911 tweaks/Lapkritis:

---I do have the "shop" manuals, but they're not the bentley set.

OK, What I've done since the engine was installed and started was the following (specifically - to the engine):

Do the initial 20 minute break-in - running with the backfire issue.

Change the oil/filter and replace both of the flexible oil hoses (from the wheel well, and from the oil tank).

Confirm my wire routing is correct, pulled the cap, inspected the rotor. When inspecting the rotor, I inspected the spring loaded advance on the distributor to ensure it would work (moved it CCW and watched it spring back into place).

Put the engine at TDC, confirmed that my #1 was indeed at the ignition position, and performed what I call a "static" timing. (turning the engine by wrench confirming that the piston positions were where they were supposed to be at - the ignition point - and the complimentary rotor position was following it's correct path).

I ran it again for the first time yesterday with intentions to fix/correct the timing issue while running, and we were able to get the timing closer, but the thing is backfiring (it doesn't sound like it's backfiring through the intake - it IS backfiring through the intake based on what I was able to see through the pop-off valve).

For kicks: I disconnected the WUR electrical connection to see if it would make a difference: nope; still backfiring like before.


Where I am today: I didn't bother starting it. I spent over an hour with a dental mirror and a flash light looking for any crack(s) in the air box (specifically around the portion where the air is metered). I also looked for hoses that some how may have come disconnected along the way. I could not find anything out of place, disconnected or cracked at all. However, just because I couldn't find it doesn't mean that there isn't one there.

And so, I will have to start the CIS trouble shooting 5Y/8d process to determine where our fault is.

The prior mechanics on this car - I have no records of what's been done to this car. It is possible based on the condition of the old air box that someone went in there and made adjustments to the rich/lean screw (which I still do not know where this animal is) as a way to tune out the poor running conditions. Before I do anything like make adjustments, I think my first tests will include fuel pressure, before dipping into the AAR or WUR, or any of the CIS components.

I suspect this as well. May I suggest 2 complete turns on the mixture to lean and start again. A friend of mine had this issue.

You can then fine tune mixture once running.

This is an awesome thread. I have an 82 911SC and am restoring mine now as well.

After listening to the YouTube video it seems to sound like it's backfiring on the same cylinder each time. Try starting it and disconnecting plug wires one by one until the backfiring stops. I'm quite sure you'll pin point the problem thereafter.

Another FYI to avoid any confusion 1979 S the dizzy turns CW. 1979 SC the dizzy turns CCW.

Idle is there, but ...
 

Today, I gave it another shot to see if we could get this thing running properly.

Per the suggestion of Charlie V, I found out where the mixture screw and gave it two full turns toward lean (left).

Then, I gave it a shot. It would start and backfire and then die.

Thinking that I may have leaned it out too much, I started turning the screw back toward rich, about a quarter turn at a time.

I got it to run, but it is still backfiring like hell. I got it to idle; and I don't have to keep my foot on the gas to keep it running. A step in the right direction - we're closer - but still no cigar.

Now that I can walk around the car while it's running, I noticed something curious about the sound being made under the hood, on the fuse/relay panel. While we're at idle, I hear the fuel pump whine, but at nearly the exact time that the backfire occurs, the fuel pump relay makes a click sound, and the pump seems to cut out for a millisecond.

Maybe the fuel "sending unit" or the relay is the culprit? Could this backfire be a function of the fuel pump/sending unit being bad?


http://youtu.be/bwfOvFu7-Tw

Simple relay check is to swap out with one of the others. The other thing is to do a jumper wire in the relay socket - make sure you have a fuse inline. See if this makes a difference.

I would also do an electrical draw test on the fuel pump. If the pump is at the end of its life, the draw will be high.

Let me know if you need the specs on this - I would need to dig it out of the shop "library".

As an FYI......I found my 82 has the same pump as a 75 VW Rabbit at about 50% of the cost of a Porsche pump.

any updates??

Updates
 

I just got back from work travel (Germany, Stuttgart area) - and I have not had time to really get back to work on the car --- yet. Only small stuff.

I have been thinking about my strategy on what to tackle next.

After some consideration, and the fact that I can get this thing to idle now, I am going to swap relays to see if the fuel pump/relay is a contributor, and then I am going to take another look at the timing. If I still cannot pinpoint the problem, I am going to run it and try to isolate the offending cylinder by pulling one ignition wire off at a time to see which cylinder(s) are causing the backfire.

If I still have a backfire and I have an idea of which cylinder it is on: compression test is next.

small progress
 

Today - I convinced dad to come by and do a little sanity check on the work thus far.

I also grabbed a fuel injection test pressure kit (fun new tool) and ruled out the possibility of a fuel problem.

SO: Here are some observations -
Dad says it's running rich: to the point of eyes burning (I agree, but I do not have a calibrated nose to give a measurement of "X PPM rich")

We hooked up the FI test kit, and ran the engine, as we had a very small window of opportunity to run the car before it rained today.

Here's a video of what it is doing as of right now.

I also swapped the fuel pump relay with one of the others to see if the problem was following the relay: nope.

Checked/adjusted the timing: now it is right on the money.

Next on the list is to see if I have a compression problem (maybe a couple of the valves are not opening at the right time; it will be worth the sanity check).

I am leaning toward massive vacuum leak as of right this second - meaning that we may be doing a partial drop to get at the CIS and "start over" in that department.

When you remove the oil filler cap as the engine is running there should a noticeable change in the idle. My car will stall after about 15 seconds because of the giant vacuum leak. If there is no change in the idle, means there is a vacuum leak somewhere in the system.

The part I'm confused about your engine is the popping and farting.

I remember changing every hose I could on the intake. Those I didn't replace were tested to ensure they were good. I also used a light film of dielectric grease on each connection to improve the seal.

Good luck.

been a while sincw i read or remember all of what u checked & not checked...popping & farting is a main indicator of a or several broken head stud(s)...have these been checked...?? to check u need to remove the top & bottom valve covers and look for nuts loose/broken off ends in the valve train and to put a wrench on ea stud to lightly check that tension is on the studs...

Vacuum leak: maybe
 

Hey all:

After thinking quite a bit about what the source could be of my backfire, I continue to think that I am chasing a vacuum leak.

I have new injector sleeves and O-rings, (Injector O-ring/sleeve/sleeve O-ring all are new) - partnered with recently serviced injectors.

I have found that the injectors are rather loose while working in the engine compartment; and I believe that there is a ton of air getting in the system as a result.

I can remove the injectors (and sleeves as a subassy) very easily by hand from the intake runner meaning that they are not secured in the port. I did not use a cold chisel to put a divot in the aluminum to hold the injector sleeve in place, nor did I trim the sleeve (flush) after install.

Thinking back, I have a hard time believing that the injector sleeve + injector subassy should be able to be pulled out so easily after install. I must have missed a step in the installation of the injector sleeves.

picture of the injector sleeves as they are today:

http://forums.pelicanparts.com/uploa...1384979135.jpg

Something is odd, my 78 looks nothing like that!

http://forums.rennlist.com/rennforum...ngine-2013.jpg

Time to test, and verify
 

Thus far, I *think* that I did everything right, but this car is not running right, so it is time to TEST this thing for vacuum leaks.

Taking a step back; head studs are fine, I checked the torque when the engine was out of the car. That was one of my concerns when I first started this project.

SO: after doing a bit more research here's the next thing I am going to do to this car:

http://forums.pelicanparts.com/porsche-911-technical-forum/717648-finding-cis-vacuum-leaks-vacuum-cleaner-pressure-test.html

I *believe* that I have a vacuum leak somewhere, so this test will (at the very least) verify that I do or do not.

Wurst cast scenario, I have to pull the CIS again.

Does a German vegetarian fear the wurst?

One of the things I do to ensure a positive seal at the injectors is to apply a film of silicon grease when assembling the parts.

I should add - did this some 3 years back and still well sealed. Includes a couple engine washes with degreaser.

Fuel injector sleeve installation.......
 

Brian,

Those fuel injector sleeves shown in the above picture is not properly installed!!!!! They are just sitting on top of the runner/s and need to be driven/pushed further down and then 'stake' the edge or rim of the hole. Compare the injector sleeves to the preceding picture after your last post.

Stop guessing and perform a pressure test. If your are not certain that there is no significant air leak in the system, you need to confirm your doubt. Not until you have done a pressure test would I agree with you that there is no significant air leak. Otherwise, you are hoping your assumption is correct that everything is OK.

Tony

CIS start up........
 

Brian,

I'm surprised that you could even make the engine to start in the first place. Looking at the video, your control fuel pressure is too much!!!!!! Check the control and system pressures by running the FP only. Do not run the engine. Post your numbers and we'll discuss what's to be done next. You already spent a lot of time and effort trying to get this engine to run correctly.

Sorry for not replying to your email promptly. I actually forgot to send my reply after partially composing it. Then I remembered it this morning after 2 weeks.

Tony

Vaccum test performed - results
 

Tony and all others ---

Huge thank you so far. I think there are a couple of things going on, and thus - on to test this car.

...so, I did a vacuum test tonight, where I cleaned out my shopvac, and put together an apparatus to pressure test the CIS. With a tennis ball in the tail pipe, and armed with my dish soap n' water mix in a spray bottle - I fashioned this device to put on the top of the intake -

http://forums.pelicanparts.com/uploa...1385436619.jpg

made from a soda bottle some electrical tape, screens on both ends of the hoses, and some plastic hose from a thing that was in the garage (a double beer funnel a friend left me as a gag house warming gift years ago - that I later installed shut-off valves on, and this evening put to a less tommy boy-esque use)

http://forums.pelicanparts.com/uploa...1385437125.jpg

As you can see I had to add a little more tape to hold the hose onto the soda bottle.

I took my spray bottle and sprayed everywhere I could think of that has a vacuum on the intake, everywhere on the airbox, all over the pop-off valve, focusing on the seam of the airbox, intake runner boots, then on all of the components of the CIS (injectors especially) and fired up the shopvac on "blow" - thinking that I was going to have an engine bay that would appear like a spring break bar in the middle of a foam party.

The results were --- one leak --- on the WUR!

http://forums.pelicanparts.com/uploa...1385437654.jpg

Not satisfied with my results, I soaked the CIS components again with the soapy water and fired up the shop vac, again looking VERY closely (with a dental mirror) at the airbox seam on the right side of the air box; and again - only bubbles were coming from the WUR.

This is really quite puzzling to me: a WUR with a vacuum leak could cause this engine to run so poorly? I don't buy it.

It (...the WUR) needs to be fixed, but now we can rule out a blown airbox, a massive vacuum leak created by my otherwise unknowing hand. Looks like I need to replace a WUR gasket (is that possible?), and get the injector sleeves in their properly installed location.