If your car is fuel injected, the electronic throttle position sensor on the throttle body could be bad. The check engine light doesn't always come on, in this situation.

Well it kind of depends on how new the car is. If it's a newer one or your lights start to go dim as one person put it, it is quite simply the governor. Fairly cheap and easy to have that problem fixed. If it's an older vehicle read some of the answers below, they're pretty accurate, although one other thing it could be is a blocked catalytic converter.

I had the same problem with my van, after many misdiagnosed repairs it turned out to be that the 02 censor was not working properly, have that checked.

I surprised myself and resolved this problem on mine: Too much dirt, etc built up in in line fuel filter. As I accelerated larger demand for fuel caused blockage and starved off motor.

Check the little things first!

I have the same problem but not the answer.

But I have just realized that when it happens the driving lights go dim.

That all depends if its a carbureted model or a fuel injected model. Carbureted model has an easy answer. You have a dead spot in the carb. you can do 1 of 2 things. Rebuild your old carb or buy a new one. Generally the float is just sticking. With fuel injected cars when you have a problem like that the check engine light should come on.

If it has a distributor, check to see that the weights under the rotor are free moving. If they stick, then the timing will be slow to advance and the engine will bog for a second or two.

MY WAGON WILL BEAT A LS1

JMHO:

Any of the above could be true. It also could be carbon build up in the intake lines, valves, & carb (if there is one.) If this is the case, a fuel intake cleaner will clear it out and a new fuel filter will also help. Carbon does the same thing to those components as cholesterol does in your arteries.

Good luck!

Just had this problem with a 350z. The car was cutting off at 5k rpms, then gradually got worst and started cutting off at 2500 rpms. Turned out it was a bad MAF sensor. I replaced mine at a very costly price! I would suggest (If applicable), clean your MAF sensor. You can buy the cleaner at autozone. Doesnt hurt to try!

the easiest way to change the timing belt is to remove the grill, center section of the radiator support, and the radiator and fans. Leave the airconditioner condesor there, it would be more difficult to remove. Once all that has been removed you then have to remove the blelts, the tensioner (completely) and the crack pully. then you have access to the timing chain cover, which you then remove and there it is. A tip when replacing the belt is to also replace the water pump since you already went through the trouble. I just did all this yesterday and the water pump cost 39.99 and belt was 35.00.

A TB is a project for someone with a good mechanical aptitude (and most likely, a shop manual), it is not just a simple fix, like a bulb or radio, etc. If you do it wrong, you'll likely leak coolant, or worse, total the engine.

Most newer engines are 'interference engines' meaning a timing belt that breaks, slips or has some other sort of misalignment causes physical (costly) damage to the engine's internals.

Usually, it is the valves that get bent, which entails about a $750 repair (in addition to the cost of the belt repair). Worse, a piston or cylinder wall gets cracked, which usually means a new engine, that can become a $2000 expense real quick.

Dealers are expensive, usually 30% more than independent shops on a timing belt.

Find a good local independent shop and consult with them, you will likely spend about $150-$200 in parts, and another $300-$400 in labor. Not cheap, but a lot better then the alternative.

HTH, Mark

ANSWER:

Not to be a prick.. but the dude (Mark) that answered above me most likely works for a mechanic shop. I have rebuilt 4 engines and have done it all by trial and error. Ask questions and/or grab a Chilton manual. The best way to save money is to do it yourself. Just keep an eye on what you are doing and be sure to mark what you disconnect so you don't forget where anything goes. EASY AS PIE!!

I just finished changing mine in a '99 Nubira. I have the DOHC and both cam gears are labeled with intake and exhaust marks. It's supposed to make the gears interchangeable, but it just adds to the confusion if you're not sure which one is which. With mine the exhaust is on the right, and the intake is on the left. As far as the crank goes, there is a mark on the crank that you line up with the bottom of the timing cover. It's not labeled very well. Mine looked like a square notch about an eighth inch deep that I had to line up. In theory, if you line up all these marks correctly everything should line up. One thing to keep in mind, if your engine is an interferance engine you probably at least bent some valves when the belt broke. I can't tell you how to tell if your's is or not. Mine is.

A copy of the factory repair manual is available online at, http://autos.groups.yahoo.com/group/daewoo/ You can download it free as a PDF file, it was a real lifesaver for me when my timing belt broke and bent all the valves.

You can get the book and all the parts for your car at Daewoous.com

There are several things that can cause this problem with Jeep Grand Cherokees. The actuator (door motor) can cause this, the door could also be broken. There is an good article that goes into more detail - the link is at the bottom of this page. Often, the actuator motors are too strong for the plastic doors, and they break over time. The typical fix involves removing the entire dash and replacing the plenum assembly. There is a DIY kit by heatertreater that provides instructions on how to perform the repair without removing the dash.

I just started experiencing this same exact issue with my 2002 Jeep Grand Cherokee Limited on a road trip yesterday! It works as it should on the driver's side, but only blows cold air on the passenger side regardless of what temperature you set it on! Also, even if I completely close the passenger vents, some cold air still comes out from them and also from the floor area!

I had the same problem! Here is my cheap quick fix. Remove the glove box lid, there are 2 rubber retainers that hold it in place, just pull them out they are easy to put back, the lid will now drop down to reveal the the door motor housing, disconnect the electrical lead(Make sure you remove the neg lead on the battery first)Undo the 2 screws and then pull out the motor. A new motor cost me approx 100 pounds. If you do take my approach make sure you test the motor before you buy new as it could be some other problem. Once you have removed the motor it's easy to open and close the door by it's spigot, just to make sure it's not stuck in any way. My final test was to check for power to the electrical lead. Reconnect the battery. While turning the temp conrol check with a meter to see if there is power to the lead.

It sounds like you have aq problem with the right temperature door assembly. I have a similar problem with my 1999 Grand Cherokee Limited, but, in my case, the unit just blows cold air. The question is: How do you access these door assemblies to change them? Help! I am a do-it-yourself person and want to know where I can locate information about how to access the AZC system door assemblies to change them? I understand it involves removing the entire dash board in order to get access to the passenger side one that is broken. To do so I need some type of repair manual.

All I know is I have the EXACT same problem with by 99 jeep grand Cherokee. It started with one side blowing cold and the other blowing hot. Now, both blow only cold air. I took it to the dealer and they wanted to charge me $800 to fix it stating it was some switch that has been going out in all jeeps this model with dual heating system yet they would not consider it under warranty as a issue. Hence, I still have no heat.

I just had the problem on my 01' jeep grand the dealer told me it was a bad bun door and actuator on the passenger side at a charge of $1200.00. If your good with cars you can do the job yourself and I mean good this job was a pain in the butt the dealer est. 12hrs (plus u need to disc. the heater core and evap. for the ac) of their time it took me exactly that. Once I got the HVAC system out of the truck I noticed since the car is temp. control zoned the passenger Sid bun door which controls the flow of heat to the passenger vents was broke. The dealer was aware of the problem picked up a new part for $200 and slapped it back together worked fine( the actuator was not bad it just doesnt respond to a broken door so don't let them sell you one, you should only need a new bun door)

The problem is a wear out mechanism with the blend doors. The doors break and are stuck in the AC position...NO HEAT. There is a new product that solves the problem. Search on Google for "heatertreater" for a complete explanation of the problem and a solution.

The problem with the system is the design of the actuators. The failure of this so called" bun" door is due to the poor design of these actuators. Over torque and excessive wear leads to failure....The only way to resolve this problem is by replacing both actuators and the temperature blend door assembly. Do not just replace the door!!!! ( note: fresh air door has same problem) I average one grand Cherokee a week in my Cooling systems repair shop. 675.00 is my going rate. It pays 6.1 hours and nothing more...don't be robbed by the dealership and stay away from driveway mechanics. Beware that your entire instrument panel must be removed along with the evacuation of the refridgerant. Not a "do-it-yourself" deal! Good luck and never by a Jeep again!

Your failure description is the classic fail description for broken blend doors, and this is a common problem on the GC. There is an inexpensive DIY kit on Ebay from heater treater that will fix the problems without having to remove the dash panel.

The HVAC system is computer controlled and when the doors break, the computer senses that the movement of the doors is out of spec and shuts the motor down. Actually it is rare for the actuator motor itself to go bad. Usually it's a broken door combined with computer control. You can check the motor with a 9V battery and a snap connector. Just touch the wires to the motor terminals and check that it turns.

I just thought that I'd add my experience: I have a 1999 Jeep Grand Cherokee Limited 6-Cyl. About a year ago heat went out on passenger side (cold air came out on passenger side when heat was on and coming out on driver's side). Spring and Summer came, so I forgot about it. This Fall (maybe 1-2 months ago) I was reminded of the problem when the cold air came back. Now, about 1-2 weeks ago, all blower functionality is gone ... a real problem if you need to defrost the windows! I'm going to try the AZC test and look into the HeaterTreater. I'd hate to put any more big money into this vehicle as it has been a true money pit. I'll never buy another Jeep. It's a classy ride, but I've put more money into repairs for this vehicle than any other two vehicles I've owned.

Easy fix is available

There is a video available that shows the complete repair process and goes into an explanation of the root cause of the problem and the solution. You can also find the video by searching on YouTube. This is a very common problem on the Grand Cherokee and the kit gives a simple effective fix for the problem and is much much cheaper than taking it to the dealer.

Assuming you are going to replace the 99/04 Jeep Grand Cherokee blend doors yourself.

You would start by disconnecting the negative battery cable.

If you are going to remove the dashboard, etc to replace the blend doors.

some websites give you complete instructions with plenty of pictures.

It will take the average person with little or no auto repair skills approximately 12 to 16 hrs.

The vehicle will have to be taken to a shop that can recover the refrigerant before you start removing the dashboard and HVAC box..

If you are going to do the type of repair where you cut an access hole in the side of the HVAC box.

A short version of how the access hole repair is done.

Disconnect the Negative battery cable.

Lower the glove box

Remove the actuator motor - You will need a Phillips screw driver

Cut an access hole in the plastic HVAC box - Use a multi-purpose cutting bit, you will need a rotary type of cutting tool, like a Dremel, RotoZip, etc. Or you could do the cutting by hand with any type of small cutting tool, it will just take longer doing it by hand. Or some people have used a narrow pointed soldering iron!

Remove the broken blend doors

Install the new Blen Dor dual control blend doors.

Replace the actuator motor.

Close the access hole - Replace the wall piece of plastic you cutout -Use foam tape or an aluminum tape to cover the groove made by cutting the wall.

Close the glove box.

It is almost as easy as what you just read, the hardest and the most time consuming thing to do is cut the access hole.

The job should take between 30 minutes to 1 ½ hours. Depending on how long it takes you to gather your tools, etc.

Before you do anything major find you hvac fuse, pull it, then put it back. It might be in the fuse box under the hood or the one inside. All mine needs is to cut the power to the havc unit then it resets.

timing belt

I would suspect the noise is either the power steering pump or one of the serpentine belt tensioners.

In fact I had a loud whining in my 2000 Saturn and it was the bearing in the serpentine belt tensioner. We replaced it ourselves, it was not too bad of a job.

Answer

I have a 96 sc2 it wined like it was a power steering pump but it was the idler pulley. To find out if that is the issue is to grab all the pulleys one at a time and see if they are tight or not. Good luck it only cost $20 dollars for the idler puolly and that fixed my problem.