bucking/backfire
#1
Rennlist Member
Thread Starter
bucking/backfire
Cross post, also on Pelican forum...
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My SC has been running PERFECTLY. A couple months ago I went to SSIs and M&K 2/1 muffler. Car has been running like a top, loud and strong. Even idle at 900, no sign of any sort of surging or hunting.
Tonight I downshifted for a slow corner, was in 2nd and it started bucking. Next it sounded like someone standing outside the driver's door shot a 44 magnum. Scared the living **** out of me. Car cut off. I pulled over, waited a second, turned the light switch off, pumped the pedal once, it started right up. About 30 or 40 yards later it shuddered, and just shut off. No backfire.
I shut off the lights, didn't pump the pedal at all. Started it right up and let it idle for a minute, then I started out smoothly, revving to match revs before downshift, didn't let it 'coast' in neutral or with clutch in, drove home about 2 miles.
No problems. Sat in the garage with it idling, checked the oil, it's just above mid-level, rev'd the **** out of it 3 times, let it idle for a few more minutes, then shut her down.
Then at a suggestion from a Pelicanite (it was damp out and had been raining today although car drove home 15 miles before parking and heading back out when the backfire occurred) I ran engine lid open full-dark in the garage, no light show, no sign of any sparks. If dampness or wet due to rain, I'd have expected this on the way home from work, before being home for about 20 min before heading back out when the backfire occurred.
Could it be wires ? PPI a bit over a year ago (June '05) doesn't mention wire replacement, just plugs. In the time I've had it over at the local tech for stuff no wire replacement, so I believe they may be original.
Thanks !!!
Looks like Magnecore wire set in my future ?
-----------------------------------------
My SC has been running PERFECTLY. A couple months ago I went to SSIs and M&K 2/1 muffler. Car has been running like a top, loud and strong. Even idle at 900, no sign of any sort of surging or hunting.
Tonight I downshifted for a slow corner, was in 2nd and it started bucking. Next it sounded like someone standing outside the driver's door shot a 44 magnum. Scared the living **** out of me. Car cut off. I pulled over, waited a second, turned the light switch off, pumped the pedal once, it started right up. About 30 or 40 yards later it shuddered, and just shut off. No backfire.
I shut off the lights, didn't pump the pedal at all. Started it right up and let it idle for a minute, then I started out smoothly, revving to match revs before downshift, didn't let it 'coast' in neutral or with clutch in, drove home about 2 miles.
No problems. Sat in the garage with it idling, checked the oil, it's just above mid-level, rev'd the **** out of it 3 times, let it idle for a few more minutes, then shut her down.
Then at a suggestion from a Pelicanite (it was damp out and had been raining today although car drove home 15 miles before parking and heading back out when the backfire occurred) I ran engine lid open full-dark in the garage, no light show, no sign of any sparks. If dampness or wet due to rain, I'd have expected this on the way home from work, before being home for about 20 min before heading back out when the backfire occurred.
Could it be wires ? PPI a bit over a year ago (June '05) doesn't mention wire replacement, just plugs. In the time I've had it over at the local tech for stuff no wire replacement, so I believe they may be original.
Thanks !!!
Looks like Magnecore wire set in my future ?
Last edited by DB_NC_95C2; 12-01-2006 at 08:55 PM.
#2
Drifting
Check for hairline cracks in the distributor cap.
My old VW bug used to have teh same problem in the winter and the problems went away after the cap was changed.
I would plan on changing thw wires if they are the orginal ones. I have Magnacor wires on my SC and they work great.
Are you going to Leith Porsche in Cary on Sat. Morning?
They will be presenting the new Targa and having a free breakfast.
John
My old VW bug used to have teh same problem in the winter and the problems went away after the cap was changed.
I would plan on changing thw wires if they are the orginal ones. I have Magnacor wires on my SC and they work great.
Are you going to Leith Porsche in Cary on Sat. Morning?
They will be presenting the new Targa and having a free breakfast.
John
#4
Burning Brakes
Has the SC got CIS? If so try cleaning the points. With the part electronic system only LV crosses the points and even the smallest speck of dirt will cause the symptoms you describe.
PJC
PJC
#6
Team Owner
I had a somewhat similar experience. it may not be the answer but it may be a clue. My wire came loose from the coil to the cap.. was running really rough. of course with CIS fuel is constantly being pumped in so when it did spark I too though A gun had gone off. For me the fix was simple but it would indicate your problem is spark timing. Of course I am sure you are aware you won't get too many chances at this before it blows your air box apart "so git er done "
Ps I hope you have a pop off valve.
Ps I hope you have a pop off valve.
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#8
Rennlist Member
Thread Starter
Originally Posted by GothingNC
Check for hairline cracks in the distributor cap.
My old VW bug used to have teh same problem in the winter and the problems went away after the cap was changed.
I would plan on changing thw wires if they are the orginal ones. I have Magnacor wires on my SC and they work great.
Are you going to Leith Porsche in Cary on Sat. Morning?
They will be presenting the new Targa and having a free breakfast.
John
My old VW bug used to have teh same problem in the winter and the problems went away after the cap was changed.
I would plan on changing thw wires if they are the orginal ones. I have Magnacor wires on my SC and they work great.
Are you going to Leith Porsche in Cary on Sat. Morning?
They will be presenting the new Targa and having a free breakfast.
John
Sorry I didn't see this in time. I didn't know about the goings on at Leith, I rarely get down there.
I just ordered a set of Magnacore wires, a new rotor and dist cap. I'm fairly
certain the wires on my car are the original, much of the wire length is a braided design, which looks like it wouldn't withstand much dampness. That must have been what happened the other night.
I am a mechanical and electrical neophyte, I'll change oil/filter, or brake pads but that's about the extent of it. Wires shouldn't be any issue, but I'm guessing it's easier to get at the plug ends from underneat the engine from what I can see ?
Thanks,
David
#9
Drifting
DB_NC,
I was not able to attend the event at Leith Porsche yesterday.
My brother stopped by and they had foof catered by Red, Hot & Blue and he checked out the new 997 Targa.
Nice car but $105,000 is a bit much and I'm sure in about 4 years it will be valued at around $50,000.
They had a LOT of Porsche's on the lot, quite a bit more then he expected.
The heat is back-dated on my Targa so I have easy access to the plugs from the top. You probably will have to move the A/C compresser and the hose for the heat, which is not a difficult job for the novice.
You should stop by at the monthly PCA meeting at Blinco's in Raleigh on Glenwood Ave. Next meeting is the 2nd Thursday in January.
Good luck
John
I was not able to attend the event at Leith Porsche yesterday.
My brother stopped by and they had foof catered by Red, Hot & Blue and he checked out the new 997 Targa.
Nice car but $105,000 is a bit much and I'm sure in about 4 years it will be valued at around $50,000.
They had a LOT of Porsche's on the lot, quite a bit more then he expected.
The heat is back-dated on my Targa so I have easy access to the plugs from the top. You probably will have to move the A/C compresser and the hose for the heat, which is not a difficult job for the novice.
You should stop by at the monthly PCA meeting at Blinco's in Raleigh on Glenwood Ave. Next meeting is the 2nd Thursday in January.
Good luck
John
#10
Burning Brakes
David,
Plug leads are 'attacked' from the top of the engine, not from underneath - the plugs are buried into the cylinder heads but the leads just pull off.
PJC
Plug leads are 'attacked' from the top of the engine, not from underneath - the plugs are buried into the cylinder heads but the leads just pull off.
PJC