My mechanic is stumped....any thoughts?
04-08-2009, 01:24 PM
#31
Rennlist Member
Ummm... spinning the cam sprocket 360 puts it right back where it was. Do you mean the crank sprocket? If this were the problem, it wouldn't have been running in the first place.
04-08-2009, 02:09 PM
#32
Got Nothin'
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Give your mech this link to clarks garage.
http://www.clarks-garage.com/shop-ma...ure-index3.htm
First, make sure the timing is now correct.
Then start trouble shooting. I once spent the better part of two nights troubleshooting this exact problem. It turned out to be a bad speed or reference sensor. Replaced that and the car started right up.
The other thing I have not seen mentioned is the DME relay. That will also render the car unstartable.
http://www.clarks-garage.com/shop-ma...ure-index3.htm
First, make sure the timing is now correct.
Then start trouble shooting. I once spent the better part of two nights troubleshooting this exact problem. It turned out to be a bad speed or reference sensor. Replaced that and the car started right up.
The other thing I have not seen mentioned is the DME relay. That will also render the car unstartable.
04-08-2009, 02:33 PM
#33
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Pete-interesting reading I've done now. the DME relay that is connected to the fuel pump relay and O2 sensor might be the x-factor. Im running a printout to my mech now.
I just wired in an aftermarket O2 sensor that was in a box from the PO. Previously, the O2 sensor had been cut and wires hanging free on the exhaust pipe and the connector unplugged.
I just wired in an aftermarket O2 sensor that was in a box from the PO. Previously, the O2 sensor had been cut and wires hanging free on the exhaust pipe and the connector unplugged.
04-08-2009, 04:03 PM
#34
Got Nothin'
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I have met porsche mechs that replace the DME relay if it is over 5 years old. These are mechanical relays that wear out over time. I don't think an 02 sensor will prevent the car from running.
It may run like crap, but it will run.
The DME relay or the ref sensors are most likely the problem. Once the timing has been double checked as correct.
It may run like crap, but it will run.
The DME relay or the ref sensors are most likely the problem. Once the timing has been double checked as correct.
04-08-2009, 05:03 PM
#35
Quit Smokin'
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A large vacuum leak will also cause a no start condition. If your mechanic left one of the intercooler pipes loose, or left the AFM out of its boot during the timing belt repair, that might also cause your problem.
04-08-2009, 05:20 PM
#36
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i agree pete, it was the reading of the dme relay that got me thinking.....the o2 heater wires are in the same circuit as the fuel relay and dme relay. it could cause problems if theres a short or something. either way, i forgot about clark's garage and i pointed him in that direction. he still hasnt touched the car.
04-08-2009, 08:20 PM
#37
Racer
Does the car have a factory alarm? Had a similar problem. Replaced DME, checked sensors. Finally by-passed alarm and it fired right up. When you turn the key to the on position does the boost guage jump right to the 1 bar reading? If it not, It could be the alarm box. When cranking the engine over I still had deflection of the tach, but the boost guage was dead. Instructions are on Clark's for alarm by-pass if needed.
04-08-2009, 08:55 PM
#38
Race Director
Give your mech this link to clarks garage.
http://www.clarks-garage.com/shop-ma...ure-index3.htm
First, make sure the timing is now correct.
Then start trouble shooting. I once spent the better part of two nights troubleshooting this exact problem. It turned out to be a bad speed or reference sensor. Replaced that and the car started right up.
The other thing I have not seen mentioned is the DME relay. That will also render the car unstartable.
http://www.clarks-garage.com/shop-ma...ure-index3.htm
First, make sure the timing is now correct.
Then start trouble shooting. I once spent the better part of two nights troubleshooting this exact problem. It turned out to be a bad speed or reference sensor. Replaced that and the car started right up.
The other thing I have not seen mentioned is the DME relay. That will also render the car unstartable.
According to what he has stated the DME should be fine.
04-09-2009, 10:26 AM
#40
Three Wheelin'
i agree pete, it was the reading of the dme relay that got me thinking.....the o2 heater wires are in the same circuit as the fuel relay and dme relay. it could cause problems if theres a short or something. either way, i forgot about clark's garage and i pointed him in that direction. he still hasnt touched the car.
04-16-2009, 09:24 PM
#41
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Problem Solved!!
after checking and double checking, he still couldn't figure it out so i had him tow it back to my house and let me have a whirl at it as if i knew what i was doing.
I checked the timing it was perfect. checked the injectors....they were spitting gas. the tach moved when the engine turned. there was compression from his tests. there was spark. I was very confused and about to cry.
as i was putting the cam sprocket cover back on, i noticed the distributer rotor was not lined up on the #1 cylinder while at TDC. it was at 6 o'clock instead of 4 oclock. gave it a twist, tighented down the sprocket cover, and it cranked right up. of all things. the valve timing was great but the spark timing was off. a week and a half at the shop and 200 dollars for a broken fuel line, retarded timing at the belt, and then advanced timing at the rotor. hehe. its a friggin rocket now, though. its running better than it has the entire time ive had it.
I checked the timing it was perfect. checked the injectors....they were spitting gas. the tach moved when the engine turned. there was compression from his tests. there was spark. I was very confused and about to cry.
as i was putting the cam sprocket cover back on, i noticed the distributer rotor was not lined up on the #1 cylinder while at TDC. it was at 6 o'clock instead of 4 oclock. gave it a twist, tighented down the sprocket cover, and it cranked right up. of all things. the valve timing was great but the spark timing was off. a week and a half at the shop and 200 dollars for a broken fuel line, retarded timing at the belt, and then advanced timing at the rotor. hehe. its a friggin rocket now, though. its running better than it has the entire time ive had it.
04-16-2009, 10:50 PM
#42
Racer
Nice! Good to see you are up and running. You might want to take the little screw (3mm allen head) that holds the rotor on, back out, and apply a small drop of removable locktight on it to make sure that won't happen again. In fact, what do you mean by gave it a twist? The rotor shouldn't move or twist on the shaft unless you are missing that aforementioned screw. Have a look ti make sure.
04-17-2009, 04:38 PM
#45
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Nice! Good to see you are up and running. You might want to take the little screw (3mm allen head) that holds the rotor on, back out, and apply a small drop of removable locktight on it to make sure that won't happen again. In fact, what do you mean by gave it a twist? The rotor shouldn't move or twist on the shaft unless you are missing that aforementioned screw. Have a look ti make sure.
when i drove back to the garage this morning, he saw me coming and met me outside and desparately wanted to know to know how i did it. he was a bit embarassed when i told him. thanks to everyone on this thread. it helped me out a lot.