News

Backfiring, etc.

Discussion in 'Technical Q&A' started by Dom, Nov 8, 2003.

  1. Dom

    Dom F1 Veteran
    Rossa Subscribed Owner

    Nov 5, 2002
    7,516
    Southern California
    Full Name:
    Dom V.
    OK, here's the story:

    Last Sat- Washed car. I did place a plastic sheet over engine (specifically spark plugs, distributors) during the wash.

    Last Sun- Drove the car to a car show (approx 1 hour away). Absolutely no problems, car ran perfectly to and from the show.

    Parked car in garage until today (sat).

    Immediately upon startup, it didn't sound right. Somewhat tinny. When I drive the car, I get backfiring on deceleration. Power seems to be there, just the sound is off, and the backfiring.

    I checked the spark plug boots, no water. Blew some compressed air in there just in case. Also checked ignition wiring (visual), nothing seems to be out of place (Car has MSD ignition).

    I'm at a loss. Could the plugs be fouled? Exhaust leak?

    I will probably try to take out the plugs tomorrow. The front bank doesn't look like it's going to be fun. But, I have a feeling that I may be barking up the wrong tree.

    Any suggestions?

    Thanks,
    Dom
     
  2. jarends

    jarends Formula Junior

    Jul 23, 2001
    567
    Princeton, NJ
    Full Name:
    John Arends
    Dom,

    I just drove our 328 today after having the same trouble.

    Before you take the plugs out, check the distributor for moisture, especially since the wash.

    We had our fixed but it was missing again last week (just posted a new thread). Went to take it in today and it ran like a charm. Stopped at the mechanics and he put in a top rate injection cleaner. Told us we had to drive it 100+ miles today. Told him thanks and spent the day on the roads in PA. Ran really well.

    John
     
  3. Dom

    Dom F1 Veteran
    Rossa Subscribed Owner

    Nov 5, 2002
    7,516
    Southern California
    Full Name:
    Dom V.
    John,

    Thanks for the advice. I tried cleaning out the distributor caps to no avail. Still running like crap...

    Dom
     
  4. f355spider

    f355spider F1 World Champ
    Rossa Subscribed Owner

    May 29, 2001
    16,557
    USA
    Full Name:
    Hugh G. Rection
    Pull the plugs, I bet you have a fouled one. I had this happen on occaision with my previous 78 308 GTS (carb) car. I used to get water down the plug holes...even after drying everything out, I ended up having to replace the fouled plug. I got new factory plug covers from T.Rutland's and never had the problem again.

    You could be fouling for another reason (since you covered the engine for the wash). What heat range plug are you using? You might try the NGK BP5ES (non resistor) or BPR5ES (resistor). The 6's always worked fine in my car, but many on the list seem to think the hotter 5 is better.
     
  5. Dom

    Dom F1 Veteran
    Rossa Subscribed Owner

    Nov 5, 2002
    7,516
    Southern California
    Full Name:
    Dom V.
    Update:

    I pulled the plugs on the front bank. All looked fine except for the first one (all the way on the drivers side). That one was covered with black soot. Of course, went to the local Kragen, and they didn;t have the plug. I tried to clean and regap, but if anything, the car runs worse now.

    I am using NGK BP7EVX plugs. When I got the electronic ignitiion installed, the mechanic said that these plugs should be fine for the car, even though they are colder than normally recommended, due to the electonic ignition. Up until this weekend, the car ran great since I got it in Feb.

    Would the gap be any different for a car that has been converted to electronic ignition? I noticed the gap appeared to be about 0.03 inches, whereas the manual states that the gap should be 0.4 mm (~0.02 inches).

    I'll have to see if I can find a local source for the plugs, or order some more.

    Dom
     
  6. f355spider

    f355spider F1 World Champ
    Rossa Subscribed Owner

    May 29, 2001
    16,557
    USA
    Full Name:
    Hugh G. Rection
    Dom,
    I had the Crane electronic ignition conversion, and still ran BPR6EVX plugs. Most others do as well, and in fact, many run 5's. I think you are running too cold a plug. The gap I ran was .034, you need to widen it a bit with the electronic ignition. I had a distinct miss at a smaller gap.

    In order to save $$$'s until you figure out what plug heat range works best, use the "standard" NGK plugs.

    Regards,
    Dave
     
  7. 4re gt4

    4re gt4 Formula 3

    Apr 23, 2002
    2,279
    Roseburg, OR
    Full Name:
    Hans E. Hansen
    Dom: Any chance you're missing an entire bank? I had a loose wire to one of my optical sensors. The real clue, however, was that the tach stopped working. If it had been the other bank, the tach still would have functioned. Did a "Lucas" repair - wiggled the wire, and all was fine.
     
  8. JOEL D.

    JOEL D. Karting

    Nov 2, 2003
    222
    Boston, MA
    Full Name:
    Joel DeLuca
    My 328 will run rough, idle worse and be down on power for a period of time and then clear. The problem has turned out to be a"plenum" whatever that is, that is screwing up the mixture. Its a mechanic fix, but takes about 15 minutes. I have never had it run rough from water or moisture. Best of luck.
     
  9. Dom

    Dom F1 Veteran
    Rossa Subscribed Owner

    Nov 5, 2002
    7,516
    Southern California
    Full Name:
    Dom V.
    I don't think it's a whole bank. The car appears to have decent power, and I imagine if I lost a bank that I would notice a decrease in power. Also, it was just one plug that was fouled. The other three on the front bank were fine.

    I think Dave Handa's suggestion about the new plug covers is good. Probably water is getting in where it shouldn't be, so I'd like to get it fixed, or else I'll never be able to wash my car again.

    I will be bringing the car into a mechanic tomorrow. I think I could replace the plugs, but I've been so strapped with time lately, that if I spend another couple of hours playing with the plugs/ignition and ignoring my wife and kids, my wife is going to kill me.

    Thanks,
    Dom
     
  10. f355spider

    f355spider F1 World Champ
    Rossa Subscribed Owner

    May 29, 2001
    16,557
    USA
    Full Name:
    Hugh G. Rection
    Dom,
    The plug covers were only $4 or so each from T.Rutland's if I remember correctly. The NGK standard plugs are $2 or maybe $2.50 each...I'm hesitant to take your car to the mechanic for something you could do yourself in a hour or two max....but understand when family calls... :)
     
  11. 4re gt4

    4re gt4 Formula 3

    Apr 23, 2002
    2,279
    Roseburg, OR
    Full Name:
    Hans E. Hansen
    You wash your car? I'm so paranoid about rust that I never wash it in the conventional sense - just a gentle sponge bath and NO HOSE!

    I wish *I* could get the same treatment.
     
  12. Dom

    Dom F1 Veteran
    Rossa Subscribed Owner

    Nov 5, 2002
    7,516
    Southern California
    Full Name:
    Dom V.
    I've only washed the car twice. Both times I had issues afterwards. The first time, I had similar simptoms. Took off the plug covers, blew compressed air into the sparkplug wells, and everything was fine. This time seems a little more complicated.

    The problem with doing it myself is it takes time. Also, I'm worried that it may not be such a simple fix this time. It will probably be simple as replacing one plug, for which the mechanic will probably charge me $200 and then I'll be bummed that I didn't do it myself. But, in the event that it is something more serious, I figure I'll let a pro do it this time, before I scew it up more...

    Dom
     
  13. Darolls

    Darolls F1 Veteran
    BANNED

    Jul 2, 2003
    6,799
    Full Name:
    Sparky
    Dom-

    You say you drove the car for 2 hrs. (1 hr each way), and it ran fine.

    I doubt that washing the car has anything to do with it, as one would think that the problem would have shown up right away.

    Did you check the spark plug extender on the fouled plug; it's possible a pinhole blew through it. Also, check the wires.
     
  14. Dom

    Dom F1 Veteran
    Rossa Subscribed Owner

    Nov 5, 2002
    7,516
    Southern California
    Full Name:
    Dom V.
    Darolls,

    Yep, I thought that was wierd also. I would have expected it to run like crap the following day, but it didn't. After I drove back from the car show, I parked the car in the garage, and didn't start it until the following weekend, when I noticed the problem.

    I will have the mechanic check the sparkplug extenders and wires.

    Thanks,
    Dom
     
  15. Sophia

    Sophia Formula Junior

    Aug 17, 2003
    298
    Dash Point/Federal W
    Full Name:
    Peter Barbin
    I had a similiar problem, turned out to be a "pinholed" a spark plug lead. I finally vented the exhaust system with the running car in a completely dark garage. The little blue spark finally showed it's path to ground, but not at the spark plug tip...but from the wire to the block.

    This problem drove me crazy since I replaced the spark plugs and the problem went away...for a while...until the wire drifted back to it's happy place...then the short again!

    Good luck!
     
  16. Dom

    Dom F1 Veteran
    Rossa Subscribed Owner

    Nov 5, 2002
    7,516
    Southern California
    Full Name:
    Dom V.
    Well, it's a good thing I'm not a professional mechanic. The ignition was fine.

    Mechanic said I blew an exhaust gasket. $12 for the gasket and ~$100 in labor, and I'm good to go.

    Dom
     
  17. Ontogenetik

    Ontogenetik Karting

    Nov 2, 2003
    149

    If you don't mind, does your car have the stock exhaust?
    What did the backfiring sound like?
    Where are the exhaust gaskets located?

    Thanks.
     
  18. Dom

    Dom F1 Veteran
    Rossa Subscribed Owner

    Nov 5, 2002
    7,516
    Southern California
    Full Name:
    Dom V.
    Ontogenetik,

    No, I have a stebro exhaust. Not sure where exactly the gaskets are located, but would guess between the headers and where the stebro connect.

    Note about the stebro exhaust: My mechanic (who is an Alfa guy) has mentioned that he's had lots of problems with the Stebro on Alfa's. Everything from poor fit to bad welds. However, the Stebro is 1/2 the price of a tubi, and sounds great. Hopefully this will be the last problem I have with the stebro.

    Dom
     
  19. Ontogenetik

    Ontogenetik Karting

    Nov 2, 2003
    149
    Thanks, Dom.
     
  20. f355spider

    f355spider F1 World Champ
    Rossa Subscribed Owner

    May 29, 2001
    16,557
    USA
    Full Name:
    Hugh G. Rection
    Dom,
    I know how this happens, and it can come back if not attended to properly. If the mounting flanges are not duplicated exactly, the exhaust gases can be in contact with the exhaust "donut" fiber gasket. This is not correct, there is supposed to be a bit of metal "sleeve" sticking out from one side of the flange (either the muffler or header pipe), if there are two connections, then one will be the opposite of the other. The idea is that this way, only the ends of the fiber "donut" gasket is contacting the flanges, and the donut is protected from direct contact with the exhaust gases. I discovered this problem with my "test pipes" on my previous carb 308. The test pipes did not duplicate the sleeve on one end of each catalyst, so the exhaust gases contacted the "donuts" and after a year and about 9k of miles, they burned out and got LOUD. The fix was to get some sintered metal exhaust donuts from the local Midas shop. Took about 1.5 hours to disasemble things, swap the donuts and button it back up. Did it myself on a friend's lift.
     
  21. Wayne 962

    Wayne 962 Formula Junior

    Nov 27, 2003
    407
    Quick question here - is it the recommendation of people here to use one of the newer-type metal exhaust gasket donuts instead of the standard replacement ones? Mine are all looking pretty bad on my car, so I was going to replace all six ($100+ for the parts).

    Anyone know of a better (metal) alternative to using these gaskets, or should I perhaps head down to the local auto parts store and see if they have one to match? I know my wife's old Honda Accord had a very similar looking gasket when I replaced it several years ago.

    -Wayne
     

Share This Page