MY87 5 speed running issues

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04 Sep 2012 13:06 #10931 by rluvsporsche
In September 2010 with a help of friend I replaced the following oil pan gasket, motor mount, upgrade to Delrin rack bushing and replace power steering line. Since doing this project my car has the following issue high idle (1200), difficult to start (when engine hot), erratic idle, Engine hesitation (leaning out) and it turns off while driving. I have done some LH Diagnostic Troubleshooting using the WSM Vol1 D24-9. Check the following based on the following test point Engine will not start, Engine hard to start, irregular idling and Engine hesitation. This is what I tested supply voltage, idle speed contact, engine temp sensor II, air mass sensor, idle speed control activation, ground and plug connection and they came up normal. I’ve swapped MAF and LH ECU which I borrowed from Andrew Olson and Tim Murphy (great thanks to both).
I’ve replaced spark plugs and check compression. Install fuel pump pressure by permanently install a Install fuel gauge to fuel rail to have a visual when engine will not running or when it decides to stop running. Inspect fly wheel ring gear by removing the cover. None of this solved the problem.
2012 I had a Porsche mechanic R&R intake manifold and replaced all necessary hoses, TPS and gasket. I Check and adjust the timing belt. I bought an idle valve per mechanic suggestion but he has not installed it. Check and adjust the timing belt. All issues disappeared except for the high idle. After R&R of intake majority of my issue disappeared except for high idle 1200RPM. Four months have past hesitation issue returns not as often but a few times I noticed while driving.
Three weeks ago my starter failed and I had R&R starter. After replacing the starter I took the car for a drive low and behold all the issues are back except for the hesitation thus far.
I hope I didn’t confuse anyone with my rumblings. It’s been a frustrating 2 yrs. I can’t enjoy a drive fear that it will stall and will not start back up.
Thanks in advance
Ariel Trajano

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04 Sep 2012 15:00 #10933 by OBehave
Replied by OBehave on topic MY87 5 speed running issues

In September 2010 with a help of friend I replaced the following oil pan gasket, motor mount, upgrade to Delrin rack bushing and replace power steering line. Since doing this project my car has the following issue high idle (1200), difficult to start (when engine hot), erratic idle, Engine hesitation (leaning out) and it turns off while driving. I have done some LH Diagnostic Troubleshooting using the WSM Vol1 D24-9. Check the following based on the following test point Engine will not start, Engine hard to start, irregular idling and Engine hesitation. This is what I tested supply voltage, idle speed contact, engine temp sensor II, air mass sensor, idle speed control activation, ground and plug connection and they came up normal. I’ve swapped MAF and LH ECU which I borrowed from Andrew Olson and Tim Murphy (great thanks to both).
I’ve replaced spark plugs and check compression. Install fuel pump pressure by permanently install a Install fuel gauge to fuel rail to have a visual when engine will not running or when it decides to stop running. Inspect fly wheel ring gear by removing the cover. None of this solved the problem.
2012 I had a Porsche mechanic R&R intake manifold and replaced all necessary hoses, TPS and gasket. I Check and adjust the timing belt. I bought an idle valve per mechanic suggestion but he has not installed it. Check and adjust the timing belt. All issues disappeared except for the high idle. After R&R of intake majority of my issue disappeared except for high idle 1200RPM. Four months have past hesitation issue returns not as often but a few times I noticed while driving.
Three weeks ago my starter failed and I had R&R starter. After replacing the starter I took the car for a drive low and behold all the issues are back except for the hesitation thus far.
I hope I didn’t confuse anyone with my rumblings. It’s been a frustrating 2 yrs. I can’t enjoy a drive fear that it will stall and will not start back up.
Thanks in advance
Ariel Trajano


I am a bit confused but I will give it a poke. Since the starter replacement,your issues have returned? I am not sure why you haven't replaced your Idle speed valve because if that is bad or at least intermittantly bad it can cause some of your issues as well.
I would check your basic 928 things so that we can get a baseline of what is good.
Check all the known grounding points for good contact.
Check to see you have a good strong battery
check the wires and connections at the starter and the alternator as well as the jump post on the right front fenderwell and make sure they ar clean and in good shape.
Make sure your alternator is properly charging the battery when at idle as well as cruise because voltage variations can screw up how your ecu functions.
Then get back to us with what you have. My .02 cents anyway.

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05 Sep 2012 12:31 #10970 by rluvsporsche
My Porsche mechanic didn’t think its bad at the time. He did think the TPS was the culprit that was replaced but did not resolve the issue. I've cleaned and inspect power and ground just to rule out the possibility of that. The alternator and starter wires have also been inspected no visual issues and charging tested.

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11 Sep 2012 11:17 #11190 by emmanuelli
my car had some issue which caused it to rev HIGH when idle and even throttle higher up to 3k rpm at times. once i had turned it off and it wouldnt start back up until it cooled down from normal temp. One night i went to the market the car was off for about 1.5 hrs. when i got back it would crank but not start. i ended up flooding it while trying to start it. in the end took it to the mechanic, he took a glance at the starter, and wrote that off as the problem. after starting it a few times and testing. he found that the RPM sensor that goes by the clutch was faulty and had it replaced. After that the car felt like new. as i havent done my own work im not sure of the real names of the parts... hope that helps pin point the issue.

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11 Sep 2012 13:33 #11194 by rluvsporsche

my car had some issue which caused it to rev HIGH when idle and even throttle higher up to 3k rpm at times. once i had turned it off and it wouldnt start back up until it cooled down from normal temp. One night i went to the market the car was off for about 1.5 hrs. when i got back it would crank but not start. i ended up flooding it while trying to start it. in the end took it to the mechanic, he took a glance at the starter, and wrote that off as the problem. after starting it a few times and testing. he found that the RPM sensor that goes by the clutch was faulty and had it replaced. After that the car felt like new. as i havent done my own work im not sure of the real names of the parts... hope that helps pin point the issue.


emmanuelli

Did you experience any other symptoms? Like the car would stop running while driving and it would be difficult to get the car to run again.

Thanks in advance.
Ariel Trajano

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11 Sep 2012 16:36 #11197 by emmanuelli
the car never shut off on me. the main issue i ran into was the trouble starting the car right after turning it off and the throttling going up on its own from time to time when i was standing still. i was glad i have a 5spd with an auto i would have rear ended some or ran so many red lights!

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11 Sep 2012 16:45 #11198 by rluvsporsche

the car never shut off on me. the main issue i ran into was the trouble starting the car right after turning it off and the throttling going up on its own from time to time when i was standing still. i was glad i have a 5spd with an auto i would have rear ended some or ran so many red lights!


I have the same symptoms and more. I'm so frustrated I can't enjoy the car. I hoping someone else would have the answer.

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12 Sep 2012 12:27 #11207 by 928mac
Replied by 928mac on topic MY87 5 speed running issues

In September 2010 with a help of friend I replaced the following oil pan gasket, motor mount, upgrade to Delrin rack bushing and replace power steering line. Since doing this project my car has the following issue high idle (1200), difficult to start (when engine hot), erratic idle, Engine hesitation (leaning out) and it turns off while driving. I have done some LH Diagnostic Troubleshooting using the WSM Vol1 D24-9. Check the following based on the following test point Engine will not start, Engine hard to start, irregular idling and Engine hesitation. This is what I tested supply voltage, idle speed contact, engine temp sensor II, air mass sensor, idle speed control activation, ground and plug connection and they came up normal. I’ve swapped MAF and LH ECU which I borrowed from Andrew Olson and Tim Murphy (great thanks to both).
I’ve replaced spark plugs and check compression. Install fuel pump pressure by permanently install a Install fuel gauge to fuel rail to have a visual when engine will not running or when it decides to stop running. Inspect fly wheel ring gear by removing the cover. None of this solved the problem.
2012 I had a Porsche mechanic R&R intake manifold and replaced all necessary hoses, TPS and gasket. I Check and adjust the timing belt. I bought an idle valve per mechanic suggestion but he has not installed it. Check and adjust the timing belt. All issues disappeared except for the high idle. After R&R of intake majority of my issue disappeared except for high idle 1200RPM. Four months have past hesitation issue returns not as often but a few times I noticed while driving.
Three weeks ago my starter failed and I had R&R starter. After replacing the starter I took the car for a drive low and behold all the issues are back except for the hesitation thus far.
I hope I didn’t confuse anyone with my rumblings. It’s been a frustrating 2 yrs. I can’t enjoy a drive fear that it will stall and will not start back up.
Thanks in advance
Ariel Trajano



To Troubleshoot this you need to start at the begining and go slow.
First thing to focus on is that you
[replaced the following oil pan gasket, motor mount, upgrade to Delrin rack bushing and replace power steering line. Since doing this project my car has the following issue high idle]

so either a vaccume hose or a wire was moved during repairs.

Then you replaced lots of parts but in your own words
None of this solved the problem.

then
[After R&R of intake majority of my issue disappeared except for high idle 1200RPM.]

So you may have had some bad hoses OR the R&R intake moved more wires.
Then after the started job issues are back.

You have a ground or wire issue!

Did you clean the 12 pin terminal on the passenger fender? Did you make sure that the large ground cable on the bottom right side of the engine was reinstalled and has good contact?

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12 Sep 2012 12:43 #11208 by the flying scotsman
Part of the intake r&r should have completed the ISV replacement and rebuild the throttle body.

The ISV (idle stability valve) typically is a wear item that can be tested for cycling it cannot be repaired. Its impossible to access without intake removal so is normally replaced at the time.

The throttle body shaft is supported by 2 single Oring needle brearings and these Orings deteriorate and leak vacuum. Replace both bearings with the newer double Oring needle bearings.

Both the above shall require the intake to come off again.

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12 Sep 2012 16:05 #11212 by rluvsporsche
928mac The 12 pin terminal connector appears to be crack. I'll replace that but can't find the part number in pets. I know it's a combination of female and male connector. I’m not sure which large ground wire you are referring too. Can you supply a picture please?

Does anyone know the part number?

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12 Sep 2012 16:14 #11215 by rluvsporsche

Part of the intake r&r should have completed the ISV replacement and rebuild the throttle body.

The ISV (idle stability valve) typically is a wear item that can be tested for cycling it cannot be repaired. Its impossible to access without intake removal so is normally replaced at the time.

The throttle body shaft is supported by 2 single Oring needle brearings and these Orings deteriorate and leak vacuum. Replace both bearings with the newer double Oring needle bearings.

Both the above shall require the intake to come off again.


Malcom
I agree that ISV should have been replaced but the mechanic did not. I was pretty disappointed. The O-rings that you mentioned we tested while the car was running sprayed carb cleaner the idle increase a little but nothing noticeable. Although you’re probably right it should be replaced while the intake was apart. I'm hoping my mechanic redo the work and install ISV and O-rings.

Thanks for your input.
Ariel

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13 Sep 2012 00:14 #11225 by 928mac
Replied by 928mac on topic MY87 5 speed running issues
On the right side of the engine and the other end attaches to the car

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13 Sep 2012 10:28 #11230 by rluvsporsche
928mac
It appears we didn’t disconnect the ground wire. I did recheck the ground this year but appears to be connected well. It does have some green corrosion build up so I spray it with anti-corrosion cleaner without removing it from the car.

Attached files [img]media/attachments/11569=1323-IMG_2435.jpg[/img]

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13 Sep 2012 10:30 #11231 by rluvsporsche
Does anyone know the part number for 12 pin terminal connector?

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13 Sep 2012 20:55 #11239 by Kiln_Red
I am not sure about the part # but take the time to thoroughly clean each of the 12 contacts while you are in there. It will very likely cure your running issue to clean these connections and the ground point from the engine to the body. Also, clean and assess the condition of your battery ground strap while you are at it. This can be a problem area as well. I had similar running issues on my '84 auto and cleaning the contacts at the 12 point harness solved my problem. My car was running rough and rich most of the time, prior to cleaning.

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13 Sep 2012 21:30 #11240 by 928mac
Replied by 928mac on topic MY87 5 speed running issues
You can use an old tooth brush on the 12 pin and if you has some steel wool or sink scouring pad to clean the engine ground strap when you remove it you will find some things will just work better.

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18 Sep 2012 20:43 #11318 by emmanuelli
i was gonna ask what are my pics doing there? when i saw the oil pan change pics, hah, yeah, i have the same car... i figure the pics would look very similar. silly me!

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02 Oct 2012 21:32 #11613 by rluvsporsche
I want to give everyone an update. The symptoms now are constant so it's a good thing for my mechanic. The car cranks but does not start. My mechanic check the following. The signal from the crank sensor has a strong signal all the way to ezk box (5ish volt). Excellent with a strong reference signal. LH, EZK and fuel pump relays were jump and still no start. There’s power to the injectors but a little suspicious as to why it’s low 10.8v. He knows the Ezk box rarely if not ever goes out but he would like to eliminate it. The battery power check out so did the ground. Can my fellow members be interested in loaning an Ezk box to me? I know this is a big favor to ask but any help will be much appreciated.

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02 Oct 2012 21:39 #11614 by pcar928fan
My guess is the injection brain for sure... You might need another mechanic if he does not have a spare brain on hand! ;) My mechanic keeps one on the shelf ready to go at all times! Of course not only does he see my 10 928's he also has one (used to have two) of his own and he works on virtually all the rest of the 928's in Austin! He is the 928 stud here in town!

James
78 Silver / Black-white #295
84 Ruby Red / Black AO84
88 Dark Blue / Linen-Black
92 Polar Silver / Dark Blue 92EURO
93 Arrow Blue / Black

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02 Oct 2012 21:48 #11618 by rluvsporsche

My guess is the injection brain for sure... You might need another mechanic if he does not have a spare brain on hand! ;) My mechanic keeps one on the shelf ready to go at all times! Of course not only does he see my 10 928's he also has one (used to have two) of his own and he works on virtually all the rest of the 928's in Austin! He is the 928 stud here in town!


Only issue with that I had a LH loaner a while ago for a couple of weeks and none of the symptoms improve. He works for the dealer so he doesn’t have a spare in hand. Thanks

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02 Oct 2012 21:50 #11619 by pcar928fan
Hmmmm... Maybe that was a bad LH too. Generally speaking though when an LH brain fails it is usually all or nothing. Car runs fine or it does not run at all. At least that has been my experience. So, while I would look at your LH, it sure might be something else.

I can't wait to hear what the final answer is to get this thing fixed!

James
78 Silver / Black-white #295
84 Ruby Red / Black AO84
88 Dark Blue / Linen-Black
92 Polar Silver / Dark Blue 92EURO
93 Arrow Blue / Black

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02 Oct 2012 22:28 #11620 by Kiln_Red
Swapping ignition boxes wouldn't be necessary IMO. You could just as simply, and much more quickly, verify spark and timing on your car as it is now.

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03 Oct 2012 01:11 #11623 by pcar928fan
If you are not getting spark it could be brain, coils, whatever else... It would tell you which part of the equation is acting up though.

James
78 Silver / Black-white #295
84 Ruby Red / Black AO84
88 Dark Blue / Linen-Black
92 Polar Silver / Dark Blue 92EURO
93 Arrow Blue / Black

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03 Oct 2012 07:56 #11626 by rluvsporsche

Hmmmm... Maybe that was a bad LH too. Generally speaking though when an LH brain fails it is usually all or nothing. Car runs fine or it does not run at all. At least that has been my experience. So, while I would look at your LH, it sure might be something else.

I can't wait to hear what the final answer is to get this thing fixed!


James
I'm sorry for the confusion. Earlier post when I said the car crank but no start that's partially true. If we crank the car multiple times it does start with rough idle and it will finally stabilize with 1200 or more idle.. It will run and can be driven but hesitates. If the car stops it's difficult to get it to run again but not impossible. The time I replaced the LH with another I had 2 of them but neither one improve the issue.
Ariel

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03 Oct 2012 07:58 #11627 by Feather
Replied by Feather on topic MY87 5 speed running issues
I think you have failed to follow the advise given by Brad about your ground wire on the engine block. When he said to check it that means that you take it off and look at the surface of the connection on both the wire end and the block.

What you said you did was look to see that it was secure, that you saw some corrosion on it, and that you cleaned the corrosion off with some kind of remover.

The problem with that is that when you have corrosion on that kind of connection it is not the corrosion that you can see that is the problem, but rather the corrrosion that has occured within the connection that you cannot see that is causing the loss of conductivity. Making it look good from the outside and having it feel secure has done NOTHING about whatever corrosion there likely is within the connection.

Do it over and do it correctly this time.

Of course, with your luck this is going to have nothing to do with your problem.

Jerry Feather

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03 Oct 2012 08:05 #11628 by Feather
Replied by Feather on topic MY87 5 speed running issues
As to you EZK, check the Vendor offer at the head of the 928 OC Forums for the offer from Rich Andrade at Electronik Repair, Inc. for free testing. For about the same amount of trouble involved in shipping a loaner back and forth it seems to me that simply shipping yours to Rich for free testing and him returning it is just about the same. Then if it is found bad by Rich he can repair it; and he is one of the best places to have that done, and he is reasonable.

But, I would properly clean the ground in question first.

Jerry Feather

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03 Oct 2012 08:11 #11629 by Feather
Replied by Feather on topic MY87 5 speed running issues
In fact, now that I think about it there are something like 14 ground points on the 928. I think it will be a very good idea for you to do the research about where they all are and CLEAN THEM ALL.

Jerry Feather

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03 Oct 2012 17:46 #11634 by pcar928fan
Jerry, is quite correct with the above...CLEAN ALL YOUR GROUNDS! That said, it is NOT brain failure if the car will start that is FOR SURE! With brain failure it will NEVER start. So at least you don't have that $500-$700 expense looking at you...

James
78 Silver / Black-white #295
84 Ruby Red / Black AO84
88 Dark Blue / Linen-Black
92 Polar Silver / Dark Blue 92EURO
93 Arrow Blue / Black

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03 Oct 2012 22:53 #11643 by wallyp
Replied by wallyp on topic MY87 5 speed running issues
If the engine will spin on the starter, but not run, the problem is likely to be one or more of the following:
- Too little fuel. If you kneel by the rear bumper and listen as the engine spins, you should hear the buzz or whine of the fuel pump. No buzz or whine, no start.
- Too little fuel. Use a mechanic's stethoscope (available from Harbor Freight or almost any auto parts store) to listen to the injectors as the engine spins. There should be a regular clicking from the injectors. No click, no start.
- Too little fuel. With the ignition switch on, but the starter not operating, listen to the injectors. If they are clicking, the LH ECU has failed.
- Too little fuel. If the Temp II sensor on the top of the coolant cross-over on the top front of the engine or its connection has failed, there will be no cold enrichment, and the engine will be very difficult to crank cold.
- Too little fuel. If there is a sizable vacuum leak, the fuel mixture will be too lean. The engine will be difficult to crank, and the idle will be poor.
- Too little fuel. If the fuel pump has failed, or the fuel hose between the internal and external pump has failed, or the fuel regulator has failed, either fuel flow or fuel pressure may be too low.
- Too little fuel. If the MAF (Mass Air Flow) sensor sends a faulty signal to the LH ECU, too little fuel may be injected.
- Too much fuel. If the MAF (Mass Air Flow) sensor sends a faulty signal to the LH ECU, too much fuel may be injected.
- Too much fuel. If the fuel pressure regulator or fuel pressure dampeners diaphragms are leaking, the pressurized fuel will leak into the intake manifold after the engine is shut down. If you try to start the warm engine, it will be "flooded" - that is it will be too rich to run. The engine will also idle poorly due to the rich mixture.
- Too much fuel. If the Temp II sensor on the top of the coolant cross-over on the top front of the engine or its connection has failed, the engine may receive cold enrichment while warm, and will be very difficult to crank when warm. The engine will also idle poorly due to the rich mixture.
- Weak or faulty ignition. The later cars basically have two four-cylinder ignition systems. If one system is faulty, the engine will be hard to crank, and idle and power will be poor. The most common problem is a faulty coil wire.

There are many, many other possible problems. Use your nose to detect too much or too little fuel at the tailpipe. Use an inductive-pickup timing light to check for spark at each spark plug. Use your ears, aided by a rubber or plastic hose, to listen for a vacuum leak.

Report what you find, in exact detail.

Wally Plumley
928 Specialists
www.928gt.com

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21 Jun 2013 22:13 #15136 by rluvsporsche
Just to give you an update. I finally found the issue causing my no run issue. It was the 14pin connector that connects the wiring harness and the ECU's. I still have a high 1000 rpm. so it's probably a vacuum leak. Any suggestion how to check?

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25 Jun 2013 11:39 #15162 by wallyp
Replied by wallyp on topic MY87 5 speed running issues
Get four feet of small rubber or plastic hose. Stick one end in your best ear, and use the other end as a probe all around the intake to listen for the hiss of a vacuum leak.

Stay away from hot and moving parts!

Wally Plumley
928 Specialists
www.928gt.com

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