When starting car, I heard loud pop, intake manifold comes disconnected from motor
#1
When starting car, I heard loud pop, intake manifold comes disconnected from motor
My car was working great two days ago, but I went to start it this morning and i heard a loud pop/bang from the rear. I take a look at the engine and the intake manifold had become disconnected on both sides to the motor inlets.
I tore apart the engine, put everything back together and the car started. I turned it back off and walked away.
I then just returned to go drive around, but once again I heard the same POP noise and sure enough, the intake manifold had come off.
I really don't know what would be causing this since up to now, nothing has changed with my car and it had been running very well prior to this.
Please help. Input is very much appreciated.
Picture of the driver side, but this also happened on the passenger side.
UPDATE: I had the injectors serviced and they found that two of them were pretty clogged (which would result in a leak). I put everything back together and the car runs like a champ.
Thanks
I tore apart the engine, put everything back together and the car started. I turned it back off and walked away.
I then just returned to go drive around, but once again I heard the same POP noise and sure enough, the intake manifold had come off.
I really don't know what would be causing this since up to now, nothing has changed with my car and it had been running very well prior to this.
Please help. Input is very much appreciated.
Picture of the driver side, but this also happened on the passenger side.
UPDATE: I had the injectors serviced and they found that two of them were pretty clogged (which would result in a leak). I put everything back together and the car runs like a champ.
Thanks
Last edited by jeanhules; 06-16-2016 at 12:45 PM.
#2
Rennlist Member
You probably snapped your distributor belt.
#3
Nordschleife Master
^ that's a good place to start troubleshooting. See if the car will start and run with either ignition module disconnected (to isolate the distributors). The ignition modules are on coil bracket.
Another issue you might be having is the fuel pressure regulator is starting to fail and dumping fuel into the intake plenum. To troubleshoot, follow the vacuum hose from the FPR to the plenum. Disconnect at the plenum and watch to see if the vacuum line burps fuel. You might have to sit there and watch it for a little while as the car idles.
Another issue you might be having is the fuel pressure regulator is starting to fail and dumping fuel into the intake plenum. To troubleshoot, follow the vacuum hose from the FPR to the plenum. Disconnect at the plenum and watch to see if the vacuum line burps fuel. You might have to sit there and watch it for a little while as the car idles.
Last edited by Vandit; 05-07-2016 at 10:15 AM.
#4
Rennlist Member
It's best not to run the engine if the belt is broke. Pull the cap on the secondary distributor and see of the rotor spins freely. if you're still not sure, pull both caps and make sure they are both lined up with the TDC notch on the distributor.
A good sign it's a faulty FPR is the car would have been difficult to start when it was warm prior to this happening.
A good sign it's a faulty FPR is the car would have been difficult to start when it was warm prior to this happening.
#5
It's best not to run the engine if the belt is broke. Pull the cap on the secondary distributor and see of the rotor spins freely. if you're still not sure, pull both caps and make sure they are both lined up with the TDC notch on the distributor.
A good sign it's a faulty FPR is the car would have been difficult to start when it was warm prior to this happening.
A good sign it's a faulty FPR is the car would have been difficult to start when it was warm prior to this happening.
When you say difficult to start, it could be difficult to start when cold, meaning it would usually start with the help of a few revs from the gas pedal. Sometimes it would die, but quickly start up again on key turn.
#6
My car My91 c2 has very similar issue. It happened Friday, lastime it was approximately a year ago. Only happens on start up almost as soon as it starts to turn over and seems to be when weather is fairly warm. Distributer belt is intact but on rare occasions instead of fireing right up I have had to press accelerator to get the car started. So in my case FPR seems the likley culprit and will be checking that thanks guys
#7
Three Wheelin'
All above are good suggestions. My car had a similar issue, only occured around one start in ten. Backfire into the inlet pops the inlet apart at the joints.
Once running it was fine but totally random when it would do it. The twenty minutes it takes to reassemble the inlet dulls the desire to go out for a quick spin or drive anywhere in case the return journey was problematic.
I tried all the above, also changed injectors but the problem was solved by replacing the HT leads and coils. One coil looked rotten with green fur and a couple of leads looked slightly suspect. But there was no real smoking gun pointing to the cause.
Once running it was fine but totally random when it would do it. The twenty minutes it takes to reassemble the inlet dulls the desire to go out for a quick spin or drive anywhere in case the return journey was problematic.
I tried all the above, also changed injectors but the problem was solved by replacing the HT leads and coils. One coil looked rotten with green fur and a couple of leads looked slightly suspect. But there was no real smoking gun pointing to the cause.
Trending Topics
#8
So I removed the distributor and looks a look inside and under the caps. I don't see any sign of wear or damage, but again this is the first time seeing this part so what do I know.
For anyone who has tinkered with the distributor, does everything look okay? I've purchased new caps, rotors and was going to have the distributor rebuilt, but rotating the rotors seem to be smooth.
For anyone who has tinkered with the distributor, does everything look okay? I've purchased new caps, rotors and was going to have the distributor rebuilt, but rotating the rotors seem to be smooth.
#9
Nordschleife Master
Those caps and rotors look like they're in pretty good condition. Do you know how old they are?
The two rotors spin together (i.e. the belt isn't broken)? That's really all you needed to check.
Dumb question, but you made sure to set the motor to TDC, or at least note the position of the rotors, before you pulled the distributor assembly?
The two rotors spin together (i.e. the belt isn't broken)? That's really all you needed to check.
Dumb question, but you made sure to set the motor to TDC, or at least note the position of the rotors, before you pulled the distributor assembly?
#11
Rennlist Member
Based on that and the fact you said it was difficult to crank when cold, sounds more like Alex's issue with the ignition components.
#12
For a person who hasn't done this before you sure did a lot. In fact you did too much. Lol. You didn't need to pull the distributor, just the caps to see if the belt was broken so both rotors were spinning. Now, like vandit said, the distributor has to be put back in the correct spot, don't rotate that engine if you didn't already TDC it. I was going to recommend changing the distributor belt while you had it out, but I believe the engine would have to be at TDC before you take that belt off. Can it be done just by taking a picture... Anyone? Going by your post you already spun the rotors off the car. And, like others said, Those caps and rotors don't look bad, but with maintenance we change them regardless of how they look.
#13
ok. so I put the distributor back in. I may or may not replace the caps and rotors with the new ones... what do you guys think?
Onto the next possible issue, FPR... here is a pic of mine. Looks pretty old, maybe original. Thankfully I ordered one of these as well so I will most likely replace it. I've read on the symptoms of these failing, but is there any visual signs (leaking, internal wear, etc)?
Just out of curiosity, how would a failed FPR cause what I understand to be a large backfire which results in the intake manifold coming disconnected on both sides?
While I have the engine apart, is there anything else I can test?
Onto the next possible issue, FPR... here is a pic of mine. Looks pretty old, maybe original. Thankfully I ordered one of these as well so I will most likely replace it. I've read on the symptoms of these failing, but is there any visual signs (leaking, internal wear, etc)?
Just out of curiosity, how would a failed FPR cause what I understand to be a large backfire which results in the intake manifold coming disconnected on both sides?
While I have the engine apart, is there anything else I can test?
#14
Nordschleife Master
Visual sign would be disconnecting the vacuum line that connects to the plenum and observing to see if it burps fuel.
Here's another thread discussing a popping intake and possible solutions.
http://forums.pelicanparts.com/porsc...non-vario.html
Here's another thread discussing a popping intake and possible solutions.
http://forums.pelicanparts.com/porsc...non-vario.html
#15
Burning Brakes
OK, so how did you get that picture of the FPR and breather housing from that angle without pulling the motor ? Or is that just some fancy finagling with your cellphone camera?
That all looks like the original bits to me...
That all looks like the original bits to me...