jakecarder

If you look down in there under the intake. You will see 3 go into one large 4in cylinder. There two of them. Those are catylic converters and you will see two o2 sensors as well. That's the problem. Heat rises from them and turns the liquid gas in fuel rail to a vapor gas. I wish we could get rid of them but its against the law for street vehicals. I've seen trail only vehicals do it but there's a lot of wiring to deal with cause them ecm needs to read those o2 sensors

Troth

Im going to do some serious insulation installation!!! could a guy find a thin heat mat to also thread between the inj and cat?

A separate, but related question: Why did Chrysler stop engineering an air flow opening (behind the driverside headlight) for the air box? on my 01, there is just a metal panel of the unibody blocking the opening????? as far as I can tell, there are no other openings from the sealed airbox. so...... the jeep is struggling to get air through a thin crack... from the hot eng compartment???? makes no sense to me!

could this hot air issue also play into this heat soak issue?

I'd like to bore out that opening behind the headlight to open the airflow to the air intake. I'd also like to engineer a K&N cone filter into the stock airbox (like I did on my 92)

what do you guys think?

salad

Yup you can do that for heat shielding if you want. Best to insulated the intake and fuel and not try wrapping the exhaust. Added heat will contribute to warpage and cracking.

The hot air in the intake has nothing to do with heatsoak. It's all residual heat after the fan has stopped spinning that bakes components or boils fuel. I know the passage you're talking about, my '99 had a rectangular opening in the stock box to the plate behind the headlights, other XJs have a tube extended all the way to the front. What you want is this: https://www.cherokeeforum.com/f67/my...snorkle-67919/

Troth

So that system is drawing air from behind the firewall? does that draw air from the door hinge gaps? Mine is more of a DD now, its stock height and has a monster bumper that was on my 92'. if im not worried about sucking mud into the air box, could I just route from behind the headlight?
I have also thought about just running it straight into the quarter panel instead of messing with the firewall. I have stock fenders, so I dont have any gaps in there for mud

salad

Nope, it draws from in front of the firewall in a box called the cowl. This is where the wiper motor sits and the HVAC gets its cold air. It does not compromised safety in any way. It's a lot easier than messing with the headlights or fender. I'd avoid going the headlight route due to driving rain, and a lot of crap ends up in the fenders from the wheels. Those plastic things are decent but not 100% effective at keeping sand and dust out.

Troth

Ok, I just bought some aluminized self adhesive thermo shield. not cheap, but ill post pics when Im done

Troth

Ok, here is my fuel injection system insulation. I double wrapped the fuel line (since it is within 2" of the manifold for about 20"), Wrapped the fuel line all the way to the rail, insulated the rail, injectors as much as possible, and refreshed the stock heat guard. I hope this works!

salad

Wow nice. Way better than the dealer!

Troth

OK GUYS!!!!! It was a success!!!! I took it for a 25 min drive on mountain roads, just like I did yesterday before the issue. I parked, let it sit for 5 min, Then fired it up. It started up just great!! there may have been a .005 second roughness when cranking, but way better!!!! Ill be installing a hood vent, and then a cold air. Thanks for all the help, especially Salad

jakecarder

A lot of guys take the intake manifold off and paint the underside with white heat reflective paint.

carbuff

Also, if you search around, there is a mod that lets the electric fan run for a minute or 2 after you shut the vehicle down helping to vent some of that hot air under the hood. Ive also heard that upgrading to the 4 hole injectors helps with this issue too. That is some nice wrapping you did there. I have the same problem with my 2000. Sometimes it will even throw a cel with a code for random misfire. I carry around my scantool so I can erase the code right away. I hate having the light on when the problem is gone.

salad

Awesome, glad to hear it's mostly resolved

Troth

thanks for the input. I hope this and a vent will work out for me!

Jeepzjlover

This isn't just a cherokee issue my 02 tj also does this. Anybody got a thread for helping the fan run for a bit after shut off?

salad

Any 4.0 with that manifold should do it, years listed in the TSB I posted earlier.

Check out these links regarding leaving your fan running.

https://www.cherokeeforum.com/f67/el...-timer-166945/
http://www.naxja.net/forum/showthread.php?p=245759298