elementsquared

Hi everybody,
I have a automatic 1997 Cherokee XJ with about 125,000 miles on it. I has been serviced according to the manual. For a while now, everytime i turn it on, it takes a good 7-10 seconds starting up, and once it does, it idles pretty rough, until i get going. This only happens on a cold start, when its hot, it turns on immedatley, and doesnt idle rough.
Now, I have been to three different places, and they have told me its everything from the fuel filter is clogged, to the transmission needs flushing, to the front and rear differental need flushing...

Does anybody have any ideas?! Thanks!

P.S. I will be moving to Alaska in a couple months, is there any steps I should take to make sure my jeep will last forever?

BlueXJ

Turn on the key when you get in and wait about 5-10 seconds before turning the motor over, This allows the fuel pressure to build in the fuel rail and should lower the cranking time by about half.
Keep in mind that the CPS needs to see at least 3 pulses and the ECU needs to see 300 RPM before the juice to the injectors is turned on by the computer.
Each Jeep is different and what works for one does not promise that it will be the same for the next one.

elementsquared

Ya, I first thought it could be the fuel pump, so the other day, I left it sitting there with it ON for about 4-5 minutes, and then tried it. It had the same results Does this mean the fuel filter is clogged? Also, because its an automatic, do you think that it needs a flush, as it could be sticking while its putting itself into neutral??

BlueXJ

Fuel pressure on the rail would be the first thing to check. Filter may cause it to have reduced power but if it starts eventually it is not the cause of your slow start. Tranny will not have any effect on starting.

elementsquared

So, your saying that I should have the fuel pump pressure checked? How much would that run me at the Jeep Dealership?

BlueXJ

You can do it yourself and then you will have the truth. Many dealers try to get you to spend money on repairs that do not need to be done so check it yourself. Go to your favorite parts house and buy a fuel pressure gauge and put it on the schrader valve on the fuel rail.(looks like a fat tire valve with a cap on it) Turn the key on and see what the pressure builds to. (Should be 39+ pounds)

elementsquared

Ya, I have not made any mods to my jeep, because im a novice when it comes to mechanical work. This is deffinatly out of my skills range, and I may have a shop do it, as If I try, I will just break it lol. Thanks for the advise though!

P.S is there anything that I can do to make sure that my Jeep will last a long time?

BlueXJ

If you can check the air pressure in your tires then you can do this.

Routine maintainence is the only thing that will keep your Jeep on the road for extended years. Replace failing parts and check everything often.

elementsquared

maybe i will give this a try tommorow. Thanks for all your help!

elementsquared

Ya, I found the little adapter on the fuel line, so im going to try to find a gauge and test it. I will let you know what it reads.
Also, how do you know when it's time to have a transmission, front and real differental flush?

BlueXJ

Change the tranny fluid no flushing with the AW4. Do the same to the diffs once a year. No matter how many miles you have put on the vehicle. That is probably more than the factory recommended.
Flushing a higher mileage tranny will loosen things that are better left alone. This loosened junk will clog the valve body and thus cause real problems. So change the fluid if you like but DO NOT FLUSH your tranny.

elementsquared

Ok, maybe i will just leave it alone, both were done about 3 years ago, but everywhere I can go to will to a pressure flush on it.

What are the benefits of flushing the diffs? Is it really worth 300 bucks, considering I had it done about 3 years ago, and almost never use the 4X4?

BlueXJ

Flushing gets the microscopic metal shavings out of the gears on the diffs and is not really required. Put a drain pan under the differential. Just pop the cover off of the diff. it will drain out. Clean the mating surface of the cover and the diff. Use a new gasket or a ribbon of RTV sealant. Put the cover back on and refill with the proper fluid as recommended in the owners manual. As for the tranny you can get one of the oil change places to drop the pan and change the filter, clean the two mating surfaces and reinstall the pan with a new gasket. Refill with Dextron IV and no flushing. Impress on them that you do not want it flushed.
BTW three years is to infrequent to have this done. YEARLY is my recommendation.

elementsquared

Lol, i dont want to sound like a whimp again, but i can do the fuel pressure gauge, but not this. I'll just pay the extra and have a pro do it Thanks!

muddeprived

If by any chance you decide to save yourself $280 (yes it costs around $20 to do the differentials yourself! ), check this out:

http://www.stu-offroad.com/misc/diff-1.htm

It's very simple, as easy as changing oil but a wee bit of cleaning involved. Nothing can be broken during this procedure.