Mechanics

HOW TO REPAIR

2000 GMC Safari

Engine problem
2000 GMC Safari 6 cyl Two Wheel Drive Automatic 189000 miles

Hello all, my vehicle has been running rough for 2 days. What I mean about rough is that it's burning rich, idles rough(about to stall at times)and the gas milage has been horrrible. An engine diagnosis came back as 'cylinder misfire'. I was told it required a tune-up, so I replaced the wires, plugs, rotor, distributor cap and fuel filter. Needless to say the vehicle ran exactly the same way, no change at all. I brought the vehicle to another shop they diagnosed it as a 'faulty sensor, so they replaced the EGR valve and still continue to have the same problem. I have spent over $700.00 up to date and have made no improvements whats so ever. The next step that is about to take place is to determine whether the mass flow senor is faulty. If there is any other solution to repair this could you please get back to me as I would appreciate any information.
P.S - I had this problem last winter and I managed to get through the season, come spring the vehicle started running great again and was fine all summer and fall, now it's winter and it's starting all over again. It almost appears as if the cold or damp weather has an impact on the situation.
Thank you in advance for any help that can be given.
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Just4now
December 12, 2007.




Is it possible that you can have the car scanned for trouble codes?

Also you should check the fuel pressure at the fuel rail. And is it a random misfire or a one cylinder or multiple cylinder misfire. If you can post back with the information I need. I can find the problem

Blackop555
Dec 12, 2007.
2000 GMC Safari Van 6 cyl. 2WD
Hello again, I cannot diagnoise the engine myself as I do not have a scanner. I have brought the vehicle to a friend of a friend shop at which time I have informed him of the situation. He is also not sure what would cause this problem, I will inform him to check the pressure at the fuel rail as you suggested. As far as the misfire, he will be checking it to determine the status. I would appreciate very much any further assistance to resolve this problem. If resolved based on your conclusions I will donate a small amount, aside from that I would like to thank you for your prompt response, bye for now.

Tiny
Just4now
Dec 13, 2007.
If its misfiring on just one cylinder then chances are the fuel pressure is good and the coil is good, it just may be a bad injector or spark plug and wire set or maybe even a sticking exhaust valve.

If its multiple, like it juumps from the #1 to the #3 then to #2 then #1 then #4 you might want to suspect bad fuel pressure, bad ignition timing, crank sensor begining to fail, bad rotor or cap. Quite different from the problems with just a single missfire!

Blackop555
Dec 14, 2007.
The shop it's currently at has performed a diagnosis once again and it was clear at this point the cylinder misfire was from cylinder # 2. Althought I had replaced the plugs and wires 6 months ago he feels the wires were of a lower quality and perhaps has caused the problem. He had told me the plugs are good so he replaced the wires only, as it seems it's running fine. The only thing is the vehicle has been indoors for 2 days now and I'm concerned the cold outdoor climate will effect it once again. This engine has been intermittent in turms of running well and not so well, so it may appear to run well now but will see tomorrow(saturday)when I pick it up and start driving it again. If you can give me some feed back in terms of your opinion, it would be much appreciated, thanks again.

Tiny
Just4now
Dec 14, 2007.
Using cheap parts is never good. Always get the best, you get what you pay for

i think the wires is what done it. Check the dist cap for a carbon build up on the metal point for that cylinder.

Blackop555
Dec 14, 2007.
Well what was thought to be the problem(changing the wires due to misfire on cyl.#2) only resolved the problem for about 2 hours. As I was driving it, it started acting up again as well as the check engine light on, no improvement what so ever. Back to the shop it went again at which time another diagnosis confirmed 'random misfire' now they changed the ignition coil and so far I have drove the vehicle for about an hour and a half and it seems tobe fine for now again just like last time, mind you the weather has been much warmer then usual. I am so sick and tired of spending money on replacement parts and having no results that I just want this f thing fixed. I might ad that when it runs rough alittle oil spits out of the exhaust pipe, please tell me this is not a sign of a blown motor. Again any further assistance is appreciated.

Tiny
Just4now
Dec 17, 2007.
With 189,000 the engine is definetely getting worn, you probably need new rings on the pistons.

If you took well care of your car and constantly checked the fuel and did tune ups then you have nothing to worry about.

A worn out piston rings can explain the random misfire also, to find out perform a compression test the lowest one should be no more then 25% LESS then the highest. Ie higest=100 lowest=75+
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Blackop555
Dec 17, 2007.
Well it appears the ignition coil did not resolve the problem, it was fine for about 3 hrs this time then failed and went back to it's roten stage again. I'm going to try to get by for at least the christmas time then bring it back in for another diagnosis. I don't get it, it was fine and running great for that short peirod of time, as soon as I parked it for the day and jumped back in, it started the instant I strated it. When it goes back i'll have him do a compression test. So far as it stands the mass flow sensor has not been address yet. This van is becoming a nightmare and very costly that I'm alsmost not able to afford any more non-sense repairs that take me nowhere! I'll let you know as soon as I have more information, again I appreciate everything you guys can suggest, I just want this to go away.

Tiny
Just4now
Dec 18, 2007.
Check and clean the MAF sensor, it can never hurt to narrow down everything! Please get back after you get the checks done.

Try putting a +12v from the batt on the coils +12v terminal coil, does it stay runnign?

Blackop555
Dec 18, 2007.
The shop has cleaned the MAF sensor and I'm concerned it may be faulty beyond cleaning. Just a reminder the ignition coil was replaced so I'm not sure if you want me to still put 12 v+ to the 12+ of the coil. Today it continues to run what seems worse then ever. I ran out of gas not realizing how much it's drinking. I put 40 litres of gas in and ran out with only 112 kms where I normally get about 300 kms, again I'm trying to get by Christmas & New Years before I return the vehicle to the shop as funds are running low. I will keep you informed if any changes have been made, thanks again guys.

Tiny
Just4now
Dec 19, 2007.

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