Vehicle: 2000 Blazer 4WD Automatic 260,000+ miles (Runs perfectly if not for something going wrong every two weeks)


  • Engine sounds rough when accelerating
  • When accelerating there's a ticking/clicking noise (similar to a card on the spokes of a bike; like what children do)
  • Check Engine light: 'Bank 2 system too lean'
  • When maintaining a steady speed it sounds completely fine.

The issue started yesterday driving home from work, I first thought oil as I hadn't checked it in about a week and a half, so I went home and added some. It's still doing it, bouncing between sounding really bad and moderately bad.


  • Master Brake Cyclinder & Distributor cap are around 2 weeks old.
  • Vacuum lines changed about a month ago.
  • Spark plugs and wires, air filter, oil filter, and oil change around 2 months ago.

Short of trying to clean the MAF sensor I'm not sure where to start for trouble-shooting this issue. Does anyone have any experience with these symptoms? Could it be the MAF Sensor, if not what else?


  • On the way up-town the Engine light went out and all I could hear was the clicking/ticking.
  • When I got back home and put it in park the clicking/ticking stopped entirely (even when giving it gas in park). I tried neutral after that and it was the same (no clicking).
  • What does it do in park at idle? in park with throttle? in drive does the the ticking/clicking get faster with tire speed or engine rpm? when you say "engine sounds rough", could you describe that alittle more?
    – HasH_BrowN
    Sep 12, 2014 at 18:21
  • The ticking gets faster with RPMs. I'm not really sure how to describe it other than rough, it sounds not lubricated I guess? I checked the oil and it's good though.
    – Shelby115
    Sep 12, 2014 at 18:29
  • The clicking type sound would indicative of valve train noise, usually called valve tapping. A valve adjustment usually fixes that, which is done with feeler guages. Will research the "rough" sound more. If you can think of any other descriptors for the "rough" sound, it'll help narrow this down to get you an answer.
    – HasH_BrowN
    Sep 12, 2014 at 18:44
  • Alright, thank you. I'll see about that in a bit when I try cleaning the MAF Sensor and take a look at it with my Dad.
    – Shelby115
    Sep 12, 2014 at 18:47
  • @HasH_BrowN the reason why the clicking is extremely noticeable when accelerating, is the engine is under a load.
    – HasH_BrowN
    Sep 12, 2014 at 18:47

2 Answers 2


There is probably one of several things wrong with your S10. I think @Hash_Brown is on the right track.

First, it might be an exhaust leak. It's amazing how the puffing of exhaust coming out where it's not supposed to sounds like a "tick". This can also cause a lean bank check engine code to appear. This is because it will actually draw air in as well as the puffing out of exhaust. This has to do with Bernoulli's Principle I believe.

Second, it could be a sticky lifter or valve. With as many miles on your truck as you have, this would not be out of the question. If the one or both of these are sticking, you could possible get it clear up with some SeaFoam or the like. Following the directions on the can, you can add about 1/3 of the can to the crank case and run the engine up to temperature. This will clean out the gunk from the lifters and allow the oil to flow more freely as well as allowing the lifters and valves to move around better as well. These directions may be a bit off because I have not used it in this manner in a while, so ensure you follow the directions. You do not want to leave it in your crank case for an extended period of time. Nothing past 100 miles is what I've been told in the past I'm pretty sure. It can also be used in the gas tank to help free up noisy injectors. NOTE: I will warn you, doing this also cleans all of the carbon off of the oil control rings and out from the bearings and wherever else it may be hiding. While you may think this is a good thing, as engines get older and build up the carbon, it actually helps to keep oil usage at bay. When you clean these deposits out, it will actually allow your engine to burn oil and you'll have the tell tale sign of blue smoke coming out of the tail pipe.

You could possibly try a rocker adjustment, but I would bet this is not the problem. If you have a dead lifter (one which no longer springs back), adjusting the rockers will not solve the issue. This would require you replace the lifters. At your mileage, you'd just want to do a rebuild at this point, since you'd have the top end of your engine apart anyway. Once the lifters are set, they very rarely need an adjustment. I'm assuming you have the 4.3L V6 engine (I don't think they ran the S10 with a 4-cyl and 4x4). The 4.3L is basically a Small Block Chevy (SBC Gen I) engine with two cylinders cut off. To adjust these rockers, you do not use a feeler gauge. If you've never done it before, I would get a friend who has to help you so you'll understand, but here's the basics:

  • Remove your valve covers
  • Move the engine so it is top dead center on the #1 piston on the compression stroke
  • Both your intake and exhaust push rods should be able to spin
  • Back the rocker nut off a full turn on your intake side
  • While spinning the push rod between your fingers, tighten your intake rocker until the push rod just stops spinning, then give it another 1/2 of a turn
  • Do the same for your exhaust rocker arm
  • Then do the same for the exhaust valves of cylinders No. 5 and 6 and the intake valves of cylinders No. 2 and 3
  • When done, turn the engine over (by hand with a socket wrench at the crank) 360 degrees
  • Then do the same for the exhaust valves of cylinders No. 2, 3 and 4 and the intake valves of cylinders No. 4, 5 and 6
  • Button the valves covers back down

You can follow this video on YouTube as it is fairly decent, but shows a V8, not your V6. (I have timed the video to 1'6" which is the meat and potatoes portion of what you need to be watching, but go back and watch the whole thing if you like.)

Third and ugliest is the possibility of a rod knock. I'm doubting this from your description. The noise would be a bit deeper in pitch than a tick, but it can show up sounding like this.

  • Let's say this is the issue, would driving it as-is cause any problems/damage?
    – Shelby115
    Sep 12, 2014 at 21:22
  • Depends on which issue it actually is. An exhaust issue will not cause any major issues, but will cause you to get worse gas mileage. The lifter issue is what it is, which is mostly noise. It will, however, eventually wear out and quit working altogether or cause sympathetic wear to other parts it comes in contact with, wearing them out sooner. If a rod knock, the engine is on the way out. It is on it's last leg and will need surgery soon to fix the issue. As I said, your description does not lend to this diagnosis. Sep 12, 2014 at 21:28
  • My Dad finally got to hear the ticking noise, he thinks the issue is an exhaust leak and that noise is just being caused by it. I'm going to wait a little while, while I research/learn more about exhaust leaks and we narrow down where it's at (somewhere in the front-passenger side is where the noise is amplified).
    – Shelby115
    Sep 13, 2014 at 18:56
  • @Shelby115 ... that would make sense with a "Bank 2 system too lean" code popping. Sep 13, 2014 at 19:10

On a lean mixture under acceleration you are describing a noise known generally as 'pinking' - clicking as in rattling. You need to check the vehicle for an air leak, (maybe a vacuum hose come off), oxygen sensor on bank 2 not working, or a knock sensor having failed. I would second place the MAF as this would produce codes to the effect of 'engine running weak' not just bank 2.

  • 1
    pin_g_ing, not pinking. :)
    – dobey
    Sep 12, 2014 at 21:20
  • 1
    @dobey ... You may want to cut Allan some slack on that one ... I would bet it is a common term in England where he's from. I used to hear such a term called "local color" way back when. Sep 13, 2014 at 19:11
  • You could also check the fuel pump/pressure and the fuel filter. In addition, if the timing is set wrong, pinging could occur.
    – Cullub
    Jul 2, 2016 at 17:43

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