Novak Conversions Jeep Wrangler TJ radiator

Red exhaust manifold

Gasman1979

Gasman1979

If it flys, floats, or fks…rent it
Original poster
Supporting Member
Joined
Jun 19, 2024
Messages
203
Location
Arkansas
Ok. So it’s me again. I put the old 2.5L TB on and threw away the stupid spacer installed previously by another owner, cause…dumb. Anywho. I still can’t seem to get the engine to turn over about 2800 rpm in 3rd (which should be easy with 32’s and 4.56 gears). And I’m barely able to hold 55 mph. It’s running very warm. I’d say about 225ish (haven’t ran with a scanner hooked up yet) and tonight I noticed that the exhaust manifold is cherry red ! A few notes before you guys go at it. The CAT is gone. Cut off and straight piped by previous owner. I have no CeL. I have replaced the upstream O2 with NGK recently. New fuel injectors. I have a new fuel pump that arrived today that will be installed tomorrow. I know all of this points to a lean condition on fuel trims. Scanner showed around 15” vacuum per MAP. Could the muffler itself be partially clogged causing this ? I’m getting irritated with the whole situation. Any advice gentlemen?
 
  • Wow
Reactions: lBasket
Disconnect the exhaust from the header and see what happens.

My guess is your Jeep, like mine needs a complete PO exorcism.

It took me two years and a complete disassembly to find all the crazy shit folks had done to my Jeep.

-Mac
 
  • Like
Reactions: Mhass, Tob and BlueC
macleanflood said:
Disconnect the exhaust from the header and see what happens.

My guess is your Jeep, like mine needs a complete PO exorcism.

It took me two years and a complete disassembly to find all the crazy shit folks had done to my Jeep.

-Mac
Click to expand...

Man you have no idea. Theres literally an add on tranny cooler zip tied horizontally to the bottom of the radiator support 😂. Wtf ?!?!? I ain’t got to dealing with that yet. But yeah. I’m still working on all the weird shit previous people did to my rig 🫣
 
  • Haha
  • Like
Reactions: lBasket and macleanflood
Gasman1979 said:
Ok. So it’s me again. I put the old 2.5L TB on and threw away the stupid spacer installed previously by another owner, cause…dumb. Anywho. I still can’t seem to get the engine to turn over about 2800 rpm in 3rd (which should be easy with 32’s and 4.56 gears). And I’m barely able to hold 55 mph. It’s running very warm. I’d say about 225ish (haven’t ran with a scanner hooked up yet) and tonight I noticed that the exhaust manifold is cherry red ! A few notes before you guys go at it. The CAT is gone. Cut off and straight piped by previous owner. I have no CeL. I have replaced the upstream O2 with NGK recently. New fuel injectors. I have a new fuel pump that arrived today that will be installed tomorrow. I know all of this points to a lean condition on fuel trims. Scanner showed around 15” vacuum per MAP. Could the muffler itself be partially clogged causing this ? I’m getting irritated with the whole situation. Any advice gentlemen?
Click to expand...

Maybe I'm wrong but I thought the PCM still needed to see the downstream O2's despite the cat's being present or not.
 
ChadH said:
Maybe I'm wrong but I thought the PCM still needed to see the downstream O2's despite the cat's being present or not.
Click to expand...

I know on newer model cars and trucks the down stream just measures catalyst efficiency and doesn’t do any adjustments to the fuel air mix. I assume it’s the same here. That being said, the downstream O2 is still there. And shockingly no CEL.
 
Gasman1979 said:
I know all of this points to a lean condition on fuel trims. Scanner showed around 15” vacuum per MAP.
Click to expand...

Obviously you recognize the sign, is 15" of vacuum within factory spec?

Gasman1979 said:
Could the muffler itself be partially clogged causing this ?
Click to expand...

Sounds plausible. You say the cat is gone, but do you know why it was removed and more importantly, do you know if the guts of the cat came out with it? If the guts got blown down the exhaust, the muffler is the most likely place where they'd get caught. You should be able to bang on the muffler with your hand and hear any rattle if that's what is happening.
 
  • Like
Reactions: Tob
I’m wondering. There’s some pissed off bumblebee in a tin can muffler on it. And the best I remember the output on it is very small. I think less than 2”. This seemed to start with the addition of the cold air intake and high flow filter. I know the engine will
Not intake more air than it can use but my current ponder is this. Could I be restricting the exhaust side now causing too much back pressure hence this issue ?
 
ChadH said:
Has your CEL bulb been pulled?
Click to expand...

Lmao! Dude that was one of the first things I checked when I kept getting weird stuff with no cel. It’s there and the bulb is good.
ChadH said:
Has your CEL bulb been pulled?
Click to expand...

i actually asked myself that same question and I happened to get a set of new blue LeD gauge bulbs yesterday so I took a gander at the CEL while I was in there. It’s there and the bulb is good. You’d think with the manifold getting that hot there would be a cel
 
  • Like
Reactions: ChadH
I know you say there is no CEL on, but an upstream exhaust leak can also cause a lean issue. Just something else to check for.
 
BlueC said:
Obviously you recognize the sign, is 15" of vacuum within factory spec?



Sounds plausible. You say the cat is gone, but do you know why it was removed and more importantly, do you know if the guts of the cat came out with it? If the guts got blown down the exhaust, the muffler is the most likely place where they'd get caught. You should be able to bang on the muffler with your hand and hear any rattle if that's what is happening.
Click to expand...

Everything I’m reading says 15” is acceptable. As for the CAT removal I dunno why. Was done prior to me. I plan to cut the muffler off tonight and replace it. I don’t like the way it sounds anyway.
 
  • Like
Reactions: Rickyd and BlueC
This is the muffler and the output (obviously) I haven’t measured it but building gas facilities for 25 years I’m pretty sure that’s less than 2”. I’m wondering if between that possible pinch point and the possibility of the muffler being partially clogged if this could all lead to here and it just really presented when I opened up the intake side of the system ???
IMG_1610.jpeg
 
Ok. Soooooo. I cut the old muffler off and welded on a new Flow Master 40 series. Dumped it just in front of the rear axel for now. Went for a drive. Still getting the same glowing red exhaust manifold. One new thing to note the first 5 or 6 mile run it ran 65 mph and did great. But the manifold glowed. On the way back down the same road it had trouble maintaining 60. Went home. Made a few adjustments to the shift down cable, second drive it did good to run 55. Turned around and came back same route and it was struggling to maintain 50. WTF if happening !
 
macleanflood said:
I'd at least pull and read a couple of spark plugs.

I'd probably do a compression and leakdown test.

-Mac
Click to expand...

I will pull the plugs just to see if they tell the same lean mix story the rest of the symptoms are. I’ll get it figured out. If I gotta rebuild the whole damn thing 😂
 
  • Like
Reactions: tr21triton, Rickyd and macleanflood
I pulled the CAI off and reset a lot of stuff to OeM. Still lean, still hot. Replaced the MAP. no dice. STFT aren’t bad negative on the road. I brought a scanner home today. Running -2 to -5 at 3000 rpm. I’m wondering if the fuel pump is failing with it seeming to get progressively worse as it heats up and I drive. Got a new pump. Just haven’t had time to put it in with pee wee football starting up and several long evenings with the dog rescue we run. I’ll get at it soon and post results for anyone interested
 
  • Like
Reactions: 5TTTj, macleanflood and glowell222

Similar threads

miksior
4500 rev limit on 4.0 (glowing exhaust)
Replies
36
Views
1,773
TJ General Discussion
miksior
miksior
F
Introduction and help with a problem
Replies
11
Views
610
TJ General Discussion
B1Toad
B1Toad
W
Misfire cylinder 2 - inherited Jeep
Replies
6
Views
859
TJ General Discussion
Wølf
W
Gasman1979
Exhaust Manifold Crack
Replies
8
Views
2,066
TJ General Discussion
txbemis69
txbemis69
A.leese
Loss of power / high fuel trim / stall under load
Replies
35
Views
3,219
TJ General Discussion
Juggernaut
J
Novak Conversions Jeep Wrangler TJ radiator
Top Bottom