Got HALF of my new motor running....please feel free to weigh in with ideas

[efhughes3]

I tell you what, I'm going to stick with building motors, the longblock part is easy! It's all the peripherals that are kicking my ass.....

I got my new fuel lines as referenced in my other thread. What a bear getting the "t-shaped" one in. Replace these while the engine is out, you may not have HAD a problem, but they'll leak... I ended up lifting the intake to get this bugger out and the new one in. Did I mention my hand wasn't quick enough on the jack, and ended up popping the oil line from the oil tank to the engine and lost a few qts of Brad Penn's finest?

At any rate, I cranked it and got some sputters. It finally caught, but was obviously not running on 6 cylinders. I checked the headers with my hand, and #1, 2 & 4 were only warm. #3, 5 & 6 were toasty. I had a friend over and we pulled the plug wire for #1, and it is sparking, so it would seem I've got ignition.

So, basically I don't have explosions in #1, 2 & 4, but it would seem not for lack of spark. Ahh, but is it at the right time??? Tomorrow, I'll put it on TDC and check the dizzy. I "thought" I had the rotor pointing to #1 at TDC, but maybe it was off a notch? I checked the order on the plug wires on the cap, and it is correct. MY GUESS (HOPE!!) is that this is the issue...

Do my symptoms of having 3 cyls firing correlate to a distributor timing problem?

The only other issue I can think of is an injector issue on the dead cyls. They were rebuilt, and the connections are good, but what are the odds of 3 injector plugs going bad from unhooking and rehooking them up? The fact that I have combustion on both cylinder banks with #3, 4 and 5 apparently firing would seem to tell me the wiring harness is OK, but that isn't to say I don't have a problem with the injectors. I don't have any experience with how to test injectors at the cylinder to determine if they are pulsing?

I will say for the very short time that it was run, the three that were firing seemed to have some power, but that is a very subjective statement on my part.

Did I mention it doesn't leak oil??

[304065]

Ed, it probably wouldnt start if the diz was way out.

162435 did you check wire order on the cap?

[efhughes3]

John: Thanks, I did check the order, it is correct. I'm wondering if having the dizzy off one notch on the shaft gear could cause this? I know I was in the vicinity. I've been searching and Chris Bennet had posted that the rotor should point to the left of the dizzy mark. I know I pointed just adjactent to the mark, but can't remember if it was to the right or left.

Being that I've got spark in the #1 cyl, and it is one of the dead ones, that would lead to not getting fuel as the other alternative off the top of my head. How can you test injectors Or their wiring, while in the car to make sure they're pulsing?

[gigem75]

pull the plugs on the ones that are not firing after it's run a sec and see if they are wet.

[304065]

Ed,

Chris is a great guy but why would the rotor point to anywhere other than the exact center of the mark on the housing? Verify #1 on the compression stroke, align the Z1 mark on the pulley with the notch in the fan housing and set the rotor so it points exactly to the notch in the distributor housing. Sure, the Motronic box actually controls the advance but if the rotor is pointing away it could cause this kind of weak running.

And not to second guess you any more than necessary but do you have the plug wires going in the correct order? I think the Motronic distributor turns clockwise when viewed from the rear of the car, just like the early cars (like all 911s, in fact, with the exception of a couple years of SCs which we don't like to talk about).

Now, before you start on the injector harness, how about the shade-tree test, crank and pull the plugs and see if they are wet with fuel.

[efhughes3]

Actually I just checked-rotor is pointed just to the left of the mark, the rotor is actually poised to where the leading edge is at the mark. Is this too "late" in the cycle. I think when I tried another notch in a more clockwise direction, that the rotor was too far past #1. I can pull the dizzy tomorrow, and see what one tooth does....

[efhughes3]

Also, I checked the order again, you are correct in that it is a clockwise direction. There is no question that the order of my wires is correct. I'll try the shade tree deal after I play with the dizzy placement.

[304065]

sensor gap thread
3.2 Carrera Brain Teaser

injector purge thread
3.2 rebuild will not start For the love of God please help

[efhughes3]

OK, the rotor does point to the left of, and before it picks up #1. If I go one tooth in the clockwise direction to advance it, it ends up after #1. I tried it out 180 degrees for grins, and got nothing. I also swapped the reference sensors, and got backfires, but wanted to take that out of the equation.

I can try the rotor one tooth in an advanced direction and see what that gets me, as well as pulling a plug to see if it's wet. My bet is now on the fuel...

[efhughes3]

Okay, progress...sort of. I pulled #2 plug, and it's drier than a bone. No Fuel!

So, I need to figure out why my rebuilt injectors aren't working. Could be injector-I'll try putting voltage to it, or it could be harness.

[304065]

[911quest]

The pintle in the injector could just be stuck from being inop try tapping on them with a hamer handle.

[Jeff Alton]

Ed, get a 12V light bulb with two spades on it and add two pigtails or get "noid light". Un plug each injector and plug the light in. It will flash as you crank the motor if the injector is getting power.

The carrera fires 1,2 and 3 together and 4,5 and 6 together if memory serves me correctly.

The other trick to test the injector is to get a 9v battery with the conector and pig tails. Un plug the injector and touch the tails from the 9v battery leads to the injector spades (polarity is not important). It should click and spray fuel if it is working.

Cheers

[john walker's workshop]

rebuilt injectors should be used immediately after you get them back or they can stick.

[AngM018]

Originally Posted by efhughes3

Actually I just checked-rotor is pointed just to the left of the mark, the rotor is actually poised to where the leading edge is at the mark. Is this too "late" in the cycle. I think when I tried another notch in a more clockwise direction, that the rotor was too far past #1. I can pull the dizzy tomorrow, and see what one tooth does....

There will be one tooth on the dizzy gear that will allow you to rotate the entire dizzy until it lines up with the #1 notch on the dizzy base. If it is like mine, the #1 notch on the dizzy is actually on the backside (PITA to see at a 90 angle). Then when I rotate the dizzy to line up w/ notch, the bolt is underneath a vacuum port (once again, another PITA). Tighten the dizzy bolt just enough to hold it in place but still allow you to move. I had to rotate the dizzy as soon as I got the engine running as it was running ruff. I also cut a wrench to fit, and tighten the bolt the rest of the way.

[Aurel]

My money is on the injectors...it makes the most sense.

Aurel

[304065]

John, the body of the distributor on a Motronic engine does not rotate relative to the case, unlike earlier engines. See the page of the FWM I posted above, you can see there's no slot in the casting that would allow it to move. The rotor ends up pointing to #1 as a result of the positioning of the distributor drive gear on the shaft and the drive gear on the crank. Since the timing is controlled by the control unit, you just have to get the rotor close enough so the spark can jump across at whatever setting the Motronic system uses for Starting. Maybe one of the 3,2 hackers can tell us what retard setting Motronic uses to start the engine.

Anyway, in Ed's case, he has a 50% chance of getting it right, so if it doesn't work perfectly one tooth up or down, chances are the distributor's not the issue.

[efhughes3]

Well the Porsche manual, which I looked at, and is the reference for your post John, differs from the Bentley. The Bentley shows the rotor with the leading edge lined up with the timing mark on the distributor.

I'm good on timing, I just need to figure out why my injectors aren't feeding fuel.

[efhughes3]

Originally Posted by Jeff Alton

Ed, get a 12V light bulb with two spades on it and add two pigtails or get "noid light". Un plug each injector and plug the light in. It will flash as you crank the motor if the injector is getting power.

The carrera fires 1,2 and 3 together and 4,5 and 6 together if memory serves me correctly.

The other trick to test the injector is to get a 9v battery with the conector and pig tails. Un plug the injector and touch the tails from the 9v battery leads to the injector spades (polarity is not important). It should click and spray fuel if it is working.

Cheers

Originally Posted by john walker's workshop

rebuilt injectors should be used immediately after you get them back or they can stick.

Thank you gents.

I think you're right, Jeff, about the firing, and the fact that I have some injectors on both sides not working would hopefully point away from a harness issue. I'll try the tests, thanks for the info.

John, my injectors were rebuilt in late July, so they weren't used immediately...is there a procedure for unsticking that I can do at home?

[john walker's workshop]

hook up a 9V battery to a spare injector plug to activate them and tap with a very small hammer is all i can think of.