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I'm almost afraid to ask but here goes...

Discussion in '348/355' started by shuff001, Aug 16, 2013.

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  1. shuff001

    shuff001 Rookie

    Jun 19, 2006
    16
    Monroe, MI
    Full Name:
    Seth Huff
    #1 shuff001, Aug 16, 2013
    Recently, I have been having some issues with a 1989 348ts. Here are the symptoms:

    -After starting the car, the idle is very low, say 500-600 rpm. Sometimes it will even stall out if you don't give it gas. Also, I have heard an occasional loud knock (although it's rare and very sporadic) and a rattling sound accompanied with a fairly strong engine vibration (this is much more common and I feel may be from the low idle since it goes away when the rpm are raised).

    -If I put my foot on the throttle to keep the rpm up at idle (between 1000-2000), the engine seems to respond at first, but then the revs will drop significantly after a few seconds, then raise again and keep doing this "back and forth" without me changing the throttle position. I have noticed this a few times while driving the car as well. The car seems to drop rpm spontaneously.

    -When driving, sometimes the car seems like it almost has no power. It's not a clutch issue where the rpm go very high but the car won't accelerate quickly, rather the rpm are appropriate for the speed, but the car just refuses to accelerate properly (think Smart Car-like acceleration).

    -Other times, however, everything seems to be fine when driving...normal power and acceleration, no odd noises, etc.

    -I thought the problem went away once the car warmed up, however I have realized that this is not necessarily the case. There seems to be no pattern as to when these issues spring up/go away.


    Here are my thoughts/things I have already tried:

    -Everything that has happened leads me to think it's some kind of issue with the fuel/air intake system. Perhaps a bad sensor? Maybe partially clogged fuel lines? I did have old gas in there and the tank was almost empty until this week when I filled it and put in ethanol stabilizer and Techron fuel system cleaner. I let it idle for a long time and drove it around for a while but nothing got better. I know it would probably take longer than that, but don't want to damage anything if it sounds like something more serious.

    -The startup issues also sounded like it could be something with oil not getting everywhere fast enough, so I changed the oil last week (10w-40 synthetic with ZDDP). Again, no change.

    -This all started after I put in a Bosh starter relay, which I'm pretty sure has nothing to do with it, but wanted to mention anyways.

    I would greatly appreciate any input that can be offered and am not afraid to wrench around and try different things (on the contrary, I quite enjoy it!) Please let me know if it sounds like I am on the right track...or if I am way off, what else I need to check/try? Thanks in advance for the help!
     
  2. plugzit

    plugzit F1 Veteran
    Silver Subscribed

    Dec 1, 2004
    7,793
    Redondo Beach, CA
    Full Name:
    Bruce Bogart
    #2 plugzit, Aug 16, 2013
    Hi Seth-
    Welcome to Fchat.
    That's not much to go on. First, find out if it's fuel or spark related. The easiest way is to check spark at each plug. Disconnect a plug wire. Stick a screwdriver in it and hold the screwdriver by the plastic handle, placing the exposed metal shaft near (1/8-1/4" away) a piece of metal. Have someone turn over the motor as if to start the car (it may even start). See if the spark jumps to the metal consistently. Reconnect the wire and go to the next one. If it does have good consistent spark on each plug, then you have good spark and you can move on to fuel. Be careful not to touch the metal part of the screwdriver while the motor is cranking or running. Let us know what happens.
     
  3. Bookum

    Bookum Karting

    Nov 3, 2010
    119
    Chester County PA
    Full Name:
    Dan
    #3 Bookum, Aug 16, 2013
    Are you getting any check engine lights? I had an idle speed issue which produced a check engine light on one of the banks. Turned out to be a dirty/oily mass air flow sensor due to an oil impregnated k&n air filter. Removed the mass air flow sensor, cleaned it with maf cleaner and it idled and ran like a champ instantly. Worth a shot, and it cost me 6 bucks to fix. Good luck.

    Sent from my SCH-I535 using Tapatalk 4
     
  4. shuff001

    shuff001 Rookie

    Jun 19, 2006
    16
    Monroe, MI
    Full Name:
    Seth Huff
    #4 shuff001, Aug 16, 2013
    I will have to get a buddy over here to help me check spark, but will let you know when I do.

    No check engine lights, but that can't hurt to check the filter/sensors anyways.
     
  5. 355redcar

    355redcar Karting
    BANNED

    Feb 21, 2013
    71
    #5 355redcar, Aug 16, 2013
    to trouble shoot this problem you have to first check FUEL PRESSURE REGULATOR
    45-55 PSI on each bank
    put 2 new all metal FUEL FILTER

    both FUEL PUMPS can be week not pushing FUEL very strong when IDLEING

    FUEL PUMPS & FILTER works well even CLOGGED when going FAST

    the REGULATOR inside is made of rubber & can be busted inside

    my 2 cents
     
  6. Miltonian

    Miltonian F1 Veteran

    Dec 11, 2002
    5,966
    Milton, Wash.
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    Jeff B.
    #6 Miltonian, Aug 16, 2013
    Last edited: Aug 16, 2013
    Has the battery died or been disconnected lately? May need to re-initialize the Motronic ECU's.

    You also may have an issue with your flywheel being worn/damaged.

    Edit: If you had your battery disconnected while you did the Bosch relay installation, it's POSSIBLE that your problem started at that point, if you didn't re-initialize after reconnecting the battery....
     
  7. shuff001

    shuff001 Rookie

    Jun 19, 2006
    16
    Monroe, MI
    Full Name:
    Seth Huff
    #7 shuff001, Aug 16, 2013
    In fact, I had the battery disconnected when installing the starter relay. How would I go about re-initializing the ECUs? I am also interested in your flywheel theory. What would be other specific signs to look for/how can I check into this further?
     
  8. Dave Monk

    Dave Monk Karting

    Apr 23, 2010
    213
    SW Virginia
    Full Name:
    David Monk
    #8 Dave Monk, Aug 16, 2013
    Every once in awhile my car does something similar. It doesn't idle right and when you hit the throttle it doesn't go for a few seconds. Typically this happens after I wash the car and really get the motor wet, or (gasp here) get caught out and have to drive in the rain.

    Now, what I have found that has fixed this problem every time on my car is to disconnect the MAF and other connectors, spray connectors with contact cleaner and blow them dry with compressed air. I think these sensors have a very sensitive resistance value and ANY corrosion or moisture reaks havoc on them. Many folks are installing gold connector kits that fix this issue, I haven't gotten around to doing that yet.

    To reset your ECU disconnect the battery for a few minutes (about 10) and restart the car and let it idle (do not touch the throttle) until the coolant fans engage. This procedure retrains the ECU's to your set up. I actually have done this a time or two, but the cleaning procedure on the connectors always fixes mine.

    If none of this fixes the problem it may be the fuel pressure system as mentioned earlier in this thread.
     
  9. pnicholasen

    pnicholasen Formula 3

    Jan 14, 2011
    1,364
    South of Philly
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    Paul Nicholasen
    #9 pnicholasen, Aug 16, 2013
    I believe you disconnect the battery again for a few minutes, then re connect it and start the engine but don't touch the gas pedal. Just let it idle for 10 or 15 minutes. That's it.
    If you get an inductive timing light you can check the spark very quickly and easily by moving the clamp from one wire to the next and watch the flashing light for consistant flashes.
    If nothing else works and you have the plugs out, it might be worth a compression check, but hopefully something listed above will do the trick.
     
  10. shuff001

    shuff001 Rookie

    Jun 19, 2006
    16
    Monroe, MI
    Full Name:
    Seth Huff
    #10 shuff001, Aug 17, 2013
    Great ideas here guys, I will clean the MAF sensor as well as any contacts I can find, put in a new air filter (which will take a few days to get here...boo) and reset the ECU. If these don't seem to help, I'll replace fuel filters/check the pressure regulators. Sounds like I may have a combination of problems! Thanks for the advice and I'll keep you posted.

    Also, the car did get wet recently so hopefully cleaning those contacts will help.

    Side note: I see K&N makes a 348 air filter (33-2656). Does anyone have experience with this or should I just go with the OEM UFI filter?
     
  11. GTO Joe

    GTO Joe Formula 3
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    Feb 15, 2013
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    Charlotte, NC
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    Joseph Troutwine
    #11 GTO Joe, Aug 17, 2013
    You may want to search here for the articles on the fuel pump gaskets that go soft from the current fuel we have and clog the system up. You mentioned old gas in the tank so this is why I mention it. As for the air cleaner, I would go with stock. The K&N have caused a lot of grief from getting oil on the maf. I have read some reports done on them and in some cases they didn't flow as much as stock for certain makes of vehicles.
     
  12. Bookum

    Bookum Karting

    Nov 3, 2010
    119
    Chester County PA
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    Dan
    #12 Bookum, Aug 17, 2013
    In my opinion, I would pass on the k&n filter. That is what caused my idling/check engine issue. The oil sucks right into the MAF's. I can't imagine the air flow difference is that noticeable. Not worth the hassle of cleaning the MAF's all the time.

    As far as your current issues go, start with removing and cleaning the MAF's and connectors. It's the easiest and cheapest thing to trouble shoot. If that has no impact, then you can move on to the hard/expensive trouble shooting.

    Sent from my SCH-I535 using Tapatalk 4
     
  13. 355redcar

    355redcar Karting
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    Feb 21, 2013
    71
    #13 355redcar, Aug 17, 2013
    what is the FUEL PRESSURE ? this is the answer to all FUEL RELATED SYSTEM ask anyone
    that fix FERRARIS
     
  14. 348Jeff

    348Jeff Formula 3

    Oct 25, 2011
    1,547
    UK
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    Jeff
    #14 348Jeff, Aug 18, 2013
    The symptons you describe would match a problem with your MAF(s). Why not try cleaning them as this is cheap to do (use proper cleaner though)

    few pics here:

    348 DIY "Restoration" - Page 46

    348 DIY "Restoration" - Page 102

    If you can persude a friendly local owner to loan you theres to swap and check you could seeif they are faulty as water gets in the eltrics of them and corrodes the electronics
     
  15. shuff001

    shuff001 Rookie

    Jun 19, 2006
    16
    Monroe, MI
    Full Name:
    Seth Huff
    #15 shuff001, Aug 31, 2013
    Thanks for all the advice. I wanted to update everyone on what I've done and my results:

    -I had already ordered the K&N filter before I got the negative feedback, so I put that in. Thinking about going back to UFI stock though?

    -Removed and cleaned both MAF sensors and used contact cleaner on sensor connections.

    -Changed the oil and filter/added ZDDP (as mentioned earlier)

    -Put new gas in with Ethanol stabilizer and Techron fuel system cleaner.

    -Disconnected the battery then re-initialized the ECU.

    After doing all of this, I started the car and allowed it to sit idle for ~20 min. At first, it still knocked and rattled, however after letting it idle, all of that went away. It no longer seems under-powered. I have taken it out on several times since then and it always starts easy and idles smooth with no rattling/knocking (Hallelujah!). Everything seems much better, except for one thing. When driving it harder, there is a noticeable loss of power starting at almost exactly 5200 rpm. At first, it was so present that it almost felt like a rev limiter kicking in. Since then, it has become less dramatic, but still noticeable. It does this in both 1st and 2nd gears (I have not really run it that high in 3rd-5th). However, if you rev the engine in neutral, there is no hesitation going past 5200. Any ideas on this? I am less concerned now than with my previous issues, but would like to figure this out as well. Thanks everyone for the input!
     
  16. 348Jeff

    348Jeff Formula 3

    Oct 25, 2011
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    Jeff
    #16 348Jeff, Aug 31, 2013
    Sounds like your making progress :)

    Might be worth looking into whether the throttle position sensor is ok.

    Keep at it!
     
  17. 3forty8

    3forty8 F1 Rookie
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    Apr 25, 2006
    2,713
    San Diego
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    Eric
    #17 3forty8, Aug 31, 2013
    You have mentioned the loss of power a few times; this seems consistent with a bank cutting out. Is your car a 2.5 or 2.7 Motronic (one TPS is a 2.5, two TPS is a 2.7)? The U.S. spec 2.7 includes the buttons to pull the codes from each ECU which could give us better info to work with.
     
  18. shuff001

    shuff001 Rookie

    Jun 19, 2006
    16
    Monroe, MI
    Full Name:
    Seth Huff
    #18 shuff001, Aug 31, 2013
    It is a 2.5 unfortunately. Any thoughts on how to proceed?
     
  19. Radiation

    Radiation Karting

    Mar 5, 2013
    74
    Alberta, Canada
    Full Name:
    Sean
    #19 Radiation, Aug 31, 2013
    Did you have an opportunity to verify the fuel pressure?
     
  20. shuff001

    shuff001 Rookie

    Jun 19, 2006
    16
    Monroe, MI
    Full Name:
    Seth Huff
    #20 shuff001, Sep 3, 2013
    Haven't checked fuel pressure....not really sure how to. Could you tell me how?
     
  21. Radiation

    Radiation Karting

    Mar 5, 2013
    74
    Alberta, Canada
    Full Name:
    Sean
    #21 Radiation, Sep 4, 2013
    Im not sure what the exact procedure would be on your car, perhaps the service manual has a procedure you can use as a guideline, I dont have one handy.
     

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