24 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHCar will NOT start. Possible cause appreciated
Leading reported evidence
Check sensor
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
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Discussions that performed work without a confirmed outcome
1
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Performed · outcome unconfirmed · Original poster
Checked the sensor on the flywheel and been through the harness but can't find the root cause.
Leading evidence: 'Check sensor' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, the most frequently mentioned possible cause is 'functioning' (1 discussions; 0 report identifying it and 1 suggest it). The most frequently discussed action is 'Check fault codes' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
Source reports, not a diagnosis or a success probability. Counts refer to discussions and can overlap.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that performed work without a confirmed outcome
1
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Performed · outcome unconfirmed · Original poster
Not quite- fitted LWF then mechanic failed to lock cams and bent valves after turnover.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that suspect a cause
1
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Suspected cause · Original poster
The car is with J3 and they are going to trace where the signals starts and ends but apparently, as I said earlier the Pulse Sensor as possible cause was functioning.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that suspect a cause
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Suspected cause
Probably the Pulse Sender that gets its signal off the flywheel.
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Discussions that contain suggestions
1
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Suggestion
Did you use a Durametric or a PST2 to check for fault codes?
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Suggestion
The constant running fuel pump is going away as this tends to pump hot fuel back into gas tank and increase vapor production from the tank which puts more demands upon the car's vapor recovery system.
These are separate views of the same evidence. Frequency alone does not establish a fix, and these counts must not be added together.
functioning
No successful repair reported for this finding.
0
Identified cause
1
Suspected cause
0
Reported fixes
Read evidence and context
Discussions that suspect a cause
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suspected cause · Original poster
The car is with J3 and they are going to trace where the signals starts and ends but apparently, as I said earlier the Pulse Sensor as possible cause was functioning.
Counts describe captured discussions, not unique people or a diagnosis. Author identities are not reliably stored. Exact duplicate evidence is counted once across matching discussions; one discussion counts at most once per action/state. Multiple repairs reported together remain a combination. Suggestions and failed attempts do not establish a fix. Matches cover whole discussions and can include related faults, model variants and incomplete threads.
24 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
0 evidence records excluded for query context · 0 excluded by outcome qualification · 0 adjusted by outcome qualification.
0 acknowledgements have no verified action link; they do not establish a repair result.
Generation: 20261026T200546Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
After new flywheel install the car turns over but will not fire.
Apparently the DME is not getting a signal off the flywheel to activate the fuel pumps.
Checked the sensor on the flywheel and been through the harness but can't find the root cause. Could it possibly be the immobilizer? Any other guesses?
TIA
Seems to be immobilizer. And can't tell whether its the key/ignition, DME or alarm unit itself. Going to try replacing all three and figuring it out later. Have a DE this w/e.
Probably the Pulse Sender that gets its signal off the flywheel. I had the exact same problem when I had my engine out and put it back in. Without a signal from this sensor the engine will turn over but will not start. Sometimes the wire gets caught and crimped when the engine is raised, or it gets damamged in installing the flywheel. The lack of a signal should show up with a PST2 or a Durametric.
It cost about $180 and is a easy replacement, unless you have alot of corrosion like I did. I had to drop the engine and take off the trans and flywheel, then beat the sender out with a hammer, it actually broke into pieces.
Any chance a re-boot would help? (disconnect battery - and re-connect?)
this is a C2 right?
everything is back together, just swapped a flywheel - thats all?
Not quite- fitted LWF then mechanic failed to lock cams and bent valves after turnover. After valves replaced car would not start but I don't think it did when the LWF was fitted- otherwise more damage than just bent valves. Yes- he's paying for it.
Yes a C2.
Indeed. I don't think it fired up after the LWF was installed. But its not the LWF itself or sensor (the OEM FW has been reinstalled temporarily). The Pulse Sensor is working. Coil packs firing. But fuel pumps not activating. Vexing to say the least.
Not sure what you mean by "lock cams" but in fitting a new flywheel there is no reason the cams and related sprockets. chains etc. should have been touched. Are you sure about this mechanic?
You're right, just removing the FW doesn't do much in of itself, but they (ex-mechanic) removed the puck as well and that allows the IMS to move- and apparently it did resulting in this (now corrected i.e. all new valves):
OK, now you really have me mystified. What is the "puck?" Never heard of one of those in a M96 engine. Did he remove one or more of the chain tensioners and start or turnover the car without them installed? I am really curious as to how a flywheel swap lead to bent valves. Sorry you had this problem.
Have you checked for power to the fuel pump? and the fuse. You should be able to use a volt meter and check for power at the leads to the fuel pump in the trunk.
How did you check the pulse sender? Did you use a Durametric or a PST2 to check for fault codes?
Remembering that I'm the least mechanically person I know and only pay for this stuff, as it was explained to me by J3 who are now dealing with this (very good reputation in SE btw- the head mechanic was voted the best by ALMS this year) the old mechanic who removed the flywheel also removed the puck/bearing behind it and this allowed the IMS to shift and with it perhaps tooth or two on the cam chains allowing the pistons to hit the valves. I may have it wrong but he showed me a schematic and the cam "locks" he uses to prevent this from moving.He fabbed his own locks (about 6" long bits of alu) but apparently Porsche make and sell them. Anyway I nodded pretending to understand.
He reasons that the car probably did not fire when this originally occured because as light as the valve stems are, they only just bent and there was no other collateral damage done.
The car is with J3 and they are going to trace where the signals starts and ends but apparently, as I said earlier the Pulse Sensor as possible cause was functioning. I don't believe there is any codes being thrown which leads me to believe that it is the immobilizer because it can activate, but not throw any codes because everything else may be functional.
It could be any number of things- e.g the elec door windows are out- perhaps the circuits need to be closed. They will just have to go through it all systematically. Stay tuned.
Update- after tracing signals seems most everything is functional (sparking, injectors etc.) but fuel pumps not operational.
Do 996s have same DME relay issues as 964/993 i.e. they are prone to failure?
Anyway this will be investigated further on Monday.
If the mechanic in replacing the flywheel even touched the IMS end plate all bets are off as to why car is not starting. I can't imagine why this was even bothered and to have it "bothered" in such a way that valve timing affected and valves bent... words fail me.
Fuel pump not running immediately upon turning on the key may simply be due to the fuel system being an on demand type. In this type of fuel system the fuel pump runs only when the engine needs fuel and this determined by a fuel pressure switch.
The constant running fuel pump is going away as this tends to pump hot fuel back into gas tank and increase vapor production from the tank which puts more demands upon the car's vapor recovery system.
The fuel pump can be forced to run though I do not have the details of what's involved. It most likely involves the signal from the fuel pressure switch needs to be interrupted and the fuel pump needs to have power sent to it by connecting some bridge points together in the wiring relay panel.
A competent shop should be able to trouble shoot this no problem but one that messes with an IMS end plate during a clutch flywheel R&R I have my doubts...
Be sure battery is fully charged. While in the shop a battery can run down as cabin or trunk or engine compartment lights are left on and the car is started or engine cranked and not run enough for the alternator to recharge the battery fully. The battery will not take kindly to being run down and can develop a bad cell or two and while it may crank the engine the engine will not start. The battery may have been on its last legs to begin with.
With a bad battery other electrical gremlin like symptoms can appear as well.
Sincerely,
Macster.
It lives!
Don't have all the precise details but the car is running. Bad fuel pump relay (and ground- which exactly, I'm not sure yet). I heard it over the tel running The new exhaust barks like a Cup car- J3 like it and said it was built by a "craftsman" which is high praise.
Just in time for Barber in 10 days.
