Engine turns over but will NOT Start

I just got through with a full rebuild on my 996. The IMS bearing and shaft self destructed causing the rebuild. After getting it all back together, I started the engine and ran it for 20 minutes. Several stops and starts later I backed it out of the garage revved it a few times to 3000 rpm and the CEL came on and the engine shutdown. Now it will turn over but will not start. Here are the facts: * It is a Tip so no clutch switch * Engine turns over will not fire * Battery is fully charged * The fuel pump does NOT prime when the switch is turned on * The fuel pump and relay are both good * I used a PIWIS and no codes are present * I can read the information from the DME * The Air Bag light blinks then stays on Any ideas are appreciated. I also posted this on RennTech.

Wow. Well congrats on the rebuild. Hopefully it's minor from here on out. Don't laugh, but someone here just finished his rebuild and it turned out his airbag warning system (steering wheel out) caused the same thing. Once the steering wheel was back in it fired right up. Have you tried unplugging battery for a while, then starting again? No codes from the DME, how about instrument, alarm, other modules? Tested for fuel pressure from the fuel rail test port?

Do you have an air bag unplugged?

Doesn't the variocam activate at ~ 3k rpm? Maybe the DME did not like the cam timing when Vcan activated?

That was me with the air bag, so yea I did laugh. My forehead is still sore from banging it on the wall. Yes to the battery disconnect question. All air bags are connected. No codes elsewhere unless "Current Fault Codes 0 module failed to initialize" qualifies. I see that on all modules except the DME. And the variocam question, I do not know since it will not run and has no codes. Keep em coming...

Ahahahahah. You got us, again. How sneaky of you. Do that one more time and ... "The Air Bag light blinks then stays on" Hmmmm..... the smoking gun perhaps? What does your PIWIS or Durametric say about air bag module say - try entering that function and fooling around? Seriously do you have a copy of the work shop manual? There is a very good chapter on Airbag system diagnosis. (diagnosis, part 2). Unless you are a dealership or $$$ indy, you probably have a clone PIWIS... I've read they aren't always 100% reliable, perhaps it is not able to talk to your airbag module. Perhaps did you activate the transport lock by any chance (disable the system while car is being transported). All else fails, try hitting it with a BFH.

I just remembered the AB light thing. If you are over 50, and I am, stuff happens to your memory. When I read codes from the AB system I get "Current Fault Codes 0 module failed to initialize". The description is that either the module is not installed as an option in the car or that it has a bad connection. Has anyone heard of this? I do have the manual and will go through it tonight. I am inclined to pull the mudule out from under the seat and do a visual on it. It is a sealed unit so cracking it open is not an option. I am in favor of the BFH right now.

"module failed to initialize" doesn't sound like your computer can talk to the module. Do you have a durametric also, or just the cloned PIWIS? I've heard bad things about the cloned PIWIS.

I just have the PIWIS but the supplier says that it will work with all systems in this year model. I just got an email back fromt them and they are telling me to check the AB module for power, connectivity, etc... I am going to pull the drivers seat back out and check it out tonight.

You have a Chinese PIWIS, which I've read about issues with - but it is possible the AB module is pissed - hey why did you have the steering wheel out again? The real Porsche PIWIS is probably out of your budget.

Did not have the Steering wheel back off. That was the first time. Right now I am heading toward a bad connection on the AB module. You are right, the real Porsche tool is wayyyyy out of the budget. The one that I have works pretty well though. Once I get the engine running I can tell better if it was worth the $$.

Working under the premise Last touched 1st checked. Are you absolutely sure that the steering wheel connection is secure? Did backing out of the garage involve turning the steering wheel? Check the fuses, B1, 8, C1,2,3, E1 etc...

I will check that also. I did have the steering wheel back on it and actually used it. (None of the Vice Grip stuff here) I can pop the AB off and check the connection pretty easily.

You said your airbag light keeps flashing or stops? Also perhaps once you're able to communicate with the module, give this a try.

I checked the connections to the Drivers AB and the AB control unit. Everything looked OK. I have not gone through the fuses again, but that is one of the first things that I looked at. When I put the key in and turn it to on, the AB lighe flashes and then stays on. So it does the "warning light flashes before locking" but it does not go out afterwards. So either it has a fault or it is not locking. I am not sure how to check that. Any ideas anyone?

A working computer or another alarm module. If you have a workshop manual it details all of the various points around the car to check using a multimeter, as well as a special tool (yes another special tool) might be required. I would mirror what was said previously though, did you double check your re-install job on the steering wheel?

Did you check if you have gas

Suggest you try and connect with Pedro Bonilla -www.pedrosgarage.com .He is very knowledgeable and I believe he had a similiar issue with his Boxster . Dave

OK, I have part of the mystery solved or at least narrowed down. It appears that the problem lies in the AirBag module. If I put a meter on the "Crash" output of the AB module I can see it start out at 12V as it goes through the self check. When it completes it, the voltage drops to 2.5v and the AB light comes on. If I open that circuit up(cut the wire) and apply a 12v signal to it, the engine cranks and runs OK. It is as if the AB module thiks that the car had been in a crash and has disabled the fuel flow. The question now is what portion of the AB circuitry has a problem and is telling it that a crash has occurred. From looking at the schematic, the parts monitored are seat belt buckles, child switch, driver airbag, passenger air bag and both side air bags. I know that the buckles and child switch will not cause a crash signal. I need to know how to test the air bags themselves. I assume that they have a resistance measurement and that once they are deployed that resistance is no longer there. If I put a Ohm meter across the airbag, will it deploy? Anyone out there an "expert" on SRS Airbags?

I have more information on the AB system. It appears that the special tool that Porsche has for testing the wiring is a 3.9 Ohm resistor. This emulates an airbag and I can check the resistance of the wiring, clockspring, etc.. When I get a few minutes, I will check these out and report back.

OK, I pulled the Drivers ABag and put in the load resistor. I should have seen 4 Ohms but all I got was 1.2. I suspect that I have either a wire pinched or a bad clockspring in the steering column. When I get a few minutes, I will disconnect it and make another measurement.

I have an extra clock spring if that turns out to be the problem.

This info may or may not be useful for you as well...

Thanks Dave, I may take you up on that. Logray: I have not gotten to the reset point yet but since it has had only 1 false activation, I hope a replacement unit is not the case.

Had a few minutes to do some more checking. I disconnected the clockspring and still get the low resistance reading. It looks like the problem is in the wiring. I have a USB snake camera that I am going to use to probe under the dash. Wish me luck.

Geez this kinda thing scares the he'll outta me!

Good luck !Not so sure that the unit has only seen one false activation .Logic would indicate that every time the key is turned it starts a new duty cycle .If that is true you are well north of the max .There may be two issues -potential short and unit is full .Just food for thought...... Dave

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Or perhaps the continuity is fine, and it is actually the airbag module after all...

Any updates?

First thing I would check is wiring off the alternator being solid and correct. Just thinking maybe an improperly wired alternator started the ball rolling since an increase of rpms makes for a solid output from the alternator which would screw things around for sure. Just thinking maybe I'd want to know why the gear picked parade time for falling on it tail.

I checked all the easy stuff and some of the hard. No smoking guns though. I ordered a Durametric and it should be here Wednesday. For now I just unplugged the ABag module and it runs ok. Dave I saw your comment on the max activations. From what I can tell, an activation is an Abag deployment. Other codes like buckle faults etc can be cleared. For now I am still putting parts back on it. We had stripped the wheel well liners, underbody, bumpers, etc to clean out all the road grime. One thing that I noticed is that the low RPM idle is a little rough. My assumption is that the DME is still re-learning the engine. Does anyone know what this learn time is? Is it munites, miles, hours.....

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Suppose it depends upon the engine, in what state of tune the engine is in, what condition the engine is in, but when I clear the check engine light of my Boxster -- with the engine running (not recommended! but I'm lazy)generally the engine reacts not at all. Sometimes I get caught off guard though the next time I start the engine cold for it kind of runs a bit uncharacteristically rough after cold start but always (so far) smooths out in just seconds. Regardless of when I clear the codes the engine really takes just seconds to recover. With the engine idling remove the oil filler tube cap and note how long it takes the engine controller to adapt -- as best it can which can be pretty darn good -- then refit the cap and listen to the engine controller adapt again. When I've done the above, it doesn't take but just seconds for the controller to adapt. Sincerely, Macster.

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For the rough idle, you probably have an intake or vacuum leak. Been there. Done that. Check all of your intake connections, and all the vacuum hoses. Even the smallest leak can make a big difference... cracked oil filler tube, intake plenum off, vacuum tube not connected, brake booster not snapped on, etc. etc. etc. etc. Why does this damn car have so many vacuum hoses. They need to call in Dyson to make it better. The DME will run smooth on idle, even with a freshly reset battery. I have not experienced a problem with idle after battery pull and DME relearn. You can even pull your MAF, has nothing to do with idle. On the AB, my guess is you have more than 3 activations or some other fault that you need to read - or maybe bad AB module, I hope the Durametric will help - it has certainly got me out of some situations.

I'm sure it will be nice to read whats up with the engine using the durametric. This could be and should be a quick diagnosis and fix time after getting the reports from the car. Just don't fancy yourself as one of the big garages working on the car and you should have the problem fixed in no time instead of taking weeks and big bucks in multiple parts daily You will like that durametric. It's a real charm. Using a laptop figure on having a power inverter so that the laptop is being charged because the durametric software warns that it might not give good reading if the laptop is running on battery power. Other than that, have fun.

Doubtful rough idle is dme learning .Air leaks highly likely-also the idle control valve can get gummed up and cause unevenness .Does it maintain rpm's and just sound uneven or big rpm flucuations ?Big rpm fluctuations point to the idle control valve (at least in my case). The Durametric should help on Airbag diagnosis .Unfortunately not a big help on verification of cam timing for a 5.2 dme .It will do bank1 but not bank 2 .Looks like they programmed to non us specs . Back to idle-a lazy injector can also be a cause there are plenty of additives to help alleviate this . You are almost done ! Dave

Wow. Impressive, methodical comments from all the posters. Nothing like a "go to solution" thread by knowledgeable Rennlisters! My hat is off to you.

Ran the Durametric tonight. No codes at all. And the engine will not run. Blows my mind. Drove into the driveway and shut it down. Now it is back to the original antics and it will turn over but will not start. No CEL at all. When I turn the key I do not hear the initial pressurization of the fuel pump. Does anyone know how to tell if the Immobilizer is activated?

I had something similar with a corrupted DME program. Car would turn over but not start. No other symptoms. No CELs, nothing, just turn and turn and turn but no burn. Perhaps you nicked or damaged or a wire broke while you were reinstalling the harness in the car. Would be a pain to have to check all the continuity though. For some reason I still think there is something with the airbag module, since you ran the car fine without it? But not now? Strange. Do you have a copy of the work shop manual? As much as a pain it is, perhaps go through each of the airbag tests to make sure the wiring is good. Can the Durametric at least connect to your airbag module? IIRC your PIWIS said it couldn't. Maybe it's time to submit to the car and take it to the stealer?

I wonder if the ignition switch is flaky ?

I can get into the AB module and it shows no codes. I even called the Owen at Durametric and made sure that there are no hidden codes. I sent hin a dump of the AB Module memory and he said it was clean. Wiring would be a PITA to check and I was very careful with it. I have a full set of the manuals and have checked most of the AB circuits but since I do not have any AB codes and the AB light is out now I think that it is related to the immobilizer. Does anyone know if, when the immobilizer is active, will the starter turn the engine over? Mine will but no run. Does the Immobilizer cut the fuel pump and injectors off? DOes it cut the Ignition off? What exactly does it do? I will also chack the ignition switch since I have read they are flakey.

I know you checked this once before, but have you gone back to the pulse sender? The symptoms you describe are the same that I had when mine failed. It could have been intermittent when the car first ran and then failed altogether.

When I had the corrupt DME program, I was told that the part that was wrong was the immobilizer code portion, which was preventing the car from starting. It was turning over but wouldn't start. I doubt this is your problem though, since I was messing around with the maps. You might try removing the transponder pill from your key, keep the pill well away from the car - and try to turn it over. This might simulate a situation where the immo would kick in. At least if you get the same symptoms perhaps it is not the immobilizer? Not sure if that logic makes sense though. Not enough coffee yet. Do you have a second key to test the car with? I was thinking the same thing Doug was last night after my post, I remember reading though a few posts on renntech about the pulse sender. And there are probably about a couple threads started per week here and there about a faulty ignition switch.

Back to the airbag control unit .There should have been at least one activation recorded when you first started the car and the windows went down .Did you ever see that activation with either the durametric or the other code reader ?If not I'll bet a six pack that the airbag control unit is the culprit . The other point is the fuel pump relay it's a dual action .I didn't study the wiring diagram b ut I'll bet that the airbag control is the second action and interrupts the dme side .A flaky relay could also be thecause .

I did check the pulse sender and it was working properly last I checked. Tried the second key and same result. I did the pill-ectomy and tried that. For all those wondering minds....If the Immobilizer activates, the starter is disabled and the engine will not even turn over. Dave there was a code for the AB Unit when I first hooked up the Durametric. That and a 1601 that just says you disconnected the battery. When I cleared the codes the AB light went out. I can use the Durametric to turn on the fuel pump and I can hear it running so I know that it is good as well as the relay. I'm gonna check the ignition switch next. May have to break down and tow it to the Porsche Stealership 45 miles away..Euccckkk!

Looks like I may owe you a six pack .There are two parts to the fuel pump relay -DME and something -I'll look at the wiring diagram tommorrow for the something .It appears something is tripping that relay . The good news is that it is unlikely the DME . Dave

I think there is an easy way to check Ignition switch and also dme .At the relay-pin 86 is Ignition switch with key on should be b+ ,pin 85 is dme which I think is the ground .With pigtails should be able to test both conditions ; voltage from ignition switch and is the dme completing the circuit .If the dme isn't completing the circuit -I am clueless Dave

Ignotion switch checks out ok. I think that the DME is toasted. All the systems are powered up and check out ok. Injectors, coils and fuel pump all have proper voltages. From what I cna gather, the DME gets signals from the AirBag module and the Alarm Module to allow engine start. If it does not get a all systems OK then it prevents spark, injector and fuel pump operation. That is what I have now. No codes and all systems have power but no DME signal to start working. Has anyone replaced a DME? Can I get this one rebuilt?

I have a PST2 and have re-flashed two DME's with it. It is somewhat a black art with the DME 5.2.2. Yours though is a 2001??? DME with Motronic 7.2.x? Failing DMEs are rare though, I would actually start with the less expensive VW part ignition switch replacement before the DME, because the DME is expensive and can also be a pain to get flashed, programming codes retrieved and changed, etc. If you can't reflash your DME, the EEPROM can be de-soldered to be re-flashed, however this is seriously geek stuff... basically micro processor repair. You would be better off to source a used DME with the codes and try to re-flash it with your car's immo, alarm, and dme codes.

Mine is a 1999 ME5.2.2. There seem to be a few folks that rebuild these. It would be great if I could get my hands on a schematic for the unit.

Can you pull the codes off the one that I have?

when you put the key in... does the window go down? It prob thinks its still in a crash... hence no spark and fuel.

You could try a DME reflash. However I wouldn't trust a clone PIWIS to do it, I've read several horror stories about that. I have done it with a clone PST2. It is seriously black magic with the 5.2.2 and a clone PST2. If you have a genuine PST2 it is less "scary", but your chances of success on a DME reflash are greatly increased with the DME on a bench out of the car. You can get the programming codes for your entire car from a dealer, just show them proof of ownership. If you want to send your DME to the "pros", here they are: http://www.protomotive.com/home.html . I agree with redridge, I still think your AB module is acting up, but you said earlier you unplugged it and the car runs? What are the guys at Durametric saying? They are REALLY knowledgeable when it comes to DMEs. IN fact, probably the most knowledgeable. You have some serious gremlins in there, I think the ignition switch is worth a try if you haven't attempted that, it's cheap, readily available at your VW/audi/porsche dealer and easy to do.

The windows do not go down when I put the key in. The ignition switch checks out with the proper voltages in all positions. At first it ran without the AB unit plugged in. Now, nothing. No fuel pump, no injector signal and no spark signal.

I believe you said that the Durametric could activate the fuel pump .This would tend to suggest that the dme might be ok .What is vague is the airbag control unit .The documentation says that after three activations it's history .Don't know what logic they used in the unit but I would think that everytime the key is activated it's a cycle -Doubtful they log a fault and ignore that same fault on the next cycle .Durametric may know answer to that . Dave

Even though the ignition switch seems to check out electrically, it might still be bad, I've read a few threads similar to this on renntech. If you try to jiggle the key or move it a little up or down or left/right does it make any difference? Other things to check are clutch switch, DME fuse, fuel pump relay. I am still a non-believer when it comes to the AB module as well, I'm surprised the car even ran without it.

Dave, I read airbag activation as a deployment. After 3 recorded instances it is time to replace it. I am getting an oscilloscope to check the signal at the Injector, crash detection and ignition coils. Maybe that will be the smoking gun that I am looking for. Owen at Durametric said that the codes looked good. Nothing there that helps much. That is what pointed me to the DME. All the input signals are correct but the DME does not tell the engine to start.

I believe the car is a tiptronic-is there any special interlock on those ?Like a neutral safety switch ?

Yep, these are to goto guys for DME reprogramming. My car is a bit of a frankenstein with a 99 chassis, a 2002 engine and the 5.2.2 DME. They can make CEL's go away and not come back.

Have you tried having everything turned off and disconnecting the battery, then let it sit over night and try reconnecting the battery being certain everything is turned off ignition switch and all? Maybe there is a continuity check you could do with the key out and battery disconnected. You've proably already done that though. Sure sounds like a pain trying to diagnose this problem. One more thing. Do you have an sudio amplifier that might be holding power so that when your battery is disconnected the amps capacitors might keep power on the system instead of the bleed down resistor doing it's thing?

Yep, tried all the easy stuff. The Tip has the standard "P" lock so you have to put it in Park to crank it up. I called today and talked with a DME specialist in FL. He gave me a couple of items to check. I did and the DME and Alarm modules are on the way to FL now. Hopefully, that will come up with something. In the mean time we are polishing and trying to decide on new clearcoat. The Pearl Black is in great shape but the clearcoat is a little dull with the 100K plus miles of nicks. I have to say that I did drive it down the street and back before it had a problem. Since it is a new rebuild, I was easy on it and did not floor it (althought I was tempted). I gave it "strong" throttle and it was like someone kicked me in the butt. Zero to 40 in 3 driveways. NOTE: (No pedestrians or small animals were injured in this childish act).

Hopefully this is the last hurdle and the DME specialist has a quick turnaround .You are certainly due a break on this project !

Well, I did buy a "project" car....

Sounds good the having th DME and alarm module checked by experts. Your saying it's a project car got me to flash on wondering if the ECU and whatever other computer stuff is also made for tiptronic. I think there is one for manual and one for tip. I'd just think sensor reading from a tip transmission might dumbfound a manual transmission ECU. Maybe this mod could work http://www.youtube.com/watch?v=6tOI5ZZEQfs

Well, project in that the IMS bearing let go and I rebuilt the engine. We did some upgrades inside like red leather seat inserts and red accents like dash stripe and instrument trim rings. New speakers, brakes rotors, pads, tranny filter and seals, LED rear lights, and a host of other little things. We are going to buff out the Black Pearl paint and likely paint the mirrors and rims a color close to arms red. My son wants a Turbo rear bumper, GT2 Front and GT2 Rear wing. That last part might be out of the budget range.

I freaking love the GT2 look. I hope the DME is the answer.

UPDATE! UPDATE! I got the DME back from ECUDoctors and they said that it is working great. Hosea said that I should get an Oscilioscope and check the signal from the crank sensor. It checked OK with a volt meter but he said that it may but if the signal is not clean it would not work. I got a scope and sure enough the sensor was sending out a real trashy signal. so.... I replaced the sensor, cleaned the ICV and replaced one of the O2 sensors. Now it runs as long as you do not go above 3000 RPM. If you do, it is like you hit a rev limiter and the "4" and "D" flash on the Tiptronic display. Has anyone seen a problem like this? Ideas? Suggestions?

I'm not sure if the sign of the rev limiter is flashing the 4 and D. Once again it depends on the rpm that the failure occurs right? Around 3k the cam change but also your alternator is throwing out more power. Trouble shoot the alternator. With a digital multimeter watch the voltage reading either at the battery or by the engine if you can while the engine revs up. Specificly watch for the positive negative sign next to the voltage reading to change. If the diode stack in your alternator is failing it will allow the altenator that emits A/C then routes through the diode stack to only put out D/C. With the diode stack loosing it the car might charge at lower rpms but higher rpms it throws out trashy A/C along with D/C. The A/C could be fouling your sensors and readouts hence the stumbling of the engine. Did you put the battery on a charger before starting the car since you have been cranking a lot? Could just be under load the diode stack fails extremely. A/C on the line could be why you get some errors in equipment when its just the power supplied to it thats flaking out. Oh yah, if the positive and negative alternate any then thats a sign of A/C getting past the diode stack.

it may also be noise issues, has the main harness been exposed to water or damaged at some point? check all your grounds and connections....

If I remember correctly in your brief test ride before replacing the sensor it didn't do this it soiunds like something is amuck with the sensor and the flywheel /torque converter .Might be a good idea to pull sensor and see if it is rubbing. Dave

I inspected and rewrapped most of the main harness while I had it out. I did not see any problems with it and it was in very good shape. Dave, that is a good thought. If the sensor is very close to the flywheel, say a few thousandths, the centrifugal force of 3000 rpm might bring it into contact. That should be readily evident on inspection.

You might want to inspect the old sensor and see if it has any marks............

does the cam position sensor look OK? I can see where the signals from the cam position sensor and the crank position sensor do not jibe at advance (higher rpm) and it trips things up.

The old sensor did not have any visible marks on it. The problem it had was that the insulation near the sensor had crystalized and flaked off resulting in intermittent or dirty signal. On the CAM sensors, they all checked out OK on the rebuild and they are a PITA to get to now. Does anyone know what kind of degree advance reading I should see ont hem and the crank sensor at 2500 to 3500 RPM?

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Good call out!!!!

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The actual angle for camshafts should read about 24 degrees by about 2000 rpm.

With the durametric and dme 5.2 you can't get cam angles -can get deviation on bank 1 .Spec is plus or minus 6 degrees at idle ..If no cel codes chances are it's ok .Plus this is a brand new bug .Likely something got disturbed . I believe that in Tiptronic cars there is a limp home mode and it sounds like you are there .Might be related to throttle body connections .Google search may provide a few clues .

Sometimes we look for much more complicated fixes to what can be simply problems. Now that the pulse sender has been replaced you can check the "limp home" problem.

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dcdrechsel, I want to say the OP has a 2000 or 2002 car, so he should be able to read actual angles... edit: sorry it is a 1999, so you are correct, you will only be able to read cam deviation... not actual angles.

oops -I thought it was a 1999 .My error Dave

It is actually, my confusion.

I have been in Alaska for the last 2 weks. Just got back yesterday. The last time I worked in it I had replaced the RPM sensor and now it will not rev above 3000 rpm. I am going to repair the old sensor and plug it back in to see what happens. I suspect a bad, although new, RPM sensor. I should know today or tomorrow.

The mystery is solved. I grabbed the old RPM sensor and repaired it. The engine runs fine now no errors or problems. It will work in a pinch but I still need a new one so I am going to return the new (bad) one for a replacement.

Finally...congrats on the fix, you must be elated.

This was an awesome thread and you guys are incredible. Thank you for all of the knowledge shared on here.