Losing power.......occasionally
09-17-2018, 06:32 PM
#1
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Losing power.......occasionally
I have an intermittent problem with my 964, it stumbles and wont rev after about an hour's driving. It starts first time when hot or cold. The first time it happened was on the motorway at 100kph when it stumbled and started losing power and by the time i had got over to the shoulder and headed for the next exit (about 700m ) it suddenly went back to normal and i drove the remaining 70km home. Second time was similar, about an hour's drive, stumbled for several hundred meters, then back to normal again.
Any suggestions on where to start looking?
Any suggestions on where to start looking?
09-17-2018, 06:42 PM
#2
Rennlist Member
Fuel pump?
09-17-2018, 11:45 PM
#3
Rennlist Member
DME relay - they do this when they get hot sometimes. Al;ways carry a spare..!
Mark
Mark
09-18-2018, 09:08 AM
#5
Race Car
This is a great article on the dme relay.
http://philipraby.co.uk/porsche-data...ays-explained/
Just an fyi.
But for sure, all of us should have a dme relay in the glove box. If for no other reason than so when your buddy w a 964 who doesn't use rennlist can't start his car, at least YOU have one to get him going again...lol.
And check coils as was mentioned. Those are the first two places to look for intermittent power loss / engine cutoff.
Fwiw, the first time i lost a dme relay, the car would chug here and there on the highway. This went on intermittently for months prior to the dme relay failing. And at that time it hadn't occurred to me to check that relay. And then finally one random day in a parking lot, it drove to the store fine, and then just zero start when i came out. The starter just motored along, and the thing just wouldn't start. When i finally woke up to the fact that it was the dme relay, i pulled the new one out of the glove box and off i went feeling like an idiot for not having immediately thought of it.
I'd like that half hour of my life back...
http://philipraby.co.uk/porsche-data...ays-explained/
Just an fyi.
But for sure, all of us should have a dme relay in the glove box. If for no other reason than so when your buddy w a 964 who doesn't use rennlist can't start his car, at least YOU have one to get him going again...lol.
And check coils as was mentioned. Those are the first two places to look for intermittent power loss / engine cutoff.
Fwiw, the first time i lost a dme relay, the car would chug here and there on the highway. This went on intermittently for months prior to the dme relay failing. And at that time it hadn't occurred to me to check that relay. And then finally one random day in a parking lot, it drove to the store fine, and then just zero start when i came out. The starter just motored along, and the thing just wouldn't start. When i finally woke up to the fact that it was the dme relay, i pulled the new one out of the glove box and off i went feeling like an idiot for not having immediately thought of it.
I'd like that half hour of my life back...
09-18-2018, 12:07 PM
#6
Burning Brakes
This is a great article on the dme relay.
http://philipraby.co.uk/porsche-data...ays-explained/
Just an fyi.
But for sure, all of us should have a dme relay in the glove box. If for no other reason than so when your buddy w a 964 who doesn't use rennlist can't start his car, at least YOU have one to get him going again...lol.
And check coils as was mentioned. Those are the first two places to look for intermittent power loss / engine cutoff.
Fwiw, the first time i lost a dme relay, the car would chug here and there on the highway. This went on intermittently for months prior to the dme relay failing. And at that time it hadn't occurred to me to check that relay. And then finally one random day in a parking lot, it drove to the store fine, and then just zero start when i came out. The starter just motored along, and the thing just wouldn't start. When i finally woke up to the fact that it was the dme relay, i pulled the new one out of the glove box and off i went feeling like an idiot for not having immediately thought of it.
I'd like that half hour of my life back...
http://philipraby.co.uk/porsche-data...ays-explained/
Just an fyi.
But for sure, all of us should have a dme relay in the glove box. If for no other reason than so when your buddy w a 964 who doesn't use rennlist can't start his car, at least YOU have one to get him going again...lol.
And check coils as was mentioned. Those are the first two places to look for intermittent power loss / engine cutoff.
Fwiw, the first time i lost a dme relay, the car would chug here and there on the highway. This went on intermittently for months prior to the dme relay failing. And at that time it hadn't occurred to me to check that relay. And then finally one random day in a parking lot, it drove to the store fine, and then just zero start when i came out. The starter just motored along, and the thing just wouldn't start. When i finally woke up to the fact that it was the dme relay, i pulled the new one out of the glove box and off i went feeling like an idiot for not having immediately thought of it.
I'd like that half hour of my life back...
09-18-2018, 12:10 PM
#7
Burning Brakes
Check the air flow meter connector as well... there is a TSB for it. Also, check for smooth movement of the flap as well as the electrical internals (the mechanical components inside can wear as well).
My AFM was getting stuck occasionally and it felt similar to what you mention.
My AFM was getting stuck occasionally and it felt similar to what you mention.
Trending Topics
09-18-2018, 12:49 PM
#8
This is a great article on the dme relay.
http://philipraby.co.uk/porsche-data...ays-explained/
Just an fyi.
But for sure, all of us should have a dme relay in the glove box. If for no other reason than so when your buddy w a 964 who doesn't use rennlist can't start his car, at least YOU have one to get him going again...lol.
And check coils as was mentioned. Those are the first two places to look for intermittent power loss / engine cutoff.
Fwiw, the first time i lost a dme relay, the car would chug here and there on the highway. This went on intermittently for months prior to the dme relay failing. And at that time it hadn't occurred to me to check that relay. And then finally one random day in a parking lot, it drove to the store fine, and then just zero start when i came out. The starter just motored along, and the thing just wouldn't start. When i finally woke up to the fact that it was the dme relay, i pulled the new one out of the glove box and off i went feeling like an idiot for not having immediately thought of it.
I'd like that half hour of my life back...
http://philipraby.co.uk/porsche-data...ays-explained/
Just an fyi.
But for sure, all of us should have a dme relay in the glove box. If for no other reason than so when your buddy w a 964 who doesn't use rennlist can't start his car, at least YOU have one to get him going again...lol.
And check coils as was mentioned. Those are the first two places to look for intermittent power loss / engine cutoff.
Fwiw, the first time i lost a dme relay, the car would chug here and there on the highway. This went on intermittently for months prior to the dme relay failing. And at that time it hadn't occurred to me to check that relay. And then finally one random day in a parking lot, it drove to the store fine, and then just zero start when i came out. The starter just motored along, and the thing just wouldn't start. When i finally woke up to the fact that it was the dme relay, i pulled the new one out of the glove box and off i went feeling like an idiot for not having immediately thought of it.
I'd like that half hour of my life back...
09-18-2018, 12:56 PM
#9
Just bought one of these solid-state DME relays (with the pump priming feature) and I'm going to use my original mechanical DME as a spare. This solid-state relay should last a lot longer because of no moving parts and the pump priming seems like a pretty cool feature
http://www.ftech9.com/new-products/?...tate+Relays%29
http://www.ftech9.com/new-products/?...tate+Relays%29
Last edited by tct118; 09-18-2018 at 03:19 PM.
09-18-2018, 02:11 PM
#10
Race Car
I've had that solid state relay for a couple years. I also have a spare oem relay in the car. But so far for me and six others here that bought them, no issues yet. Happy w the product.
09-19-2018, 12:33 PM
#12
Rennlist Member
I been experiencing a no-start issue that went from occasional to frequent. It seemed to be DME related, so I popped in a new one and it start started right away. Thought I was in the clear...
During the first drive with the new DME relay, the car started to feel jumpy during smooth throttle and the idle started to surge. Parked the car in the garage and it won't start.
I remembered this comment and checked on the relay. You are not kidding, it was very hot! I retried after it cooed down. Still no start.
The occasional no start, then turned into a jumpy feeling during part throttle (car only felt smooth @ 4,000+ RPM, power felt normal) and then all of a sudden the idle was lumpy.
So it's either a faulty DME fuel relay (even though I just installed a new one), an issue with the coils, plug wires or fuel pump. All over my head...
To respect OP thread, I will start a new one with more details. Please check it out (short video included).
During the first drive with the new DME relay, the car started to feel jumpy during smooth throttle and the idle started to surge. Parked the car in the garage and it won't start.
And check coils as was mentioned. Those are the first two places to look for intermittent power loss / engine cutoff.
Fwiw, the first time i lost a dme relay, the car would chug here and there on the highway. This went on intermittently for months prior to the dme relay failing.
Fwiw, the first time i lost a dme relay, the car would chug here and there on the highway. This went on intermittently for months prior to the dme relay failing.
So it's either a faulty DME fuel relay (even though I just installed a new one), an issue with the coils, plug wires or fuel pump. All over my head...
To respect OP thread, I will start a new one with more details. Please check it out (short video included).
09-20-2018, 08:24 PM
#13
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Update:
Thanks for the input guys......i too figured it was most likely the DME relay. In my mind i had replaced the relay 'not so long ago', however when i checked my records it was 8 years ago! No problem i thought, just grab the spare out of the glove box.........it wasn't there.........then i remembered i had given it to friend a couple of years ago to help solve his 964 issues and he had replaced it with a new one. Obviously i had put it away in the garage in one of those boxes of "spare parts" (we all have them on the shelf in the garage right?), found it along with a fuel filter. So replaced them both as the old filter was 11 years old.
A spirited drive around local rural roads and all seems well.
Thanks for the input guys......i too figured it was most likely the DME relay. In my mind i had replaced the relay 'not so long ago', however when i checked my records it was 8 years ago! No problem i thought, just grab the spare out of the glove box.........it wasn't there.........then i remembered i had given it to friend a couple of years ago to help solve his 964 issues and he had replaced it with a new one. Obviously i had put it away in the garage in one of those boxes of "spare parts" (we all have them on the shelf in the garage right?), found it along with a fuel filter. So replaced them both as the old filter was 11 years old.
A spirited drive around local rural roads and all seems well.
09-20-2018, 08:38 PM
#14
Update:
Thanks for the input guys......i too figured it was most likely the DME relay. In my mind i had replaced the relay 'not so long ago', however when i checked my records it was 8 years ago! No problem i thought, just grab the spare out of the glove box.........it wasn't there.........then i remembered i had given it to friend a couple of years ago to help solve his 964 issues and he had replaced it with a new one. Obviously i had put it away in the garage in one of those boxes of "spare parts" (we all have them on the shelf in the garage right?), found it along with a fuel filter. So replaced them both as the old filter was 11 years old.
A spirited drive around local rural roads and all seems well.
Thanks for the input guys......i too figured it was most likely the DME relay. In my mind i had replaced the relay 'not so long ago', however when i checked my records it was 8 years ago! No problem i thought, just grab the spare out of the glove box.........it wasn't there.........then i remembered i had given it to friend a couple of years ago to help solve his 964 issues and he had replaced it with a new one. Obviously i had put it away in the garage in one of those boxes of "spare parts" (we all have them on the shelf in the garage right?), found it along with a fuel filter. So replaced them both as the old filter was 11 years old.
A spirited drive around local rural roads and all seems well.