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Tue Jun 07, 2005 2:12 pm

Hey all! my 71 fastback is still burning alot of fuel. I replaced the pressure sensor hose, which was cracked, ran a little cleaner. I put new plugs and wires on it, it runs much stronger now, but still running rich. The charging system checks out fine, what else should I check :?:

Tue Jun 07, 2005 3:58 pm

Make sure your air filter is cleaned and serviced with the proper amount of oil. THEN,
Check valve adjustment, point gap, timing. If OK,
Then, check Temp Sensor 2- the one on the cylinder head. If within specs BOTH hot and cold, THEN
Remove / disassemble/ clean your mass air sensor with ELECTRONICS cleaner. If it's already clean, or cleaning it doesn't help, THEN:
If you're up to it, scrape out the plastic gluey crap over the big plug on the pressure sensor and take out the big slotted cap screw. Under that is a smaller mixture adjustment screw. Reinstall the reassembled sensor, and beg, borrow, or steal an exhaust analyser. Run the car to operating temperature , hook up the analyser, and set the CO value to 13 using the screw in the pressure sensor.

DO NOT ignore the other steps and jump right to the pressure sensor thing, and DO NOT attempt to adjust the mixture without a sniffer, or you'll be sorry. :wink:

Tue Jun 07, 2005 4:16 pm

I'm just curious Tram, what does a CO reading of 13 mean?

Tue Jun 07, 2005 4:37 pm

baja5 wrote: I'm just curious Tram, what does a CO reading of 13 mean?
13 parts per million of CO. vs. other gases in the exhaust.

Tue Jun 07, 2005 5:41 pm

Co is read in percent, not ppm. hydrocarbons are read in ppm. i just thought you forgot the . in the 13. 1.3 percent Co is ok but a little lean on a vw. i set mine at around 2 % Co.

Tue Jun 07, 2005 6:41 pm

baja5 wrote: Co is read in percent, not ppm. hydrocarbons are read in ppm. i just thought you forgot the . in the 13. 1.3 percent Co is ok but a little lean on a vw. i set mine at around 2 % Co.

Both of my gauges have a range of 10- 15 for the CO values. No decimals anywhere. Years ago at both VW and Mercedes engine- management schools, we measured in PPM.

Tue Jun 07, 2005 8:16 pm

Those must be vintage guages, but thanks for clearing that up. i've never seen Co measured in ppm.

Fri Mar 03, 2006 11:11 am

OK. I'm stuck. I'm just getting the '69 Square up and running on the new motor, and it's running rich. Everything is stock. It's running rich enough to make a whisp of black smoke in the exhaust after warmup. I have a heated O2 sensor rigged up in a pipe that slips on the tailpipe with one of those LED A/F meters on the other end. It's one of those that has 5 lean marks, 4 normal marks, and 5 rich marks. It reads steady 3 bars into the rich area at idle and under load. When I let off the throttle it swings over to lean then climbs back to the rich side.

It idles fine, accelerates well, and runs great at lower speeds. When I'm cruising around 60 or 65 it starts cutting out. After a 20min run that included about 5min of highway speed the oil temp was 185 - ambient was around 60 at the time.

I've already checked the following:
Voltage - 14.2v at the battery and terminals 86 & 87 on the main relay. 13.5v at terminal 15 on the coil.
Fuel pressure - actually set a little low right now around 25psi. Was at 28. Didn't seem to make a difference.
Head Temp Sensor - checks out at all temperatures according to Russ's chart.
Vacuum lines - all new hose and clamped at all connections.
Intake gaskets - proper FI style gaskets.
MPS - clean and holds vacuum, epoxy plug still in place.
AAR - electric style, closes down to a low draw when warm.

I hooked up a violated MPS, and was able to tweak the mixture into the normal area, but it wandered all over the place from there.

What else do I need to look at?

Fri Mar 03, 2006 11:48 am

leaky injectors??

Fri Mar 03, 2006 12:37 pm

SquareTone wrote: OK. I'm stuck. I'm just getting the '69 Square up and running on the new motor, and it's running rich. Everything is stock. It's running rich enough to make a whisp of black smoke in the exhaust after warmup. I have a heated O2 sensor rigged up in a pipe that slips on the tailpipe with one of those LED A/F meters on the other end. It's one of those that has 5 lean marks, 4 normal marks, and 5 rich marks. It reads steady 3 bars into the rich area at idle and under load. When I let off the throttle it swings over to lean then climbs back to the rich side.

It idles fine, accelerates well, and runs great at lower speeds. When I'm cruising around 60 or 65 it starts cutting out. After a 20min run that included about 5min of highway speed the oil temp was 185 - ambient was around 60 at the time.

I've already checked the following:
Voltage - 14.2v at the battery and terminals 86 & 87 on the main relay. 13.5v at terminal 15 on the coil.
Fuel pressure - actually set a little low right now around 25psi. Was at 28. Didn't seem to make a difference.
Head Temp Sensor - checks out at all temperatures according to Russ's chart.
Vacuum lines - all new hose and clamped at all connections.
Intake gaskets - proper FI style gaskets.
MPS - clean and holds vacuum, epoxy plug still in place.
AAR - electric style, closes down to a low draw when warm.

I hooked up a violated MPS, and was able to tweak the mixture into the normal area, but it wandered all over the place from there.

What else do I need to look at?

Wandering around excessively indicates too lean. Put your fuel pressure back to specs and re- tweak the mix. If that doesn't help, I would "violate" your known good MPS and adjust it from there. Open it up and clean the oil out first. Use electronics cleaner.
Is the ignition system- Point gap and timing- correct? If you're not sure, check that first.

Fri Mar 03, 2006 3:40 pm

It's not the engine speed that wandering around, just the reading on the A/F meter.

The gap and timing are good. I think I'll go ahead and put in new points and condenser to make sure. Also trying to get my hands on a proper exhaust analyzer. If anybody has one I can borrow in the Tulsa area I'll be your friend forever.

Tue Mar 07, 2006 10:39 am

Thank goodness for the lack of emission checks in my State, it sounds like a nightmare. Would a high volt coil help with your rich fuel mixture?

Tue Mar 07, 2006 10:47 am

SquareTone wrote: It's not the engine speed that wandering around, just the reading on the A/F meter.

The gap and timing are good. I think I'll go ahead and put in new points and condenser to make sure. Also trying to get my hands on a proper exhaust analyzer. If anybody has one I can borrow in the Tulsa area I'll be your friend forever.
I don't have an EGA, but you could bring it by Der German and I'll look at it :wink:

Fri Mar 10, 2006 7:32 am

WOOHOOO! It's alive!
OK. Here's the story:
- tried another MPS that already had the plug out; was able to get some control over the mixture, still cutting out on the highway
- replaced points, condenser, rotor, cap, plug wires; running smooth, but couldn't get the idle below 1200 without retarding the timing
- had noticed before that the throttle could swing past closed; replaced the butterfly with one from a spare IAD, got control of the idle. - readjusted everything

I drove it to work today. My commute includes about 23 miles of expressway so it makes a pretty good shakedown. Running great, no problems. Oil temp was 160 when I parked with outside temp around 45 so that looks OK.

Now I just need about 1 more inch of throttle cable so I can get it to close without having the return spring so blasted tight. The clamp is right on the end, and the pedal is really heavy. Scares me since I've read so many stories of broken cables.

Thanks for the help.

Fri Mar 10, 2006 7:55 am

you can buy a cable extension at Bughaus or Dynabug, I think I might have one at Der German but I'm not sure. Call 834-2234 ask for Robert :wink:

Fri Mar 10, 2006 3:18 pm

Tram wrote: beg, borrow, or steal an exhaust analyser. Run the car to operating temperature , hook up the analyser, and set the CO value to 13 using the screw in the pressure sensor.

Are the Heathkit CL-1080 sniffers that seem to turn up on eBay a lot suitable for this job?

In any case, if I bought a sniffer how would I be able to calibrate it?