No fancy-schmancy thread title here.

Stinky was running like he was on 7 cylinders the other day and #2 was a banger - and I didn't stop to get CCT (it was 100 degrees outside). The weather has since cooled down (75 degrees and a series of storms - to tame the wildfires) and I can't get him to misbehave. Every time it gets hot outside, I get some form of grief from da big Stink's nose. Cooler weather always puts him on his best behavior.

It's hard to figure this stuff out when the gauges say all is well, and I have to drag out the AE on a hot day (when I really don't have the time or want to be outside). If it's a funky injector, I have #9 in a box. If it's aerated fuel, I'll work on the fuel line. If it's aerated oil - I'm at a loss. The Engine Oil Temp never gets above 210 degrees, ICP, IPR, FIPW all read normal, but I feel Torque Pro has reached it's limit on this.

I am now running daily with AE up and recording, waiting for Stinky to hiccup - then I can swap to CCT as fast as a wife can change her mind.

Anybody have any theories as to why injectors will revolt with high air temps?

 

Know idea on this. Kind of sounds like electrical when hot out. You know for sure it was #2 injector? And know codes, doesn't seem right. Sorry I'm know help Rich but I wanted to weigh in and follow your finding. You help so many, wish I could help ya.

 

No ideas for you Rich, but your problems sound very similar to what a local guy (Drake / "cutlass") is going through with his truck.

I let him borrow my AE multiple times but he never really got to the bottom of it. I just remember him saying his miss was always worse in hot weather.

 

Another thing to monitor is IAT and see if it looks realistic. Maybe it glitches at the higher temps and tricks the PCM into doing... something.

 

IDM... Gets hot and acts up.

Just a guess at this point. Also check all your wire harness connections. If there getting heat the plastic can swell and might make a normally good connection bad. UVC, UVC gasket. Even injector harnesses.

Do you use Dielectric grease on everything?

 

My brothers truck did something close. It would run great then a week later when eot got to 165 it would lose a injector then let it cool and it would work good then hot back to bad. it was the vch it would ohm good but if you heated it up it would open up and number 5 would stop working.
Maybe something like that electronics can do funny things.

 

I would agree looking at the electrical side would be a good place to start since you have it narrowed down to a particular injector. Oil/fuel won't affect just one. IDM will typically shut down more than one when things go funky, so I'd focus on wiring and connections first.

 

Rich,

Unfortunately (hopefully not in your case), it appears these issues are electrical. I have found the same on many gassers. Often its a connection that is expanding and contracting with environmental changes. Not easy to locate as they come and go quickly not allowing for the Technician to witness it. And, not so easy to find and fix on our trucks.

Good luck!

I'll see if I can find something in the database.

 

I have a working theory.

I am recalling back to all the issues I've had in the past 3 years, and I think I should share these to aid in troubleshooting. #7 and #2 have been my problem children ever since I started analyzing the truck. I've had to swap #7 out for out-of-control cackle countless times, and #2 gets funky once in a while, then I've swapped it out maybe three times (total). #2 is building cackle right now, and it's been in there for about 6 months and 10,000 miles. I just swapped #7 (again) about 500 miles ago, it would miss badly when hot, and the #9 injector seems to have taken care of that. One time I was climbing a very steep grade at 45 MPH with 1100-degree EGTs, and the #7 cackle grew insanely loud in a matter of seconds.

We all know aerated fuel causes cackle, but my fuel system has been modified to avoid air in fuel. So... what if I'm still getting aerated fuel, but not from the usual suspects? What if the fuel is boiling in that long metal tube that runs down the valley and right next to...

wait for it...

the hot side of the turbo and the 4" downpipe?

I'm going to install some insulation on the fuel lines, but the tricky part will be to find a material that can take the temperatures near the downpipe. Anybody who remembers the old days of "Vapor Lock" will know exactly what I'm talking about.

 

This whole scenario has me recalling a PIXAR short that's on "The Incredibles" Blu-Ray: "Jack Jack Attack"



Stinky is Jack Jack, and I reprised the role of Kari - the babysitter.

 

Vapor lock on a diesel? That's one I never heard of. Ain't saying it ain't possible though.
The thing about vapor lock, that I remember, is that it always happened to me on hot days while driving in stop and go traffic. Never out on the open road.
Would air in the HPOP cause this to happen too?

 

The boiling point of #2 fuel oil is 340F - 675F at atmospheric pressure. At 60 psi gauge pressure, it is substantially higher. Boiling doesn't introduce air to anything; it vaporizes the liquid. When the vapor cools to below its boiling point, it condenses to its original liquid state.

 

Reflective Mylar maybe? I used it to wrap the starter in my '79 Trans Am to keep the header heat away.
I know vapor lock well. I stuffed a small block in a '77 Vega back in the day and it was plagued with vapor lock. A Phenolic spacer solved my problem, but that's not going to help in your situation. Just thinking out loud...

 

I'm not thinking a full boil... I'm thinking those tiny bubbles like the ones you see in a pot of water that's heating up. With the small amount of fuel these injectors use per cycle, the tiniest bubbles (that reach #2 and # 7 first) can wreak havoc.

It's just a theory and an experiment at this stage - no declarations. It does coincide with the frequency of the issues with #7 and the less-frequent #2 - the fuel line is always cooler on the driver side.

Electrical - what if the fuel bowl heater is stuck on? I'll look at that as well. IDM has been swapped out with no change. UVCH and VC gaskets replaced while troubleshooting. PCM swapped out. Many wildly different tunes have been tried... including stock. The stock injectors had this same failure - before any mods had been added.

 

Could this be a fuel distribution problem? #2 is the first on the drivers side, and #7 is last on the passenger side. Perhaps some crap in the banjo bolts? Do you have the FRx?