Runs rough and lost umph

Driving Green Coupe to work today. Dropped my son off at school. All seems normal and then engine suddenly seems to run rougher. No where near as much power. Checked plug wires & distributer. All seems ok. It idles decent, but in higher RPMs it is noticeably rougher and less powerful. Sluggish describes it. Much more vibration it seems. Exhaust is smoky too.

Got this advice from JPS:
Engine guy says it sounds like a dirty idle jet. You can pull one plug wire at a time from the distributor to see which one does not affect the idle, that will isolate the dirty jet. Chance of dirt or small fiber from filters in the carb or fuel would be the cause.

Before you do the wire test, with the engine off pull each wire from the distributor cap and re-install gently so they come out easy while the engine is running. After the test with the engine off, confirm all wires back in tight.

Ideas or suggestions?

Typically, if you have dual carb's and an idle jet is plugged, it will backfire and run sluggish until you reach 3000 to 3500 RPM's then it will have full power.

Cleaning the idle jets should be a routine maintenance item so go ahead but,, also check your fuel filters and your fuel pump.

A weak pump will allow the car to idle but give poor performance as you drive. A clogged fuel filter will do the same.

Larry's dead on regarding the pump and filer! I almost didn't make it home from a 25 mile drive last year. Started out just fine, ended up limping home at just above idle. Clogged filter. Happened again the next day. Clogged in-pump filter screen.

Cleaned the pump changed the remote filter, like a NEW engine. Must have been happening gradually and I didn't notice until it reached crucial.

Above info all good. Been through those issues as well.
Here's a new one I experienced on the way home from Morro Bay.
Same MO as you're reporting. Cleaned jets, checked fuel filter (new), isolated suspect cylinder as #4 (wire test), checked plug (thanks, Fast Eddie!), replaced plug, replaced rotor (directional notch broken off),
Problem still there. However, while doing the wire test, we observed a slight popping when the wire was close to contact. Exhaust leak? Checked under the car and looked at the #4 exhaust flange. BINGO! BOTH studs were gone.
Stock VW studs are 8mm X 1.25 X 20mm. I have an A1 exhaust and the flanges Tiger uses are TWICE the thickness of stock flanges. We installed 8X125X25 bolts, along with a new gasket and the problem was fixed.
Now I need to replace all the stock studs.

Tom, if you car's been sitting a lot, it may be the same issue with tank liner residue clogging up the fuel system that I experienced. It sure sounds like it. My final solution was to drain the gas, get the tank thoroughly cleaned out, replace fuel filters and lines, and thoroughly clean the carbs. A pain it the butt, to be sure, but quite common with these cars if they aren't driven much when the tank is new. It seems that the folks who make the tanks coat the inside with cosmoline, a waxy layer that is intended to prevent rust prior to filling the tank, and then dissolve in the gas. It's not a problem if you run several tanks through the car fairly quickly, but if it takes a while to burn through those first couple of tanks, watch out. that goop will clog everything.

Try replacing filters, cleaning your carbs, and running some Techron through there. If that doesn't fix it, you may have to do the whole shootin' match.

Bad gas maybe? Had you recently filled up?
I had a clogged fuel filter act like this in the past.

Tom:

Do the wire test to try to isolate the weak cylinder. If that works, then pull the idle and main jet for that cylinder, as well as the mixture screw. Blow out the jets with 20-30 lbs. of compressed air, then blow out the rest of the circuit by sending compressed air in through the mixture screw hole. One blast there should do it. Be careful removing the mixture screw! Some of them have an o-ring on the screw shaft - don't lose it!

If that doesn't fix it, you might have a leaking gasket between the intake manifold and head. One of mine just let go today and it acted as you describe. Bad enough that I wondered if I would make it home.

Just got them in and it's too late to try a test run (and I wanted to give it some time for the permatex to cure) so I'll report tomorrow.

Always sumthin, ain't it??

gn

All of the comments, so far, are valid....If you idle well and the problem is at higher speeds, try looking at your jet stacks.....
Loose or improperly seated stacks or jets could be a problem....I did this to my self once......In my case the engine was in an over rich condition....

Tom:

Just went for a run since replacing my intake manifold to head gaskets. All back to normal. I should have thought something was up when the last time I went up to Lane's it didn't seem to be quite as smooth as it had been. It finally blew one out totally and really ran poorly; very rough, seemed to be running on only two cyls and no power at all, but when I stopped it idled more-or-less OK, although 300-400 rpm lower than normal. I should have looked at my air/fuel meter to see what was going on, but didn't think of that.

If you have a clogged idle jet, as Larry said, it should straighten out when you get over 3000 rpm or so and switch to the main jets.

Good luck.
gn

Thanks to all for the help.

Gordon,
That sounds a lot like what I'm experiencing. Power is off about 40%. I'm gonna dig into it this weekend and have it scheduled into my mechanic next friday as a backup.

It'll kill me not to have this car working well and at at Carlisle. Still I am currently the owner of two cars so I will be there with one - if not both.

Speaking of both - read my post on the Carlisle head count thread under events. I'm looking for help getting my speedy to the show. Anyone interested PM me.

If for some reason, all the above produces a mixed result, don't forget the "hand built car law". Are all the mini heim joint screws on the carb linkage still tight? Is the throttle arm loose on the hex bar? Has a return spring come adrift? Are any carb base or manifold nuts loose?

The law: "If you have ever had it apart, then it will come loose again, at the worst possible time, in the worst possible place."

Tom:

It took me about 1-1/2 hours, including Guinness time, to change out both lower manifold gaskets last night. That was soup to njuts, including removal/replacement of the Hex linkage, too.

Fortunately, since I seem to go through a pair of gaskets every year about this time, I have a bunch of extras in stock, even down here.

This time I added a light film of Copper Permatex, just to see what happens in the long run, but I fully expect to be changing them in late April, 2009, too. Don't know why, I just do.

Chris and I can stop on the way by to pick up your extra car. Chris'll drive it in for you. Call or email with an address for the GPS.

gn

Gordon and all......I run C B Perf's fibre composite intake manifold gaskets and have never had an issue.....The compressability assures a proper seal, and a little "soft" locktite keeps the nuts torqued...

Just a thought.......

Damn! Didn't even THINK of the locktite on the nuts!

Well, I'll squirt'em with locktite before Carlisle.

Thanks for the idea!

I have a pair of those CB thick gaskets, but they're up North

8>(

i use nylock nuts on the intake - but that's a good idea

Not much room around my manifolds, used 11mm steel nuts from Bugpack. Both sides of gasket coated with Loctite 517 anaerobic gasket maker, loctite on the studs.

An out of sync engine(carbs) will vibrate the manifolds loose.

I wish VW used a three or four bolt setup instead of only two.

Of course, the dual port was designed for 50-60 hp, with much smaller ports than we have. Also, lots of leverage from those big carbs up on tall manifolds.

"the dual port was designed for 50-60 hp, with much smaller ports than we have. Also, lots of leverage from those big carbs up on tall manifolds"

Yeah, and the central, single carb mouted on a relatively rigid intake manifold didn't hurt the cause, either!

Oh, well......I just buy intake gaskets by the box and sit back and wait for the inevitible.....

I just dropped the Coupe with Jim & his son Christian at Klasse 356 for a once over. They are very confident it will be easy to resolve. Should know in a day or so. For me better to get some knowledgeable hands on it with only a week or so to the big dance in Carlisle.

Don't forget your "Poodle Skirt".....

Kristian @ Klasse 356 worked on my 2332 and now runs smooth and strong. Timing was way off, some fuel and carb issues, and valves way out of adjustment - all addressed. Seems great except . . . now it's very smokey. I won't be able to get it back to Klasse until after Carlisle. Hope some of the clan there will have a few ideas.

Smokey: I assume you mean dark smoke = rich carb setting ~Alan

Blue smoke and lots of black soot at the tailpipe. Changed to a high volume fuel pump set at 3.5psi.

runs great

but anyone behind me at a light is thinking my "german car" has a different purpose . . .

Black smoke (rich condition), blue smoke (oil consumption, bad oil rings or guides), sudden drop in power (compression loss or valve adjustment), valves out of adjustment and timing way off . . . cause or result of over heating.

Waa the timing advanced initially? It sounds like they may have had the engine set too far advanced to mask carb adjustment/idle/performance problems and the engine may have run too hot as a result. This would explain the power loss and valves going out of adjustment, and be the reason for the possible out-of-round cylinders that MAY be responsible for all that smoke.


Sure HOPE not, but the symptoms fit. They also fit a sloppy set-up as well. What were the cold compression readings? Wet? Dry? These would confirm or rule out guides vs rings as a source of the blue oil smoke.

Either way, LUCK ! ! !

TC