Major Maintenance coming up, what else should i address?

[Steveinfl]

Hello Everyone,

Turns out the storm brought nothing but weak thunderstorms to Central Florida. I ended up searching around on amazon and pricing out replacement parts.

-The vehicle is a 2003 LT 4.2. Only modifications currently are cosmetic the hollowing out of the air box. 82K miles

I am driving to visit a friend in Boston towards the end of the year and figured its just time to catch up, and do some preventative as well. Past maintenance has been good, here is a summary:

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Date Odometer Provider Work Warranty

8/11/2005 22,232 Holler Chev Brake fluid flush
Injection Clean


2/12/2007 34,419 Mobil Lube Power Steering Flush
Belts: Poly Rib Belt

7/12/2007 37,083 Holler Chev Fan Cluth replaced


4/18/2008 41,833 Mobil Lube Air Filter


6/9/2008 42,641 Firestone 4 New Tires
Tire Rotation Lifetime Rotation & Alignment Service


5/27/2010 59,485 Firestone replaced CAM position senson
replaced thermostat
Did TWICE (see below) replaced upper/lower radiator hoses
Coolant Flush W/Sealer - Antifreeze Good for 50,000 miles


6/25/2010 60,416 Firestone AC - blower motor resistor

fluids change at 60,000

10/28/2011 72,600 OIL CHANGE, fuel filter, cleaned throttlebody, spark plugs, techron, tire rotation


4/26/2012 78,200 OIL CHANGE, fuel filter, techron, tire rotation, new brake pads and rotors, FLUSHED brake fluid, changed differential fluid


NOTES: I took ownership of the vehicle in 2011, immediately performed the services shown starting 10/28/2011. The rear diff oil was disgusting and changed when I noticed it intermittently locking up. The coolant was the wrong color and I am still running several (no more than 214) degrees above normal when in stop and go. I modified the weather stripping significantly and cut the noise down some, it is still a loud vehicle above 75 on the highway. I need to commandeer an assistant and complete the brake flush, very little luck with the one person vacuum kits. I will try a bleeder bottle next. I feel but have not verified that I have a weak fuel pump, it is the OEM unit. It is either a weak pump, broken check valve or potentially malfunctioning FPR. I am unsure how to test the pressure past the main line schrader valve, as in past the FPR. Vehicle otherwise runs very well, I am nit picky and notice every little thing which is off. I realize that there are certainly other things which need to be changed. These include all suspension components, bushings, motor mounts, trans pad, still on OEM wheel bearings, more than I care to think about or list.


The following list is what I have tentatively planned for the next several weeks. If there are any other jobs I should do while I have things apart please let me know. I tried to consider as much of it as I could already.

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Cooling Related

1. Fan Clutch 15-40133 ( or EFAN, open to suggestions)
2. 4069015 Gatorback serpentine belt
3. bosch 96166 water pump (competitive to the delco unit in price)
4. stant 14695 thermostat
5. 213963 Coolant temperature sensor
6. 12573024 Drive belt tensioner assembly
7. Idler Pulley 15-20679

Fuel

1. MU1837 Fuel pump module Delco
2. 217-1445 Fuel pressure regulator
3. gt276 Fuel Cap (current one doesn't always pass pressure test)
4. 213-1551 front oxygen sensor ( so many part numbers for this, is this the right one?)

Other Miscellaneous

1. Fuel, oil and trans filter change
2. 5 Gallons of trans fluid so I can change the fluid myself according to our writeup. ( I am going to attempt to use a drill operated pump for fresh fluid while it pumps out)
3. Spark Plugs just because
4. Air temp sensor for intake
5. Map Sensor? (does this wear out)
6. CPAS- I am unable to find a part number here. I think amazon just doesn't carry the OEM part, just dorman which I will not use.
7. Go to a junkyard and buy a handful of ignition coils for spares and replacements. Is there a good way to bench test them with a 12v power supply?

I am not necessarily looking for a how to on these items, just if there is anything else that I should consider. The vehicle used to take many short drives, I drive farther usually than the previous owner but it is still a city vehicle. My mileage has declined steadily, I average ~11 in the city ( not awful considering my right foot) and 17 on the highway ( at reasonable speeds). Techron treatments with each oil change have not improved this. The average driver would not even notice these little things, they are minor. I just can't help but notice the gremlins, as is the case for most of you.

Thanks and War Eagle

 

[MAY03LT]

I feel but have not verified that I have a weak fuel pump, it is the OEM unit. It is either a weak pump, broken check valve or potentially malfunctioning FPR.

I would expect to see lean fuel trims at the very least. IIRC the threshold for setting a lean code is 25%. Do you have any data to confirm your suspicions?

I am going to attempt to use a drill operated pump for fresh fluid while it pumps out

This is relevant to my interests. Are you planning on pumping in through the cooler line?

Go to a junkyard and buy a handful of ignition coils for spares and replacements. Is there a good way to bench test them with a 12v power supply?

I wish there was! I bought all my spares off of ebay. I install them in mine for testing, then pull them out and have them sit on the shelf where they wait for their big day.

 

[Steveinfl]

I would expect to see lean fuel trims at the very least. IIRC the threshold for setting a lean code is 25%. Do you have any data to confirm your suspicions?



This is relevant to my interests. Are you planning on pumping in through the cooler line?



I wish there was! I bought all my spares off of ebay. I install them in mine for testing, then pull them out and have them sit on the shelf where they wait for their big day.

Hey thanks for the reply and your videos as well. I fully intend to bring the laptop to the garage when I start tearing things apart. I do tend to run a little bit lean according to the OBDII scanner I have ( a cheap one but it gives me the basics). I don't believe I cross the 25% threshold. What I have noticed is when in neutral or park I can watch my cam advance run up to the high teens cyclically followed by a leaning of the fuel supply and an idle drop to ~590. My idle in both neutral and park is about 615 +- 30. It never stalls, throttle body should be clean, I am hoping this is sensor related and will clear itself up. I'll try to post a video of this tomorrow. I believe the fuel system has a fault because once the truck sits for an hour plus I need to prime the fuel system 4 times (the magic number) before it will start. It will crank immediately but not start unless I have primed it several times. Meanwhile I can drive from Orlando to Miami at 80 without a noticeable fuel supply issue. This has been the case ever since I changed my fuel filter the first time. I replaced the fuel filter thinking it may be faulty, and it is impossible to install backwards. I have attempted to confuse the FPR by disconnecting the vacuum hose connected to it and did not observe any idle RPM change whatsoever. I'm not sure if this indicates anything or not.

As per the transmission fluid pump I hadn't yet thought of where I would connect it. That is a great idea to hook up to the cooler return line. I had initially thought to run a small tube into the dipstick and pump it in there. I'm going to visit a local industrial salvage store and see if I can find a more suitable pump as the drill pumps are rather low flow.

I suppose I will just get a couple extra and try them as necessary regarding the coil packs.

* The only thing that will be OEM in the vehicle and probably ought to be replaced is the ignition switch. I have read many horror stories here and mine has been working for almost a decade. Might not hurt to pull it out and replace.

 

[Steveinfl]

Slight delay on video. My laptop shot out a poof of smoke the other night. I guess 220 degree core temp is too high. Building a new rig in the next few days.

 

[The_Roadie]

... I have attempted to confuse the FPR by disconnecting the vacuum hose connected to it and did not observe any idle RPM change whatsoever. ...

I've seen idle jump to 900 RPM when that hose is off. I'll try mine by tonight to confirm.

 

[Steveinfl]

I'm sure you are right Roadie. I just remember reading somewhere in the forum about people experiencing a change in rpm due to that hose being broken or disconnected. Just got back from Compusa and spent entirely too much. A powerful desktop shall take shape shortly.

 

[Steveinfl]

I apologize for where this came from but I had to find the post about 900 rpm. Coincidentally enough it came from the Roadie himself.

 

[Steveinfl]

Sorry it has been a while. Took a while to find the time to change out those parts.


- After installation of new belt, tensioner and idler pulley the squek stopped. It was very, very tight to get on and all parts were correct.

-Replaced upstream 02 sensor. ~1-2 mpg gain. It is mostly city driving for me, will see about highway soon enough.

At this point the vehicle was running better but the rhythmic hiccup was still there.

- Replaced the CPAS (which looked intact as far as the screens go, but was most definitely leaking oil. )

Running better!! (not perfect)

-Replaced fuel pump (surprisingly easy with two people and the right tools, ~3 hours start to finish)

No longer have to repeatedly prime the fuel pump to start in the mornings.

So over all it is running much better, that said it only ever stalled once. There is still a slight rhythmic "tick" or minor stumble that isn't discernible to most. It is noticeably worse when cold then up to temp and goes away in neutral. My next step is purchasing a transmission cooler, a 5 gallon pail of dex6 and the appropriate fittings. Now that I have a good mechanic that will help me on weekends and charges less if I help. The right tools really make things easy. I am hoping that a filter change, extensive flush and clean will resolve that. To my knowledge the transmission fluid was changed at 50K and the truck is at 83K as of now, so it should be a non issue but that is the next step.

Questions:

• Any Objections to my thought process?
• Should I run a product through the transmission prior to the flush and fill?
• Any particular type of cooler better than others, I am looking at the self regulated trucool LDP series?
• What size cooler should I use / Can I fit?

As always thanks in advance.

When I do the transmission flush I fully intend to rig up some way to fill through the drain pan (weld in a bung) as it pumps out the cooler exit line. I will post a write up whenever I can get to it in the next month. Thinking about using gravity, a 5 gallon pail and a simple gate valve with some clear hose .

 

[tblazerdude]

can someone post a picture of where the FPR hose goes into the manifold if you do not have a factory intake? IE aftermarket or DIY intake where the resonator is deleted? I can post a picture of mine, but I believe it is connected to the throttle body resonator. Will do it later. This high idle topic on 2004 TB's is becoming a recurring theme here.

 

[CaptainXL]

Nice work. I commend you on your preventative maintenance skills. Don't forget to replace the fpr and fuel filter. Run some fuel system cleaner while your at it.

I wish there was! I bought all my spares off of ebay. I install them in mine for testing, then pull them out and have them sit on the shelf where they wait for their big day.

Haven't been to a junk yard in a while. Are these types of engine pieces for our vehicles normally gone? What is typically left?

 

[tblazerdude]

I took some photos to double check I have my vacuum hoses hooked up right. Does this look correct?

View attachment 23577

 

[CaptainXL]

Where is your fpr hooked up to? It should be connected before the throttle plate and not afterward at the intake plenum. Looks like that smaller hose at the bottom might be going to the fpr which is wrong. Put a rubber grommet where that black piece of tape is covering that hole and connect the fpr hose to it. Should be golden.

 

[tblazerdude]

Look here for a closeup of the FPR hose. http://gmtnation.com/f24/intermittant-900-rpm-idle-p0171-code-reduced-fuel-mileage-5449/ I thought the FPR needed true vacuum? (where it is hooked up now) If I hook it up to the intake tube pre-throttle body (the black tape hole) I feel there will be very little suction, except maybe when at WOT.

 

[CaptainXL]

Here is where the fpr connects. It seems odd but it's true. So yes, in response to your observation you only need the vacuum to pull at wot because thats how it works. It pulls the fpr diaphragm to allow more fuel volume.

You are running rich yes?

View attachment 23579

 

[tblazerdude]

no codes, but the exhaust does smell a little rich. The strange recurring issue was the 900 rpm idle. I will move the hose.

 

[CaptainXL]

no codes, but the exhaust does smell a little rich. The strange recurring issue was the 900 rpm idle. I will move the hose.

High idle is probably from a bad fpr that is allowing extra fuel in past the diaphragm. I would replace it if it's leaking fuel.

 

[The_Roadie]

can someone post a picture of where the FPR hose goes into the manifold if you do not have a factory intake?

Answered in the other thread you asked in.

 

[CaptainXL]

Bill. I was helping this guy out and you go ahead and post the same thing. I'm not gonna post anymore if you insist on butting in and stealing people's hard won efforts at helping others out I feel like I don't even need to post because you just reiterate after everyone else.

 

[The_Roadie]

Sorry you feel that way. I thought I added information to the other thread about the reason behind the system's design. But the issue was being discussed on Trailvoy for many years.

 

[CaptainXL]

Sorry you feel that way. I thought I added information to the other thread about the reason behind the system's design. But the issue was being discussed on Trailvoy for many years.

Ah. No biggie. I understand.

 

[tblazerdude]

Sorry for duplicating questions, it wasn't intentional. I simply forgot which thread I said I would post the pictures. It was partly for my reference but also for the gentleman who started the thread. Both are useful. Cap'nxl just answered my question over here first, possibly helping the person who started the thread as well. Everybody play nice. (-: