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Spark Misfire? ANY advice please!!!
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tylercle  



Joined: 17 Aug 2012
Posts: 27
Location: Denton

PostPosted: Mon Aug 27, 2012 5:53 am    Post subject: Reply with quote

nope didn't know I had to do that...timing light, can I get that from an auto store?
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'77 924 "Penelope Cruz" all stock n/a, 70K.

"...actually, ambition won't get you that far. You'll shift gears. You'll see something that's shinier. But if you believe... then you're the long-distance runner." - Sam Abell
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ideola  



Joined: 01 Oct 2004
Posts: 15506
Location: Woodstock IL

PostPosted: Mon Aug 27, 2012 6:09 am    Post subject: Reply with quote

tylercle wrote:
Upon aligning the cam, car actually starts with low idle again, and the timing gets off a few teeth after running.


I don't understand what you mean when you say this. It sounds to me like when you're putting the belt onto the cam sprocket and tensioning it that you're allowing the flywheel to rotate...this isn't too hard to do because with the piston at TDC, you'll have compression in the cylinder wanting to force it down. This is why I said to use a 24mm socket and 1/2 drive ratchet on the front crank bolt, because you need to make absolutely certain the crank is not turning when you're installing and adjusting the belt.

Once you have it all together correctly, you will need to tweak the timing by rotating the distributor (with the car running and using a timing light) to dial in the proper timing for your model year. Yes, you can get a timing light at your FLAPS (friendly local auto parts store), but if you didn't know that, I'm guessing you may not know how to use one??? Here is a basic tutorial: http://www.ehow.com/how_4752560_use-timing-light.html
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75 Fiat X1/9 | 80 US 928 | 80 US 931 '941' | 78 D-Prod Replica | 78 Poli-Form
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fiat22turbo  



Joined: 18 Jan 2006
Posts: 4040
Location: Portland, OR

PostPosted: Mon Aug 27, 2012 7:02 am    Post subject: Reply with quote

Also, once you get the belt on and the tensioner adjusted, rotate the motor by hand a full turn or two, stop at TDC and double check your timing position and belt tension.

If the timing is correct, then make sure the belt is tensioned so that you can barely twist it 90 degrees in the middle of the longest length between pulleys.

It isn't uncommon to see it off a tooth after rotating the motor a couple of times, correct it and rotate a couple more, etc. until it is correct.

Button it all up and start the car, let it warm up and fine tune the timing with the distributor and a timing light.
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1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose)
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tylercle  



Joined: 17 Aug 2012
Posts: 27
Location: Denton

PostPosted: Mon Aug 27, 2012 5:22 pm    Post subject: Reply with quote

Earlier, I had to adjust the cam to match the TDC marker on the crank (using mark seen through clutch housing to be sure). I mistakenly turned the cam and crank on their own while fiddling, but now everything is aligned and I feel (and hear!) power when pushing accelerator - just a low idle (and somewhat bouncy engine).

So would the timing light alleviate a low idle, like 3(00) rpm?
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'77 924 "Penelope Cruz" all stock n/a, 70K.

"...actually, ambition won't get you that far. You'll shift gears. You'll see something that's shinier. But if you believe... then you're the long-distance runner." - Sam Abell
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Paul  



Joined: 02 Nov 2002
Posts: 9451
Location: Southeast Wisconsin

PostPosted: Mon Aug 27, 2012 9:25 pm    Post subject: Reply with quote

Most likely.
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Silver 98 986 3.6l 320 HP "Frank N Stein"
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Porsche: It's not driving, it's therapy.
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ideola  



Joined: 01 Oct 2004
Posts: 15506
Location: Woodstock IL

PostPosted: Mon Aug 27, 2012 11:27 pm    Post subject: Reply with quote

Never ASSume that there is only one problem. You may have the timing properly adjusted now, but the idle setting could definitely be off, either due to vacuum leaks, incorrect ignition timing, incorrect fuel mixture settings, or inccorect idle settings. These things are all inter-related.

Once you have the ignition timing set correctly (follow the settings listed on your underhood sticker, use a timing light on the flywheel mark, loosen the distributor nut, and then twist the distributor one way or the other to get the flywheel mark aligned with the pointer in the bell-housing window), the very next thing you should do is hunt down all vacuum leaks.

Each and every bit of rubber or braided hose under the hood is suspect. Ideally, you should replace them all. I use silicone tubing in 4mm, 13mm, and 19mm diameters, and then I use clamps or zip ties on each of the ends. Short of replacing them all, what you can do to find vac leaks is get a spray bottle and fill it with water. Spray a fine mist around every single joint, elbow, tee, or other interface where vacuum should exist while the car is running. If the car starts to bog when you spray in a particular area, then it's sucking the water in through a leak. This method isn't fool proof, it won't find all of the leaks, but it will help you find the worst ones.

Pay special attention to the big plastic and rubber boots that connect the AFM to the throttle body. These are prone to cracking, and can even be pinched from overtightening of the band clamps.

Other areas to check are each of the four injector inserts. The old style inserts are prone to cracking and leaking. Also check all of the intake manifold interfaces: at the head, at the throttle body, and all all of the smaller ports.

Once you've done all that, THEN you can use the idle adjust screw to bring the idle up. Don't confuse the idle stop screw for the idle adjust screw. The adjust screw is relatively large and sits in sort of a tube that is cast into the throttle body. On the NA, it is on the front face of the TB.

It *really* helps to have a vacuum gauge installed. I have one mounted permanently in my NA, and it has helped me identify and isolate newly developing vac leaks early on (due to new cracks in vac lines, vac lines that came loose, a crack that developed in the main TB boot, etc.). At 900 RPM idle, you should be able to pull 14-18 Hg of vacuum. Ideally, it should be on the high end of that range, but if it's less than 14, you definitely have a leak somewhere. Also be aware that valve adjustments can affect vacuum. Finding and eliminating all of the leaks is an extremely tedious and iterative process, but it is absolutely vital if you want the car to run well and reliably.

After you do all that, then go get yourself a proper CIS tester and make sure your system and control pressures are in the correct range. Then you can do fine tuning to the fuel mixture. DO NOT touch the fuel mixture until you are relatively certain you've eliminated all vac leaks, as you WILL badly munge up the settings if there are vac leaks.
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tylercle  



Joined: 17 Aug 2012
Posts: 27
Location: Denton

PostPosted: Fri Sep 21, 2012 8:17 am    Post subject: FIXED Reply with quote

Car is FIXED! The timing needed to be advanced, but I wasn't sure how to do this. I drove it to a shop down the street that offered to look at her, they adjusted the bolt underneath the distributor, and BAM, the porsche purr is back. Thanks again to all the exceptional advice! Now I'm searching for a way to remove the air pump belt since the pump itself is immovable due to a coolant hose wedged in-between it and the water pump. I want to change my timing belt at some point.
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'77 924 "Penelope Cruz" all stock n/a, 70K.

"...actually, ambition won't get you that far. You'll shift gears. You'll see something that's shinier. But if you believe... then you're the long-distance runner." - Sam Abell
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pmcaya2  



Joined: 24 Nov 2005
Posts: 183
Location: Scio, NY USA

PostPosted: Sat Sep 22, 2012 3:15 pm    Post subject: Reply with quote

Take another deep breath, read again Ideola's post, and then look at my short description of "Timing Belt Alignment" in the how to forum - your car should start. - Peter

PS - just read the recent post - congrats if its fixed - now have some fun and drive this great car
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555mk555  



Joined: 09 Mar 2011
Posts: 42
Location: South Africa (Cape Town)

PostPosted: Sat Sep 22, 2012 11:28 pm    Post subject: Reply with quote

Hey man...

This might seem a little too easy... but I had a similar problem and was only firing on 3 cylinders and idling heavy... I thought it was all kinds of things that was the cause.. I used some injector cleaner fluid... the type that also cleans valves etc. Poured it in... started engine.. let it get warm... revved the engine a bit and boom.. firing on all 4. One of the cylinders must have been sticking.. (engine was not running for a few weeks) purrs like a kitten now.

Mick
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