Question about 1999 Pontiac Montana
I get good spark untill about 3700 rpm and then the engine lunges
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Posted on Jan 02, 2017
Ok, based on the firing order from your vehicle there are (6) cylinders, and (3) are on the front of the engine and (3) are on the back. I have never even looked under the hood of one of these types of vehicles, however, You MAY need to remove the large plastic engine covering (not sure for your vehicle). If that is the case you may have to remove the engine oil (tube). The cap that you open up to add oil, twist and pull on the actual tube and it should twist off (if needed on this vehicle). Once this is removed if requiered on your vehicle, you can then remove the large plastic covering to have access to each cylinder. Once the large plastic covering is removed, put the oil fill tube back in place for the moment so no contamination gets in your engine. I would start with the back side first because that is hardest. I checked on Autozone.com and they have it listed for this vehicle that the iginition coil is set up on the left side. You should see six wires coming from this area with (3) going to the front and (3) going to the back of the engine. Start on the back side with the whichever of these wires/cables goes to the left side of the back of the engine. Please only do one at a time to avoid confusion as to the placement. What I would do in all honesty if you are doing the tune-up is to replace the spark plug wires as well. What I have used on all of my vehicles and have had great success is NGK plugs and NAPA auto parts has plug wires Belden Maxx (this is only a suggestion and I am only sharing what has worked well for ME). OK, prior to starting what you will want to do is take each individual plug one at a time, and using a spark plug gap tool (readily available at all parts places) Place the non-porcelin end (the one that has the arc in it) into the gap tool at the lowest end and slide it around until you have reached the required gap. For this vehicle it is .60 Even if they tell you at the factory it is pre-gapped and you don't have to check it, believe me it is always a good idea. I just did a vehicle and all (6) were not gapped correctly. Put each one back in the box until needed. Once you have done this,starting on the back of the engine left side find the spark plug cable/wire that goes to that side and where it goes into the engine it will have an end with a boot on it. This covers the spark plug. Twist this boot off the spark plug, it may take some effort. Once that is off if you are replacing the spark plug wires take this one and match it up with the new set (They will be different lengths). Now for the fun part, removing the plug. Using a spark plug socket (available at parts places, has rubber on the inside to grip, and protect the socket) a small extention and your ratchet, place this over the plug and apply pressure until the plug begins to turn. Once you have the old plug out, place the new plug in the spark socket and thread it in by hand (it will be in the socket but don't use the ratchet yet. Once you have the plug in as far as you can by hand tighten it down with the ratchet (don't overtighten). Place the new or old spark plug wire (boot) over the new plug and move on to the next cylinder. Do each one the same way (ONE AT A TIME, to avoid confusion). This is a long explanation but I hope it will help someone...Thanks
Posted on Mar 02, 2009
I went to bulldogsecurity.com and looked up the wiring diagram for this vehcle. However, prior to checking this part, I would check to see if you have a blown fuse. It doesn't hurt and only takes a few minutes. There should be a fuse for that either somewhere on the side of the dash or near the brake pedal area. If not it may be under the hood, but it should be inside the vehicle. You may have multiple fuse boxes. If it has (2) sliding doors it will have a wire for the auto doors in each kick panel (under the plastic trim/molding) when you open the door and look down you will see all of the trim/molding it should snap out or may be held in place with a screw or (2). Once you remove that you should see the wires. It says for the left side it is either light blue or black and the right side is definitely light blue. Trace this wire until you find out where it ends (the motor or switch to control the auto doors) Then test the switch/motor to see if it is bad.
Posted on Mar 02, 2009
Yes, it can be removed and run without the thermostat. However, your gas mileage will suffer and the heater may not work very well.
Posted on Apr 29, 2009
The OBD II code for P0400 is Exhaust Gas Recirculation Flow Malfunction.
I'm sure the only thing you have left is you may have to replace the EGR valve or check for any leak from the vaccum lines going to to EGR valve.
Posted on Jun 01, 2009
There are a few ways to doing this, and it takes time and a few band aids. You can remove the alternator to give you some room to access the rear spark plug with an extension and swivel spark plug socket. You can also get to the plugs from under neath if you have a ramp and long arm, an extension and swivel spark plug socket will help. You may have to use a 2x4 to wedge the engine to give you some room if you have larger arms. The other way is to tilt the engine forward by disconnecting the two top engine mounts. First replace the 3 front plugs and wire one at a time so you don't cross them. After you have changed the front plugs have a friend help you. Make sure the parking brakes are on and disconnect the two top engine mounts, release the parking brakes and let the transmission in park. Push the van forward slowly to tilt the engine forward far enough to give you room with out pushing it to far in to the radiator. Put the parking brakes on again to keep the van from rolling back and place a block of wood behind and in front of the rear wheels. Don't want to lose an arm. Replace the rear plugs with extensions and a swivel spark plug socket. Note, your going to have to replace the spark plug wire since the rear ones are really hard to remove and pulling on then will destroy them, not worth the headache trying to save them. Use platinum plugs so you can get 100.000 miles before you have to change them again so use anti-seize on the plugs so you can remove them again. Good luck and hope this helps, I personally go from under the van.
Posted on Jul 06, 2009
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