall that Autozone will take an OBD reading for free, but if it's not throwing codes, it is probably ok.

In reply to alfadriver:

It seems to run close loop, yes, but I don't know that for fact; how can I tell? Let's assume the CEL is burned out, there'd be no real way to tell would there? This isn't like a 6th gen VFR where VTEC only works after it is warmed up enough to go into closed loop, so is there something else obvious to look for? And I don't know for fact that the CEL is burned out, it's just a 16 year old car and the PO told me he's had to replace cluster bulbs in the past.

I was kind of hoping for something like "stoich running will have header temps around 350F; 400F is too lean and 300F is too fat", like using thermocouple probes on each header tube, only with a gun for ease of setup (since it wouldn't really require any). But that seems like a kind of tall order...

In reply to Don49:

The plugs are coming out nearly white. I don't think that's okay. I've thrown a new set of NGK V-Power's in (UR45's) and I'm doing a new set of plug wires, cap and rotor, and a fuel filter before I restart this thing along with a pile of other unrelated items. Trying to get this thing back into shape before I take it on a small road trip that should use a couple tanks of gas, by which time the plugs should have a good amount of time on them for another read. I'll probably throw in a bottle of Berryman fuel system cleaner as well.

Thanks for the carb cleaner and brush idea, didn't know if that stuff was to be avoided or not. The good thing here, if there is one, is they call came out very close to the same color, so I don't have to hunt something that would affect just a few cylinders or one bank and not the other.

In reply to pres589:

If you have a volt meter (and I'm assuming you do), it's a pretty easy check if you can't monitor the PIDS via the OBD port. I wish I knew that answer- I don't know if the '95 is OBDII or not.

That would work.

I can't say that the infra red would.

I do know one thing... IF the car is running well, and IF the O2 sensors were dead, and IF the light it out... the failure mode is to run rich. It keeps the catalyst and a whole lot of other things safe. So if you see a lean plug, odds are the O2 sensor is right, and when you are not running the car hard, it's stoich.

Oh, and I don't think white plugs are a bad thing.... It's an area that doesn't get much in terms of deposits anymore.

In reply to alfadriver:

1994 and 1995 Mustangs with the 5.0 are OBD-1 cars. It really is a Fox Mustang in an SN-95 suit. I'll have to turn the key on and see what the CEL does with the engine off, if I get a light then I know the bulb is ok.

The car runs okay but it had a light lean-miss at steady cruise at low RPM, low loads (think 30 mph in 3rd) on flat ground. The tune on these things from the factory seems to run somewhat lean. I'm not getting bad smells out of the thing like an overly rich situation and the cats seem okay, although the entire exhaust looks original, and who knows what sort of material is actually in them at this point. The car is also what feels like a little low on power; it seems no faster than my Olds Intrigue, and an impromptu drag race away from an on-ramp (long story, not something I actually wanted to get into) with a full sized circa 2002 Chevrolet truck didn't seem too impressive; I could not get away from that thing, the guy couldn't gain on me until I let out at 75 mph. Seems like it should be quicker.

Like I said I'll see what the fuel filter swap does to the thing. There's also the chance that the fuel pressure regulator has drifted downward on pressure, which seems kind of common on these cars during researching this issue.

If the car is stock it is slow. I don't remember the HP ratings for those but 200-225? So ya it is a slow car by todays standards. How about a compression check?

I have an IR camera that I purchased for my company. It is the $20K type. It is very accurate and very sensitive. I have used it on my cars to look at bearings etc. The issue you will have is heat soak. By the time a car gets to temp heat soak will make things less defined. Even with the best camera you are still looking at something that is not an accurate representation of what you are trying to read. Since you are reading the exterior temp of the header it will be much less accurate than reading the actual temp in the pipe. Conduction, flow restrictions etc make exterior temp reading imprecise. Especially where you are only looking for variances with in a 100 deg range. Where I have found it useful is on cold startup watching things come up to temp. You can see if a cylinder is heating up in unison with others. This will tell you to go look at that cylinder and find the problem.

They are slow cars. I used to pick on them with a Dodge Intrepid back in the day.

As for using a cheap IR pyrometer as a tuning tool, i would say no. As a DIAGNOSTIC tool, i would say yes. You can definitely identify a dead or down on power cylinder by comparing temps at the exhaust port outlets. What you CANT do is try to tune in EGTS with it because the only situations you can use the pyrometer in are when you're standing next to a car thats not moving and isnt under load at different rpm ranges, and you wouldnt know when to stop either because i dont think a 1500 degree EGT equates to a 1500 degree surface temp on the exhaust manifold under MOST conditions.

tuna55 wrote: I had an EXCELLENT Fluke infrared camera at work. It would take a picture with temperatures shown in various colors. It was amazing, but also a few grand.

I have played with those before. So cool, so useful, really with they were not several thousand dollars!

Way back when we used to spit on a finger and shake a drop on the header tubes, if it didn't hiss that was the dead cylinder. I used my HF temp gun to narrow down clogged jets on a DCOE equipped Spitfire and also a sorta half ass balance the carbs on the street tracker (used two vacuum gauges to finish the job). So yeah they can be useful for that type of thing but there is no magic temp, unfortunately.

Lots of emissions car spark plugs will come out white, yellow or sometimes with a small tan ring around the center electrode (looks sorta like an aureola ).

if it surges at 'tip in' (that point where you just barely cause the engine to accelerate or work a little harder) or at steady cruise speed I'd look at the EGR. We used to get that complaint all the time, the techs would fix it with an SSB3 (stainless steel ball 3mm diameter) stuffed into the EGR vacuum hose.

as far as header temps for proper a/f hmmmm assuming i remember this properly i was told by my instructor 430 to 450 one inch from flange (will not work on cast manifolds) ive never done it before always stuck with just using a temp gun to determine proper placement of an x-pipe

edit: below 400 is pig rich above 475 is lean. over 500 is very lean. and lastly the temp is purely an idea i wouldnt use it as an endall because depending on engine gauge of header size of pipe and materiel your going to get different readings for optimal.

otherwise change out the fuel sock and fuel filter. and decard the top end. a mix of seafoam and atf for 1 pint followed by a pint of water (yes water no you wont hydro lock) drip it slow through a vaccum line for both at about 1300 rpms the car will smoke like no bodies business and it will ruin the plugs in it when you do it. but that with a new sock and filter will really smooth things out and gain you back some power. carbon is becoming an issue in 90's model cars especially because they were not designed for e10 altho safe to run carbon from e10 is 50% worse than str8t gas so with the e10 its bad,.

In reply to Curmudgeon:

Yeah, I had forgotten about Ford's EGR issues from that era, and I am also now dealing with my first car equipped with an air injection pump. And since I want this to remain a 50 state legal car, I guess that garbage gets to say in the way, making things like spark plug change much more annoying than they would be on the pass side of the car. In any case, I had already considered the SSB3 solution and may be doing that soon.

hmm that is a new one to me curmudgeon i thought i was familiar with all fords egr issues as evidenced by my insistance on other vehicles.

Lots of emissions car spark plugs will come out white, yellow or sometimes with a small tan ring around the center electrode

It's true.

Trying to read plutgs with todays fuel is a waste of time. Those plugs sound perfectly normal to me.

The cheap IR temp guns have their place, but with several caveats. You can fool yourself rather badly.

Various materials have different emissivities - they show their temperature differently, depending on material, surface condition, and geometry. Polished metals are like mirrors: What color is a mirror? Look at one and you see what's reflected in it, not the silver of the mirror itself. If you don't know the emissivity and can't adjust for it anyway, the temp numbers aren't good for much.

Duller, darker surfaces tend to be better emitters (higher emissivity), and give better indications of the surface temperatures. For some areas, I use strips of good electrical tape or even Dr Scholls foot spray. There are special stickers available used by thermographers. For high temperatures like exhaust manifolds, I'd consider a non-metallic high temperature paint.

The best you can do is to try to shoot high-emissivity spots on the surfaces of interest from a consistent angle. Make sure that there's nothing particularly hot or cold that would be reflected on that spot if it were a mirror. Be as consistent as you can.

Also beware that the laser spot on some guns has nothing to do with the temperature measurement. It is supposed to show you where it's pointing. Verify! Try heating a small object like a nail, then seeing how far way you can zero in on it with the laser spot.

Here's a time-lapse video I made of my Slant Six warming up. About 10 minutes real time in 33 seconds of video. Done with my old Raytheon ExplorIR.

Slant Six Warmup

I need to remake it with my FLIR P640. Much better resolution.

In reply to Zomby woof:

Bringing this back from the dead, the car now has a fresh fuel filter, new plugs/cap/rotor/wires, and it runs from idle to redline much better now. When I pulled the fuel filter (and dumped gasoline on myself) the outlet side spilled clean looking fuel. Tipped the other way... and greeted with gasoline, sludge and rust. Fresh Wix fixed that up, and this weekend I'll take a road trip with a bottle of fuel system cleaner tossed in for luck. Car doesn't have near the low speed lean miss / bucking that it had before.

Before it was almost like a diesel with all the power down low, now it runs much closer to what I expect from the thing. I think a fresh exhaust (150k miles on the stock exhaust, including cats) would help the thing out quite a bit for the next phase of improvements.