• 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.

exhaust glowing red

R

Roadcone

NAXJA Forum User
Location
H.B.
i have a problem with my 93 xj exhaust glowing red. with the stock 4.0l. then i stroked it to 4.6 my 95 doesnot have this problem i used a master tech scan tool all peramiters are in spec, same as my 95. i have zero back pressure. no cat and a spin tech muffler. the only thing that is the same is the wireing loom. it also has a new computer, o2 sensor. every thing on the motor is new. i even took it to a specialist and they didnt even know where to start. can anyone please help!!!!!!!!!!!!!!
 
where is it glowing red? At the manifold or further down the pipe?
Can you take it somewhere and have the exhaust tested?
It's something with the mixture most likely. Too lean would make it hot, and too ich and fuel might be burning down the exhaust.
 
something that came up in another thread made me thing of this.
Have you done anything with the MAP sensor or injectors? You increased the displacement.
increased displacement=more air
If you've not compensated for that with a MAP adjuster/higher fuel pressure/larger injectors your motor will be running lean.
 
I had a glowing red exhaust manifold once.. was a bad MAP sensor causing it to run too lean. Got so hot at the muffler that it melted wiring under my back seat and even melted the carpet.
 
i took it to a smog specialist and he said the map sensor was fine but i have not replaced it. i am running 24lbs/hr injectors and he also the injectors are rumming in paramiters i think it was 5-6 miliseconds. the timing was off so i had put a adjustable cps to corect it. its dead on now i do have a 2.5'' exhaust. im thinking burning gas is still exiting right when the valves are opening because i have 0 backpressure
 
I didn't think 0 back pressure was a good think. You have to have some in-order to obtain the correct scaveging effect which helps to draw the hot exhaust gasses out of the exhaust quicker. Unless you have open headers and nothing else then you really wouldn't need the scavenging effect, but this is not your case.

I don't know if I should have used effect or affect in the above statement, but I'm sure someone on here can correct my grammar for me.
 
Last edited:
thanks im going to put a restricter plate on my exhaust and see how it works. isnt around .5 to 1 psi effective? i totaly forgot about byou needing backpressure. i let you know what happens, thanks
 
Roadcone said:
thanks im going to put a restricter plate on my exhaust and see how it works. isnt around .5 to 1 psi effective? i totaly forgot about byou needing backpressure. i let you know what happens, thanks
Click to expand...
No problem, that's the only thing I could think of right off hand that could be wrong with it...unless like everyone else has said and your air to fuel mixture is leaning itself out too much.
 
adjustable CPS?
that's a new one. can I get a part number?
if the timing was off you need to reset the distributor.
 
it was off ever so slightly its only adjustable up to 3 deg it also gives you a snapy bottom end i will look for the info and give to you
 
================================
If you've not compensated for that with a MAP adjuster/higher fuel pressure/larger injectors your motor will be running lean.
================================
NOT TRUE well maybe not true.
Many non air metering fuel system or blind systems as I like to call them. Do compensate for increased or decreased displacement with in some limits.
For that mater the computer does not know or care what size engine it is on. On a new Jeep or one that it's computer has been reset. Once the computer enters the "RUN" or "NORMAL" mode. It starts listening to the O2s and the MAP the SAP, air temp etc., starts to learn how to feed gas to whatever engine it is on. After some time if figures it knows how to do it's job and will carve some numbers in stone. Then the next time you start your car it don't have to start all over again. IT just looks them numbers up.
So onces reset the fuel system don't care if it put on a V6 3.0 a I6 4.0 or a H6 5.0 It just learns to feed it.
 
Last edited:
You must log in or register to reply here.

Similar threads

X
Redoing my entire Exhaust
Replies
7
Views
3K
XJEEPER
XJEEPER
X
2.5 exhaust Questions
Replies
5
Views
5K
75SV1
7
X
Help me my Obi Wan Kenobi's
2 3
Replies
47
Views
13K
75SV1
7
cherokeefan_1
2000 4.0 build questions
Replies
5
Views
2K
75SV1
7
G
98 XJ tick tick ticking!
2
Replies
29
Views
5K
straws
S
Back
Top