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Discussion Starter #1
Just thought I'd get some outside insight on this one. My grandparents FINALLY decided to part with their 93 Roadmaster, and I'm the lucky new owner. It was purchased new in April 94 with 69 miles on it. Car now has a grand total of. . . .46,000 miles on it.

That's not to say it hasn't had it's share of issues. We've already dumped about a grand into shocks/springs, and another $1000 on injectors. Before the car would idle high and knock between 40-60 with very light throttle. Now it surges and stutters at idle as well. The transmission also started leaking a little bit sometime last night or this morning.

So at this point I'm torn. it's a 21 year old car. I'm absolutely in LOVE with it, but i'm not mechanically inclined, so I'm stuck depending on a mechanic. . . who may or may not even be familiar with more. . late model vehicles. Internally and externally she's in great shape. I've been digging around these forums for a week or so now, so I have a rough idea what MAY be wrong with it, but how much money is "too much" to dump into repairs for a vehicle that I'll NEED to be reliable?

Ultimately, I'm trying to discern whether my investment will yield me a relatively dependable car for the next year or three. Is it worth continuing to put money into it, or should I cut my losses and get what I can out of her?
 

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Please post a pic...These cars are for people who like to work on vehicles..You can get 200K miles out of them easy...Sounds like you need a better mechanic..$1K for injectors? Springs at that low of mileage? I doubt it...If it is not a rust bucket I would keep it and either do the work yourself or go to a wrench that it not ripping your off....Last GM Full Frame RWD car..For you fix it could be many little things...look at the EGR valve...
 

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Discussion Starter #3 (Edited)












Sounds like you need a better mechanic..$1K for injectors? Springs at that low of mileage? I doubt it...If it is not a rust bucket I would keep it and either do the work yourself or go to a wrench that it not ripping you off....Last GM Full Frame RWD car..For you fix it could be many little things...look at the EGR valve...
I agree, I DEFINITELY need a better mechanic... Their recommendation was to run mid grade gas in it for a month. My problem is I just don't have much experience working on these things, and I'm a little timid to attempt it myself.
 

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That is a nice car, sir! Hey- we all had to start somewhere when it comes to being "mechanically inclined". Better yet, make it known your location and I would guess that some forum member(s) live near you and would be happy to lend a hand. Does not matter so much that it is an old car!
 

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Looks great! No vinyl roof and cloth seats...the way I like them...if you have the time search the threads for your issues and you will find hints...have a mechanic check the EGR valve...As far as your original questions..These cars..Impala,Caprice, Fleetwood, Roadmaster of the 1991-96 years are some of the best cars GM ever made and can be the most reliable things on the road...They are "Old school" in a modern way and easy to work on. They were not cop cars and taxi's for no reason. Find an old honest mechanic (the good ones enjoy working on these cars) and he will fix your car up for many miles...or better yet do it yourself!!
 

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EGR is easy to test and change. It is mounted on the intake manifold with a little black vacuum hose going to it.
If it is not working properly it can cause a low throttle stumble.
The search on this site doesn't accept 3 letter entries, but it will take egr*.
To test the egr pull the vacuum line off and put a golf tee in to block off the black hose. If your problem goes away, change the egr.
Crawl under the car and look for the tranny leak. Could be on the cooler lines which are small lines going the side of your radiator.
Sounds like a nice car, I would keep it.
It should look like the black egr in this photo.
 

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Discussion Starter #8 (Edited)
EGR is easy to test and change. It is mounted on the intake manifold with a little black vacuum hose going to it.
If it is not working properly it can cause a low throttle stumble.
The search on this site doesn't accept 3 letter entries, but it will take egr*.
To test the egr pull the vacuum line off and put a golf tee in to block off the black hose. If your problem goes away, change the egr.
Crawl under the car and look for the tranny leak. Could be on the cooler lines which are small lines going the side of your radiator.
Thank you for this. Helps to know what I'm looking at. Will test and report back as soon as it cools down enough under the hood to get my hands in there.

Update: Had no issues finding the EGR, blocked off the hose, no change.
 

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What all did they do when the did the TBI Injectors? I can't believe they gave you the car back still running poorly after charging $1K.. Plugs and wires have been checked?? Distributor? Of course the cat convertor it known to plug on the single exhaust TBI 350's. Also has the Oxygen sensor been changed? Be patient and it will pay off...
 

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Discussion Starter #10
Replaced injectors, gaskets, new plugs, wires, coolant flush...

I was kind of shocked that nobody mentioned anything about the idle issues until I was ready to leave. They handed me the keys, told me it was "knocking a little" and that "running mid grade gasoline in it for a month should resolve the issue"

I still needed to get the headlight switch diagnosed [when you pull back on the stick it just sits there. . seems like perhaps a spring is missing] I figured I'd just take it up with them again today. Car has a follow up scheduled for Wed.

Speaking of which, if anyone has a suggestion for a good place to take this car in the Ft. Worth Texas area, I'd be very appreciative ;) .

Here's the issue in action:

https://www.youtube.com/watch?v=1zUDAn63Fw8&feature=youtu.be
 

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Yeah..Sounds like a bunch a lazy heads...They might have created another issue..Vacuum leak?..or they did not do what they stated on your invoice...Take it to a good shop...Can't help you directly..In FLA...Good Luck..
 

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If you plan on keeping it, I believe the consensus here is the TBI motors are pretty simple, reliable and long lasting.
Good luck.
Too bad the EGR wasn't the issue - cheap and easy.
 

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Did you try changing the PCV valve? You can check for suction at the hose, and rattle the valve to see if it is still good (it should rattle). There should be suction on the hose if you pull it off of the valve. It is located right behind the alternator, on the driver's side valve cover.

You can check for vacuum leaks by placing a couple of drops of dishwashing fluid in a squeeze bottle full of water, and spraying it on the top of the engine everywhere there is a seam between two parts, or a hose connection. If you see or hear it being sucked into the engine, you have a leak there. A leak anywhere is a cause for high idle.

The worse case scenario is if the internal fuel tank hose is beginning to crack, and you have to drop the tank to replace it.

You should watch your check engine light. If it comes on, get a wire or paperclip and cross the A and B pins with the ignition on (engine off) to get the light to show you the codes. There is an inexpensive tool for the same test with instructions, that you can get at Autozone, Advanced Auto,, or similar parts stores. The check engine light will flash for the code numbers in sets of 2, 3 times.

Knowing if there are any codes helps you diagnose the problems. If there aren't any codes (12 is OK), you may have a fuel feed problem, because fuel problems do not throw codes.

There are some easy things to do that can help. On the thermostat cover, the stud on the passenger's side is the ground for the computer and the O2 sensor. Removal and s good cleaning may be in order. Only do this when the engine is cold.

Idling high is an indicator of a vacuum leak, so I would look there first. A high speed running issue could be a fuel issue. If the idle is not stable and swoops up and down, it may be the in tank fuel hose. I would not bother with the IAC, or the ignition module. Another easy to replace sensor is a MAP sensor that hooks to the back of the TBI, but it will throw a code that you can read from the check engine light.
 

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Discussion Starter #14
PCV valve was changed at the last oil change [done last week].

Spoke to my grandparents last night, and they mentioned that since they bought it they'd complained that it idled high, but apparently nobody could find the issue. No details on what may or may not have been checked, however.
 

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PCV valve was changed at the last oil change [done last week].

Spoke to my grandparents last night, and they mentioned that since they bought it they'd complained that it idled high, but apparently nobody could find the issue. No details on what may or may not have been checked, however.
Check the ignition timing. If it is set too high the engine will idle fast and knock under acceleration. I ran into this problem with my Caprice when I first got it.
 

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KEEP the car.

Here are some VERY quick and mostly free things to check:

First, if you don't have one, get a shop manual. They're always on Ebay. Even if you have someone else do work, at least you can see what they're going to do, and make them use the book. It also has lots of diagnostic charts buried throughout.

Now, about your idle/knocking problem. Let's assume the shop actually put in new, correct injectors, did it properly, and didn't just remove and "clean" the old ones before they cleaned your wallet. The idle problem is an old one, according to your relatives. Either way, get a new mechanic.

Your car has low mileage, so I'm guessing it probably had a fair amount of in-town, low RPM, stop-and-go driving, sometimes called "the granny cycle" :) This can lead to carbon build-up in certain places.

1. Look at every vacuum line you can find on the top of the engine and make sure they're connected. I'm not familiar with that engine, so I can't point you to likely trouble spots. However, I don't think it's a vacuum line, since nobody seems to have been messing with the car much.

2. The ECM (computer) on your car tries to control idle and the fuel mixture based on the info it gets and the components it can control. The fact that the idle fluctuates probably means that the ECM is trying to hold the correct idle but that the engine's fuel and air management control components aren't working right. And, most likely, given the car's low mileage, it means that just one thing isn't working right.

3. See the pic in post #7. It has labeled three common sources of idle problems--EGR, IAC, and TPS. Two of these you can diagnose in 15 minutes without spending a dime.

4. The EGR. Blocking off the hose won't necessarily identify an EGR problem because it is electronically controlled by that solenoid in the picture. On your engine the EGR is easy to remove (unlike on the LT1). Remove it, check that the valve moves freely and that there is no carbon build-up in the passages, on the valve, or in the engine holes. Carbon would mean the valve can't seal like it should, so this is a primary cause of idle problems and maybe lean running (which could cause the knocks you mentioned). Also, the EGR has a vacuum diaphragm in it. With so many years of probably low speed driving with high underhood temps, it may have failed. Once you remove it, you can test it by sucking on the vacuum fitting to see if the valve moves like it should and if it stays open with your tongue tip sealing the fitting. A new one is $50-70 and is easy to install.

5. The IAC--idle air control valve. This also is easy to remove, and carbon can build up on the end of it or in the hole in the manifold. Never attempt to adjust it by rotating the pintle or moving it in or out, just make sure it's clean. A tiny motor moves it in and out. If the engine spends a lot of time going on and off idle, the IAC can just wear out. A new one is $30-50, and is easy to install.

6. The TPS--throttle position sensor, which tells the computer how open the throttle is. Symptoms of a bad TPS include surging, poor idle, and poor performance at certain speeds. It is essentially a rheostat with contacts inside, so they can wear out.

A new one is $25-35 and is easy to install. However, you need the shop manual for this, because if you have electronic traction control there is a process for the engine computer to "learn" the new correct TPS position.

Here is an informative 2-minute video from Airtex/Wells explaining the TPS. http://www.wellsve.com/advantage_throttle.html

There's also a big TPS symptoms section in the shop manual (6E3-B in my Fleetwood book), in the driveability and emissions chapter.

7. Your car looks to be in beautiful shape inside and out, and nobody has been hacking/modding/abusing it. You don't have to bring it back to great condition--it's already there. Some stuff may be slightly neglected (e.g., the idle, and the cooling system, belts, hoses), but if you get it up to snuff and maintain it along the way with high-quality parts, it will be a reliable, safe, and very inexpensive ride for many years and miles. The comfort and size are very addictive, too. It's a DEFINITE keeper!

Good luck, and let us know what you find out.
 

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I was at the junk yard the other day, and came across an LO5 in a 93 police car. I was going to get the cam, and when I started removing the intake manifold, I was surprised to find that the bolts were never torqued down. I could remove a number of them with my fingers. You should retorque the manifold bolts just to make sure you are not getting any leaks. The leaks would cause a high idle.

Check the cable length for the throttle pedal. If the bracket is bent slightly, or the cable is tight, it could be holding the butterfly plates open at idle. A small movement of the bracket, either by unbolting it or bending it could make a difference. Reset the trans kickdown cable if you move the bracket more than a 32nd of an inch.

If you decide to reset the kickdown cable, press the button (very stiff) on the end of the cable in the bracket until it releases the adjuster, then rotate the TBI throttle bracket for the cables to full throttle, and the cable adjuster should ratchet to the correct position.
 

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Discussion Starter #18
Sorry for the lack of updates, it's been a monumentally INSANE week.

I took her back to the dealership that did the original work, had some [very diplomatic] words with them, and presented them a list of things to check. Needed to get the gasket on the trans + fluid done anyway, as I'm just not equipped to do it here.

Tested for vacuum leaks, nothing found. EGR + solenoid bad, carbon buildup. Parts are on order, HOPEFULLY that'll be the end of it.

I do, however, think I'm going to see about obtaining a shop manual and start dealing with these less involved repairs myself. There is also no longer any question: I am DEFINITELY keeping the thing until it turns to dust on me. I can't exactly put my finger on it, but I'm ADDICTED to the thing. it's not fast, it's not maneuverable, it's not fuel efficient. My wife hates it, only the left side speakers work, and I have no idea HOW I'm going to fit it into my garage.... But I haven't enjoyed actually DRIVING a vehicle this much since my first car ['89 Bonneville, which strangely ALSO had a blue/wood grain interior]
 

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When it is all correct that Roadmaster can get 27mpg at 65-70mph on the highway..that is very good for a 4200lbs 4 door V8 car...
 

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When it is all correct that Roadmaster can get 27mpg at 65-70mph on the highway..that is very good for a 4200lbs 4 door V8 car...
That may be true for most people, but I'm afraid my right foot suffers from a severe gravitational anomaly....




:D
 
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