Last post on Oct 27, 2013 at 2:09 AM
You are in the Chevrolet Suburban & Tahoe
What is this discussion about?
Chevrolet Tahoe, SUV
#6056 of 6471 Re: 01 Tahoe [rockman59]
Sep 16, 2006 (10:05 am)
Dear Rockman, regarding your engine light. I Own a 2004 Chevy Tahoe Z71. My engine light came on once since I've own it. I was towing my trailer and going down hill on a country road. I had the transmission in 2nd gear so I wouldn't have to use my brakes that much. I must have been lugging the engine, because I think it backfired on me. It was hard to tell with the beifed up exhaust on the Tahoe. I noticed the engine light was on. It did however after a couple of days finally go off. When I got home from my vacation I plugged my analizer into the port below the steering wheel. I bought the analizer at Auto Zone some time ago. After I plugged it in and had it read the codes it came back with 3 codes. So I wrote them down and then pushed the reset on the analizer to erase the codes. They all erased because the problem had corrected itself. I looked up the codes and they were all saying low octane level. Just in case your not familiar with octane, it's the difference in fuel. I use 87 octane or just the plain unleaded fuel. That is all this vehicle requires, 87 Octane. So the engine light came on because I was lugging my engine towing my trailer in 2nd gear downhill. This could have been your problem, low octane. The easiest and cheapest way to find out why your engine light came on is to plug the analizer into the port below your steering wheel. They aren't cheap, but Auto Zone will let you try one for free in front of their store. They are as simple to use as tying your shoes. Just plug it in, just like plugging in a lamp. The only difference is the plug end. Then push a button that says read. It will return on the screen either No codes found, which means everything is ok, or list codes found, which will tell you in the book that comes with the analizer what the codes mean. It saves Mechanic bills which could be hundreds or even thousands of wasted dollars and takes the guessing out to try and figure out the problem. I hope this helped.
#6057 of 6471 Re: 01 Tahoe [johnny4016]
Sep 16, 2006 (10:58 am)
Dear Rockman, regarding your engine light
That was good information you posted Johnny but I was not the one with the engine light problem.
#6059 of 6471 Re: Check your intake manifold bolt tightness. [arrie]
Sep 18, 2006 (5:48 am)
Just a reminder...this type modification will give your dealer ample reason to void any existing warranty.
Finding all 10 intake manifold bolts loose probably means someone worked on the engine...who didn't tighten the bolts according to GM specs. Inexperience no training, or plain just forgot...is the likely cause.
Most intake manifold leaks are easy to detect. They produce a high pitched whistling sound. Air rushing into the leak opening causes the noise. An experienced mechanic will pick that up very quickly.
#6060 of 6471 Re: Check your intake manifold bolt tightness. [rspencer]
Sep 18, 2006 (8:47 am)
An 'experienced mechanic' at my dealer did not pick it up while the vehicle was under warranty and yes, it did make a high pitched whistling sound just like you suggested.
Replacing intake manifold fastening bolts with a better design might give this dealer what ever reason to void warranty. Well, it is well beyond their warranty and it doesn't matter any more.
Tightening the manifold bolts and changing it to an arrangement that really makes the gasket tight actually helps to maintain the engine since it keeps unfiltered air from entering in the engine.
Just a detail from this all. When I first purchased my '04 Tahoe it gave me 17 MPG fuel economy on interstate highway. It gradually went worse and after about 1500 miles my fuel mileage really went bad to about 13 MPG during same driving conditions that first gave me 17 MPG. When I complained about this the dealer said it will get better when the engine is broken in. It just did not happen.
At that time I also noticed the whistling sound, which actually sounded like a radio sometimes does when it picks up disturbance from the alternator. Sound did not go away when I turned the radio off.
My dealer could not find where the sound was coming from and since the computer did not set a code they said nothing is wrong Even when every body could see that my Tahoe's tail pipe was as black as an old junk burning a gallon of oil per 1000 miles. And my truck didn't burn any, nor does it now. Tail pipe now is clean though.
I seriously recommend anybody who has a Chevy truck with the plastic intake manifold to check the tightness of the fastening bolts. It is very easy to do and I'm sure there are plenty of them with the same problem.
And I can assure you that nobody worked on My Tahoe's manifold bolts before I found them loose. They just vibrated loose during those first 1500 miles, which can happen to anybody as they might just have an improperly calibrated tool where the engines are built. My truck was built in Arlington, TX. I don't know where the engine comes from.
What comes to GM warranty, you can wipe my a.. with it. They even advertise 100 000 mile powertrain warranty now. What good is that when they dont respect it when it is only 36 000 miles long?
I don't believe I'll buy another GM made vehicle again. I don't think that someone, like me, who spends almost $40 000 to get his hands on one of their vehicles should receive treatment as I have during warranty period.
I already bought a new Chrysler Pacifica for my wife instead of a Chevy Trail Blazer as I first had thought. I traded in the '01 Pontiac Grand Am.
Pacifica seems to be very solid car and when it is time for me to get another vehicle a Pacifica it will be, unless they screw up like Ford and Chevrolet already have. In that case I just have to give up and go with people who don't treat their customers as junk after the point of sales has taken place. Those folks come from across the big water...
#6062 of 6471 Re: Check your intake manifold bolt tightness. [arrie]
Sep 19, 2006 (11:04 am)
I decided to check my manifold bolts after reading your message. They were loose, from 1/8 to 1/4 turn. I couldn't check a few because I don't have a deep socket. I was surprised that they were so loose. My engine has never been worked on. I was also surprise that the intake is plastic. Do you have an opinion on the plastic intake manifold? Should it be replaced with a cast iron or aluminum? Or is the plastic better?
#6063 of 6471 Re: Check your intake manifold bolt tightness. [johnny4016]
Sep 20, 2006 (11:57 am)
Your intake manifold bolts being only 1/8 to 1/4 turn loose is really not that bad. Mine were almost two full turns on every bolt.
About the material, an aluminum or cast iron would be better. Reason for this is that metallic materials are much stiffer and keep much better pressure on the gasket between fastening bolts than what plastic does.
Also, plastic manifold easily is warped, like mine is, which can cause problems with sealing especially when the fastening bolt design is that stupid one what it is like I explained in my earlier post.
I don't think you can just replace the plastic intake manifold with different material one, but perhaps it is possible.
Plastic is better ONLY for the vehicle maker as it is cheaper to produce. It is not better in any way for the end user like you or me.
#6065 of 6471 Before you squawk about rights
Sep 20, 2006 (7:04 pm)
Remember we are all guests on these forums and pay nothing for the privilege. As the owner and provider, Edmunds has the right to edit and/or delete postings that do not conform to the user agreement.
And yes, I have had some of my comments removed in the past.