99 Blazer tries to "die" while driving slowly

[bmzyg]

Hi..I hope someone can help. I have a 99 4x4 blazer that started acting weird on Halloween weekend. About every two days, when I start it and am driving slowly on the side roads (20-25 mph), it starts making a noise like it's going to stall and begins to jerk. To me (mind you, I know NOTHING about cars), it seems like it's not getting enough fuel. This has happened five or six times in the past two weeks. It has been to the shop several times about this problem (my Chevy dealer, who does all the maintenance). He has changed the spark plugs and wires, the rotor and cap, and the filters. He cleaned the carburator. It has a new battery. Yesterday (at the cost of over $500) he changed the "fuel module." The problem is, after nearly $900 in repairs, the car is still not running right. Yet again this morning it did the same thing (bucking and jerking down the road like the Beverly Hillbillies). The dealer, who we have purchased vehicles from for 15 years, is a reputable mechanic. He says there are "no codes" and that whenever they test drive it (over 40 miles of test driving), it acts fine. What the heck could be the problem? I am at my wit's end with this!!!!

[xjcamaro89]

Try cleaning the Mass Airflow Sensor, i had a similar probem in my 2000, when i started off from a stop (like under 15-20 mph) it would almost die but after a few seconds of that and slowly accelerating it would kick in and go, so i pulled my MAF sensor and cleaned all the black nasty stuff off of it with some paint thinner and it was like i was driving a completely different car and engine. Just a quick ?, is it hard to accelerate up a hill, or hard to give it gas to make it drop down a gear and get going? If so it might be the MAF sensor, and if it is, and you take it to the dealer to get the MAF checked out, dont let them talk you into a new one ($300-$400) because you dont need it, just tell them to clean all the black gunk off the thin wires. Good Luck!

[bmzyg]

It's not hard to get up a hill, although for the past several months there has been an exhaust odor while going up very long hills. But now that you mention it, it does seem like when the acelerator is pressed it sometimes takes a few seconds of the engine "wooshing" (my highly non-technical term) to get moving faster, but generally only in the mornings. I do not believe that the mechanic cleaned this sensor. Is it something a reasonably competant (i.e. he just installed a new alternator in his Kia Sephia) husband could do?
P.S. Thanks for the response!

[xjcamaro89]

Yes, you should be able to, what you are going to look for is a cast aluminum square peice installed in the tube going from you air cleaner box to the throttle body. Loosen the two big hose clamps that attach the air tube to both sides of the MAF. Remove the sensor electrical connection, and pull the MAF sensor free from both sides of the air tube. Now you will see on one side of the sensor is open and on the other side is a screen, there should be 4 screws on the perimiter of the sensor, remove those 4 screws and you should be able to pull that screen part of the sensor off. Once removed you should be able to see 3 horitontal bars and 3 vertical wires, you might even notice at this time that the bars and wires are black, or have a coat of black gunk on them. BE VERY CAREFULL WITH THE VERTICAL WIRES THEY ARE EXTREMELY FRAGILE AND IF YOU SNAP ONE, THE UNIT IS SHOT. take a Q-tip and some kind of cleaned, i.e.-carb and choke cleaner, paint thinner, brake cleaner. Any of those will work and very gently clean the bars and wires with very little pressure, you might have to go over them a couple times to get them all clean. When done use a clean Q-tip and just wipe over them to remove any reisdue from your cleaning agent. Now install the 4 screws to put the screen back on the MAF, and reinstall the MAF back into the air tube, reconnect the electrical connection and tighten up you air tube hose clamps and take it for a drive, if this is the problem you should notice an extreme difference especially from the problems you indicated above, give it a try and let me know how it worked. This should only take about 5-10 mins of work. Good luck!!!

[xjcamaro89]

Sorry but i cant express enough about how fragile the wires are on the bars in the MAF. Please be very careful!, thanks!

[BlazerLT]

Originally Posted by bmzyg

Hi..I hope someone can help. I have a 99 4x4 blazer that started acting weird on Halloween weekend. About every two days, when I start it and am driving slowly on the side roads (20-25 mph), it starts making a noise like it's going to stall and begins to jerk. To me (mind you, I know NOTHING about cars), it seems like it's not getting enough fuel. This has happened five or six times in the past two weeks. It has been to the shop several times about this problem (my Chevy dealer, who does all the maintenance). He has changed the spark plugs and wires, the rotor and cap, and the filters. He cleaned the carburator. It has a new battery. Yesterday (at the cost of over $500) he changed the "fuel module." The problem is, after nearly $900 in repairs, the car is still not running right. Yet again this morning it did the same thing (bucking and jerking down the road like the Beverly Hillbillies). The dealer, who we have purchased vehicles from for 15 years, is a reputable mechanic. He says there are "no codes" and that whenever they test drive it (over 40 miles of test driving), it acts fine. What the heck could be the problem? I am at my wit's end with this!!!!

Is the check engine light on?

Also, I would talk to the dealer manager, you shouldn't be paying all this money for their idiotic troubleshooting.

[bmzyg]

Originally Posted by BlazerLT

Is the check engine light on?

Also, I would talk to the dealer manager, you shouldn't be paying all this money for their idiotic troubleshooting.

Nope, no check engine light. I think they think I am hallucinating the performance problems, because they cannot replicate them. They drove about 40 miles trying to get it to act up, but nothing happened. I know it has nothing to do with my personal driving technique (which is what they seem to think), because it never happened until two weeks ago, and because it also happened twice when my husband was driving. In fact, after yesterday's new "fuel module" installation, the mechanic told me that the reason it was acting up was becuase there "were only about three gallons of gas in it." Somehow, I didn't buy that as a reasonable explanation, but as soon as we picked the vehicle up, we filled it at the dealer's own gas pump. And still the problem occurred this morning, and it was even more alarming and severe that the last few times it happened!

[BlazerLT]

Originally Posted by bmzyg

Nope, no check engine light. I think they think I am hallucinating the performance problems, because they cannot replicate them. They drove about 40 miles trying to get it to act up, but nothing happened. I know it has nothing to do with my personal driving technique (which is what they seem to think), because it never happened until two weeks ago, and because it also happened twice when my husband was driving. In fact, after yesterday's new "fuel module" installation, the mechanic told me that the reason it was acting up was becuase there "were only about three gallons of gas in it." Somehow, I didn't buy that as a reasonable explanation, but as soon as we picked the vehicle up, we filled it at the dealer's own gas pump. And still the problem occurred this morning, and it was even more alarming and severe that the last few times it happened!

So explain exactly what happens, it all of a sudden just starts to studder?

[drdd]

did your exhaust odor smell like "rotten eggs" ?

Originally Posted by bmzyg

It's not hard to get up a hill, although for the past several months there has been an exhaust odor while going up very long hills. But now that you mention it, it does seem like when the acelerator is pressed it sometimes takes a few seconds of the engine "wooshing" (my highly non-technical term) to get moving faster, but generally only in the mornings. I do not believe that the mechanic cleaned this sensor. Is it something a reasonably competant (i.e. he just installed a new alternator in his Kia Sephia) husband could do?
P.S. Thanks for the response!

[bmzyg]

Originally Posted by BlazerLT

So explain exactly what happens, it all of a sudden just starts to studder?

After first starting it in the morning (air temp is in the 50's-60's) and driving less than 1 mile, the vehicle starts to "chug" and jerk violently as it is driving. It lasts about 15 seconds, then the vehicle runs normally. It seems like it wants to stall, but it doesn't. This only happens within the first 5 minutes/1 mile of driving, and seems to happen most frequently when accelerating from a stop or a very low speed. In addition, this morning the vehicle would not start. It went "rrr,rrr,rrr,rrr", but it wouldn't catch. This is what happened a couple of days ago...I had it towed to the shop, and they replaced the fuel module. The mechanic said it would not start that day because there were "only three gallons of gas in the tank" (which ought to be enough to start and drive the vehicle, one would think). At the moment, there is a full tank of gas and it's sitting in the driveway and will not start!

[bmzyg]

Originally Posted by drdd

did your exhaust odor smell like "rotten eggs" ?

Yes, the first time the "chugging" and bucking and jerking happened, there was a strong "rotten eggs" smell. However, the smell has not occurred in conjunction with subsequent episodes of the vehicle acting up. There has been an exhaust smell when climbing long hills, and this has been happening for a few months. When the vehicle went for state inspection and emissions testing, I mentioned it to the mechanic. He said it passed all the emissions tests and that the smell was caused by the vents sucking in exhaust when the car was at a certain angle. The problem with that theory is that the exhaust smell was not present when climbing hills until this past summer, and we purchased the Blazer new in 1999!

[xjcamaro89]

Maybe also a clogged catalytic converter?

[bmzyg]

Originally Posted by xjcamaro89

Maybe also a clogged catalytic converter?

They said they checked the catalytic converter. The mechanics were just here (yes, they actually sent 2 guys to my house), and thankfully the vehicle would not start for them either. Since the problem never occurred when they were test driving it, I suspect they thought I was exaggerating or something. Anyway, they tried starting it while looking under the hood, and the ignition coil was sending out sparks! They went back to the garage, brought a new coil and installed it, and now it starts up with no problem. Of course, yesterday it also started up with no problem, but it would not start today. I had the mechanic point out the MAF sensor and I asked him if cleaning it would be useful. He, of course, said no. However, this is also the person who said three days ago that the reason I couldn't start it up was because there were "only" three gallons of gas in the tank! If the new coil does not solve the problem, we will (very carefully!!!) clean the MAF sensor and hope it helps.

[redwheeler]

check your coolant level sometimes when it is low the air can pass by the coolant temp senser telling the comp that the temp changed and it will adjust the ratio and the truck will chug

[xjcamaro89]

I dont know why the mechanic would tell you that cleaning the MAF wouldnt help, after all the MAF measures air passing through the delicate wires in the MAF and then the MAF tells the computer then how to adjust fuel air mixture to run the car correct, and if the wires are covered in black gunk how can then measure the air correctly, sounds like some mechanic needs to think about the common sense stuff.