Does your Idle feel jumpy
 

Just wondering how everyone elses XJ idles. Mine feels a little jumpy. I have heard that is common with these 4.0's. I have a 2001 and at stop lights it feels a little jumpy and the idle rpms seem to bounce just a little. Just wanted to see how it compares or if it is normal.

Seafoam.

Mine does the same thing got a tune up and replaced all fluids gaskets ect. And still does it I asked the tech at the Jeep Dealership and he said its normal so I think your good.

I have been thinking about that but I have heard good and bad things.

I read it seemed normal but I have never felt a vehicle idle like this before. I have never driven another XJ before so I have nothing to compare to.

I had a rough/jumpy idle on mine. Seafoam cured it completely, I can't even hear my jeep's engine at idle anymore.

I put a third of a can directly into the throttle body (be careful with this, go slow)

Then I put the rest of the can into my gas tank.

That stuff is amazing, I was expecting to maybe notice a slight increase. But I was blown away. The Jeep has never run this smooth, I am now sold on the Seafoam product completely.

I am nervous to use it, but I will think about running some.

try using gumout with regaine in it maybe two times following the instructs. it helped mine course just bought in July so dont have full history on it

Seafoam is a great product, I would run a can of that, and after you do, then go through and manualy clean your throtle body. Manualy cleaning your throtle body after running the Seafoam might not be completly necessary but I think it is a good idea just to make sure it is really clean. I used to run that stuff through all of my Chevys and always had great results.

I did remove the TB earlier this year, cleaned it up and replaced the IAC. Its an IAC I ordered off ebay so I dont know if it was a good quality one. Maybe I will buy another one from the parts store this time and replace it.

If it was a new IAC that you bought, I would doubt that would be your problem. Usually when your IAC is bad or dirty you will know it. The car will idle like complete crap, and more times than not stall out at idle. Cleaning your throttle body and replacing the IAC says nothing for the inside of your motor. And if there is a substantial amount of carbon build up in there, then that could very well be causing the symptoms you are experiancing. Just do the Seafoam treatment, it is super simple and inexpensive. After you have done that, then you can be sure that the inside of the engine is clean. At that point you can be fairly sure that soot or carbon build up in the engine isn't causing your problem. But even after the Seafoam, if the car still isn't running to your standards, then you can start throwing parts at it if you want, but at this point if I were you, I would start with the easiest most cost effective solution which is the Seafoam, and then go up from there.

By the way I almost forgot, attached is a link to a quick resistance test that you can do on IAC. Good Luck.

http://www.ehow.com/how_5560848_chec...rol-valve.html

Seafoam also made my jeep quiet during idle... Best solution I've found...

Dont try to fix something that isnt broken. it will likely cause more problems. My has done this sinse I bought it but it throws no codes and doesn't really bother me at all. I know If I try to mess with it ill kick my self in the tail and end up worse then i started. Everybody that I trail ride with that has a 97 up XJ all does this.

Start with whats probably wrong, IAC.

Seafoam isnt the cure for everything, "jumpy" idle, in most cases seafoam wont affect it.

Its not super jumpy, just a slight adjustment is what it feels like. When I am sitting idle it feels like the engine is correcting itself every few seconds. Watching the RPM needle it looks like it just drops a hair and bumps back up. I read that the computer will adjust the idle as it sees fit for any fluctuations and that is all it feels like but I would like it to be more consistant. Its not throwing any codes right now so I am not to worried about it but I want to head off any potential problems. I have heard anything from timing to O2 sensors but again there are no codes so it could just be doing its job but I am just a little more sensitve to the idle movement.

BTW... I replaced the IAC earlier this year.

MAP Sensor and Vac lines.

Isn't Seafoam the magic elixer that knocks 100K miles of abuse off all XJ's? :jester:

My idle/driveability issues were resolved by a tune-up and thorough cleaning of the t-body, IAC, and greasing all the sensor connectors. I followed that up with a can of BG 44K in the tank and have been running fine ever since.

It adds liek 50928 HP to the wheels and lots of torque and madd deebeez if you got subs.

Mechanic in a can, no such thing yet.

Nuh UH!!! I herdz CEEfoams is ASE certified now.:jester:

Tis, has more ase certs than me......

Haha, back to maturity.

I have been thinking about the MAP. That should throw a code though I thought.

BG 44k > Sea Foam.

I was having a slight miss at idle and a can of BG 44k cleared it up.

Things that affect idle speed; TPS, IAC and O2 sensors. The IAC and 02's can get lazy and send a false signal/current to the ECM.

I have read good stuff about BG-44k but it looks like its only sold at dealerships. Anyone know if it can be purchased anywhere else other than online.

Use the BG 44k website to locate a local dealer. I got mine from a local Chevrolet dealer at the parts counter. Just ask for a can of BG 44k, they will know what you are talking about. BG 44k is what most dealers use for their $300 fuel injection system cleaning. Given they cycle it through the system on a machine its the same chemical make up.

Found some BG 44k at the Marathon service station down the road. These guys seem to love it (maybe they get a kick back). I did notice a little better Idle performance but we will see how long it lasts. They said they sell non-ethanol gas and they recommend that I try that after I run this tank out. The mechanic claims he gets better MPG and the engine runs smoother also. I think its worth a shot. Can anyone give their opinion on the non-ethanol gas?

Mine has a jumpy idle... Seafoamed 2 times, replaced all ignition parts. Then did a compression and leak down test. Also checked my fuel injectors and with my Cyl 1 code popping up found out my injector is opertating randomly. Then... While doing my 3 compression checks i have a bad exhaust valve in cyl 4. So I will be replacing my cylinder head and injector next month. You may want to do a compression test.

Definitely get some of that no-ethanol gas. When I was up in Laramie visiting my brother I got some (60 miles uphill on 287 took almost 1/4 tank) and it runs much better. I felt more power, smoother idle, and more efficiency. This was with low grade, I usually run mid.
Get gas there from now on if you can help it.
But even with the good gas and seafoam it will still run rough, just seems to be the nature of the 4.0.

Ethanol has a lower energy content than regular gasoline. That's why vehicles that run E-85 fuel get such crap-tastic gas mileage.

Good for the farming industry...not good for power.

Mine Idle LOW - like 650RPM causing Vibrations but no stall
 

I'm new here guys whats up.. I love Jeep Cherokee.. I leased a 2001 Limited Fully loaded back in 2000.. Now 10 years later I bought one with 177K on it.. Im fairly good with fixing cars but here is the issue. I try to first get suggestiongs from this website that go from cheapest to expensive until fixed.. lol.. I find this is best..

Anyway, I had a cylinder 3 misfire code thrown at me in hot soak. I git this car over the summer, so I tunned everything up.. New coil pack, air, plugs etc.. There is no PVC valve right? Anyway, turns out there is a TSP on Injector 3 to be wrapped in insulation due to vaporizing fuel in the injector because its too close to header. 7 bucks.. I spend 200 on tuneup parts.. I cleaned out the throttle body like mad.. FILTHY as hell.. 177K never touched..

The truck idles and works fine but it IDLES LOW.. like 650rpm when in drive.. about 675rom in park and normal 750rpm with AC turned on,, Its wont stall but causes exahust to shake or vibrate...

Seafoam? IAC, MAP.. etc.. What do you think? I would settle for adjusting the idle upward BUT apparently you cant adjut it? Is that right?

Non adjustable. IAC, MAP and vac lines.

First off, how do you know what you are idling at? There is only 1,2,3 etc on the RPM guage... So how do you know when its at 650,675 or 750. all I can see is my needle is sitting at the notch in between 0 and 1. Is that notch 500 or what? Mine sits just below the half notch and it bounces just a little below that unless the fan kicks on then it sits right on the half notch.
Second if you are having a heat soak issue or a missfire, try and take the fuel rail off and clean all your injectors. If the TB was that bad, I can only imagine what your injectors look like, replace the o-rings while your at it. Running some injector cleaner might help but I think taking the time to remove them and actually clean them is even better.

My 89 4.0 does the same thing. It starts up beautifully, idles really nice for about 10 seconds, then starts to have a jumpy idle... its not that its rough, its just like it can't decide what rpm to idle at so it just jumps around? I have neon injectors, and it helped a whole lot with the low idle, but the jumpy idle is still there. I just rebuilt it around 4 months ago, and when i did i cleaned and polished EVERYTHING! so no carbon in TB, or intake manifold inside or out. and obviously the head was machined, so no carbon in that or anywhere else in the motor, so i don't think carbon build up is the issue. It even had the jumpy idle even before i rebuilt it, so its looking like its either a normal 4.0 thing, or maybe something weird in the fuel/ignition system? I have ran a bunch of fuel cleaner through, but didn't really help. Like i said, its not like its running rough, its just not running at a constant idle.

So if anyone figures this out, i would love to know how to fix it...

Thanks, it seems to be the same from what I am reading. I have read several guys say their XJ purrs and I think mine idles pretty darn good, it just has the occasional jumpy feeling like it is trying to kick itself up a little and then drops back down. I am just going to be thankful it starts every day and no check engine light.

If you have A/C...could just be your hi/lo switch on the A/C system shutting off and turning back on....mine does this - goes away if I I shut off the fans competely

Thanks for responding! I am just estimating the idle. Either way its idling too low.. With AC on it purrs.. I was going to put thos BOCHE injectors from ebay.. from those guys in FL they cost 119.00 on their website with 4 holes on there.. What do you think?

Go to a JY and grab some 703s out of a neon. Perform just as good if not better than the bosche.

Single Hole Better then 4 Hole Injector by Ford? Please LOOK!
 

:excl:Look at this about injectors: http://www.ausjeepoffroad.com/forum/...ad.php?t=92236

I just bought the Ford Mustang Injectors: XR3E 9F593 A4B which according to these guys is the best one and its SINGLE hole.. What do you think? You have to read the link.. I have a 2001 so I need EV6 - 703s wont work since no UCAR..

4 holes is superior to one, for your year though, looks like thats your best option.

I just installed the Ford: XR3E 9F593 A4B Motorcraft Part Number: CM4956 for my 2001
 

I just installed the Ford: XR3E 9F593 A4B Motorcraft Part Number: CM4956

for my 2001 Cherokee 4.0L

I DID NOT REMOVE FUEL RAIL
THESE INJECTORS DO NOT USE THE STOCK CLIPNUTS

I completed the job in 1.5 hours start to finish. A monkey with a screwdriver and a pliers could do this job. I DID NOT remove the fuel line from the fuel rail. I was able to rotate the rail a bit upward while connected to fuel line and I removed and installed the new injectors.

The truck runs smoother at idle. Its quick as all hell but it was before as well since I ran that seafoam crap.. That stuff works man!

Anyway, I see very little difference.. At least they work and apparently according to that post at http://www.ausjeepoffroad.com/forum/...ad.php?t=92236 they are the best ones.

I can assure you they work for my 2001 without clipnuts and its an easy job!! DO IT!! You can buy them on the company website as well for 60.00!! Look em up on eBay..

I just spoke with http://www.mrinjector.us/ Bill.. I bought Filters and O rings for my stock units and for some used injectors Boche 784's that are on the way.. He told me for this style Intake spray pattern is not critical if not relevant at all. Thats why Jeep kept using these injectors that shoot gas like a water gun. Spray pattern is critical in OTHER applications but not on the 4 liter because, according to Bill, this style intake will put gas in a READY mode for use during driving and that gas can SIT inside the motor/ head/ cylynder until its used.. So spray patter is meaningless.. Somehting like this he told me.. Im no motor genius.. These guys have all the rebuild parts for the stock injectors. Anyway, I now have in my possession the fords stated here, I have 2 sets of stock injectors that will be refurbished to new, and I have a set of 784's that Im rebuilding with new rings, filters and caps, I will also be ordering the c4b's. When I am done I will have mileage specs on ALL 4 sets of injectors.. I will run two tanks out on each style to see what gas mileage I get.. When im done the results will be exacting.. Right now im lucky to get 15mpg with these fords Im running as stated in this thread. By the time Im done I will have spend hundreds of dollars to rebuild and buy injectors.. So much so i will begin to sell them off.. I even bought a Jewlry cleaner to clean the tips. lol.. All in the persuit of better gas mileage.. Im starting to spend so much on injectors that I wont make it up on gas..