Bogs down at 3000 RPM in most gears, and now backfiring.

[john walker's workshop]

Did you look inside the distributor cap yet? Check shaft wobble when it's off too. Bosch silver coil?

[fizh]

Have yet to look at the distributor cap. Will do that in the morning when I have light again.

[fizh]

Looking through the CIS Primer some more, it looks like '81 SC should have: 87b 87 30 86 85

The one I have is: 87 87 30 86 85

http://imgur.com/slIyWmD
http://imgur.com/48xPjw7

Is going to be an issue?

[john walker's workshop]

Regardless, both 87 terminals need to get 12v when activated.

[fizh]

Seeing that it does not have the Diode in the relay schematics. Perhaps nothing major.

Do these sensors make audible noise? I remember earlier in the week there was a faint ticking noise that sounded like it was coming from the passenger door. But perhaps it was the sensor. I heard the noise again at another stop light a few days after that. Forgot about it until now. Sign of a faulty sensor?

[fizh]

Hoping someone can enlighten me... as I have found connection without its counterpart under the passenger seat.

Based on what I can research it may be called one of the following names: Acceleration Enrichment Control, Enrichment Relay, control Unit Acceleration Enrichment?

I can't seem to find much info on it.

See image from someone else I marked up to show what piece is missing:
https://i.imgur.com/uUBN9w5.png

[pmax]

Originally Posted by fizh

See image from someone else I marked up to show what piece is missing:
https://i.imgur.com/uUBN9w5.png

Not sure what the effect is with the enrichment unit missing, given the lambda control unit is analog circuitry and the floating wires.

[fizh]

Got the Enrichment Relay yesterday and put it in. I have not had the problem after driving 100 miles or so. I'll continue driving and see if the problem crops up again.

Seems like a number of things (throttle switch, microswitch, temperature switch, oxygen relay) run through it to the control unit itself, so I am hopeful.
http://cis911primer.com/pages/elec_lambda.html

[pmax]

Originally Posted by fizh

Got the Enrichment Relay yesterday and put it in. I have not had the problem after driving 100 miles or so. I'll continue driving and see if the problem crops up again.

Seems like a number of things (throttle switch, microswitch, temperature switch, oxygen relay) run through it to the control unit itself, so I am hopeful.
911 CIS Primer - Lambda Electrics

If the root cause is in fact the missing enrichment unit, then I'm puzzled how it ran completely fine a few weeks back without it as you stated in the OP. The other thing is the unit is for cold enrichment but the hesistation and bogging is at temp, right (?) .

[fizh]

Pmax, hopefully you like to read.

I purchased it about a month ago, put about 1000 miles on it and the problem started for me. I was babying the car a bit just getting a feel for how this one drove. I live in the mountains on great fun driving roads, so once I got used to the vehicle a bit, I pushed the car harder during my drives to and from home on those mountain roads. Then the problem started. A very casual drive home. The problem continued to stick around. Coming and going. But became consistent on the tail end of the last two weeks. So, I got a new oxygen sensor relay... didn't do anything. Fiddled with the interior lights and got those working... still no change. And a few more things per the suggestions of others on this thread. Then during my research on CISPrimer and scouring images of CIS and digging through other threads.. even slightly related ones... I noticed the enrichment relay. Then I remembered the empty plug next to the oxygen sensor. CISPrimer informed me it was the Enrichment relay... and turns out I didn't have one of those. Found one on Ebay and got it a few days later (yesterday). Put it in today. At this point I have driven 250 miles in different conditions, operating temperatures and it is driving impressively good. Maybe better then when I drove it home a month ago. Probably a fluke knowing my luck.

.... Another interesting tidbit, or conspiracy, is that the past owner had not put any miles on the vehicle for quite some time (3 years and 500ish miles)... and I had some service records from him that I glanced through when I first got it. Figured I looked through those a bit more today. Voila! A couple years back he was having potentially the same issues... described as bucking at 3000 RPMs. The service record states the ER and OS was no longer working. They replaced them.

Could this be the enrichment relay and oxygen sensor?

But... the past owner kept going back based on more service records, saying the car was running poorly, the tach is glitching out, engine runs rough, etc. with random tune ups here. Replacing the fuel filter, air filter, adjusting mixture, etc.

... A long shot but maybe they never actually put the Enrichment relay back in and this is the reason for his bucking and the reason for my bogging?

Or perhaps I just drove it enough for this problem to rear its ugly head again and I got lucky today.

[SCadaddle]

Originally Posted by fizh

Pmax, hopefully you like to read.

I purchased it about a month ago, put about 1000 miles on it and the problem started for me. I was babying the car a bit just getting a feel for how this one drove. I live in the mountains on great fun driving roads, so once I got used to the vehicle a bit, I pushed the car harder during my drives to and from home on those mountain roads. Then the problem started. A very casual drive home. The problem continued to stick around. Coming and going. But became consistent on the tail end of the last two weeks. So, I got a new oxygen sensor relay... didn't do anything. Fiddled with the interior lights and got those working... still no change. And a few more things per the suggestions of others on this thread. Then during my research on CISPrimer and scouring images of CIS and digging through other threads.. even slightly related ones... I noticed the enrichment relay. Then I remembered the empty plug next to the oxygen sensor. CISPrimer informed me it was the Enrichment relay... and turns out I didn't have one of those. Found one on Ebay and got it a few days later (yesterday). Put it in today. At this point I have driven 250 miles in different conditions, operating temperatures and it is driving impressively good. Maybe better then when I drove it home a month ago. Probably a fluke knowing my luck.

.... Another interesting tidbit, or conspiracy, is that the past owner had not put any miles on the vehicle for quite some time (3 years and 500ish miles)... and I had some service records from him that I glanced through when I first got it. Figured I looked through those a bit more today. Voila! A couple years back he was having potentially the same issues... described as bucking at 3000 RPMs. The service record states the ER and OS was no longer working. They replaced them.

Could this be the enrichment relay and oxygen sensor?

But... the past owner kept going back based on more service records, saying the car was running poorly, the tach is glitching out, engine runs rough, etc. with random tune ups here. Replacing the fuel filter, air filter, adjusting mixture, etc.

... A long shot but maybe they never actually put the Enrichment relay back in and this is the reason for his bucking and the reason for my bogging?

Or perhaps I just drove it enough for this problem to rear its ugly head again and I got lucky today.

John Walker mentioned above to take a look at your ignition distributor.
I agree with him. Take the distributor cap off and look inside of it at the terminals. Are they simply worn from the arcing of the spark or are they missing chunks of the metal in the terminals. Grab the rotor see if you can twist it just a bit and have it return to where it was. Then grab the rotor and see if you can detect any side to side play. Finally, grab the rotor and see if you can lift it up with the shaft more than a couple millimeters. Does the engine make a "crunchy" sound when idling? If so (or not) grab the body of the distributor while the engine is running. Does the "crunch" sound correlate with a "crunchy" feeling in your hand? If so more than likely the shim that always wears out and falls apart on the shaft of the distributor between the gear on the bottom of the distributor and the lower part of the distributor body is gone. That will certainly make your tach "bounce". Take a look at it.

[mikedsilva]

Just a guess.. and a really wild one at that.. maybe a coil that is starting to go bad?

[fizh]

Distributor was one of the things that was replaced in the service records. Looks new. Almost no wear. Engine idles fine. No crunching.
I think the "bouncing tach" was just poorly described in the service records and it was the anchoring at 3000 rpm.
Based on the records the shop the guy was taking it to is not a Porsche specific shop so they may have been doing some guess work.

I'll be going on another long drive today and see if it comes up again.

[pmax]

Originally Posted by fizh

Pmax, hopefully you like to read.

Mysteries are a good read !

... A long shot but maybe they never actually put the Enrichment relay back in and this is the reason for his bucking and the reason for my bogging?

Or perhaps I just drove it enough for this problem to rear its ugly head again and I got lucky today.

Perhaps you have inadvertently fixed a flaky connector which was causing the lambda unit to drop out. Is the tach behaving weird at all, bouncing around etc could be a sign of a failing regulator ?

[fizh]

Still nothing today. Drove it another 100+ miles.

When I first got the car, the tach was turned 90* degrees and the light was out. I took it out, replaced the lights, and aligned and squared it up.

The tach functions as it should and the vehicle has had no other problems to this point.

[patkeefe]

Everything works well, until it doesn't. Stuff goes bad. If the enrichment relay fixes it, then, great!
Also, don't go to the same mechanic as the PO. Looks like he had trouble fixing it.

[RarlyL8]

May have a fuel pump trying to go out. Do you have a way to check fuel pressure or AFR when these events occur?

[fizh]

Alrighty... took the vehicle in for a major tune up. Valves, oil, etc etc.
He had to cut the cat off due to how the past shop welded it on. Apparently it blocked the valve cover. In doing that, the cat was completely boogered up. Pretty confident this was the cause of the issue.

The REALLY ****ty part is one of the head studs broke off when he took the valve cover off. So... now I am looking at a nice little $10k+ fix on that.

[SCadaddle]

Originally Posted by fizh

Alrighty... took the vehicle in for a major tune up. Valves, oil, etc etc.
He had to cut the cat off due to how the past shop welded it on. Apparently it blocked the valve cover. In doing that, the cat was completely boogered up. Pretty confident this was the cause of the issue.

The REALLY ****ty part is one of the head studs broke off when he took the valve cover off. So... now I am looking at a nice little $10k+ fix on that.

That's the real gut punch of owning an SC, 3.2 Carrera or a 964. It was probably broken before you bought the car unless you had a PPI done and accounted for all the head studs.

[john walker's workshop]

Post 2. Typical cat symptom.