Major or minor....?

[g3ngs]

Hello folks,

A first post in the 964 forum, though a long term 911 owner only recently of a 964 (which is the most modern one I have owned) and was wondering if I could get some pointers as to whether I have a major or minor problem.....

964 running absolutely fine.....
Noticed an oil leak from the thermostat region,
Traced to the pipe running from the oil tank toward the filter
Had it replaced and decided that now was a good enough a time to get the oil changed along with the plugs.
Following that, the car decided to start up but then as it warmed up to stall.

(It hasn't a lightened flywheel)

So was hoping if anyone had faced this problem before and what has been or what has cocked up along the way and if the fix is simple (if such a thing exists - one can dream)

Thanks in advance



Thanks in advance

[LouZ]

Since you only touched the plugs and changed the oil, start there:
1. are the plugs properly seated, are the wires attached? Did you cross any wires?
2. did you OVERFILL the oil? This would leave to excess oil getting into the intake barndoor & runners and the ISV valve, usually causing your symptoms.

[g3ngs]

LouZ - thanks for the advice, I'll check 1 and 2 and feedback.

Thanks again

[g3ngs]

Hi Louz,

Well I tried taking off some oil and ensured that the plugs were all seated properly and still no joy.......

Before the above, the battery was totally flat and so jumped it (took a while - and after a couple of false starts of idling and then dieing and not holding the charge it going) and then took it for a run and all was well, speed performance and idling.

Open to suggestions, thoughts, ideas....... totally baffled as to how am oil pipe change and pretty basic service could have this effect.

Thanks in advance

[lucittm]

Probably a coincidence. The 964 is pretty advanced electrically from earlier models. It likes to have a fully charged battery. You didn't say how many Kms are on the odometer, but it may be time to have the alternator checked. The brushes do wear down eventually and when they do there is a period of quirkyness until they are no longer able to carry sufficient current to keep the battery charged. Almost any garage can check the output of the alternator under load for you. The alternative is to just replace it with a rebuilt unit. This is what I did with 75,000 miles on the odometer. Now I have peace of mind.

Good Luck,
Mark

[g3ngs]

The battery is now all good so I'm crossing that off the list for now

But the problem persists and is totally baffling (at least to me and guy helping me...)

Changed the DME, well why not, and this had the effect of the car actually and starting and idling evenly, and even reving. yippee!

But then it started to die off, and now it will start, but you can forget idling or reving. (Could there be something that it causing the DME to start to fail?)

The current line of thought is that this is a fuelling issue that is incidental to the change of the plugs and oil.

Can anyone tell me what the sensor would be at the end of this connector... (and any resistance values would be a huge help too)


The plug for which came out of this hole....



(I'd really rather not remove everything if its a wild goose chase.... especially as its -4C here at the moment )

Any thoughts appreciated,
Thanks in advance

[Newsboy]

You didn't say whether the oil was over filled? If oil got into the intake, it would have to be burned off by driving. Did you clean the ISV valve? Is your alternator putting out the correct Voltage? Battery fully charged. Poor running can often be caused by coils. They can have internal faults, even if they test to spec. If they have never been changed, you might want to change them.

[Jeff Burger]

that connector is for the let side knock sensor. it goes in the rear left side connector holder along with the flywheel timing connectors (metal bracket behind the connector in the last picture. I doubt the knock sensor is your problem but it makes me wonder why it is not connected - they don't just fall off. Check to make sure you haven't got any air leaks from hoses taken off /switched/ clamp not tightened

good luck

[Traveller]

Originally Posted by g3ngs

The battery is now all good so I'm crossing that off the list for now.

I'm assuming so since you are able to start it, but what is the voltage at the battery prior to doing so? Hopefully at least 12.65V and what is it when it stalls?

Can you check fuel pressure?

Are both distributor rotors connected via the internal belt?

[Flying Dutchman]

if it is idling at a normal rate, and sounding fine, the DME is fine, the sparkplug cables are all connected to the right sparkplugs (!) the alternator is ok, than the problem is that it isn't making revs.

This is caused by something different probably related to A. air-fuel mixture or B. ignition (timing). Easy checks:
1. DId you get any fault warnings on your dash? And if so, check them with scanner.
2. Check if air filter and/or gas-valve house(what is the English/Armerican word) and/or throttle bodies are still attached properly. Due to worn rubbers, adjustmens by earlier owners/workshops these sometines losen up.
3.When it idles, stand behind the car, and make it rev with the gas cable when you stand at the back. You can better hear what is happening (maybe this should be number 1 ).
4. Recheck all cables and lines especially near the upper spark plugs of both sides. Lots of cables there.
5. Check your O2 sensor Above the left cilinder bank there is a plug wich isn't easy to losen up, but since you found other sensor cables losen up. Maybe this one got disattached. Maybe even check the lines of the O2 sensor up-to you catalyst.
6. Clean up ISV (explained lot of times here, you probably know how to) and check gas valve function at intake.
7. Check rotors. I think you can open them if you think there is a problem here (check diy first about the rotors). Are they vented (if not, you could vent them, but this is probably something else). The rotors distribute the electric pulses to the spark plugs. Maybe even a cable got disattached here.

If all these things seem fine, you have the correct plugs, correct amount of oil your car should fire up and rev. Otherwise I would suspect (my suggestion) the fuel pump isn't working properly (just behind front axle under the car) or the fuel filter (next to oil filler cap) is very dirty.

A quite smart mechanic ( Ex-owner Dutch Renntech) once told me: Make a list of all suggested causes (which are somehow able to cause to problem) and check them all. Working this way will ease up the process and help diagnose the problem, also if earlier suggestions did not solve the problem.

[techman1]

Did not get anything sucked into the air filter housing, did you?

[g3ngs]

Right tearing my hair out over this (and frankly I don't have that much left to lose)

Plugged everything back in and turned it on, and ran perfectly, revved perfectly and let it run for ten minutes without issue.

Turned it on today and here's how it is........

It turns on but won't idle, hesitates and then cuts out.

When you turn it on and try and rev it up with your foot punping the throttle t'll try and hold 3,500 - 4,000 but then start to hesitate and pop and when your foot off it'll run for about a second and then cut out.

Looking back, the times that it has decided to run properly or better than above, the battery has been disconnected for 24 hours plus. Is this relevant? Is there somekind of fault that is developing and then being cleared with the battery being disconnected?

[dlpalumbo]

Disconnecting the battery is one method of forcing the ECU to recalibrate the fuel mixture. When the ECU loses its calibration it resorts to a default mixture, then over time, adjust the mixture accordingly.

Could your O2 sensor be bad?? Hard to believe a faulty O2 sensor would cause the ECU to lean (or richen) the mixture to the point the engine would stall, but maybe. I would guess you'd also get a check engine light.

If it is a fuel mixture problem, you can tell if you're going lean or rich by pulling a plug and looking at it.

Dan

[g3ngs]

Hi Dan

Thanks, well it won't hurt to explore the O2 avenue for a while, I only wanted to change a duff oil pipe and give it basic service...

Many thanks to all for the recent suggestions, they've been gone through and eliminated (sadly) so I'm hoping that there is some mileage in the disconnecting and reconnecting the battery scenario....

I'm hoping that when this is all done that it'll reveal itself to be something simple and then I can post it up on the "admit to your stupidy" thead.... fingers crossed.

Thanks again for everyone's suggestions and ideas

[cjoenck]

So let's explore the following scenarios:
Issue is related to recent maintenance
- Did they remove the air flow meter and forgot to plug the connector back in? There is a connector at the back of the air flow meter - you can only feel it but not see it.
- Check all other connections that may have been removed during the maintenance.

Issue is NOT related to recent maintenance
- Disconnecting the battery resets the ECU so you may have an ECU going bad
- Did you check the ICV function?
- O2 sensor going bad should not create a stall
- Does the fuel pump work properly? Any way you can check fuel pressure?

Since she is running fine for a while, I would look at ECU, alternator, fuel pump - probably in that order.

In the end the most simple explanation is probably right and coincidences are rare. Can you retrace your steps and look at every part that was touched during the maintenance?

Good luck.

[sml]

I had some sort of similar symptoms ...

Symptoms ...
- would only start with the throttle
- would not idle without the throttle
- sort of driveable for an urgent short trip

Cause
- dodgy dry solder joints on ECU/DME board

Solution
- take to old TV repair guy to check board solder joints for $30
- re-install & solved

But there must be some trouble-shooting steps before trying that! I had a hint something was wrong as i had been playing with the chip in the weeks prior.

[g3ngs]

Thanks all for the pointers towards the ECU.

This was the only thing that had not been touched and after sourcing one of ebay and fitting it in............. it still didn't work.......

But the good news is as part of that process a wiggle of wiring of the loom into the ECU appears to make all in the world of my 964 right...... so with the suggestion that there is a wire that is past its best has anyone a map / indication of the ECU pin outs so that the offending wire can be dealt with.

Many thanks in advance

[MBEngineering]

HI g3ngs
is this any good, from a 1990 ? what year is your car?









please note the pins are in the correct position, but the wiring loom should enter from the bottom not as the diag' from the top, drop me a PM as to where you are and if poss I could run a systems adaptation for you with the Bosch Hammer or the PST2 for you, will be round the Milton Keynes area on Monday the 27th Feb.

regards mike

[g3ngs]

Well after some serious arseing around, changing the ecu, bypassing the ecu, changing the dme and going through every aspect of what was touched during the service..........

Drum roll please.....

There was a fault with one of the coils.

Coil swapped, problem gone.

Howwouldavethunkit........

For UK folks......... Porsche GB quoted me £138 for a coil , Eurocarparts £59 (same Bosch part), the fine folks at Pelican $57, but after months of mucking about I went for the local (and more cost effective) option.

[g3ngs]

I should also add, that there was a duff wire coming into the DME which wasn't powering up the ECU, which without Mike's posts would have been even more of a pain in the arse to sort out. And so combined with the equally duff coil was causing all the head scratching...... of the problem being identified and fixed, but symptoms remaining.....

Live and learn......

Anyone in the market for the ECU I bought but didn't need fully tested and definitely working....... 911.618.214.01