Delayed start, rough idle when cold, and multiple CEL codes

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Krischick33

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Hi. New to the forum. Purchase used 2001 Wrangler SE 2,5L 5 speed. 106K miles. CEL was on but I guess I overlooked since the body and frame were solid.

Issue: Very rough idle when cold. Gets a little better when warm. Auto zone CEL codes are P0303, P0132, P0304, P0138, P0455, P0303, P0442. I started throwing part at it but can't continue. So far I have done - Plugs, wires, cap, ignition coil. Cleaned the TB and IAC (broke the bottom bolt off. will need to fix at a later time).

I need to focus on one issue at a time. Looking for suggestions on why I should do next. Above average DIY'er. Thanks in advance for any suggestions.
 
First and foremost, before throwing copious amounts of money at it, check your wiring harness very, very thoroughly. Sometimes all it takes is a short in the wiring harness to cause a plethora of codes like this, and misfiring too.

See this thread as an example: More check engine lights caused by wiring

You have to inspect the wiring really thoroughly, but it pays to rule this out, as often times when there are tons of codes like this, it can be attributed to a short in the wiring.

Since many of those codes are O2 sensor related, I would strongly suggest changing out all your O2 sensors. O2 sensors are a general wear-and-tear item that should be replaced every 80k miles or so. Make 100% certain you ONLY use NGK sensors, as anything else will cause issues.

I suggest seeing this thread: The Official Jeep Wrangler TJ Oxygen (O2) Sensor Thread

That thread has the correct O2 sensors you'll want to use, plus other important information regarding O2 sensors on our vehicles.
 
Thanks for the quick response. I purchased 2 O2 sensors. NTK 23141 and 23138. Tried to remove the upstream one this am but it won't budge. Need to soak it and get O2 wrench. Will replace both then check all wiring harness and confections.
 
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Report back with your findings. I suspect the new O2 sensors will at least take care of some of the codes.

Kroil is my favorite to soak stuff in (y)
 
Ok. Back with an update. Wiring harness seems fine. I broke down and brought to shop who knows jeeps for a diagnostic. Figured they could zero in on the issue but I would fix.. Vacuum leak found. One under the TB and another line from gas tank...rotten. Both relatively easy fixes. The other identified issue is leaking exhaust/intake manifold gasket. $15 part but another of work. Can anyone recommend a good video or post that outlines all the steps on a 2001 2.5l 5sp. I don't want to remove the fender. I've started spraying all the bolts already. Thanks
 
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Ahhh yes, vacuum leaks can cause issues like this and be very tricky to track down without a smoke test machine.

The best source of guidance for replacing the intake / exhaust manifold gasket is the FSM. You can download it here for free: Jeep Wrangler TJ Factory Service Manuals (FSM) & Technical Documentation

That will have the step-by-step procedure, as well as all the proper torque specs and information.
 
Ok. After reading post, viewing videos and soaking the 7 exhaust and intake manifold bolt for a couple days I started tearing into the gasket replacement project. So far everything is going well. All the bolts came out without an issue. I'll pick up a new gasket tomorrow.
I have a few questions comment.
- I tried to bleed the schrader valve on the fuel rail but no gas shot out. I'm assuming this is another issue I will need to deal with. Seems like the system is not holding pressure. This kind of makes sense since I have had to do the key on off 4-5 times routine before starting. Add this issue to the list
- Fuel injectors. I'm here..the injectors are out. Can I soak to clean? I definitely think I should get new o rings at a minimum? On a budget so would prefer not to just replace unless I have to. Any recommendations for 4 injectors $100 total of less. I've seen some stuff on ebay? Also, see Carquest and re-manufactured AUS in the $30 per range.
- Should I get new bolts and washers?
- Should I put anti seize on the bolts?
- Should I use copper spray? I've heard people mention it on the forum?

Sorry for all the question but appreciate any feedback.

Thanks
 
Ok. Completed the exhaust/intake manifold gasket job. Everything went like butter. While everything was apart I rigged a fuel injector cleaner/tester and blew through both sides. Seemed like all good.
Started the engine and still freakn rough idle!!!! Could fuel pressure issue cause the issue? Any other guidance on what to look at next?
 
Krischick33 said:
Ok. Completed the exhaust/intake manifold gasket job. Everything went like butter. While everything was apart I rigged a fuel injector cleaner/tester and blew through both sides. Seemed like all good.
Started the engine and still freakn rough idle!!!! Could fuel pressure issue cause the issue? Any other guidance on what to look at next?
Click to expand...

You should have the schrader on the fuel rail so go ahead and test your pressure as that can cause issues, also a rough idle can be caused by a dirty idle air control in the throttle body.
 
Yes absolutely low fuel pressure will definitely cause that problem and the fact no fuel sprayed out when you pushed the Schrader valve pin adds to that likelihood. Sounds to me like your fuel pump needs to be replaced and make sure to install a Bosch, avoid store brands or online brands like Airtex or Spectre.

Don't use an O2 sensor socket with a slot cut into the side for the wiring. That type of wrench is only for installing a new O2 sensor, it's not strong enough to remove an old sensor. It will spread open at the slot from the pressure needed to remove an old seized O2 sensor and slip off. Use a 7/8 closed-end wrench after letting the engine run long enough to get it good and hot.

I don't know how the 2.5 O2 sensor is mounted but if there's room you can add a second open-end/box-end wrench to the 7/8" to gain enough extra leverage to get the O2 sensor out. I've had to do this on a couple O2 sensors over the years.

Like this....

2 box end wrenches locked together.JPG
 
Ok, back it. Gonna hold off on the O2 sensor for now. I was finally able to get a loaner fuel pressure test kit from Autozone. Connected it and turned the key to initiate the fuel pump. 1st time...maybe 1-2lbs, 2nd time...5lbs. After 6-7 time I only got up to 20lbs. Then I started the engine. After a few minutes it got up to 49-50lbs. As soon as I turned off the engine pressure immediately started going down back to single digits. I can actually hear it gurgling. I'm assuming its rushing back down to the fuel tank.
I wanted to pinch the fuel line to determine if the fuel was leaking through 1 or more injectors or the tank. I couldn't find a place to pitch it but I don't think there is any possibility that much fuel is leaking through the injectors?
I think my next project is to drop the tank. I saw a fuel connector just popping out from the top passenger side of the tank. I assume I need to disconnect this to drop the tank?
 
I have an opportunity to buy a used fuel tank with work fuel pump from a 2000 sahara. I believe this will work on my 2001 SE. Based on my description of fuel pressure above does anyone think this is a worthwhile project to help solve my issue?
 
Krischick33 said:
I have an opportunity to buy a used fuel tank with work fuel pump from a 2000 sahara. I believe this will work on my 2001 SE. Based on my description of fuel pressure above does anyone think this is a worthwhile project to help solve my issue?
Click to expand...

It's a direct replacement and as long as the pump is good it should resolve the pressure problem.
 
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I purchased the used tank and pump. I have a new gasket on order. Does any know how I could test the fuel pump and pressure check valve before installing everything?
 
This is an older thread but I thought I'd add to it. Maybe help someone with similar issue. I've had the jeep for over a year now and love it just frustrated that I can resolve the rough idle issue. I've replace almost all the usual suspects over the year.
Something that I've noticed is that my oil level always seems high. It's actually get higher. I fill to the second hole one the dipstick and over time is goes above. After reading a few post it was mentioned that a leaky fuel injector could be leaking fuel down the cylinders into the crankcase.
I purchased a ser of 4 remanufactured OEM Siemans injectors from Ebay for $40. I was a little skeptical about remanufactured but but the reviews were all positive. I installed last week and think my problem is solved. I'm sure there were other issues so the $'s spent on other sensors and maintenance items was worth it but nothing worked 100%.
The new injectors did the job. Idle is now smooth. I can accelerate pas 3k without a flat spot.
Anyway, I know it's been said that injectors don't go bad often but for $40 it may be worth it for anyone else having rough idle issues.
 
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