Howdy guys!

Im back with another question, its not really a problem.

My 99 Blazer shakes when its stopped at a light in drive or when stopped in reverse. It does not shake when its in neutral or park.

Im not sure where to start looking to find any problems, but I am hoping one of you can give me a solution... here are my trucks specs:

1999 Chevy Blazer 2DR 4x4
192, 869 miles.
Just changed (like a week ago) Spark Plugs, Spark Wires, Battery, Distributor Cap, and Rotor.

Things I know need to be changed: Fuel Filter, Oil & Oil Filter, Antifreeze Fluid (It looks brown when I look at it through the top of the tank), and I would also like to change the Transmission Fluid and Filter (I bought this vehicle used and im sure this has not been changed in a while).

Other things that bug me: When I hit a bump in the road, I get a squeak or crunching noise that sounds like granny's rocking chair on the front porch. Not sure if this is ball joints or suspension, hopefully you guys know what this is?

Thanks, there are some other issues with the car that im working on (such as the exhaust leak which throws Carbon Manoxide into the cabin when I try to turn on the AC), but I know I can get this puppy running good with your guys' help.


Appreciate it, Nick.

 

My truck did the exact same thing when my Idle Air Control valve was going bad, but that may or may not be your problem. If you didn't already know, IAC valve controls how much air the engine gets at idle and if it doesn't work properly it causes a the engine to run rough under load at idle (drive or reverse) so that would be my guess but you should find the testing procedure for the IAC on this forum before you replace it

Also, what brand parts did you use for the tune up? These trucks run like crap on most everything accept AC Delco or Delphi. That could also have something to do with the idle

 

In addition to what cherryblazer said, recheck the work that was just done. For example, you may have crossed a s/p wire or may not have snapped the s/p wire connector on tight, so it isn't making a good connection. With the engine running, sometimes you can hear it 'popping' or actually see it if it is dark and you open the hood. Also check that you didn't accidentally knock off a vacuum line.

 

I re-checked everything. My plugs, wires, and the cap and rotor. Everything is plugged in tight and working appropriately. There dont appear to be any hoses loose. Can anyone tell me where I can find the IAC Vac line?

Thanks.

 

Mr. 'X', here is a site that has a step by step, how to test pin no.by pin no. such items as the ICM that you often read about as problematic here. I find the photo's helpful in locating the different components crammed under the hood. I thought that a V6 engine would be easy to work on until I opened the hood and found it harder than my 94 Impala V8 to access. Back to the easyautodiagnostics.com site, go look at that and see if it helps. I don't think the IAC has a vacuum line. It should be on the TB and have electrical connections. BTW, I just took a look at the items covered by the easy diag. site and although it covers ICM, EGR, MAP, O2, and crank position sensors,it doesn't cover the IAC. Sorry. I still say to 'bookmark' that helpful source for future ref. EGR is another item ,if you have one, to look at and clean and re install with a new Fel Pro gasket. My 2003 happens to NOT HAVE one. I would also check and clean or replace the PCV valve.....if you haven't already. HTH, Jim in SC


HOW TO TEST IGNITION CONTROL MODULES and MASS AIR FLOW SENSORS and MORE. Easy, simple and fast test articles!

 

Mr. X , the site URL didn't come out as I copied it. It is:
easyautodiagnostics.com ; then select 'GM' ; then 4.3, 5.0 and 5.7. They lump the 4.3L V6's in with the big brother V8's of 5.0 and 5.7 L because they are the same Vortec design with the same spider and TB, ICM, and other components. Have fun and good luck.Jim
Oh, yes, when you get the rattles quiet, please write up a detailed post on how you did that feat. Lot's of folks here will want to hear that.
Brown antifreeze is a common issue here. I say it is a Dex Cool problem which is known to turn to a nasty brown sludge when D/C is mixed with the 'green' antifreeze. Please do a BF 'search' for that and you will have a lot of reading to wade through. Summary: flush numerous flushes and be sure to get the reservoir and the heater core and the block passages. IOW not just the radiator. That brown sludge is deposited everywhere that the coolant goes. some have ended up replacing the radiator and the reservoir. Caution: this is a sensitive subject and some are in denial in regards to Dex Cool. But try Googling it on the web.

 

There is no iac vac line, but the IAC valve is connected to the throttle body. There is also a Throttle Positioning Sensor (TPS) attached to the throttle body but it is attached to the throttle plate. It should be easy to tell the difference, let us know if you still can't find it