wolv

Hey all,

Newbie with an engine back-fire in a 964.
I spoke to a couple of people to find out what causes this.

Local dealer says Distributor needs changing and are charging ($2713 OUCH)
but is sure that after the car will run fine.

Do you guys know if that'll solve the problem?
If yes, where can I find:
Part number is 930 602 015 AX (not paying them 2k+)

also Tachometer is broken. (their quote $1004)
964 641 801 00.

What's a good site to order?

I'm not in the US btw, in South-East Asia.

Andy Roe

I'm not a mechanic, but I don't see how changing the distributor would stop a backfire? Sounds more like a timing issue to me? Plenty of people on here know a lot more than I do so I'm sure you'll get more replies!

A new tach is a couple of hundred dollars max and easy to swap out if that's all they're gonna do, although you do need to remove the steering wheel.

ilko

Actually you don't. Once you take the gauge out of the socket, you can twist and align it so that it can come all the way out. Its shape is not completely cylindrical on the inside.

Further on the tach issue, I would test the gauge with a 9V battery and see if the needle moves. There is a wiring schematic on the back of the tach and you can see which leads you need to connect to the battery. If the needle moves, then it's not a faulty gauge, you'll need to look for the problem elsewhere. If the problem is with the tach, you can get a used 964 or a 993 tach for a fraction of what you've been quoted by the dealer.

Regarding backfiring, did the dealer scan the car with the Bosch Hammer and pinpoint the issue to the distributor? The distributor is a purely mechanical item with a number of parts inside that are relatively cheap to replace - belt, caps, rotors, etc.

tbennett017

But it could be backfiring due to a distributor belt break? That could be really bad. I wouldn't run the engine until you can determine if that is the case. Search here for "distributor belt" to do some reading on the subject. If it is broken, you could damage the engine pretty seriously... so please be careful.

If you are into working on it yourself, pull off the distributor caps, and check that the lower (left) distributor rotor does not spin freely. If so, the belt is broken and needs a fix before you do anything.

BTW, I have a used standard tach that works if you want to talk.

tbennett017

That depends on the tach. If it is a stock one it is not too deep, but the OBC version is pretty deep, and was much easier to move without the steering wheel in place.

wolv

Hey Andy, thanks for the reply.

It's actually the ignition distributor, but yea im skeptical about that fix for the backfire.

Alternator and timing belt has already been changed.

I've also found a tach on LA Porsche Dismantler for around $200.

wolv

Hey, all thanks for the swift/helpful replies.
tbennet, I'll send you a PM reg your used tach.

Ilko - i'm not sure what they did to check tbh, I'm quite new at this and i've found the caps/rotos/sparks etc on eBay but I also found a Bosch ignition distributor for around US$800. I think that's what the dealer is asking me to replace.

tbennet - no I'm not working on it myself, but I am quite sure the belt is fine tho.

Btw this is what I found with the part number: http://www.partsgeek.com/search/?pro...015+AX&x=0&y=0

darth

Backfires are typically caused by a vacume leaks on the intake side - engine mechanics 101. Check vacume lines for leaks or those rubber intake manifold couplings etc.

Hope this helps
Bill
90C2

Rocket Rob

+1 on the broken distributor belt theory. See
https://rennlist.com/forums/964-foru...-now-what.html
https://rennlist.com/forums/964-foru...elt-re-do.html

demonfish

could the tacho fault and misfire be linked i wonder....

wolv

Yes, I did think of that actually.

Because of the two, I was leaning more towards the tach then the ignition distributor.

Thanks for all the replies so far, I'll check and get back to you guys soon.

Indycam

When a cylinder does not fire and the charge get pushed out the exhaust valve it can blow up in the exhaust system . I would be looking for a non firing cylinder . Bad caps / bad rotors / bad wires / bad spark plugs / bad coil/s .

I would send the tach in for repairs . No need to buy a new one if the old one can be repaired .

wolv

The first pic with the red circle is the failing distributor, technician says it's not working so engine is getting 1/2 the power, hence the backfire.

He also confirmed that the part I linked is what I need to get it running smoothly.

As for the tach, it's not repairable, but that's least of my worries atm.

The distributor belt is fine, there are no intake leakages.

What'd you fellas think? (sad truth is people here know more than the local dealer)

I'm sorry for the bad pics, I'll get more up when she's looking better. The car's a mess now.

klr10

When you say the distributor belt is fine, if that is the case, and if the cap and rotor on the offending distributor are both good then there must be a problem with an HT coil or wiring. Are you sure the belt is definitely OK? You can tell by removing both the distributor caps and making sure both the rotors turn together when the engine is turned over on the starter.

wolv

I actually asked the technician to remove the caps (the car is at dealer) and he said they're fine, furthermore, he mentioned changing the belts.