disconnected FPR on a Nissan and no codes?
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Community Lounge, Introductions and General Discussion Discussion, disconnected FPR on a Nissan and no codes? in General Discussion; Was working on my friend's 2000 Nissan Xterra 3.5L V6 this weekend, had the intake plenum off for a valve ...
  1. #1
    mhamilton is offline Cadillac Owners Connoisseur
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    disconnected FPR on a Nissan and no codes?

    Was working on my friend's 2000 Nissan Xterra 3.5L V6 this weekend, had the intake plenum off for a valve cover gasket change. Found a 3/16" vac line on the back of the plenum hanging in the wind, and next to it the fuel pressure regulator with no vacuum line connected to it. He had complained about terrible gas mileage (which we both assumed was due to the horrible low gearing in this truck-- 3k rpm on the highway in top gear). Of course we put back the vac line to the FPR and will see how it changes.

    But my question, how could this not set a CEL or show some other drivablity problem? If the FPR was disconnected from vac, it would always be at high pressure. The PCM has enough latitude to cut back fuel to keep the mixture in check without setting the CEL? (on most cars after the LTFT gets > +/- 20% it sets a rich or lean code). Since it didn't set any codes, I suppose he won't see any improvement in MPG since apparently the PCM was keeping the mixture correct.

    I know the N* engines would show up with all kinds of hard starting and other issues with a failed FPR...

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    Kingoftypos is online now Cadillac Owners Master
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    Re: disconnected FPR on a Nissan and no codes?

    I can't explain it. But I do know that a couple of my past cars, I could unplug the Mass Air Flow sensor. Drive around for days like that and no check engine light what so ever. Just like your friend's, unplugging the MAF should of sent a CEL right away.

    It's like the engineers forgot a thing or two for monitoring. lol

    KOT

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    orconn is offline Cadillac Owners 10000+ Posts
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    Re: disconnected FPR on a Nissan and no codes?

    Probably would have cost an extra 50 cents to include the MAF in the warning system. What is the saying about automobile business, "When it is all said and done, making cars is really a nickel and dime business!"

    Bean counters probably nixed the cost!
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    Kingoftypos is online now Cadillac Owners Master
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    Re: disconnected FPR on a Nissan and no codes?

    Quote Originally Posted by orconn View Post
    Probably would have cost an extra 50 cents to include the MAF in the warning system. What is the saying about automobile business, "When it is all said and done, making cars is really a nickel and dime business!"

    Bean counters probably nixed the cost!
    Yeah, and how many years did it take Chrysler to put a $5 item for the brake inter-lock? Where the brake pedal needs to be depressed in order to take it out of park. Chrysler was the last company to put that device in. Heck they might of done it because it was the law for that model year. I know other companies, GM, had been installing them for years before it became law. In the mean time, severals lives were lost by Chrysler cars.

    KOT

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    Re: disconnected FPR on a Nissan and no codes?

    If lives were lost to Chrysler's not putting the interlock between the brake and the gear change lever, bet they paid dearly for their cost effective omission .... not!

    That law came about because of Audi's (very real) problem with spontaneous acceleration, beginning in1984. Cadillacs were also subject to spontaneous acceleration, but it wasn't as highly publicized.

    The law became effective around 1986, my Audi was retrofitted with the lockout device and they stuck a sticker on the center console.

    My Audi actually suffered from spontaneous acceleration, but unlike the claim by those involved in accidents, the brakes would hold the car at a stop as the engine revved in "Drive."

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    Re: disconnected FPR on a Nissan and no codes?

    Quote Originally Posted by orconn View Post
    Cadillacs were also subject to spontaneous acceleration, but it wasn't as highly publicized.
    Well yeah, but we all knew it was only a matter of time before Grandma's time was up.
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    Quote Originally Posted by CadillacLuke24 View Post

    Well yeah, but we all knew it was only a matter of time before Grandma's time was up.
    "Spontaneous acceleration" in a 4100 (I'm guessing since thats what most all caddys cars had in the mid 80s) seems like a misnomer.

    Now, the lesabre has spontaneously accelerated (due to a cruise control issue with the "resume" button occassionally causing the car to go WOT.) My dad had hit resume cruise while going up a hill on the highway. The car downshifted and went WOT. Pressing the resume cruise button did not make it stop (it is supposed to, but the it goes off then comes right back on) and tapping the brakes did not stop it either. My dad ended up having the stomp on the brakes 3 or 4 times until it finally turned off. Thankfully we were on an empty stretch of highway.
    His solution is to never use the cruise control. I have used it a few times on city streets, but it does not always turn off when you tap the brakes.
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    drewsdeville is offline Cadillac Owners Master
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    Re: disconnected FPR on a Nissan and no codes?

    That sounds to me like an intermittent problem with the brake light switch

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    Kingoftypos is online now Cadillac Owners Master
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    Quote Originally Posted by orconn
    If lives were lost to Chrysler's not putting the interlock between the brake and the gear change lever, bet they paid dearly for their cost effective omission .... not! That law came about because of Audi's (very real) problem with spontaneous acceleration, beginning in1984. Cadillacs were also subject to spontaneous acceleration, but it wasn't as highly publicized. The law became effective around 1986, my Audi was retrofitted with the lockout device and they stuck a sticker on the center console. My Audi actually suffered from spontaneous acceleration, but unlike the claim by those involved in accidents, the brakes would hold the car at a stop as the engine revved in "Drive."
    Are we talking about the same item? Because the brake interlock system I am talking didn't become law until 2006.

    http://www.nhtsa.gov/Vehicle+Safety/...terlock+(BTSI)

    KOT

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    Re: disconnected FPR on a Nissan and no codes?

    It sounds like they are functionally the same, but the article states that this became law to prevent children from accidentally putting an automatic equipped car in 'Drive." I wasn't aware that up until 2007 there wasn't a law mandating this safety interlock system. As I said my Audi was retrofitted with this system in 2006. If I remember correctly, the '93 Seville STS also had the system, and of course the newer Sevilles have both had it. I just assume it was mandated federal law long before 2007.

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    Kingoftypos is online now Cadillac Owners Master
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    Quote Originally Posted by orconn
    It sounds like they are functionally the same, but the article states that this became law to prevent children from accidentally putting an automatic equipped car in 'Drive." I wasn't aware that up until 2007 there wasn't a law mandating this safety interlock system. As I said my Audi was retrofitted with this system in 2006. If I remember correctly, the '93 Seville STS also had the system, and of course the newer Sevilles have both had it. I just assume it was mandated federal law long before 2007.
    Oh you know what. I think your talking about the type of interlock before the brake interlock. Where if a floor shift was installed. You have to press a button to move it from Park. Or if on steering column, you had to pull towards you. This can be done with out pressing the brake pedal.

    Or better yet. You had to have the shift in park before you can remove the key. I remember on my parents 85 Plymouth Horizon you could have it in any gear and still remove the key. Heck, you could move it from park even with the key out. This can be done with out the brake pedal too.

    KOT

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    Re: disconnected FPR on a Nissan and no codes?

    No, it was a brake transmission interlock just like the one on my 1995 Seville STS. You can't move the transmission lever into gear till you step on the brake. Same as the one installed on the '85 Audi 5000S Avant.

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    Kingoftypos is online now Cadillac Owners Master
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    I knew GM did that kinda early. Well A LOT earlier than Chrysler. Ha

    KOT

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