If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below. |
|
|
Thread Tools | Display Modes |
#31
|
|||
|
|||
Damaged SOMETHING with backfiring ...
when trying to locate a running problem with the engine it is a good idea to
test the condition of the engine. My definition A compression test will determine how much the engine will compress air. There are certain procedures to do this, such as disable ign system, remove plugs, open throttle, crank over engine and watch compression gauge during all strokes. The first stroke will be important also, so that needs to be watched. A leak down test, injecting a cylinder with air and watching a gauge, will check how well the engine can hold that compression. Compressed air will leak out via piston rings, valves and possibly elsewhere. It can help determine where that leak is too. Piston needs to be at TDC in firing position. "Fred Mann" > wrote in message ... >I don't know what a leak-down test is and I haven't done a compression >test. > Do I need to do both? > Also, I can't seem to find the timing marks anywhere. I looked inside the > port that is on the bell of the transmission and I didn't see any marks. I > rolled the car in high gear and looked in there with a flashlight --- > nothin'. Am I looking in the right place? |
Ads |
#32
|
|||
|
|||
Damaged SOMETHING with backfiring ...
I'm going to check timing first since it should be easiest. BUT there is no
mark OR pointer. (I removed the plastic plug) I think I have found TDC on piston 1 using the techniques above, but I still don't know how I'm going to locate 6 degrees BTDC. I can put a dab of paint on the flywheel, but still, I don't which way is "before" and which is "after" or how far 6 degrees is. Also, do I need to pull the vacuum advance hose? And as for the exhaust problem ... is it possible that a piece of the gasket is stuck in the manifold? I was just wondering if I might have an exhaust clog somewhere before the catalytic converter .... |
#33
|
|||
|
|||
Damaged SOMETHING with backfiring ...
Fred Mann wrote:
> Also, I can feel some pulsing air when I put my hand around the back side of > the engine, so maybe this noise is some exhaust leak? But then why would I > have a loss of power and why would it be isolated to #2 piston? Hmmmmm..... > > For # 2 cylinder, check compression, plug wire, fuel injector operation. |
#34
|
|||
|
|||
Damaged SOMETHING with backfiring ...
Compression test results:
I removed all plugs, put the pedal to the metal and cranked the engine. The results were nearly identical for each cylinder. First crank was roughly 95-100 PSI for each cyl. After about 5 cranks, the guage leveled out around 175-180 PSI. I doubt there was more than 5 PSI difference at any stage across the board. I'm assuming this means my engine is okay. At least by this measure. However, I am still operating with the rear half of the exhaust system removed (catalytic converter and tailpipe disconnected). As is, I have seen some smoke when I rev up the engine. Is this a sign of another problem, or is this to be expected when the converter is removed? |
#35
|
|||
|
|||
Damaged SOMETHING with backfiring ...
PS -- I have not replaced the plugs, but I have replaced cap, rotor and
wires. One of the towers on my newish rotor already had some damage -- pretty heavy carbon deposits, and what appear to be a slightly displaced inner metal sleeve |
#36
|
|||
|
|||
Damaged SOMETHING with backfiring ...
On Wed, 11 Jul 2007 16:08:02 -0400, "Fred Mann"
> wrote: >I'm going to check timing first since it should be easiest. BUT there is no >mark OR pointer. (I removed the plastic plug) I think I have found TDC on >piston 1 using the techniques above, but I still don't know how I'm going to >locate 6 degrees BTDC. I can put a dab of paint on the flywheel, but still, >I don't which way is "before" and which is "after" or how far 6 degrees is. >Also, do I need to pull the vacuum advance hose? >And as for the exhaust problem ... is it possible that a piece of the gasket >is stuck in the manifold? I was just wondering if I might have an exhaust >clog somewhere before the catalytic converter .... > It is covered in the Bentley manual. See page 68. You do not have an exhaust clog. Banish that idea from your mind. http://cgi.ebay.com/ebaymotors/VW-Ra...spagenameZWDVW |
#37
|
|||
|
|||
Damaged SOMETHING with backfiring ...
Good now you can proceed to other issues like ignition, fuel exhaust, etc
since the engine passes the comp test.. Yes replace any known bad component to eliminate that as a possibility. You have identified that #2 noise as an exhaust manifold/gasket leak. Fix that if the tick is annoying or very loud. And you think the loss of power is due to a clogged cat??? There are inexpensive "universal" cats out there or you can temporarily install a test pipe on the exhaust in place of the cat. I vote you install a bolt on cat and be done, unless you are not sure about having a bad cat. ;-) "Fred Mann" > wrote in message ... > Compression test results: > I removed all plugs, put the pedal to the metal and cranked the engine. > The > results were nearly identical for each cylinder. > First crank was roughly 95-100 PSI for each cyl. > After about 5 cranks, the guage leveled out around 175-180 PSI. I doubt > there was more than 5 PSI difference at any stage across the board. > I'm assuming this means my engine is okay. At least by this measure. > However, I am still operating with the rear half of the exhaust system > removed (catalytic converter and tailpipe disconnected). As is, I have > seen > some smoke when I rev up the engine. Is this a sign of another problem, or > is this to be expected when the converter is removed? > > > PS -- I have not replaced the plugs, but I have replaced cap, rotor and > wires. One > of the towers on my newish rotor already had some damage -- pretty heavy > carbon deposits, and what appear to be a slightly displaced inner metal > sleeve > > |
#38
|
|||
|
|||
Damaged SOMETHING with backfiring ...
Well, I finally got my catalytic converter all the way off. I had to cut the
screws off with a dremel. Anyway, it's completely hollow. I'm not sure if it's supposed to be like that. My concern is that the backfires blew some of the "guts" of the CC down the pipe and possibly cause a clog there or in the muffler. Any thoughts? Also, when I replaced the hall sender, I used an old one from my other rabbit. I assume it's working fine since the car runs without cutting out now (unlike before I replaced it). As far as I know, hall senders just send a signal to the coil and it either works or it doesn't. That is, it can't send a "weak" signal. But I just wanted to make sure that I didn't overlook something or use an inferior part. Again, any thoughts would be greatly appreciated!!! Fred "dave AKA vwdoc1" > wrote in message t... > Good now you can proceed to other issues like ignition, fuel exhaust, etc > since the engine passes the comp test.. > Yes replace any known bad component to eliminate that as a possibility. > You have identified that #2 noise as an exhaust manifold/gasket leak. > Fix that if the tick is annoying or very loud. > > And you think the loss of power is due to a clogged cat??? > There are inexpensive "universal" cats out there or you can temporarily > install a test pipe on the exhaust in place of the cat. I vote you install > a bolt on cat and be done, unless you are not sure about having a bad cat. > ;-) > > > "Fred Mann" > wrote in message > ... > > Compression test results: > > I removed all plugs, put the pedal to the metal and cranked the engine. > > The > > results were nearly identical for each cylinder. > > First crank was roughly 95-100 PSI for each cyl. > > After about 5 cranks, the guage leveled out around 175-180 PSI. I doubt > > there was more than 5 PSI difference at any stage across the board. > > I'm assuming this means my engine is okay. At least by this measure. > > However, I am still operating with the rear half of the exhaust system > > removed (catalytic converter and tailpipe disconnected). As is, I have > > seen > > some smoke when I rev up the engine. Is this a sign of another problem, or > > is this to be expected when the converter is removed? > > > > > > PS -- I have not replaced the plugs, but I have replaced cap, rotor and > > wires. One > > of the towers on my newish rotor already had some damage -- pretty heavy > > carbon deposits, and what appear to be a slightly displaced inner metal > > sleeve > > > > > > |
#39
|
|||
|
|||
Damaged SOMETHING with backfiring ...
"Fred Mann" > wrote in message
... > Well, I finally got my catalytic converter all the way off. I had to cut > the > screws off with a dremel. Anyway, it's completely hollow. I'm not sure if > it's supposed to be like that. My concern is that the backfires blew some > of > the "guts" of the CC down the pipe and possibly cause a clog there or in > the > muffler. Shouldn't be hollow and yeah the guts could be plugging your mufflers. > Any thoughts? It's probably more than you wanted but could very well be time for a cat-back exhaust. |
#40
|
|||
|
|||
Damaged SOMETHING with backfiring ...
On Mon, 16 Jul 2007 17:49:13 -0700, "Matt B." >
wrote: >"Fred Mann" > wrote in message ... >> Well, I finally got my catalytic converter all the way off. I had to cut >> the >> screws off with a dremel. Anyway, it's completely hollow. I'm not sure if >> it's supposed to be like that. My concern is that the backfires blew some >> of >> the "guts" of the CC down the pipe and possibly cause a clog there or in >> the >> muffler. > >Shouldn't be hollow and yeah the guts could be plugging your mufflers. > >> Any thoughts? > >It's probably more than you wanted but could very well be time for a >cat-back exhaust. > Old post to answer too. If it is completely hollow then somone probably gutted it with a screwdriver. On my cars they tended to melt down and chunks would break loose. Those chunks either rattled making a noisy car noisier or the car would not run due to a corked up exhaust. The converter is supposed to look like a honeycomb. But the grid is a lot smaller than the honycomb you buy at the store to chew on. The holes might be .5 mm in size. Maybe it is a bit bigger but it is fairly small. You can hold a good converter up to light and see through it input to output. A failed one meaning one that has clogged or melted down will not pass light or you will see melted parts. Go to any parts store and ask to see a new one. Do not put a new converter on until your car is running perfectly. You will just destroy a converter in short order if the car is running rich, lean, or if the camshaft or ignition timing is significantly off. I prefered to get someone to attach a sniffing probe to the sniffing port to make sure the mixture was correct before installing a new converter. The procedure is in the Bentley. Since the converter is hollow you could just exhaust sniff from the tailpipe. The challenge is finding someone with an old style exhaust analyzer that will let you work for 15 minutes. |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
NR2003 Backfiring sounds | Jim Barbieri | Simulators | 3 | June 17th 07 01:26 PM |
CJ - backfiring problem help (a little long) | [email protected] | Jeep | 10 | June 15th 06 04:12 AM |
1987 BMW 535i BackFiring | James | BMW | 0 | January 12th 06 03:59 AM |
Backfiring | elaich | Ford Mustang | 1 | November 28th 05 01:48 PM |
backfiring | Ford Mustang | 3 | May 3rd 05 08:21 PM |