Just to throw it out there, I previously wrapped the rail and injectors and have the dealer installed heat shield but was still having heat soak.

Today I switched out the top two o2 sensors and haven't had a hint of the heat soak issue all day and it was 104 here in nc. I had read of another guy having heat soak and swapping them out to fix it, so I tried it and so far so good.

 

Wow rritch, that's quite a masterful monologue. However, I see a few holes in your rebuff to the OP and others

1) Physics also dictates that warm fuel is harder to combust than cool fuel and, with cylinders 3 and 4 running the hottest, it would make sense that those two would be most affected by heat soak.

2) It seems that this problem mostly affects later model (00,01) XJs (the ones with more CATs to generate additional heat underneath the fuel rail).

3) Fuel pressure probably explains why the problem only lasts for about 30 seconds (long enough to clear the fuel rail of heated fuel but not fast enough to not trigger codes during rough idle)

Just my 2 cents.

 

and theres the key part.

you're not going to magically compress fuel that's been heated to that point. expanded molecules take more than just a few extra PSI of fuel to bring them back to normal.

 

Yea. At the risk of spurring on this dead horse. I believe a gas will collapse to a liquid state when the pressure and temp dictates that. Not the same as a gas dissolving into another substance. Sort of the opposite happens when a liquid lp valve is opened. Course a pump couldn't pump a "gas"...

It's got to take some time for a gas to compress back. Anyway, maybe pressure dropping, sitting with a bad check valve could let it vaporize there. Sorry I didn't read it through word for word.

 

Rrich - The problem we are discussing is fuel being boiled into vapor in the injectors after a heatsoak.

We both agree on that right? Good.

Now, Your "fix" is to "add fuel pressure"

Our "fix" is a heat shield between the injectors and manifolds.


The "correct fix" for vapor forming in the fuel injectors is to keep them shielded from excessive heat. Less heat = no vapor = no rough running after a heatsoak

Your fix /IS/ the "bandaid" "candywrapper" "bubblegum" fix. More fuel pressure may make it where you dont /notice/ a rough idle (because the vapor is being expelled faster than a factory setup would) but you STILL HAVE VAPOR IN THE INJECTOR.


A correct "fix" corrects the root cause of the complaint. Your "fix" doesnt correct the vapor building up in.the injectors, so shut it.

 

My fix is correct the real problem - low pressure in the rail.
Correct it to stock original specs - problem goes away.

Do you guys really believe NASA gets their heat shields from PEP BOYS or Wrigleys?

Look at the FACTORY SERVICE MANUAL - IT TELLS YOU IN BIG LETTERS:
Fuel pressure running is supposed to be about 31 with everything connected.
But with the vacuum to the pressure regulator disconnected - it should raise up between 8 to 10 psi higher than the 31. Budd - that's MORE THAN 31! That's in the FSM.

Engine off there is no vacuum to the FPR! Budd - that's 0 VACUUM to it - same as disconnected!

The pressure with engine off, key on, ENGINE NOT RUNNING but the pump is running it should be 39-41 psi (8-10 higher than the 31.)

BEFORE STARTING OR CRANKING THE ENGINE - more than enough pressure for the vapor to turn back to liquid. Budd - even if you do tape the gauge to the windshield. (Did you get a Patent on that?)

Budd - you said AFTER IT STARTS YOU WATCH THE PRESSURE COME UP WHEN IT STARTS RUNNING FINE - read my post again - or have someone read it to you.

Complaints of hard to start are often the same - just at lower temps. 80 degrees is not hot!

Simply compare PRESSURES with the so called "heat soak problem" with one that doesn't have it! Most don't.

Too difficult? Then use your bubble gum wrappers to show what a fool you are.

A weak FPR will only get weaker and eventually fail. Save those gum wrappers - you'll need them in your boots to cover the holes when you start walking!

A liquid converts to vapor at the same speed as going from vapor to liquid - micro seconds! Do a little research on the internet.

Warm fuel ignites easier than cold fuel - that's why all the heat tubes and carb heating for cold start start systems to help it ignite better.
The opposite impression comes from the use of "COLD CANS" on drag cars - keeping it cold condenses the fuel so more can be packed in - more energy. Same idea as an intercooler to cool the air - to get more oxygen in.

Do a search on "VAPOR ENGINES" - not much power but great for stationary engines - pumps etc. Interesting reading.

Go ahead - continue to make fools of yourselves.

 

Just to help people from getting too confused, those are specs for up to about 96 IIRC. OP's 2001 is up in the 40's.

 

rrich, you are a complete idiot. There, I said it.

 

This has to be one of the best threads I've ever seen! While it was extremely aggravating to read the complete disregard rrich has for common sense, years of engineering experience, expert recommendations, proven results, facts, etc., it was definitely entertaining.

I have to hand it to you 77olds, I would have lost my mind and told this aooclown to check his fuel pressure at the rail while in freefall off a cliff. But, I guess you were blessed with greater patience than I.

 

This thread has proven some people can't read or understand much of anything.

How many times did I have to repeat how to read the simple gauge? And when?

Somebody tell YO YO he can take the taped-on gauge off his windshield now - it will take another 1000 words to tell him how.

77 olds - coming from you that's a real compliment - THANK YOU!

 

How about everyone knocks off the high school girl argument bullsh!t and moves on... Geez

Update: the only code I've had since wrapping the injectors was a P1494 which turned out to be a vaccume line off of the intake. So far so good.

 

Hey, great PM. so I guess a couple of us were wrong thinking the TPS code meant something......Glad you got it!

 

With out all the colorful words/thoughts/comments, how else would your original thread have gone 8 pages and 117 posts. As a newbie, and OPer, my hat's off to ya for striking such a nerve. I think there are valid points/good arguments on both sides. Haven't seen a thread (including motor oil) get this spicy in a long time.

 

Maybe we need to.draw it with crayons on.construction paper so he could fvcking understand. Rrich, you head is in the right spot, but your wrong son. Sorry. Hate it for you.

Good luck on your future endeavors "correcting" driveability issues.

 

Come on guys, this thread is getting a tad ridiculous and offensive. This site is supposed to be about coming together and helping a community of like minded individuals enjoy their vehicles a bit more, let's take a step back and relax