#1 cylinder in my 2005 Trailblazer has no compression. I applied air pressure and it sounded like the exhaust for no air came out f the throttle body. There was air coming out of my # 5 cylinder with the #1 at TDC. wanted your opinion on if you think it is an exhaust valve not seating?
ProTech
Yes, I would think that is your problem. Those cylinder heads on the inline 6 engines have been known to have problems with valves. Usually not repairable, and will require cylinder head replacement. Do all of the other cylinders have good compression?
Also what is a variable valve timing solenoid and would it cause this? cheaper route. it is the famous Chevy 4.3l.
OK, so you’ve got an old style Blazer then, right?
Sorry Internet problems
That’s OK, so you have the ‘old’ style Blazer, correct?
No, it’s an 2005 4.2L.
You said 4.3 in a previous comment, I thought you had the V6, but you DO have the inline 6?
I have the inline 6 cylinder engine. I ran a compression test with over 220 psi in the 2-6 but zero in #1
As for the variable timing solenoid, also called a cam phaser….that would NOT cause you to have an issue like you’re facing. Looks like the head will have to come off.
Was I supposed to pull the valve stem out for the pressure gauge in order to run the test? I am fishing for simple solutions.
Leave the valve stem in to do a compression test, and take it out to put air in the cylinder….you seemed to have done it correctly. Unfortunately, there is NOT a simple solution to your problem. Most likely will need a new cylinder head!
Thank you. lastly when applying pressure, would it force the oil that I used to verify it was a faulty head back through the piston rings?
Not usually, unless they are really loose, in which case you would have heard air coming out the oil fill or dipstick tube.
Ahh. Didn’t hear that. So the air coming out of the #5 was probably do to the open exhaust valve in the #1 through the valve cover to the #5 valve?
If you had number 1 cylinder at TDC, neither valve should have been open. You mentioned hearing air out the exhaust, which would tell me a burned valve or a valve that is not seating. It should not have transferred through cylinders.
I wonder if I should have turned the crank shaft a bit more on the down for the #1 to be at actual TDC? I stopped right at the top of its stroke. air was definitely coming out of the exhaust though.
Well, with zero compression, and I’m sure you have a misfire on that cylinder, there is really nothing to re-check. It’s a mechanical problem of some kind in the head itself.
Borescope came out good for the piston and the walls. some gunk but no holes.
I’ve seen this over and over on the inline 5 and 6 cylinders in the Trailblazers and Colorado’s
Well computer is saying 0301 I think.
Yes, that code is for a misfire on #1 cylinder.
Now the decision to get an engine or head. I think the engine is only a couple hundred more. how long can you run it like that. or would the valve possibly stay open and contact the piston. what might be some of the outcomes to run it fr a bit longer?
Do you have a lot of miles on the engine as of right now?
It has 85000 miles.
It doesn’t really hurt to run it, you’ll just have to deal with the misfire and lack of power. The only thing would be, that the fuel getting dumped into #1 and not burned would end up in the catalytic converter which can damage it.
Was looking at car-parts.com
If the engine was maintained well, and still in good shape I would probably just go with a head. Otherwise I’d probably do a new engine.
Oh. alright. thank you for your opinion. stumbled upon this live chat and could have used it for some time. will have to save it to my favorites. take care sir/ma’am.
You’re welcome, glad to help! Come back anytime you need a question answered!
Will do.
And check our forums out too, they can be helpful.
I also have a 1994 Ford I am sprucing up for towing. NO tow package. I was jus looking, is there an application on the Iphone that has this live chat feature as well?
Not at this time. This website is mobile ready and we are looking into making a mobile phone app, so check back!
Alright ty very much.
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6 Comments on "2005 Chevy Trailblazer Runs Rough at Idle With No Compression"
Hi my name is scott ive got a Chevy trailblazer 04 model with the inline 6 4.2 L had a blowed head gasket and my head was warped 20 thouzands I couldnhave bought a refurbished head for 200 dollar in state I got a head out of a junkyard cost me 100 dollars anyway I got it all put back together and it had no compression on 156. Any thoughts and I like 98 percent sure its right but even it timing was out it wouldnt have no compression on 3 cylinders right so took heD off made sure valves were close poured gas on them and sure enough. They were leaking lime crazy
04 Sierra I power washed the engine yesterday ,today after driving about 4miles ses and t/c lamp came on and it quit pulling did I get tps wet?
I have a 2006 h3 Hummer I recently replaced the motor with a crate engine because of reduced engine power issues Now I’m having the same issues only when cold weather a rises in the morning on the first start it gives me the reduce engine power message I have replaced throttle body,camshaft sensors,bank 1 o2 sensor,knock sensor,crankshaft sensors,catalytic converter,pcm,and engine wire harness,battery,and alternator,also one ignition coil and clean map sensor and I also sprayed carb cleaner on intake to look for leak didn’t find a leak going in the hole and lost need help !!!!!
I have a 2005 trailblazer with 79,000 mls. on the 6cyl. yesterday it started running rough like it was misfiring. i took it to local auto parts store, they plugged in the code machine. code came up p0017. 1. intermittent connection, 2failed crank or cam sensor, 3engine mechanical condition. i changed both sensors. seems to be worse now. any advice. i really cant afford to take it in to get fixed.
ProTech: The P0017 is really a cam timing code. You can try changing the exhaust cam phaser (actuator) which is located in the side of the cylinder head, but more than likely you have an internal timing problem due to a stretched timing chain. This is not a cheap repair, as basically the entire top half of the engine has to come apart. Usually after trying the cam sensor and/or phaser, the code will come back and the engine will still run rough. Unfortunately, you’re either going to have to deal with the problem and just leave it, or take it and get it repaired. You’re probably looking at around $1000 to fix this problem.
I have a Chevy 2003 Trailblazer and the key will not go into the lock position, we changed the ignition switch and are still having problems.
If you are sure that you timed the ignition switch properly, then sound like you have a problem with the shifter no going all the way in park. Try pushing the shifter in park a little harder a few times while turning the key back and forth.