So for months now the 1999 Jeep Grand Cherokee has been running like crap. Takes 2-3 turns of key to start, rough idle, not a lot of power, especially going up hill. When I hit 45 mph there is a "popping" noise coming from the glove compartment area, right where the blend doors apparently are. The longer it idles the worse it gets, sometimes vibrating and increasing to shaking. Long enough at idle and it stalls. ( like in the drive through). Once it stalls it may take 10 min to restart, when it does, it stutters and lurches, even if gas is floored, but eventually it seems to click and its driveable again. When pushing down the gas pedal it almost feels like there is resistance and its trying to push back. It has only died while driving once, while at idle, but everytime Im at a light im praying for green because it feels like it wants to die. So far I have changed, o2 sensors, spark plugs, wires, fuel pump and crank shaft sensor. Crank shaft sensor was last and after that it came up with the code for "to rich", ( i forget the exact code) but supposedly it may be a vac leak? could that be the "popping" from the blend door area? Blend doors do not work either, no heat. When I change the plugs every seems fine for a day or so, than its back to normal. Problem seems the worst if I do a lot of stopping, say stop at store, come back out, go to pt b, , pt c etc, the more times I stop and park the worse it gets. Usually by the 3rd stop, when I restart it does the lurch / shake thing , i drive around the parking lot once or twice and it seems to "catch" and drive "almost" fine. So basically my question would be the possible vac leak, which is probably tied to the blend doors, would it cause all those symptoms? Oh and including crappy gas mileage.
If you don't have the dual electronic climate control, the system is run by vacuum. It appears that you do have a vacuum leak since your issues are at idle and low rpm. If the truck runs good at higher speeds that would again point to a vacuum leak because there is little or no vacuum at open throttle.
The code was p1071 , which from what I've read may be a vac leak. Could this have been the problem the entire time and not the infamous "jeep stalling " problem which usually leads to the crank shaft pos sensor or the PCM replacement? The code did not appear until after changing the Crank shaft pos sensor, although the blend doors have not worked prior to all this starting. The jeep actually ran great until I took it to a new place for an inspection, 2 days later the CEL came on, it was leaking fluids, the battery cables were extremely loose and it began to run like crap. It does run a lot better after changing the crankshaft sensor but I can tell it still doesnt run right. They quoted me $1200 to fix the blend doors, taking the dash out etc. Not something I would trust myself doing without a lot of extra parts after removal. A buddy said he'll do it for $500 .
Search wj blend door fix. You will learn you can do it with out removing the dash for under $100
I bought mine at www.blendorstore.com. Mine is a dual zone AZC. I bought the blend doors for mine and replaced them. Since I have the 4.7l HO V8, my actuators are electronic motors. I don't know what you guys have, but reading the posts on here, most of the 4.0L I6 use a vacuum line and they find that the vacuum line running under he battery is dry-rotted. Fixing that line helped them.
Yea I thought about doing the blend door fix myself through the glove compartment but not confident enough in my ability and no one I know wants to try it. I was just wondering that if I have a vac leak, could the blend doors actually not be broke, but instead not working due to the vac leak. And would that vac leak cause the poor running of the jeep? I did look over all the hoses ( I know not good enough im sure) and the only thing I noticed was at the bottom passenger side, kind of near the head light, there is a small hose coming out about 5 inches not connected to anything. Its a very small diameter hose just kind of sitting there. I cant find anything close enough that it may have come unattached from. I did try blocking it no change. I did notice that when I turn the AC on the idle changes immediately. I saw some other posts about checking if air only blows from certain areas and if cruise control works. Both check out. Switch to heat and nothing happens. It def runs much better after changing crank sensor but still has that hard to start problem (2-3 turns of key if im lucky) and upon hitting 40-45 mph there is a pop coming from where the blend doors are behind glovebox. I guess tom morrow I'll attempt to take the battery out and check that suspect hose with the high failure rate underneath. It would be nice to find out its as simple as fixing a hose but I'm not holding my breath. On another note, could this vac leak (which code just appeared) mimic a bad fuel pump? Just curious cause the first diagnosis was change the pump, which we did with no change at all, than then the plugs, wires, o2 sensors, and finally the crank shaft sensor.
That little hose could be the root of all your problems. If it is by the passenger front headlight, it could be going to your vacuum reserve reservoir, which is under the front passenger headlight. Why don't you go buy a vacuum gauge for $15 and confirm your low vacuum? Then replace ALL the vacuum lines on your 14 year old rig. At this point, that should be a no brainer and can't cost more than $20 to do them all.
That was my plan for today, well actually I'm gonna pay a buddy $50 to go through them all while I sit and observe. Your talking to a guy (embarrassing enough) that 2 months ago couldnt even change his own spark plugs. After this debacle, I've slowly but surely been learning, much in part due to this forum. Thanks for the tip , now I know where to start the process.
As said, go through all the vacuum lines as there's probably a leak somewhere.
As for the starting, turn and pause on "on" before going to start. I had issues with starting on my ZJ and that's what I had to do or it was hard to start. I out of habit do it all the time now, and doing so my WJ starts up first time every time. I tried without doing it this way and it would crank a couple times before starting. What it does is give the lines time to pressurize and get fuel to the rail before starting. Always good to do regardless as well is to make sure your battery connection is clean and tight, as well as the ground line from battery to the block on the block side.
The beatings will continue until attitudes improve!
It cost's nowhere near $500 to fix the vacuum line to the blend doors. Most likely it's on the firewall side of motor. Does your cruise control work. If no I'll guarantee it's on the firewall side because the 2 vacuum line comes off the same diverter. It on the passenger side of the firewall and the cruise control vacuum hose is about 3/8 on diameter and runs along the very bottom of the drip edge of the cowl that has the wipers. Follow this line to the passenger side and you'll see where they both go into the diverter. Any shop out to be able to fix that for less than $76-100 including parts.
yea the cruise control works, they were quoting me having to take the dash apart to get to the blend doors. Which I think might not be a vac problem because the spindle of the motor in the glove box turns all the way around. Which if I understand right it should only turn about 90 degrees meaning the little tip on the blend door is broken. There is a hose almost under the passenger head light, about 5 inchs long that is just hanging there, but I dont see anything it would connect to. When I get to the blend doors Im just going to go through the glove box with the hot knife method. I think I was a able to upload a pic of the hanging hose.
I got a reply from Amsterdam mechanic and he said that if the vacu motor doesn't move when you switch modes that this could be the problem. It's under the dash on the heater box and to access it you need to remove the under dash panels on both the driver's & passenger sides. It Ty doesn't move when you turn the control. It it moves in one on the positions, then the vacuum motor is bad. If there is no vacuum at the motor in either position then it's a bad switch at the control head or no vacuum to the switch. I'll look at the hose you pictured me on my Jeep and see if I can figure out where it goes to and I'll get back to you. Keep me posted if you try this fix.