Engine won't start after engine drop

Poor-sche Lover · Poor-sche Lover's Garage

I know you're probably tired of hearing the same issues over and over again, but I've read previous threads until I'm blue in the face, and I haven't seemed to get anywhere.

FACTS:
1. The engine seems to crank fine. All the electricals (radio, windows, etc.) work fine with the ignition on.

2. I have tried switching the connectors on the speed sensor and reference sensors to no avail.

3. With the ignition on, the battery light stays on.

I am assuming something is wrong with my alternator connections or something, but wouldn't it still start, and just run off the battery? Are there any other commonly forgotten connections that I should check? I may need to reset the gap on the speed sensor as well. Would this cause my starting issue as well? Thanks.

88-diamondblue · 07-25-2009, 08:54 PM

Did you remember to connect the four pin connector on the firewall for the fuel injection. BTDT.
You can see the four pin connector at the bottom of the picture.

Poor-sche Lover · Poor-sche Lover's Garage

Sure did.....

kidrock · 07-25-2009, 09:32 PM

Have you double-checked to make sure you're getting fuel all the way to the throttle body?

rllevin · 07-26-2009, 02:57 AM

Unrelated DME relay failure? Sounds like what happens when it stops working. Occasionally in cars, as in people, when you hear hoofbeats it IS a zebra, not horses.

gregwils · gregwils's Garage

I am more of a part replacer than a diagnostic mechanic, so I hate dilemmas like this. However, it basically comes down to fuel and spark.

I kept a separate list of everything I did on my car for the first engine drop. If you didn't do that, this grab Wayne's 101 book and go back through the list. Unless you have done that five times already.

You need to confirm the plugs are firing and fuel is getting to the cylinders. You should be able to smell fuel if you are cranking for extended periods. Pull a plug wire and attach it to an old plug to verify spark.

pantera · 07-26-2009, 04:20 AM

I would also double check all your grounds. There is a transmission ground strap to chassis and a whole gaggle of brown wires that come off one harness that attach to the side of the intake manifold. They are easily lost and forgotten about when reinstalling the engine.

Dan

Dixie · Dixie's Garage

You most likely are overlooking something simple. The car should start. If your alternator is bad the car should still start. If the sensor gap is off, even quite a bit, the car should start.

Have you verified you have spark?
Have you verified you have gas?

Dixie · Dixie's Garage

Quote:

Pull a plug wire and attach it to an old plug to verify spark.

And if you hold the wire, you'll know if it's working really quick.

A timing light would be easier and less jolting.

Tom '74 911 · 07-26-2009, 08:30 AM

Are the plug wires in the correct order on the cap? (know that one from personal experience).

dtw · 07-26-2009, 09:04 AM

Why was the engine out?

Were your flywheel sensors ever replaced? What about the sensor bracket?

Engine drops on 3.2s can make that assembly unhappy. An old sensor bracket can crack, causing the sensor gap to become inconsistent/variable. Maybe the sensor(s) got knocked around during reinstallation of the drivetrain.

Other than that, it should start. Did you look at the various DME pigtails? Are they in the right places? Did you reconnect the DME ground harness? Did you get fuel connections right? What about your coil - is it wired?

Go back and check every connection. Then get back to basics. Air, fuel, compression, spark. If you didn't have the engine apart, compression should be fine. If you crank the motor 10 seconds or so, do you smell fuel in the tailpipe(s)? Is the ICV buzzing with the key on? Are your plugs sparking?

Go spend an hour or two answering some of these questions. Chances are, you find your problem. If not, report back, and we'll work through it.

Poor-sche Lover · Poor-sche Lover's Garage

Okay, let me try to respond. Both the grounds (at the firewall and on the intake runner #1) are clean and tight. When I dropped the engine, I did it to fix a bunch of oil leaks. When I took off the plug wires, I took them off still connected to the cap. I just removed the whole assembly, cap, wires, and all. I have determined that I have power through the coil to the top of the distributor cap. I tested from the inside of the cap. However, I have NO spark at all. I am confused because the rotor does not have continuity between the top and the end. The rotor is trash, then, right? I just can't imagine that the rotor was fine prior to this, and it all of a sudden went bad. The flywheel sensors have not been replaced, but they may need to be. I had a hell of a time disconnecting them from the transmission. Again, it may need adjustment. I should get a rotor on Tuesday. Nobody ever has anything in stock around here.

Tom '74 911 · 07-26-2009, 03:44 PM

Is it possible you put the rotor on 180 deg. out? I think I can do that on my car (2.7 CIS).

Tom

Poor-sche Lover · Poor-sche Lover's Garage

Tom, no I don't think that's possible in mine. There's a notch in the distributor shaft that lines up with the rotor. Also, I took off the rotor completely, and there's no continuity at all between the top contact and the end of the rotor. If I understand how electricity works, that's not supposed to happen! We'll see what else is wrong on Tuesday.

dtw · 07-26-2009, 08:52 PM

So your coil wire is throwing juice down the rotor? If so your DME wiring & sensors should be OK...

kidrock · 07-26-2009, 09:09 PM

dumb question #1: did you replace the coil while your motor was out?

Poor-sche Lover · Poor-sche Lover's Garage

Yes, Dave. Power is getting through the coil wire and through the distributor cap. I put the leads on ground and the underside of the cap, and got sufficient voltage. When you say the DME wiring and sensors are okay, are you referring to the speed/reference sensors, or some other DME sensor that I don't know about?

kidrock, no I did not replace the coil. I never touched it except to remove the primary wire, which was amazingly difficult, by the way.

dtw · 07-26-2009, 10:35 PM

Alan,
OK, I don't think I have ever tested for spark that way. Not sure about DME, but the CDI-powered cars would not be happy about discharging the coil without the output being grounded properly. Lots of threads warn about testing spark at the coil wire. I'd proceed carefully. But anyway...good that you are getting a signal from the coil.

No, I just mean the two flywheel sensors. I don't think you'd be getting coil output if those sensors weren't talking to the DME. However, someone like Ingo or another of the 3.2 DME gurus should verify that.

Sounds like your cap and rotor need to be replaced before doing much else.

Still, I am thinking about your sensor bracket and sensors. If you're feeling bored before you get a new rotor, maybe check over them.

I chased an intermittent no-start on a 3.2 down to a faulty coil. The car was new to me last year but has a stack of receipts. Looking through them, the coil was the only part of the ignition circuit that hadn't been replaced in the last few thousand miles - including the DME...

Mitch Leland · Mitch Leland's Garage

I know there's been a lot of talk about wires and plugs, so this is probably redundant... but if you haven't, then reverse the two black plugs...

Poor-sche Lover · Poor-sche Lover's Garage

Well, I got a new rotor, but I was confused because there is still no continuity between the top and the edge of the rotor. So, I pulled out the Bentley again, and started testing some more. It says the resistance should be about 1k ohms. My old one had 1,196, and the new one has 5,130!!! I don't know what to think. In some more testing, it looks like my coil may be bad (resistance is too high), as well as one of the flywheel sensors (I'm replacing both anyway), and a new distributor cap for good measure. At least I get to use Wayne's new 3-day shipping to the middle of the country.

Oh well, it's only money, right?