hesitation on highway

[y2msu]

wife informed me this morning her 99 montana has been intermitantly hesitating on the highway, has 85,000 on it. happened over last several gas fill ups so i don't think it's bad gas. guages all ok, no engine light. this last time she thought it might stall?

plug wires, fuel filter, and air filter come to mind, anyone else have this problem? what was the solution? or anyone else have any recomendations. in the past i just start changing things and usually narrow it down, but i would prefer to take a more logical approach.

by the way, where is the fuel filter(s) at on this thing? how many are there?

thanks

[rajjhauf]

Very hard to tell for sure but the only fuel filter is located on the inside of the frame on the drivers side, just about under the seat area. Not too hard to change but you really need a lift to get to it.
Hope this helps.

[BKVic]

The fuel filter jumps to my mind after reading your post. At $10 Id replace it first before jumping to the plugs and wires.


BKVic

[tsg]

Changing the wires and/or plugs is TIME CONSUMING . . . bad engine design . . anyway . .


Did you find out what the fix was ??? If so . . please post since I'm having the same problem and already replaced injector 6 . . .now cilinder 4 is mis firing . . . no idea what the REAL problem is

Tony

[bertmaster2000]

again, check the air filter.

believe it or not, i was having problems with our 2000 van cutting out intermittently at all speeds. changed the fuel filter, then had codes deleted. then had the problem again. checked the codes and they indicated low fuel pressure, so paid $500 for new install of new fuel pump. problem persisted, so i checked the air filter (no small job on the 3.4 l engine), and a dang mouse had shredded it such that filter paper was ocassionally getting sucked into the intake manifold! i changed the air filter ($8) and fixed the problem.

good luck,
berto

[ranbl]

OK
For over a year, I have had a similar problem on my 97 montana. It may drive for a day and run great, then start to miss a bit especially in the 50 to 60 mph range. It may do the same thing whan first driving it , then get over it. There is no way to predict whrn it will start or how long last. I have replaced spark plugs, plug wires, fuel pump, cleaned fuel tank, Run cleaner through the system several times, replacd filter three times in 18 months. I have been to three dealers and three shops and no one can help. we have 160,000 on this car and otherwise it runs great. I am still looking for an answer.

[CSI-LEVEL3]

I have a 2000 Montana, had the same problem. Had the plugs, wires, fuel filter, and injectors cleaned at the dealer. Still had the problem. Dealer recomended allowing them to go throught the transmission, to troubleshoot the hesitation, miss. Dealer prices are high, I had already spent around $475 for repairs, and was told to open and check the transmission could be around $600-$1200. I did some research, and talked to my local parts place. Decided to try their advice and replace both oxygen sensors. cost approximately $160 for the sensors at Autozone and took about 30-60 minutes to install. Fixed all problems. I have never had and do not have transmission problems. Van runs like new again, and starts immediatly. Worth a try.

[sbobinsky]

Originally Posted by CSI-LEVEL3

I have a 2000 Montana, had the same problem. Had the plugs, wires, fuel filter, and injectors cleaned at the dealer. Still had the problem. Dealer recomended allowing them to go throught the transmission, to troubleshoot the hesitation, miss. Dealer prices are high, I had already spent around $475 for repairs, and was told to open and check the transmission could be around $600-$1200. I did some research, and talked to my local parts place. Decided to try their advice and replace both oxygen sensors. cost approximately $160 for the sensors at Autozone and took about 30-60 minutes to install. Fixed all problems. I have never had and do not have transmission problems. Van runs like new again, and starts immediatly. Worth a try.

I have the same problem with my 2000 Montana. I have already changed the fuel filter, air filter, and started to change the plugs. The front 3 were fine, any advise on getting to and changing the back 3 plugs?

Also, I will now plan on changing the oxygen sensors, where are they located? Thanks

[CSI-LEVEL3]

Originally Posted by sbobinsky

I have the same problem with my 2000 Montana. I have already changed the fuel filter, air filter, and started to change the plugs. The front 3 were fine, any advise on getting to and changing the back 3 plugs?

Also, I will now plan on changing the oxygen sensors, where are they located? Thanks

Back plugs are tough. I got to mine by removing the coil packs and reaching behind the engine. Took about 45 min. for back three. I recommend replacing the wires while your there. As for the oxygen sensors, you can access them from under the vehicle. One is easily located in the middle of the exhaust. The second is up high by the motor on the exhaust. You do need a special socket to remove and install the oxygen sensors (about $6.99-$9.99 at autozone). Not to hard. Word of warning, I replaced the spark plugs the first time with Bosch Platinum +4's, and the van started running terrible and rough 3 months later. GM vehicles don't like the +4's. I put new Delco platinums, and running perfect with 30000 plus miles. Good Luck.

[chicksmom]

Originally Posted by CSI-LEVEL3

Back plugs are tough. I got to mine by removing the coil packs and reaching behind the engine. Took about 45 min. for back three. I recommend replacing the wires while your there. As for the oxygen sensors, you can access them from under the vehicle. One is easily located in the middle of the exhaust. The second is up high by the motor on the exhaust. You do need a special socket to remove and install the oxygen sensors (about $6.99-$9.99 at autozone). Not to hard. Word of warning, I replaced the spark plugs the first time with Bosch Platinum +4's, and the van started running terrible and rough 3 months later. GM vehicles don't like the +4's. I put new Delco platinums, and running perfect with 30000 plus miles. Good Luck.

I have the same problem with my 1998 venture, had diagnostic ran and they told me needed new plugs and wires. was coming up with multiple cylinders misfiring. had new plugs and wires put on, and still same problem. SES light still on, but sometimes it goes off and runs fine and some times it runs rough, at idle it runs rough and at speeds around 50-60 mph it misses. I have ran 2 bottles of seafoam in it and I took it back to the shop and they suggested doing a fuel injection cleaning service. They checked the pressure at I believe around 10, (not sure) but found no problem, but stated it was hard to check at high speeds. If it was a fuel filter wouldnt it come up `wit