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Rough Idle 95 355

Discussion in '348/355' started by dt930, Jun 18, 2009.

  1. dt930

    dt930 Karting

    Dec 2, 2004
    57
    Wisconsin
    Full Name:
    David C. Treichel
    Ok guys, I'm getting a code 1121 (rpm sensor) on both banks. Car runs good, no check engine lights, has a bit of a rough idle. Recent 30k service. What are the chances of both of the sensor going bad at once? I was under the car and unpluged the sensors one at a time while the engine was running, they were definately working because the car would almost die when I unpluged each one. I cleared the codes, drove the car, pulled the codes and both ecu's gave me the 1121. I worked the ecu connectors a bit and also worked the connectors for the two sensors thinking maybe it was a bad connection, disconnected the battery to reset the ecu's, let it idle for 10 minutes, cooling fan cycled, drove the car, same thing, rough idle and 1121 on both banks. It seems to idle smoother when I first start (cold start) it then gets rough as I drive it for a bit. It's not terrible just annoying. Car has a tubi with test pipes. New NTK o2 sensors, throttle bodies balanced, injectors cleaned and tested. Cams timed (not just lined up to the marks)

    Anyone run into this?

    Thanks
     
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  3. Euromog

    Euromog Karting

    Apr 5, 2009
    102
    Oakhurst, CA
    Full Name:
    John Wessels
    If I remember correctly the Motronic 2.7 will flag a code for the rpm sensor if the engine is not running. The rpm sensors produce an AC signal and from my experience either they work or they don't. Still best way to verify for a weak one is with a lab scope. In other branded european cars they usually fail when hot then work when cooled off. IE the car will run fine or won't run at all.

    I assume that your compression and leak down tests show all is OK? If so I would want to use an exhaust gas analyzer downstream and upstream of the cats left and right sides. An SD2 will be needed to check the fuel trim and that is some info I would really like to know.

    Who tested your injectors? I have seen injectors "tested and cleaned" by one well known company that soon turned back to garbage shortly after. At first the fuel trim was great but soon it went back to just as bad if not worse than before. The idle quality also became very poor.
     
  4. dt930

    dt930 Karting

    Dec 2, 2004
    57
    Wisconsin
    Full Name:
    David C. Treichel
    The injectors were tested by RC engineering, (reccomended by someone here)
     
  5. Euromog

    Euromog Karting

    Apr 5, 2009
    102
    Oakhurst, CA
    Full Name:
    John Wessels
    That is who we used as well. Had absolutley no luck with them. We found another California company that has been in business for over 30 years. They can test your injectors and if any fail rebuild them to factory specs. I am not affiated with them but can verify their work was done correctly. I am not sure they deal with the public and might be wholesale only. I am heading out of town for the weekend and will have to call them on Monday.
     
  6. davehelms

    davehelms F1 Rookie

    Jan 3, 2004
    4,629
    Full Name:
    Dave Helms
    Un plug the O2 sensors and go for a drive.

    The 2.7's were never really smooth unless both banks O2 sensors are in perfect sinc running 180 degrees apart, on occation they are and it sounds smooth. The fact you have an open exhaust on the car will allow you to hear what others do not with the stock exhaust.

    A half hearted effort on cleaning a couple of sensor contacts doesnt make it on the 2.7's. To realize all of the benifits of that system the whole connection package needs to be renewed.

    At what spec's were the cams set? This too could have something to do with the idle quality, dealing with that on a 2.7 right now.
     
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  8. dt930

    dt930 Karting

    Dec 2, 2004
    57
    Wisconsin
    Full Name:
    David C. Treichel
    Bank 1-4 intake 2.30 at tdc overlap. Exhaust 2.22. Bank 5-8 intake 2.45. exhaust 2.22. I will try unpluging the o2 sensors.
     
  9. No Doubt

    No Doubt Six Time F1 World Champ
    Consultant

    May 21, 2005
    67,323
    Vegas+Alabama
    Full Name:
    Mr. Sideways
    Can you *slowly* increase engine rpms via your throttle foot to notice if the engine gets smoother at some reasonable point above idle, or is it rough at all rpms once hot?
     
  10. dt930

    dt930 Karting

    Dec 2, 2004
    57
    Wisconsin
    Full Name:
    David C. Treichel
    It's smooth as silk above idle all the way to redline. The on/off throttle transition is fine, especially for a 355. I spent a lot of time balancing the throttle bodies.
     
  11. No Doubt

    No Doubt Six Time F1 World Champ
    Consultant

    May 21, 2005
    67,323
    Vegas+Alabama
    Full Name:
    Mr. Sideways
    Consider checking your idle air valves, then.
     
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  13. dt930

    dt930 Karting

    Dec 2, 2004
    57
    Wisconsin
    Full Name:
    David C. Treichel
    I unplugged the o2 sensors, drove the car, first the 5-8 check engine light came on then the 1-4 light came on about 5 minutes later. I pulled over, shut the car off and plugged the sensors back in. Lights went off but it still had a bit of a burbling at idle. Although, if I put the a/c on, the drag from the compressor makes the idle smooth out. Maybe like Dave said I can hear thing more because of the tubi and test pipes.
     
  14. sub rosa

    sub rosa Rookie

    Oct 20, 2010
    15
    Tampa
    For DT, et al., did you reach a conclusion / fix for your 95 355 rough idle issue? I have an August 1995 build F355 GTB with identical symptoms. The idle is worst (not misfiring, but not good) when the A/C is off - in "stop" mode. With A/C on, the idle smooths out considerably. The car is running good otherwise and has been well maintained. Was your issue related to O2 sensors, cam position sensor, idle air valves or other? Would like to know your outcome as I troubleshoot! Thanks.
     
  15. Kaivball

    Kaivball Three Time F1 World Champ
    Owner

    Jan 11, 2007
    35,882
    Kalifornia
    3 words: gold connector kit.

    it's worth the time and money. Your car will not be the same.

    You'll get smooth idle, eager acceleration and no more CEL's.

    Kai
     
  16. 355rockit

    355rockit Formula Junior

    Dec 1, 2010
    871
    San Marcos, CA
    Full Name:
    Vas
    I had a slightly rough idle on my '95 355GTB. I usually drive with the A/C in stop mode. When Cavallo was doing a routine inspection on the engine recently after I had some climate control work done, they found a broken engine vacuum line near the exhaust header that had become brittle and broken due to possible heat. It now idles much better with a smoother launch from stop and seems more happy overall. Just as an aside, I had one of the exhaust manifolds and oxygen sensors replaced earlier this year due to 5-8 CEL.
     
  17. sub rosa

    sub rosa Rookie

    Oct 20, 2010
    15
    Tampa
    I have read great things about Dave Helm's Gold Connector Kit, and that is a well-received suggestion, but I'm not ready to take the plunge today! Maybe worth mentioning that the car starts easily and does not have any CELs. I get the very rare and brief (1 sec?) flash of a CEL 5-8 sometimes while driving, not at idle, but it goes out immediately. Running test pipes and Nouvalari Supersport -- sounds amazing! -- no other mods.
     
  18. GerryD

    GerryD Formula 3

    May 5, 2010
    2,357
    North of TO
    Full Name:
    Guido
    #15 GerryD, May 14, 2011
    Last edited: May 14, 2011
    Are you kidding? The majority of 355 owners are not going to fork out that money. They will complain when something is wrong but fork out money for something they cant see, ha.
    Give all 355 owners about another 2 years and then if a 355 does not have the kit, its not worth buying. How many times do 355 owners have to be told that the gold kit is a MUST HAVE. Those that avoid spending those meagre amount of dollars and time to let this car run as it should are pobably prone to not spending much time or money on any maintenance. They drive and complain and then sell.
     
  19. Arturin

    Arturin Karting

    Aug 16, 2009
    199
    Spain
    I´m also having some problems with starting from stop and unstable idling, apart from other electrical "gremmlings" that don´t have any negative effect on driving but are there anyways. Every possible thing has been checked and everything is to spec. I´m sure It all has to do with the damn connectors (found some ECU corroded pins on the last major). I´m just waiting to order SR`s gold kit next month hopefully when all the problems going on with customs in here have been solved, fingers crossed :)
     
  20. rob308

    rob308 Rookie

    Nov 19, 2009
    13
    Did you get your rough idle/burbling sorted out?, if so what did you find, have same here, and changed everything ,including swopping out ecu's,still have problem,but runs fine above idle.
     
  21. mpodgor

    mpodgor Formula Junior

    Aug 15, 2005
    661
    San Mateo, Ca.
    Full Name:
    Michael J Podgorski
    I use this stuff called DeOxit D5. It is a contact cleaner that removes the oxidation and protects. I sprayed onto every connector I could find. It runs about $20. You can google it. I ran across it when I boul an old Pioneer reciever that had scratchy pots. All the audio guys use it. Just thought I throw it out there.
     
  22. 355rockit

    355rockit Formula Junior

    Dec 1, 2010
    871
    San Marcos, CA
    Full Name:
    Vas
    I cleaned all the connector contacts I could find yesterday using CRC QD Contact cleaner (electrical grade). It is quick drying, no residue and plastic safe. I sprayed out the connector with canned air, sprayed with the cleaner and then sprayed again with canned air to dry. The F355 seems to idle smoother and sound better. There was one connector that had a yellowish tinge on the contacts that didn't come off too well with the spray. My F355 would be a good candidate for the Gold Kit at some point when I have time.
     
  23. sub rosa

    sub rosa Rookie

    Oct 20, 2010
    15
    Tampa
    I am satisfied with the way my '95 F355 is running right now... At least until my next major. Since posting, I replaced both O2 sensors. While in there, I cleaned all connections I could reach with the CRC electronics cleaner that others have mentioned, dried out with compressed air and treated with DeOxit before reconnecting. CRC cleaned out a lot of yellow sticky gunk from most connectors, which I assume was old dielectric grease. Zero CELs since then (knocking right now on wood)!

    I also discussed the idle roughness with the lead tech at Ferrari of Tampa Bay and he suggested a double dose of Techron (2x bottles in one full tank of Shell 93), which I really think helped clean and smooth her out. He also noted that they have had good results by synchronizing the throttle bodies on a mercury column, which they now do as part majors on F355s. He also told me that the '95 F355 never idled as smoothly as the later cars because of the nature of the Motronic 2.7 management system. Yes, it is normal that running the HVAC settles the idle some, because it bumps up the revs a bit. His other advice -- you'll hear this again -- drive it more! Hope that all helps.
     

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