4.5PFI Tune-up tips?
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HT4100 4.1, 4.5, 4.9 Discussion, 4.5PFI Tune-up tips? in Cadillac Engine Technical Discussion; Hey guys, tomorrow im buying another Cad. a '90 Sed Dev, white with blu leather, its basically a beater/wither car ...
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    highonchai's Avatar
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    Question 4.5PFI Tune-up tips?

    Hey guys, tomorrow im buying another Cad. a '90 Sed Dev, white with blu leather, its basically a beater/wither car for me, trying to keep the miles down on my '89. Its not in the best shape and the amount im paying for it reflects that, but it should be dependable (knock on wood). So the first thing i need to do to it is give it a tune-up oil change etc... the 4.5 PFI doesnt start very well, youve gotta give it gas to keep it started, but once its running it runs well. What would you suggest i should do to tune it up?? i figure check the timing, new plugs and wires, oil change, maybe a trani and radiator flush. What do you guys think?? Thanks everyone!!

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    Re: 4.5PFI Tune-up tips?

    I would change all the fluids, do a regualr tune up (which includs changing the fluids) plugs/wires, CLEAN THE THROTTLE BODY <----- that's a big one, and I may even bet why it has a hard time starting.... I would run Lucas fuel injecotr cleaner through it 2 tank fulls in a row (only run premium gas in it) scan for any error codes.... change the filters etc.... you should be good to go.....

    ...but why must you use a Cadillac as a winter beater shame shame

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    Wink Re: 4.5PFI Tune-up tips?

    Thanks Night, I'll defineately do those things, Can you suggest a method of removing and cleaning the TB? I have an identical engine in my wrecked hearse that i can steal parts from so im not too worried, And i would of course run premium, though its damn expensive.

    Ok im sorry i used the term 'beater' But why drive anything but a Cadillac?? i see no reason why one should deprive themselves of such craftsmenship, grace, beauty, and comfort, even during the winter months. So i take it back, it will be my winter luxury sedan, sorry , what was i thinking?:drinker Thanks again!

    Oh and i ran diag. today when i went to look at it, E52 was the only code, no biggie 'ECM Memory Reset Indicator'

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    Re: 4.5PFI Tune-up tips?

    on my CDV (4.9) I just removed the plastic stuff for the intake and got my TB cleaner and an old toothbrush.... it wasn't too bad, but I scrubbed the walls, the butterfly valves etc.... it was pretty good.... on my Olds (3800 V6), which has the TB mounted sideways, there was a screen I coudln't remove, but I had the car running, and used a stick to hold the gas down, and sprayed the TB cleaner in the TB with the engine running, that cleaned it up.... for whatever reason, it just happened one day, when ever the car would be at idle or anything it would die out... I had to keep shifitng in to neutral aorund turns, coasting, stop lights etc... to keep the engine running....

    the 4.5 and 4.9 are very similar, just remove the plastic nut over the TB, and the 4 thumb screws on the air box, and there is a little hose behind the TB area connected to the plastic... I forgot what sensor it goes to, but you just pull it off.....

    ...I would disconnect the battery for a bit and see if any codes come back....

    Make sure to give the winter luxury car a bath.....like once a week

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    Re: 4.5PFI Tune-up tips?

    Quote Originally Posted by highonchai
    Hey guys, tomorrow im buying another Cad. a '90 Sed Dev, white with blu leather, its basically a beater/wither car for me, trying to keep the miles down on my '89. Its not in the best shape and the amount im paying for it reflects that, but it should be dependable (knock on wood). So the first thing i need to do to it is give it a tune-up oil change etc... the 4.5 PFI doesnt start very well, youve gotta give it gas to keep it started, but once its running it runs well. What would you suggest i should do to tune it up?? i figure check the timing, new plugs and wires, oil change, maybe a trani and radiator flush. What do you guys think?? Thanks everyone!!
    Clean the throttle body by holding the throttle blades wide open and spraying with carb cleaner and scrubbing with an old tooth brush. Do the perimeter of the throttle bores beneath the blades and the back side of the blades. While you are in there, see those two tubes sticking up at you from the floor of the intake manifold..???...they are the EGR delivery tubes and they are supposed to be clean, not full of carbon. Rod them out with a piece of coat hanger wire to clean them. Disconnect the battery negative cable for 30 seconds when you clean the t'body to reset the idle learn offsets.

    Plugs and wires..???

    Oil and filter.

    Drain the cooling system and refill with fresh 50/50 green silicated coolant. Do not flush. Add the GM Coolant Supplement Pellets (6) or two tubes of the BarsLeaks "golden seal" cooling system sealer. Mandatory in your 90 and the 89 to guard against internal cooling system leaks/coolant intrusion into the oil.

    Don't flush the trans. Just asking for trouble. Just drain and refill with fresh fluid if the trans fluid color doesn't look good.

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    highonchai's Avatar
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    Re: 4.5PFI Tune-up tips?

    Wow, great tips guys, Thanks a lot, i knew there would be a few secrets out there about Caddy tune-ups. I just paid for it tonight, having it towed or trailered home tomorrow, just to be safe, and tomorrow afternoon after a trip to autozone will its time under the fine tooth comb, making it as graceful as ever.

    I'm thinking about replacing the fuel filter, and pcv valve, theyre cheap enough to replace, and i assume easy. any tips where to find those, they should be right next to eachother correct? The only car ive replaced this on was my '91 Buick PAU (what a POS, except the engine and suspension.) its filter was up behind the front passenger side fender and popped on and off with a couple clips, easy job.
    About spark plugs, are the AC Delco Rapidfires a good way to go? or should i opt for the dual platnum jobs? Thanks again guys, You are truely the Cadillac of Cadillac owners!!!

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    Re: 4.5PFI Tune-up tips?

    Quote Originally Posted by highonchai
    Wow, great tips guys, Thanks a lot, i knew there would be a few secrets out there about Caddy tune-ups. I just paid for it tonight, having it towed or trailered home tomorrow, just to be safe, and tomorrow afternoon after a trip to autozone will its time under the fine tooth comb, making it as graceful as ever.

    I'm thinking about replacing the fuel filter, and pcv valve, theyre cheap enough to replace, and i assume easy. any tips where to find those, they should be right next to eachother correct? The only car ive replaced this on was my '91 Buick PAU (what a POS, except the engine and suspension.) its filter was up behind the front passenger side fender and popped on and off with a couple clips, easy job.
    About spark plugs, are the AC Delco Rapidfires a good way to go? or should i opt for the dual platnum jobs? Thanks again guys, You are truely the Cadillac of Cadillac owners!!!
    The AC dual platinum plugs (like for a 95 4.9) are the best...but pricey...but you'll never need to replace them again. The Rapidfires are probably the best bet for the money for a "beater"....LOL

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