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Old 04-29-2017, 11:40 AM
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95 2.5l running rich, what to check?

Like it says, my 95 2.5l is running extreamly rich. So rich that after 500 miles I had to do another oil change because there was so much fuel in the oil. I have to fill up every 100 miles. I've checked and replaced vacuum lines, put a new o2 sensor on, plugs, wires, cap and rotor. What else can I check or test?

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Old 04-29-2017, 01:34 PM   #2
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check fuel pressure, see if it is too high.

Then check for leaking injectors..

also triple check the little vacuum lines and the boots and 90degree pieces.

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Old 04-29-2017, 10:39 PM   #3
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Test for above but your case seems rather extreme. If you don't find any issues in fuel pressure, injectors, or vacuum lines, check the engine cylinder compression.
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Old 04-30-2017, 01:00 PM
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Thanks for the leads. I will look into this stuff this week and see what I find.
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Old 05-04-2017, 01:40 PM   #5
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might be dumb...but also the idle could be set just too high. that and leaking injectors was my problem
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Old 05-04-2017, 03:17 PM   #6
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The 95 dont have adjustable idle..
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Old 05-05-2017, 06:53 PM   #7
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Not supposed to adjust the idle but I removed and flipped the throttle body and adjusted the allen set in and set my idle at 1100 rpms just to keep the engine idled up just a little while winching and crawling around in the woods. Yours may be adjusted to high. I really don't see how that would rich up the fuel mixture, its just like pressing the throttle a little more. I'm thinking the map sensor may send more fuel if reading wrong as well. Firewall middle above engine. Check wiring and hoses going to it. Study how to troubleshoot it.
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Old 05-05-2017, 08:03 PM
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95 idle is computer controlled. Found out it was partially a bad o2 sensor (even though I just replaced it). Guessing bad from factory. So put a new on in and it's running much better but still a bit rich. I think I'm just gonna start replacing parts reguardless. Figure they are 22 years old and probably never replaced before. So I'll be replacing MAP, temp, fuel pressure regulator, etc. will report back with which one actually fixed it.
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Old 05-05-2017, 10:38 PM   #9
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Not a good idea, replacing parts adds so many variables because most of those parts are bad out of the box.
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Old 05-06-2017, 06:47 AM   #10
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I have used the process of elimination as well but try really hard to do diagnostics first and foremost. I would have to agree about bad parts out of the box especially buying cheap parts from any parts store that starts with and A or O unless you know the brand of part your buying. I find they normally stock the cheap parts and have to order the more expensive parts so as to make me have two trips involved to pick up one part, NOT now I order all parts myself from Quadratec and make no trips to pick up parts and order enough to get free shipping and no tax. The amount I save on trips, shipping and tax many times saves me enough to buy the more expensive part for my jeep for the same money.
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Old 05-07-2017, 11:26 AM   #11
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yeap never go adding parts unless you have tested and tested to be sure what you replace needed to be replaced..
Too many NEW parts that are not good and then you really scratching your head.
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Old 05-07-2017, 02:01 PM   #12
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Plus these sensors aren't "wear" items. They're not like ball joints, u joints, or bearings that wear out. Oxygen sensors are the most common sensor to wear out because of the heat cycles, but that's about it.
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Old 05-09-2017, 08:56 AM
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The new O2 sensor seems to have helped a lot. I was able to get 145 miles before I got to E on the fuel gauge, averaged about 11.4 MPG. Still smells like its running rich. Haven't had a good day to diagnose anything with all the rain lately. Plus have had a few other things go wrong that needed attention first. Hopefully the rain stops today long enough to do some diag.
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Old 05-15-2017, 07:36 AM   #14
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You need to replace your fuel injectors. I had low idle issues, excessive fuel usage, hesitation when accelerating and you probably will be able to see around the top of your throttle body that its wet....The jeep is probably back firing as well plus you will be able to smell gas every once in awhile inside the cab......You need to buy a new set of fuel injectors.....How do i know this? I just replaced mine (4 days ago) Thursday May 11th, 2017. It fixed the issue!! Back in Action! Went from 8-9mpg back to 15-16mpg like i was normally getting!

You DO NOT want to start buying parts and replacing them just because they are "OLD"!...Like several already mentioned, there are parts that are BAD right out of the box! When you have issues there is a few simple steps to follow as a general rule...Check fuel pressure at the rail, check spark plugs, fuel filter, air filter etc...Then check to see if you have any vacuum leaks...Like the rubber cap as a example that is on the side of the throttle body real close to the TPS....Mine was dry rotted so i replaced it!

Your richness is too much FUEL!....Replace Fuel Injectors & check ALL your vacuum lines.
Dont forget if it fixes your problem then come back to this forum and let everyone know!.....Good Luck!!
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Old 05-19-2017, 01:28 PM
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I dont think its the injectors. Idles is fine @ about 600 rpm. Doesnt really have any hesitation when accelerating. Then again how can you tell it has hesitation in the 4 banger anyways. throttle body is not wt either. I really dont think its injectors. However on that subject, Ive heard injectors from a mustang fit perfect and help with the lack of power the 4 banger has. Anyone have any input on this? is there anything else I would have to change? Or other parts needed?
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Old 05-19-2017, 01:31 PM
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I just put a new tranny in this past weekend and that seems to have helped as well with milage still seems to be running a bit rich. I havnt had time to test anything lately but hopefully I will this weekend with the wife being out of town.
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Old 05-20-2017, 09:57 AM   #17
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I have 4 Bosch 4 hole upgrade fuel injectors, i bought them off ebay cause i heard the same exact thing that they was compatible and that it would give the jeep more power and all the above!...It ran like it was only running on 1-2 cyl.....Check engine light came on & showed #3 & #4 injector failed...I went with 4 new injectors from the parts store. But just yesterday im back to having hesitation on inclines only!...Everything is fine except going up hill or slight inclines....I wished someone that had the same situation would chime in. I been working on mine for 7 mths now! I was only getting 7 mpg approx...Im gettin 10-11 mpg but its just not where it used to be which was 15mpg plus the hesitation/chugging up hill and/or inclines is what im trying to figure out....Only thing that i havent replaced is the fuel pump & spark plug wires! This is crazy trying to figure it out!...I thought i had it fixed...It ran good for 3 days..Thats another thing....It can run good one day and run like crap the next...Its why its so hard to fix!
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Old 05-22-2017, 06:32 PM
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It seems to be doing much better lately. Still smells like its running richer than it should. I'm getting about 14 +or- MPG lately based on my calculations. I'm still going to test a couple things you guys have suggested, if the d#$n rain would ever stop long enough!
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Old 05-27-2019, 05:26 AM   #19
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In my case, it was a failed coolant temp sensor. Had the same symptoms from 2 separate vehicles recently: rough running after start and/or hard starting. In both cases, it took some time to determine that the coolant temp sensor had failed and was sending a faulty signal to the computer in the vehicle, resulting in an incorrect amount of fuel being delivered when cold. Replaced the coolant temp sensor, and noticed an immediate improvement.
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Old 05-27-2019, 08:16 AM   #20
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Quote:
Originally Posted by vert_wheeler View Post
In my case, it was a failed coolant temp sensor. Had the same symptoms from 2 separate vehicles recently: rough running after start and/or hard starting. In both cases, it took some time to determine that the coolant temp sensor had failed and was sending a faulty signal to the computer in the vehicle, resulting in an incorrect amount of fuel being delivered when cold. Replaced the coolant temp sensor, and noticed an immediate improvement.
Welcome V-wheeler, Your post is really great info, one solution I haven't seen offered up yet.

This thread is a little old (2 yrs), I doubt the original posters still have the issue, but I'd bet there's somebody out there going through a similar issue right now.

Here's a link you should read through and fill in your sig so everyone knows what your driving and pertinent build info. we like to see whats going on so Pics are always good.

https://www.wranglerforum.com/f218/a...m-2341475.html


Welcome again

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