2.5L Tune Up Q?

Discussion in '2.5 Engine' started by DeanMk, May 22, 2015.

  1. DeanMk

    DeanMk Member

    I've got a '98 XL with 2.5L and it will soon pass 15K since the last tune-up (plugs and wires).

    Back in the good ol' days it was recommended that one get a tune up once a year, but in this modern world of DIS ignition systems, is this still the practice?
    I know the car makers mention that DIS allows for long intervals between tune-ups. I remember GM mentioning at one time that there was no need to change plugs and wires for 100K miles, but I'm skeptical of these super long intervals.
    The wires and plugs have not changed, only the way they're lit.

    So what do you guys do?

    Do you adhere to the "tried and true" yearly schedule, or do you go by a certain mileage, or are you asking What is this "Tune, Up" that you speak of?

    I've got an oil & filter change coming up, so I thought I'd hit both at the same time, but this is my first vehicle with DIS.

    FWIW, it's running fine. I just want to keep it that way.

    Last edited: Sep 10, 2019
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  3. ZappyBear

    ZappyBear Member

    I will pull out my chilton manual this evening after work and check. And about your rough idle issue, I heard on either the 2.3 or 2.5 it was common for a pretty large vacuum line between the engine and firewall to develop a hole. I guess having the same effect as unplugging your brake booster and letting the hose hang.
  4. OP

    DeanMk Member

    Thanks for helping me out.
    Interested to see what your manual says.
    As for the issues I'm currently having with the truck, I changed out the IAC and the idle smoothed out.
    What I have now is an erratic throttle response.
    VIOLENTLY erractic throttle response.
    I tried driving it up the road (maybe, 1/2 mile) and barely got home.
    Kept my foot about half throttle and it liked to buck so hard, it almost shook the truck apart.
    It was like the engine was going from idle to WOT and back, very rapidly.
    When the throttle is moved, the engine is also slow to respond.
    ….doesn't sound like a bad vacuum line to me, but thanks for your suggestion anyway.
    Last edited: Sep 10, 2019
  5. ZappyBear

    ZappyBear Member

    20190911_221443~3.jpg 20190911_221443~3.jpg
    Sorry about the late response. Been rather busy with work this week. Chilton manual says 4 cylinder 8 plug engines have a max service intervals for spark plugs are 60k. My 4.0l was doing the same thing, but it'd be random as to weather or not it ran fine. Turns out I pinched and sliced almost every injector O-ring I put in making a giant vacuum leak. As for the 2.3l vaccum leak issue, I will have to look for that hose on my 2.3l and get a picture of it.

    Attached Files:

  6. OP

    DeanMk Member

    Thanks for your help, Zappy Bear.
    I have a 2.5. It does have 8 plugs. I had a tune up done about 22K miles ago. Interval for Ford is 30K per tuneup (what they told me at the dealership).
    I have been no where near the injectors, so no way I could have upset them in any way.

    Does your manual make any correlation between violently erratic throttle response and the Camshaft Synchronizer Assembly?
  7. ZappyBear

    ZappyBear Member

    Hadn't thought about that, definitely could be throwing off injector timing. My injector reference was to say your issue sounded alot like when I made a giant vacuum leak. I will go through my Chilton and Haynes manuals and see what I can find. Pictures will be cropped down quite a bit though. File size ends up being too large.
    DeanMk likes this.
  8. OP

    DeanMk Member

    If you're using a PC, you can resize pics in Paint without having to crop them.
  9. ZappyBear

    ZappyBear Member

    Well, finally got around to looking all that up in my manual. I couldn't find anything correlating erratic throttle operation with the cam position sensor. I'd say to try google, as a second source. Just watch out for those websites that redirect you to those fake "you have been selected for" scams. Which is why I always search here first for information. Now that I have time, I will go look at my 2.3 for that vaccuum hose so you can see if yours has the same one.
    DeanMk likes this.
  10. OP

    DeanMk Member

    Thanks for trying, Zap.

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