• Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

Another heat soak thread

H

HotBox

NAXJA Forum User
Location
NY
I'm sure everyone is probably tired of reading about heatsoak but I can't get my check engine light off for long enough to pass inspection

My 2001 sport had always had codes for multiple cylinder misfire + cylinder 3 misfire in the summer months or after sitting for 10 mins and restarting

But now as the hot weather has come this year is seems like it's coming on all the time. I bought that heat shield kit made for 4.0s on Amazon and it didnt help anything

Last year I swapped out my pre cats because I was getting a catalyst code, so I can say surely my underwood temps aren't rising because of overheated cats

I just dont know what else to do. I already have know tested and good working 4 hole injectors, my spark plugs were changed in December, and im constantly getting P0303 code


The only thing I haven't tested (because it's just about impossible to test) is the coil rail. I don't really have any reason to think it's bad at 140k miles though
 
Forgot to say.... when I bought the DEI kit from Amazon for the heat shield. It did stop the "random cylinder misfire" code. So I can't say it did nothing. Wrapping the fuel rail probably did help a lot, but not for cylinder 3
 
00-01s are just a giant pain. Mine had the coil already swapped out before I got it 170k, under 20k and it burned through another one, so your coil could very well be shot. You also gotta remember it's 20 years old at this point.
 
Unclewolverine said:
00-01s are just a giant pain. Mine had the coil already swapped out before I got it 170k, under 20k and it burned through another one, so your coil could very well be shot. You also gotta remember it's 20 years old at this point.
Click to expand...


I'm more than willing to accept its no good. I just find it to be a terrible coincidence that I went all winter with no misfire, then warm weather comes and I get random misfire plus cylinder 3.

In any case, I thought about replacing the coil just for good measure since it's definitely original. But I still wanted to hear from everyone for any more recommendations
 
I made my heat shield that goes from the valve cover to just pass the fuel rail and it is about 3 layers thick . it stopped my heat soak problem . mine covers more of the engine and exhaust manifold so it keeps more heat off the fuel rail and injectors .
 
tech1001 said:
I made my heat shield that goes from the valve cover to just pass the fuel rail and it is about 3 layers thick . it stopped my heat soak problem . mine covers more of the engine and exhaust manifold so it keeps more heat off the fuel rail and injectors .
Click to expand...



Is there any chance you have a picture or a source for the shield material? I'd be more than happy to stuff whatevers needed under there to give it a shot at this point
 
I think most people attach sticky-back heat reflecting insulation, such as DEI Reflect-a-gold, to the bottom of the intake manifold. I did this and is seems to have made a small difference. I may try another layer using DEI Floor and Tunnel Shield II, although the product info for this stuff says that the sticky side shouldn't be exposed to heat. However, I think it can handle intake manifold temperatures.

Another option would be to fabricate a free standing heat shield that would be bolted to something on the engine.

A completely different approach would be to try to get the engine bay cooler:

- Hood vents are a common approach.
- Another approach that's occurred to me but I haven't seen discussed on NAXJA would be to manually operate the efan when stuck in traffic. This will help flow air through the driver side of the engine block. Even though the air coming off the efan probably 180-200F air, its going to be cooler than the hot air produced by the exhaust manifold and cat.
 
I'm going through the same thing with my new-to-me 01 XJ. The factory insulation was gone for some reason, so I bought the DEI kit and it is on the way. I was also thinking about hood vents or doing the spacers underneath the hood hinges to raise rear of hood some. Anyone had success with that?

Also, on a weird side note, when I experience the heat soak issue, I can put in drive and go forward, no problems, but when I put in reverse, the motor dies. Open hood, let cool for a few minutes, goes back to normal. Weird that it's not a rough idle?
 
I forgot to mention that another possible way to help reduce transfer to the fuel system would be to insulate the fuel line leading to the fuel rail. The fuel line is exposed directly to the heat coming off the exhaust. This would probably help a running engine. DEI and Themotec both sell split insulation.
 
maxbraketorque said:
I think most people attach sticky-back heat reflecting insulation, such as DEI Reflect-a-gold, to the bottom of the intake manifold. I did this and is seems to have made a small difference. I may try another layer using DEI Floor and Tunnel Shield II, although the product info for this stuff says that the sticky side shouldn't be exposed to heat. However, I think it can handle intake manifold temperatures.

Another option would be to fabricate a free standing heat shield that would be bolted to something on the engine.

A completely different approach would be to try to get the engine bay cooler:

- Hood vents are a common approach.
- Another approach that's occurred to me but I haven't seen discussed on NAXJA would be to manually operate the efan when stuck in traffic. This will help flow air through the driver side of the engine block. Even though the air coming off the efan probably 180-200F air, its going to be cooler than the hot air produced by the exhaust manifold and cat.
Click to expand...




I've thought about hood louvers but I get a fair amount of rain and snow during the year, I've heard that can be an issue.

What's interesting is my under hood temps (According to the temp gauge) never goes more than 210. My Egan turns on when necessary and turns off when satisfied. These damn pre cats make so much heat it's really horrible
 
HotBox said:
My heat soak is not just when the jeep has been sitting. It has also triggered the CEL while stuck in traffic during 90° days. I dont believe this would totally solve it 😔
Click to expand...

Depends how you set it up. Mine's set so that I can manually run the fan at any time. When I turn it off, it runs a shutdown timer for 3 minutes.
 
IslanderOffRoad said:
Depends how you set it up. Mine's set so that I can manually run the fan at any time. When I turn it off, it runs a shutdown timer for 3 minutes.
Click to expand...

As IslanderOffRoad suggests, run the efan manually while the engine is running. If you get suck in stop-n-go traffic, flip it on. Of you could wire in a temperature switch with an external thermocouple.
 
Hood vents work on my 2000, no pre-cats, but I did see an operating temp reduction, and a shorter e-fan cycle time. No problems with thunderstorms, snow/ice, or the car wash.

If the Jeep has issues and the temps are 210*, I would suspect a faulty mechanical fan clutch, or an OBD engine sensor that is heat sensitive.
 
boncrshr said:
I'm going through the same thing with my new-to-me 01 XJ. The factory insulation was gone for some reason, so I bought the DEI kit and it is on the way. I was also thinking about hood vents or doing the spacers underneath the hood hinges to raise rear of hood some. Anyone had success with that?

Also, on a weird side note, when I experience the heat soak issue, I can put in drive and go forward, no problems, but when I put in reverse, the motor dies. Open hood, let cool for a few minutes, goes back to normal. Weird that it's not a rough idle?
Click to expand...

When mine started dieing when put in reverse I found it was a wire rubbed on the back of the intake. As for jacking the back of the hood I found it greatly helped at slow speed but hurt cooling at highway speed.
 
Tim_MN said:
Hood vents work on my 2000, no pre-cats, but I did see an operating temp reduction, and a shorter e-fan cycle time. No problems with thunderstorms, snow/ice, or the car wash.

If the Jeep has issues and the temps are 210*, I would suspect a faulty mechanical fan clutch, or an OBD engine sensor that is heat sensitive.
Click to expand...




I didnt even know they made 2000-2001 XJs without the precats. I feel like they're the root of my problem

I've thought about taking some 16 gauge sheet metal and making a huge heat shield that would essentially block the cats away from the engine side and intake like a giant L shape.

I checked out the fan clutch, it seems to test fine but it hasn't been replaced in a while. Injadnt considered that since it doesn't come close to overheating

I've never read about any sensor being heat sensitive. Which sensor(s) should I check?
 
Unclewolverine said:
When mine started dieing when put in reverse I found it was a wire rubbed on the back of the intake. As for jacking the back of the hood I found it greatly helped at slow speed but hurt cooling at highway speed.
Click to expand...

Interesting, I will look at the wiring harness there. Strange that it only does it after engine is hot though.
 
You must log in or register to reply here.

Similar threads

biztyke
2001 Heat soak and aftermarket header advice.
Replies
18
Views
2K
Agreen
A
C
92 High Fuel Pressure/Stinks/Runs Rough
Replies
4
Views
959
tech1001
T
A
Intermittent Idle/Bog
Replies
0
Views
294
azhang253
A
J
XJ wouldn't run on a hot start unless I reset the ECM
Replies
5
Views
945
pearlheartgtr
P
S
Need Recommendations For Reman Engine
Replies
3
Views
857
MotoBoss
M
Back
Top