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'83 944 NA starts but immediately stalls

 
Old 04-05-2019, 11:03 PM
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DeepEnd944
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Default '83 944 NA starts but immediately stalls

So like the title says, I have an '83 944 NA that had to get towed last week due to the car not being able to drive safely. When I start the car, the car will die within 3-4 seconds if the throttle isn't revved. Based on the Haynes manual, it says the issue could be in the distributor, ignition coil, or other related parts. I first checked the distributor cap and rotor (see photos) and there was some corrosion on the terminals, as well as a carbon deposit peppered on the inside (more than in photo as I'd cleaned it yesterday. The center terminal (coming from the ignition coil) was also covered heavily in a carbon deposit to the point it left a graphite-like residue. The rotor also had a decent amount of corrosion on the tip (see photos). I also checked the ignition coil per the Haynes manual and the #4 terminal hole (usually covered with rubber stopper) has a dirty, cakey residue inside it. The primary terminals (#1 and #15) have 4.6 ohms across, while the secondary terminals (#1 and #4) were reading as infinite resistance. As far as what else I checked, the battery was stable at 12.45v. I've also attached photos of a spark plug which all had identical wear patterns. As far as more involved testing, I plan on checking DME and airflow meter continuity stuff. Willing to check whatever anyone recommends. I'm a college student so I was looking to get some help before I started spending big bucks on new parts.


Spark plug

Distributor rotor (front)

Distributor rotor (back)

Close-up of distributor cap terminal

View of center terminal inside distributor cap
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Old 04-06-2019, 06:10 PM
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Default Re: '83 944 NA starts but immediately stalls

To add a note, a person on the PCA tech forum recommended that I check my airflow so I pulled out the airflow meter. Based on the Clarks garage article about the AFM (http://www.clarks-garage.com/shop-manual/elect-22.htm) I tested it and found mixed results. With closed/open air-flap, voltage across the potentiometer strip using 9vDC battery was 0.16V and 7.81V respectively. I also checked the DME (fuel pump) relay (http://www.clarks-garage.com/shop-manual/fuel-05.htm) and had 0.7 ohms between pins #2 and #4 and pretty identical results (0.8 ohms) across pins #2 and #8. Like it usually goes, happy it wasn't the AFM but i'm still unsure what's causing this issue.
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Old 04-07-2019, 09:47 AM
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T&T Racing
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Using RL, use advance search inputting key words to find threads relating to the symptoms.

Based on your thread, does the engine continuously run if the throttle is partially open, ie off idle? Does the engine sound OK from part throttle to wide open, back to part throttle, etc?
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Old 04-08-2019, 03:39 PM
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Engine sounds fine. Is it possible it could be the alarm system that got triggered and is causing it to shut off?
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Old 04-08-2019, 07:39 PM
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Originally Posted by DeepEnd944 View Post
Engine sounds fine. Is it possible it could be the alarm system that got triggered and is causing it to shut off?
Review all Clark Garage maintenance related items. Seems like it is in the idle circuit. Also use RL advance search with key words stalls at idle
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Old 04-09-2019, 09:32 PM
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Default Re: '83 944 NA starts but immediately stalls

Originally Posted by DeepEnd944 View Post
Engine sounds fine. Is it possible it could be the alarm system that got triggered and is causing it to shut off?
Took a video if it helps -->
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Old 04-10-2019, 02:01 PM
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Engine sounds OK, but I would run a test. Warm up the engine and then. Use an infrared pyrometer to measure exhaust header temperature from each cylinder when the engine is running. If there is a large delta between on or more cylinders, the lowest temperature could indicate an air leak to that cylinder or a cylinder valve leak. The next step would be a cylinder compression test.

If all the exhaust cylinder temperatures are within 50 F, but are on the low side, say less than 375 F, then there could be an air leak between downstream of the AFM to the intake manifold.

Another thought is to first look at the interior of the J boot as the first step in the diagnostics. If there is oil inside the J boot, then the AOS seals are leaking unmetered air into the intake causing a low fuel/air ratio, thus a stall at idle.
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Old 04-20-2019, 12:46 PM
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Default Re: '83 944 NA starts but immediately stalls

Does your car bog down/stutter/lose power when accelerating too? If so, I might consider fuel pressure as a possible problem and look at the fuel pressure regulator. Had similar idle problems with my 83 many years ago.

Last edited by TurboPropRob; 04-20-2019 at 04:40 PM.
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Old 05-01-2019, 06:36 PM
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It sounds like you are getting ignition, but a fuel pressure check would be the next thing to do. You'll need a special adapter to go between the fuel rail end(brass cap) and the pressure tester. If the pressure is low, change the filters. The in-tank as well as the big one next to the pump. then test again. It could also be the DME relay heating up and causing the fuel cut off after it's been running a bit. If you want a bulletproof deal with that, go to Ftech on here and get the solid state one...Don't get a URO brand...cheap yes, but with a high failure rate...jus sayin' OH BTW, you might use some sandpaper on the end of the rotor tip and scrape off any corrosion on the dizzy cap posts..Hope this helps some.
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Old 05-01-2019, 06:40 PM
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Exactly what I was looking for. Thanks!
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