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DyerWolf
2007-Mar-14, 08:35 PM
I've owned two cars in my life: a carbureted 1975 Chevy Blazer and a fuel-injected 1997 GMC Yukon. Both 4wd and V-8. I used to do all the maintenance on the Blazer, but since buying the Yukon, there's not much I can do - aside from changing the oil and filters regularly (which I've done religiously).

Aside from things breaking (poorly designed fuel pump suicidally overheats on these models) the Yukon has been hassle free. I DO NOT trust dealerships to give good advice / fair price (Dealerships try to slither out from under parts and labor warranties by claiming poorly installed parts are a "workmanship" issue (not a labor issue) and thus not covered under the warranty.)

Anyway, the Yukon is supposed to have a 100 k engine.

Well, I just passed the 100k mark . I know I need a new serpentine belt, and figured while I'm at it, I probably need a tune-up.

Thing is: what does that entail with these new engines?

Do I need new spark-plugs only? Should I replace the ignition wires? Rotor? (Do these new electronic ignition engines have rotors?)

Suggestions?

BTW - I've tried googling, and get TONS of useless info. Hoping to find an auto enthusiast who knows the answer(s) or can point me to a reliable GMC/Chevy board.

TIA

Larry Jacks
2007-Mar-14, 08:54 PM
I think it's probably a good idea to replace the plug wires and the plugs at the 100K mark. You might want to consider replacing your hoses and belts. They may look fine but they're 10 years old and could let you down.

Other things to consider are replacing your fuel filter and transmission fluid, lubricating the chassis, and checking various seals to see if they need replacing.

Donnie B.
2007-Mar-14, 08:59 PM
You could call the Tappet Brothers for advice...

Actually, is there an independent mechanic you trust? He or she would probably know what the typical trouble spots are on that particular make and model.

If all else fails, you could pull out your owner's manual and see what maintenance items it recommends for various service intervals.

ciderman
2007-Mar-15, 02:12 AM
Despite never previously hearing of the Tappet Bro's I would otherwise endorse the good sounding advice above.
Glad to hear you've kept up with the oil & filter changes, that's the big thing IMO.
At that mileage it would be nice to get it into a big dealer with lots of dianostics to plug in to monitor all sort of dohickys regarding combustion & stuff, & then alter the injection settings for 'correction' (may be more biased for emmissions than getting it producing power these days)
Would be nice to get in touch with someone who has access to such technological wonders but is ameanable to a set up which is not by the book;)
This used to be a lot easier with good ol' carbs, as I'm sure you know(colortune anyone:D)

Really must agree with changing the plugs & leads though. I've used expensive platinum/palladium electrode plugs in m/cycle engines for some years now & would recomend them(nice thin electrodes for a better charge density & better spark, or so the theory went..).

Jeff Root
2007-Mar-15, 02:34 AM
I know little about cars. Why do ignition wires need to be replaced?

Larry, what parts of a chassis would need to be lubricated?

-- Jeff, in Minneapolis

Maksutov
2007-Mar-15, 02:50 AM
I know little about cars. Why do ignition wires need to be replaced?

Larry, what parts of a chassis would need to be lubricated?

-- Jeff, in MinneapolisAfter a while, having been exposed to heat/cold, wet/dry, oily, etc., conditions, the insulation starts to break down and the high voltage finds its way to places other than the spark plug gap.

Chassis lubrication depends on what's available re grease fittings. Most current vehicles have "permanent" sealed lube points for ball joints, etc. About the only thing I ever lubed on my FWD Olds was the CV joint covers, to make sure they didn't dry out and crack. They lasted 263,000 miles.

publius
2007-Mar-15, 02:59 AM
The days of shade-tree mechanicing where you just go by your gut are pretty much over. Computer controls are getting very sophisticated. If you want to do your own, you're just going to have cuss and invest in a code-reader/scanner at the very least.

I broke about two years and bought a $300 Auto-Xray OBDII/I scanner. You will be amazed at all the data the system's computer can give you with the proper tool. And the system has a self-diagnostic mode that such a scanner can initiate and tell you all sorts of good stuff.

And if you get one of the good OBD scanners be careful. Me, when I first got it, I was like a kid in a candy store watching all the data channels I had -- RPM, timing advance, manifold air pressure, air flow, O2 sensor output, calculate engine load, fuel delivery, etc, etc. I plugged into my '01 CV, got out and did some extended WOT (wide open throttle :) ) just to watch all that data.

Then it hit me that I was doing 95MPH on a two lane road, looking down and fidling with that scanner's display........ bad business indeed.

Plugs, wires, belts and hoses are a good investment at 100K. A PCV valve is also a good idea. You have checked your brakes, too haven't. With my driving, the front pads usually are about gone around 70K, but I get over 100K out of the rears.

Whether it has a rotor or not depends. "COP" = coil on plug is something they've been doing lately that eliminates wires entirely. My '01 Crown Vic has that. My old '93 Crown vic has the "coil bank", with no rotor -- the design there is rather interesting. You've got two HV coils essentially in series through two plugs on "opposite cylinders". That is the pair of cylinders where when one is coming up on the compression stroke, the other is at the same stop on the exhaust stroke. The thing actually fires twice per cycle, once on the compression, which is the one you need, and another one on the exhaust that's superfluous.

That can actually trip you up trying to detect a misfire with a timing light. The thing may fail or be marginal on the compression stroke on one cylinder, but spark fine on the exhaust, and you'll see that flashing your light.

Besides that, cleaning out some critical sensors can be desirable as well. My Crown Vics have a "MAF" (Mass air flow) sensor in the intake box behind the air filter that is responsible for detecting air flow, which is one of the inputs the computer uses to decide how much fuel it should shoot for. Those things can stand a good cleaning every once in a while.


-Richard

DyerWolf
2007-Mar-15, 01:56 PM
Thanks all for the advice.

I was a fair shade tree mechanic back in the day, and enjoyed crawling into (you actually could) the engine compartment to work on my Blazer. Now I can hardly fit my hands into there with all the emissions and other paraphernalia crammed under the hood (resulting in a MASSIVE 5 mpg improvement < 15 vs 10 > over the '75...).

I've taken care of what I can - brakes checked regularly, pads and shoes changed as needed (lead foot + mountain driving). Tires rotated regularly, etc. Overall, its a good truck, and I intend to keep it that way.


If all else fails, you could pull out your owner's manual and see what maintenance items it recommends for various service intervals. The user's manual and the Chilton's guide weren't as helpful on what should be changed / checked. The mfr has an interest in keeping its dealerships cashflow coming; Chiltons' presumes you already know what you want to change...


Then it hit me that I was doing 95MPH on a two lane road - In a Crown Vic, folks probably assumed you were a cop and got out of your way...

Haven't thought about the computer analysis aspect. Wonder where I can get that done, short of buying a comp.

I figure I can replace the plugs and wires.

Hoses - well it almost looks like you need to drop the engine to get in there... maybe I'll farm that out to a local mechanic if I can find one with a good rep.

Anything weird to look out for with the new pink radiator fluid?

publius
2007-Mar-15, 07:07 PM
- In a Crown Vic, folks probably assumed you were a cop and got out of your way...

Haven't thought about the computer analysis aspect. Wonder where I can get that done, short of buying a comp.

I figure I can replace the plugs and wires.

Hoses - well it almost looks like you need to drop the engine to get in there... maybe I'll farm that out to a local mechanic if I can find one with a good rep.

Anything weird to look out for with the new pink radiator fluid?

Well, I live out in the country, and *luckily* there wasn't any traffic. Now, there were some driveways where someone could've pulled out at any time, and I shudder to think about it. Easy to get carried away with stuff like that.

You can get a decent "code reader" fairly cheap, but a full scanner will cost some bucks. A code reader will tell you the fault code that trips the "idiot light" (Check Engine). Well, it tells you what the computer doesn't like. Whether that is really the problem or just a symptom is something else entirely.

Many autoparts stores will "read codes" for you, but keep in mind they like to sell parts, and if a code points to some particular sensor, they'd like to sell you one.

The sophistication of the computer and it's diagnostics are ever increasing. My '01 CV and '04 F-150 have loads of data in there. As it's running, it runs a variety of diagnostic routines on schedule, and then stores the results. Some abnormalities will not trip the idiot light, but they will be noted and stored.

For example, it keeps a running "misfire" count. The sophistication blows my mind. It uses the crankshaft position sensor to detect misfires. If an engine is running normally, you get a certain accleration profile (that's how accurate the sensor is). Each fire produces a little beat of acceleration, and it can detect a missed beat. Mechanical noise can be filtered out of the signal (ie you hit a bump in the road and that causes variation in crankshaft velocity).

Anyway, with my OBDII reader, I can see how many misfires it registered. I noticed that on my '01 CV, two cylinders, the ones on the left rear would consisently register a few misfires -- it was well below the threshold to worry about, but the other 6 showed no misfires. The reason for that, I learned, was those cylinders are a "hot spot" in the heads due to the way coolant flow works. :)

Finding information on just what some of all that data means is also difficult -- they don't like you learning too much. :)
-Richard

Larry Jacks
2007-Mar-15, 08:58 PM
Now I can hardly fit my hands into there with all the emissions and other paraphernalia crammed under the hood (resulting in a MASSIVE 5 mpg improvement < 15 vs 10 > over the '75...).

Look at it this way, going from 10 MPG to 15 MPG is a 50% improvement. That isn't too shabby, especially when you consider that the old vehicle probably had emissions at least 100 times as bad as the newer vehicle. To improve mileage by that much (and in some cases, power is also increased) while reducing emissions that much is a pretty remarkable engineering achievement. Unfortunately, to do that, they had to add a lot of complexity such as fuel injection, catalytic converters, oxygen sensors, and the like. I don't think it's even remotely possible to get those numbers using carb technology.

DyerWolf
2007-Mar-15, 09:48 PM
Look at it this way, going from 10 MPG to 15 MPG is a 50% improvement. That isn't too shabby, especially when you consider that the old vehicle probably had emissions at least 100 times as bad as the newer vehicle. To improve mileage by that much (and in some cases, power is also increased) while reducing emissions that much is a pretty remarkable engineering achievement. Unfortunately, to do that, they had to add a lot of complexity such as fuel injection, catalytic converters, oxygen sensors, and the like. I don't think it's even remotely possible to get those numbers using carb technology.

True. We got 25 good years out of that truck. It ran on regular gas, which after a while you could only get in Oregon and Nevada, then, nowhere, then it ran on unleaded just fine. It would also go just about anywhere. Felt a lot more rugged than my new one; also had a rollbar, Lo-Fi AM Mono, 2-55 AC and the heater fan never turned off, but you had to break something to get it stuck.

Wife 1.0 is much more compatable with the new truck, however.

DyerWolf
2007-Mar-15, 09:51 PM
The sophistication of the computer and it's diagnostics are ever increasing. My '01 CV and '04 F-150 have loads of data in there. As it's running, it runs a variety of diagnostic routines on schedule, and then stores the results. Some abnormalities will not trip the idiot light, but they will be noted and stored.

For example, it keeps a running "misfire" count. The sophistication blows my mind. It uses the crankshaft position sensor to detect misfires. If an engine is running normally, you get a certain accleration profile (that's how accurate the sensor is). Each fire produces a little beat of acceleration, and it can detect a missed beat. Mechanical noise can be filtered out of the signal (ie you hit a bump in the road and that causes variation in crankshaft velocity).

Anyway, with my OBDII reader, I can see how many misfires it registered. I noticed that on my '01 CV, two cylinders, the ones on the left rear would consisently register a few misfires -- it was well below the threshold to worry about, but the other 6 showed no misfires. The reason for that, I learned, was those cylinders are a "hot spot" in the heads due to the way coolant flow works. :)

Finding information on just what some of all that data means is also difficult -- they don't like you learning too much. :)
-Richard


Can you get realtime data?

I've always lamented the limited tell-tales available on cars (rpm, temp, oil pressure, engine light) and wish I could see what's going on when the engine decided to make a funny sound or give off a funny smell.

publius
2007-Mar-15, 11:23 PM
Can you get realtime data?

I've always lamented the limited tell-tales available on cars (rpm, temp, oil pressure, engine light) and wish I could see what's going on when the engine decided to make a funny sound or give off a funny smell.

Yes, you can get real time data with the proper scan tool. Basically, spend more money and get more data. The manufacturers have properitary data streams (heck, the interface defintions and formats are a subject unto themselves. Law forced them to standardize on one common interface, OBDII ('95 or '96), and required a certain standard data set be made available). But there are loads of manufacturer specific stuff in addition to the basics, and you can pay extra for the tools to get that stuff.

They make stand-alone scanners as well as software/interface hardware for laptops, PDAs, etc. If you've got a laptop, that's the best route.

Now, besides standard stuff, there's a culture of hacking out there too, where hackers go in and try to decipher secrets. One thing is reprogramming the basic alogorithms. There's been a replacement ROM chip market out there, but many of the newer systems apparently have a (secret) way to actually re-program them via the OBD-II interface. But that's a whole world unto itself. Some directed Googling will find the door to that world.

I've been out of my redneck hotrod phase for years, but if I had the stuff that's available now back then, woooo boy, I could've had fun (and spent money too).

For example, Holley now makes custom fuel injection systems that are completely computer controlled. You can customize everything with your laptop, going down the road and watching all the data in real time and adjusting fuel-trim/ignition and other parameters on the go. Basically, the system has an algorithm where the basic game is calculate how much fuel we need to spray in for the current inputs. You can program that to your heart's content with stuff like this.

Get into the hacking, and you may be able to do that with stock systems, depending.

Yep, I probably would've killed my fool self and spent wads of money doing it back in my day.

-Richard

JohnD
2007-Mar-15, 11:29 PM
DyerWolf,
Dump that modern piece of rubbish and get yourself a classic car!
You can take apart every nut and bolt, and re-assemble, without a special tool too!
You'd call these LBCs, Little British Cars - http://www.totallytriumph.net/cgi-bin/dcforum/dcboard.cgi - but there are plenty of US cars of the same vintage out there.
Ban electronic ignition! And have more fun!

John

publius
2007-Mar-15, 11:43 PM
Oh, with Ford's old OBD-I systems (various early EEC generations), there used to be a seat of the pants way to read diagnostic codes and put the system in self-test mode. Basically you hooked up a 12V light, grounded a pin as an input signal. It would flash out info via the light -- you counted flashes to get the code number. A scan tool can get it much faster of course, by signalling the system. But they had that very manual way of it doing it.

But with the standarized OBD-II you've got to have a scan tool.

Again, if you're interested in doing your mechanicin', these things are a must.

And it's just fun to watch all that data, too. My '04 F-150 has "fly by wire" throttling. There is *no mechnical connection* to the throttle plate at all. The computer controls throttle position via a servo motor. The gas pedal is simply connected to a position sensor that gives the computer a "how much oomph does the user desire" input. :lol: That allows the computer to much better control engine operation by putting the throttle at the optimum position.

I did not like that at all at first, pretty leery of it, thinking about a WOT failure. But after reading, there's enough redunancy in there that a WOT failure is supposedly impossible. Well, no more likely that a stuck mechanical throttle linkage. It has a sanity check parrallel routine for safety as well: say the main system has decided the throttle needs to be wide open. THe sanity check routine will look at other inputs. For example, if the user has his foot on the brake while that is going on, or the gear shift is in neutral, that would be an indication that something is awry. :)

Anyway, I watched all that data in real time with my scanner. Take a WOT throttle start off. Well foot pedal to the floor start off. THe system will not open the throttle wide instantly -- no need for that rapid transient drop in manifold vacuum requiring an "accelerator pump" style shot of extra fuel from the injectors. Open it fast, but not too fast.

Now, when the transmission is about to shift (which it controls as well), close down on the throttle during the shift to help get it from jerking.

With my scanner in data collection mode, I made a WOT start off, got up to about 80MPH or so, then went back on and looked at the data streams vs time. I had throttle position vs time, seeing the computer close the throttle during the gear shifting. Torque (calculated) vs time.. speed vs time, air flow, RPM, fuel trim, etc, etc.

You can go to town. Speed vs time was interesing. You can see the "stepping" of acceleration as it runs through each gear.

-Richard

JohnD
2007-Mar-16, 05:21 PM
Aaaaaaaaaaaaaaagh!
Publius! What's your right foot for? Throttle and brake!
Why want an electronic idiot between that and the pedal?
Even one that has a "sanity check routine"?

Don't listen, DW, this way lies insanity.
Get those cubic inches under YOUR control!

John

publius
2007-Mar-16, 06:21 PM
Aaaaaaaaaaaaaaagh!
Publius! What's your right foot for? Throttle and brake!
Why want an electronic idiot between that and the pedal?
Even one that has a "sanity check routine"?

Don't listen, DW, this way lies insanity.
Get those cubic inches under YOUR control!

John

Resistance is futile, you will be assimilated. Fly-by-wire is the way they're going and you might as well get with the program. Heck, the brake may soon be electronic. That scares me to death more than the throttle, but as it is now, with most of the anti-lock systems, the computer could go crazy and block off and even bleed off all the pressure to the cylinders no matter how hard you were depressing the pedal.


Which reminds me, if you ever need to bleed out one of the modern anti-lock systems, you'd better read up on it, because it is complex. You can really screw one up trying to do it the old fashioned way. Some of the anti-lock systems have a dedicated computer of their own, with its own diagnostic interface and all that. And they are not too forthcoming with the info on how to do it. IIRC, on some of them, you've got to go through complex procedure with the control unit to bleed it.


The reason for all this is just tighter control of operation which is required as emissions and fuel economy standards get tighter and tighter. By letting the computer control the throttle plate angle, they can achieve better control of the operating "envelope" of the engine.

The only problems with the electronic throttle that I've seen so far is sluggish repsonse -- the system doesn't respond when you step on it. That may happen, but it may just be a problem with how you expect it to behave.

For example, with my F-150, I noticed something with a load going uphill. I was going along, speed had dropped some, and I pressed the gas down a little more. No immediate response, so you end up pressing it down more than you normally would. It doesn't feel right. Now, what is happenning there, is the computer had actually been opening the throttle plate *on its own*. It was noticing the same increasing load conditions and was already adjusting for it somewhat. You notice the same thing, but with a little time lag, which causes that feeling that it is not responding like a regular throttle control.

-Richard

JohnD
2007-Mar-16, 08:53 PM
Publius,
I understand everything you say - my modern road car has a fly-by-wire throttle, which is un-nerving on cruise control as the pedal doesn't move when it meets a hill.
But said cruise control sets a speed at, say, 60mph, while the speedo shows 58-65mph. Which am I doing? Which do I blame for the speeding ticket the officer is about to give me?
But I can judge my speed by the NOISE of my race car engine.

Old technology rules!

John

publius
2007-Mar-17, 03:11 AM
Publius,
I understand everything you say - my modern road car has a fly-by-wire throttle, which is un-nerving on cruise control as the pedal doesn't move when it meets a hill.
But said cruise control sets a speed at, say, 60mph, while the speedo shows 58-65mph. Which am I doing? Which do I blame for the speeding ticket the officer is about to give me?
But I can judge my speed by the NOISE of my race car engine.

Old technology rules!

John

The pedal doesn't move on mine either with cruise control -- that was strange at first. You know, all the cruise controls have a range there, and I think the actual design behavior varies -- sort of what whoever happens to be in charge thinks is the best way.

My '93 and '01 Crown Vics (wait a minute, you're across the pond so these models probably aren't any more familiar to you than yours are to me) cruise control is just a parallel throttle cable to the throttle body. They have port injection, and the throttle body just sits on top -- it points foward on the '93, but sits sideways on the '01. The cruise control is a vacuum operated doohickey off to the side, through which the speedometer cable goes.

I'm not sure, but I think the computer uses a separate speed sensor, maybe the same one that the anti-lock brake uses. The OBD-II interface spits out a speed reading, and that comes from the other. Now, what I don't know if the "fly-by-wire" F-150 actually uses the computer speed sensor, and not the regular speedometer. I'm not even sure if there is a separate speedometer system, come to think of it.

Anyway, the cruise control on the two Crown Vics has always been a "fast" for me, especially on the '01. It will downshift going uphill, and I don't like that. I'd rather let speed drop than do that, and I can actually get a tad better mileage with my own foot than the cruise control. I can do that, of course. Some others around here have feetsies that are much worse than cruise control. I tell them, become one with the vehicle, think and feel what it feels. They cannot.

The fly-by-wire is supposed to be as good as my own foot, though.

-Richard