1987 Deville 4.1 to 4.9 Conversion - Page 2
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HT4100 4.1, 4.5, 4.9 Discussion, 1987 Deville 4.1 to 4.9 Conversion in Cadillac Engine Technical Discussion; That's neat that you got a 4.9 working in it and without much extra work by the sounds of it. ...
  1. #16
    brougham is offline Cadillac Owners Master
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    Re: 1987 Deville 4.1 to 4.9 Conversion

    That's neat that you got a 4.9 working in it and without much extra work by the sounds of it. Why did you use 350 fuel injectors? 305 would have been sized better for that engine.

  2. #17
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    Re: 1987 Deville 4.1 to 4.9 Conversion

    Quote Originally Posted by brougham View Post
    That's neat that you got a 4.9 working in it and without much extra work by the sounds of it. Why did you use 350 fuel injectors? 305 would have been sized better for that engine.
    I got the engine running on 4.1 injectors but it was hardly derivable from being too lean so I installed a set of 350 fuel injectors that I had laying around. Eventually, I'm going to install a 4.5 throttle body with 4.5 injectors. The 4.5 throttle body is a lot larger CFM than the 4.1 so it should match the 4.9 engine a lot better.

  3. #18
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    Re: 1987 Deville 4.1 to 4.9 Conversion

    Be careful with your injector selection. The pcm's integrator algorithm has it's limits, and the 4.5 injectors will flow about 15% less than the 4.9 would ideally take.

    You'll want to choose the injector that gets you closest to the ideal fuel integrator value of 128. You should be able to view this through your on-board diagnostics.

  4. #19
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    Re: 1987 Deville 4.1 to 4.9 Conversion

    Quote Originally Posted by drewsdeville View Post
    Be careful with your injector selection. The pcm's integrator algorithm has it's limits, and the 4.5 injectors will flow about 15% less than the 4.9 would ideally take.

    You'll want to choose the injector that gets you closest to the ideal fuel integrator value of 128. You should be able to view this through your on-board diagnostics.
    With 350 injectors, I'm getting a fuel integrator value of around 123 while accelerating. At idle, it'll go down to 99 at times. While coasting, it's usually 128.

    I tried running mixing a 350 injector with a 4.1 injector and it ran poorly and the fuel integrator value was generally around 135.

    Is 305 TBI injectors the best choice or is there something that's even a better choice?

  5. #20
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    Re: 1987 Deville 4.1 to 4.9 Conversion

    Quote Originally Posted by Edahall View Post
    With 350 injectors, I'm getting a fuel integrator value of around 123 while accelerating. At idle, it'll go down to 99 at times. While coasting, it's usually 128.

    I tried running mixing a 350 injector with a 4.1 injector and it ran poorly and the fuel integrator value was generally around 135.

    Is 305 TBI injectors the best choice or is there something that's even a better choice?
    I would assume that the 305 injectors would be a decent match, but I can't offer any experience-derived advice. Ehall has done this swap, as he mentioned. Maybe he can post what kind of integrator values he gets.

  6. #21
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    Re: 1987 Deville 4.1 to 4.9 Conversion

    My 85 ECM doesnt seem to publish an integrator value. The nearest display option is injector pulse width (0.6), which runs from about 2.5 at cold idle to 1.7 at warm idle.

    Also just noticed that the car did not go into open loop after about 10 minutes of driving. Coolant temperature got warm enough, so maybe the O2 readings are confusing the computer (the sensor does not have an integrated heater or temperature switch). Could also be the replacement ECM having trouble. That would certainly explain why fuel economy is so poor. I'll have to check into it, but I need another battery first, and want to install an adj. FPR in the TBI, and need a few other things, but I'm working on other stuff that is more important right now. /hijack

  7. #22
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    Re: 1987 Deville 4.1 to 4.9 Conversion

    Try this to get your Fuel Integrator value.

    1. Press (Off & Warmer) simultaneously to enter diagnostics.
    2. Wait until code .7.0 is displayed.
    3. Press (Lo) repeatedly until P.1.4 is displayed
    4. It'll show a Fuel Integrator value ranging from 0 to 255.

  8. #23
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    Re: 1987 Deville 4.1 to 4.9 Conversion

    My 85 doesn't have 1.4. It stops at 1.3 (PROM ID). I can give you injector width (above) and there is an O2 reading that might be useful for something.

  9. #24
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    Re: 1987 Deville 4.1 to 4.9 Conversion

    Quote Originally Posted by Edahall View Post
    With 350 injectors, I'm getting a fuel integrator value of around 123 while accelerating. At idle, it'll go down to 99 at times. While coasting, it's usually 128.

    I tried running mixing a 350 injector with a 4.1 injector and it ran poorly and the fuel integrator value was generally around 135.

    Is 305 TBI injectors the best choice or is there something that's even a better choice?
    I think the 4.5 throttle body would be the best match unless the 305 is similar in size sine it is closer to 4.9. Cadillac engines are oddballs but I think the 4.9L uses the smaller injector size that is probably the same as a 305. 350 uses bigger injectors.

  10. #25
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    Re: 1987 Deville 4.1 to 4.9 Conversion

    What's the current status? Any more changes?

  11. #26
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    Re: 1987 Deville 4.1 to 4.9 Conversion

    Quote Originally Posted by ehall View Post
    What's the current status? Any more changes?
    Yes, I ended up installing a 350 throttle body.

  12. #27
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    Re: 1987 Deville 4.1 to 4.9 Conversion

    Great thread. Not sure I want or need to go that route myself. My 4.1 actually runs great, after a bunch of fooling around with it. Getting rid of the converter surely helped. It has to come out ( again) to replace the rear main seal. I put new main bearings in it last year, and should never have replaced the rear mains, because I disturbed the rear seal when I removed that rear bearing cap. At least I got rid of the typical "thump" at idle.
    Had oil pump problems, because of the pickup tube breaking off twice, on new pumps.
    Biggest problem with this car is the brakes, which really suck. Vacuum pump is a sick joke.
    Good to hear that the 4.9 is working out though.....

  13. #28
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    Wink Re: 1987 Deville 4.1 to 4.9 Conversion

    That is a pretty ambitious project. I do believe tho that if a car is otherwise good, it is worth replacing an engine on one. I am not sure if I would try it on mine though. However it could be easier than what you are facing being as mine is an 84 Deville with the 4.1 engine. BTW, I have only 126,000 on my car, so I suspect it may outlast me. Other than being underpowered as all of the 4.1 engine cars were, I have had no complaints whatsoever. Mine has been extremely reliable, although not popular. In our part of town, it is easily the oldest car in any parking lot nearly any day of the year. I still have the original freon in the air cond. system.

    I did have to replace a water pump and it really sucked. Worst water pump replacement I ever did, bar none! Thought because of all of that room in front of the engine after shroud removed would be a piece of cake. Nope! Had to do my '95 BMw which I thought would be bad due to lack of any extra space and it turned out to be the easiest I ever did. Who knew?

    I am surprised that wire harness, etc would work on such a conversion. I thought of removing the tranny to replace the rear main seal on the engine, a real leaker. But the thing looks like more trouble than it is worth. I park it over a drip pan and that takes care of that! Torx bolts to pull from bellhousing. Never saw those before and looks to be a bit tight to work on, for a rear wheel drive car. Maybe I am wrong and it is not a bad job???? Anyone know???

    Good luck on your conversion.

    Gerry

  14. #29
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    Re: 1987 Deville 4.1 to 4.9 Conversion

    Great thread. Very interesting.

    Your car must be a woot to drive now.
    I just understood the throttle body injector (TBI) general concept.

    Can you post a picture of it sometime?

    Also I am curious whether that system is controlled by the onboard computer and whether you used the original computer or replaced it with a 4.9 L engine computer/eprom ?

  15. #30
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    Re: 1987 Deville 4.1 to 4.9 Conversion

    Quote Originally Posted by The Gold View Post
    Great thread. Very interesting.

    Your car must be a woot to drive now.
    I just understood the throttle body injector (TBI) general concept.

    Can you post a picture of it sometime?

    Also I am curious whether that system is controlled by the onboard computer and whether you used the original computer or replaced it with a 4.9 L engine computer/eprom ?
    Yes the system is still controlled by the original 4.1L computer. There was no change whatsoever there. From the pictures, nobody can tell that the engine is not original other than the fact that the valve covers say PFI. But when you get into the car to drive it, it doesn't feel like a 4.1L.
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