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Rough Idle, Loss power, Backfire

Discussion in 'Mondial' started by soucorp, Apr 18, 2012.

  1. soucorp

    soucorp F1 Rookie

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    #1 soucorp, Apr 18, 2012
    Last edited: Apr 18, 2012
    Yesterday, my car starting acting up. Looks like downtime will start sooner than later for me. I have noticed for a few days now that at cold starts, the idling RPM seems to dip abit and goes back up to normal ~1000rpm. It never stalls but does this a few times than all is normal. I drove home from work yesterday, sunny and in the 70s, going about 40mph in traffic, noticed a dip in the power for a sec as if to stall a few times and I think it also backfired, I gave it some gas and it was fine. Made it home and the rough idle was gone. It almost seems as if there was water in the gas, but I know that's not the case.

    Car is a 1988 Mondial 3.2 cabrio US Spec:
    Did some research on rough idles and found a few threads about this issue:

    1) Ignition coils going bad?

    2) Protection Relay going bad?

    3) Backfire is often an indication that your idle mixture is too lean and needs to be richened out a bit.

    4) Throttle assembly is dirty?


    I will be replacing my fuel filter this weekend, replacing the spark plugs and extenders, distributor cap and rotors. Will check for any vacuum leaks also.

    Any ideas on what it could be that I have missed and what I can try?
    Thanks,
    Mike
     
  2. PV Dirk

    PV Dirk F1 Veteran

    Jul 26, 2009
    5,401
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    My peanut gallery opinion is that you've nailed it. It appears intermittant, for me that usually points to electrical. If you are doing wires/ plugs/ extenders you're probably there. The other thing to keep in mind is general electrical connections. A faulty ground can cause all sorts of nightmares. As you are in these areas make sure any connections you come across are clean. I use deoxit and then dielectric grease on all connections as I'm going through regular electrical connections. If you find fuzz or other uglies maybe a bit more cleaning effort.

    If it was a mixture issue it would have been present and wouldn't be likely to come and go. Your plugs will also tell a story as you pull them. I always set the plugs up in pattern so I can review each cylinder against the others. If you throw them in a pile you might lose valuable info in the process. Although one black one can be caused by a bad wire or plug or extender. If you have one super lean then you might have a solo injector issue but it's unlikely to have a single bad after all these years.

    When I pulled my caps with wires I put them on the kitchen table and ran an ohm meter test on them and I found one off the chart, much resistance. So you can take your problem finder hat in that direction so you'll know when you've found a problem.

    All this is not to say it might not be something else but this is a great place to start. IMO.

    PS, if you already purchased caps and rotors and the ones that come off and are clean, hold onto them or put them back and get a refund. Used ones either to sell or donate to some broke newbie in the future. I had connection to a group called the poverty riders, a group of motorcyclists that found creative ways to fix their machines. Hand me downs were huge in that group.
     
  3. soucorp

    soucorp F1 Rookie

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    #3 soucorp, Apr 18, 2012
    Last edited: Apr 18, 2012
    Thanks PV Dirk, I will start with the basics: plugs/extenders/wires/distrib cap/rotor, then see what else I can find that does not look right. While I'm at it, will replace the fuel filter and clutch slave cylinder that's been dripping oil.

    I like your idea of mapping out the plugs as it comes out, that's brilliant and tells alot in troubleshooting this idling problem. Once she runs fine again, I'll tackle the timing belt and maybe the valve clearance in a few weeks but I think those are fine for now.

    -Mike
     
  4. trendsetterx

    trendsetterx Karting

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    #4 trendsetterx, Apr 18, 2012
    Last edited by a moderator: Sep 7, 2017
    Try looking at all the least expensive yet possible solutions first. Check for any vacuum leaks, I had the same problem with #8 being corroded. Also check #3,#12 and the battery connection. Sometimes the battery connection might look clean with no corrosion, but if the wires feel to hot to touch, then the end connection might be failing. Many Fchatters fixed thier idle problem by changing a relay that failed, which is located in the trunk. Its the big relay with a red fuse. Good luck and happy hunting
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  5. trendsetterx

    trendsetterx Karting

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    #5 trendsetterx, Apr 18, 2012
    Last edited by a moderator: Sep 7, 2017
    If I remember correctly, you can tell if the relay failed by listening to the frequency valve(#26) if the frequency valve is not buzzing, then you need to replace either the fuse or relay.
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  6. soucorp

    soucorp F1 Rookie

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    Sweet, thanks Raul. I will look at these also, I do here the buzzing so may not be the relay but will check that last. I already have all of the supplies when I ordered my major service kit from Ricambi a while back so its not going to cost me any more to start replacing some of these items that I had plans to do anyways.

    thanks again.
     
  7. PT 328

    PT 328 F1 Rookie
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    Other causes could be the auxiliary air valve AAV or the WUR
     
  8. Wade

    Wade Three Time F1 World Champ
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    Mike, check out this thread and especially Steve's posts.

    http://www.ferrarichat.com/forum/showthread.php?t=340474&highlight=buzzing
     
  9. soucorp

    soucorp F1 Rookie

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  10. soucorp

    soucorp F1 Rookie

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    Thanks Dan, what is the auxiliary air valve AAV or WUR and what do I look for?
     
  11. davebdave

    davebdave Formula 3
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    If it was a Mondial t...One word..."Crank Sensor!!!!" Nevermind, I meant "O2 sensor"...one or the other, but I digress..

    Dave
     
  12. soucorp

    soucorp F1 Rookie

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    Thanks Dave, I know my 3.2 has an O2 sensor, but not sure about crank sensor, will look it up.
    -Mike
     
  13. davebdave

    davebdave Formula 3
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    Oh, You have one...just ask Jay Goodman :)
     
  14. PT 328

    PT 328 F1 Rookie
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    #14 PT 328, Apr 18, 2012
    Last edited: Apr 18, 2012
    I believe I read you were having this issue in the recent past that you thought was resolved with a tank of fresh gas. Correct me if I am wrong.

    The auxiliary air valve (AAV) is item #44 and the warm up regulator (WUR) is #9 in the link below.

    http://www.ricambiamerica.com/parts_catalogs.php?M=FE&P=&V=diag&I=2555

    The warm up regulator can be rebuilt by F-Chatter, Larry Fletcher. If needed he can be reached at http://www.cisflowtech.com/

    With your intermittent issues my bet is on a protection relay that is going bad. The part is available at Pelican Parts. I believe I purchased my replacement for around $90.
     
  15. jgoodman

    jgoodman F1 Rookie
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    #15 jgoodman, Apr 19, 2012
    Last edited: Apr 19, 2012
    Supposedly on/near the flywheel in the bellhousing. I didn't see it on the Ricambi parts list. But this left me dead in the water a few years ago during the Joe Zaff Mille Miglia in Quarryville PA, right in the middle of Lancaster dairy country. I'm going to check out my repair invoice. I haven't thought about this for a while but it really bothered me at the time, knowing that some rock or gravel flying up into the bell housing knocked some sensor pin out supposedly. I don't know.
     
  16. soucorp

    soucorp F1 Rookie

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    #16 soucorp, Apr 19, 2012
    Last edited: Apr 19, 2012
    That is pretty weird Jay. It does not sound like its the source of my idle problems but I will keep that in mind. My car never stalled, just a few times of intermittent rough idling, then its fine. Thanks.
     
  17. soucorp

    soucorp F1 Rookie

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    #17 soucorp, Apr 19, 2012
    Last edited: Apr 19, 2012
    I tried the fresh tank of gas and also added a clean system fuel additive to get rid of possible water in tank but no luck, it was still off and on rough idling. It sounds like it could be the Protection Relay, I will need to test for it as Steve described to Ron from the other thread. A dirty spark plug/wire can cause this as well so I will pull those out to check condition. Thanks.
     
  18. rob

    rob F1 Rookie

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    My 3.2 started running rough and they diagnosed it as a bad o2 sensor after the new one went in it ran/idled fine.
     
  19. soucorp

    soucorp F1 Rookie

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    Thanks Rob, did it ever stall? Running rough all the time or just at start ups or was the idling problem intermittent?
     
  20. Mule

    Mule F1 Rookie
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    Mike,
    Regarding the comments on the Frequency Valve Relay in the trunk - mine took 18 months to fully die. It was occasionally intermittent with the symptoms you describe. I did replace a lot of parts (wires, extenders, plugs etc) thinking I had solved it, but a month or two later it would come back. I don't know if it was temperature or driving conditions that would cause it to act up, but it was frustrating since it was unpredictable. FINALLY it died full time and I was able to solve it.

    The replaced parts were nice to have, but the root of the problem was that relay for me.

    Yours may die one day, so buying a new one for the shelf is not a bad idea. Swap it in and see if that is it. If not, put it away until you need it. Of course, if it is just in the beginning of dying, it may take a while to confirm that was it.

    best of luck
     
  21. soucorp

    soucorp F1 Rookie

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    I think you may be right, I will pick up a Protection Relay just in case. The advantage of doing these things myself is that I have extra money for other parts that maybe going bad when I start digging into it.
    Thank you.
     
  22. rob

    rob F1 Rookie

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    Mike this occured while my car was being sorted at the shop. They put about 100 miles on it while they were working on it to make sure everything was working properly and they said that at one point it was running/idling rough and they diagnosed it as a bad o2 sensor and I've only driven it once since the service but it runs/idles great.
    I think one way to check would be to disconnect the sensor and see if that changes the way the car is running. Hope this helps and best of luck.
     
  23. soucorp

    soucorp F1 Rookie

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    Thanks, found this to be a good read: Can a bad O2 sensor damage your car ?
    The O2 sensor (oxygen sensor) measures the amount of oxygen present in the exhaust gas. For proper combustion to occur, you need 14.7 grams of air per 1 gram of fuel. The car has sensors to measure the amount of air flowing into the engine, and can take a pretty good guess at the amount of fuel going into the engine, so it can do a pretty good job of keeping the air to fuel ratio around the 14.7:1 mark. When the engine is cool or under heavier load, that's what it does (it may even run rich, or more fuel than needed, for extra power). Once the engine warms up, and you're cruising, it will go into closed-loop operation. At that point, it uses the O2 sensor to sense the amount of oxygen in the exhaust, and fine tune the amount of fuel going in.

    If the O2 sensor is not working, it can't do this fine tuning. So long as it stays close to 14.7:1, you're ok. However, if it starts wandering, you can have problems. Too rich and your catalytic converter can destroy itself. Running rich will release a lot of unburned hydrocarbons (fuel) because there isn't enough oxygen to burn them. Those will go into the catalytic converter, which will do its best to get rid of them, but the better job it does there, the hotter it will get, and could melt. You'd likely have problems with any emissions testing. Plus, your gas mileage will suffer.
    On the flip side, if you drift lean (not enough fuel), your exhaust temperatures will rise (unless you go way to lean, in which case you may start misfiring) and you might get your cat (or your engine) too hot, with obvious consequences. The extra heat and oxygen will allow the formation of increased levels of nitrous oxides (another emission problem). The only good side to this is that running lean can help your fuel economy (assuming everything else in your car can handle it).
    So yes, a malfunctioning O2 sensor can damage your car.
     
  24. rob

    rob F1 Rookie

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    Good read Mike also I would guess from reading that, that our slow down lights would go on for the cats if we ran our cars for an extended period of time with a bad 02 sensor.
     
  25. soucorp

    soucorp F1 Rookie

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    If the cat over heats, it will trigger the slow down light to come on for sure.
    I was just shopping for a new o2 sensor, can't believe the range in prices anywhere from $55 - $400, seriously and they all say it fits my 88 3.2!
     

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