Not idling, sputtering

Keep it on topic, it will make it easier to find what you need.
Observer
Posts: 39
Joined: Thu Apr 12, 2012 9:04 am
Your car is a: 81Spider Pininfarina
Location: Canada

Not idling, sputtering

Postby Observer » Sat Sep 09, 2017 12:24 pm

Car starts up fine and runs for a while.
Then it begins to sputter badly and I have to rev the engine for a while, very strong smell of fuel and I am burning gas like crazy.
I can run the car on the highway fine, but once I slow down in traffic it sputters badly and stalls if I don't rev the engine quite high.

Replaced the Large Intake Hose.
Checked all the hose for cracks and potential leakes
Cleaned the Cold start Sensor and tightened the clip.

narfire
Posts: 3959
Joined: Sat Dec 27, 2008 2:14 am
Your car is a: 1980 124 spider
Location: Naramata B.C.

Re: Not idling, sputtering

Postby narfire » Sun Sep 10, 2017 10:24 pm

Not sure but unmetered air getting into the intake? Check with someone manning the throttle and you with a propane bottle on low and wave it about close to the black intake, around the throttle position sensor, brake vacuum line, get the idea? if the car revs up at a point, you have an air leak. Not sure how you checked, if you did it this way, that's great
remember propane sinks so be careful.
Not sure what your skill set is but the AFM has an arm/pin? that rotates( with the plate you see inside) as airflow increases. If you take the black plastic top off very carefully ( can be a pain) you'll notice an arm on the vertical pin. End of that moves along a strip. The very small pins on the end will have made two tracks along this strip and the beginning part of the strip ( idle and low rpm) it can be warn and give you issues at low rpm. If you can, loosen the screws and VERY carefully perhaps bent that fragile arm just a tad so those pins are perhaps 1/2 to 1mm over and into fresh part of the track. Can clear that issue up.
Just a couple of causes...
Plugs?
Fuel lines rot and leak over time as well. Perhaps have a injector line that is compromised?
80 FI spider
72 work in progress
2017 Golf R ( APR Stg. 1)
2018 F350 crew long box

User avatar
lglade
Patron 2018
Patron 2018
Posts: 327
Joined: Sat Dec 07, 2013 7:05 am
Your car is a: 1984 Pininfarina
Location: Mukilteo, WA

Re: Not idling, sputtering

Postby lglade » Sun Sep 10, 2017 10:54 pm

Narfire has some great suggestions, and here's another one. My 1984 was doing the same thing and it turned out to be a short in the wire to the coolant temperature sensor, although a bad sensor will to the same thing. With the engine idling, grab the wire to the sensor and see if the problem stops.

Here's a video:
https://www.youtube.com/watch?v=4ypYUq5ri_k
Lloyd Glade- Mukilteo, WA
1984 Pininfarina Spider Azzurra
1962 Fiat 500D - wife's car
2015 Subaru Outback
2017 Ford Focus RS

Observer
Posts: 39
Joined: Thu Apr 12, 2012 9:04 am
Your car is a: 81Spider Pininfarina
Location: Canada

Re: Not idling, sputtering

Postby Observer » Mon Sep 11, 2017 10:37 am

lglade wrote:Narfire has some great suggestions, and here's another one. My 1984 was doing the same thing and it turned out to be a short in the wire to the coolant temperature sensor, although a bad sensor will to the same thing. With the engine idling, grab the wire to the sensor and see if the problem stops.

Here's a video:
https://www.youtube.com/watch?v=4ypYUq5ri_k


Thank you. I tried as suggested no change. However, if I unplug the coolant temperature sensor with car idling the engine cuts off.

micbrody
Patron 2018
Patron 2018
Posts: 443
Joined: Tue Nov 04, 2014 4:50 pm
Your car is a: 1981 fiat 2000
Location: Munster, IN (Northwest Indiana near Chicago)

Re: Not idling, sputtering

Postby micbrody » Mon Sep 11, 2017 11:53 am

Have you checked idle screw o-ring? Maybe as car gets to operating temperature, the small expansion of metal is causing too much idle screw air to come through; or maybe maybe just really dirty.
In any event:
Remove idle screw; inspect gasket for cracks; use carb cleaner in hole and on screw; also clean hole with q-tips.
Then reinsert screw. Get car started; once it is going, let it come to operating temp (two radiator fan cycles). Then adjust the idle and throttle stop screw: screw idle screw totally in/closed . Then adjust throttle screw stop to get idle around 850ish rpm. Once there, open up idle screw to get Rpms to 900-950.

I forgot to mention two more things:
Check the throttle position sensor. When throttle plate just barely opens, you should hear a click (there is a way to use ohm meter to check for "continuity click", but off the top of my head I don't remember which of the three terminal to put probes on)

The other thing to check: does your Rpms change at rest when you hit brakes on and off? Maybe a leaky brake booster or hose leading to brake booster. One way to check is to just clamp hose from intake manifold that goes to brake booster; or just remove hose and cover hole with tape(heat resistant) . See if idle improves. (Be careful about driving as you won't have any brake boost to help )

User avatar
KevAndAndi
Posts: 531
Joined: Fri Oct 03, 2014 12:14 pm
Your car is a: 1981 Fiat Spider 2000
Location: Chatham, NJ

Re: Not idling, sputtering

Postby KevAndAndi » Tue Sep 12, 2017 12:16 pm

I had the same problem, which turned out to be caused by an AFM that was not working correctly. I had it rebuilt, and now the car runs great.
Kevin
1981 Spider 2000

Observer
Posts: 39
Joined: Thu Apr 12, 2012 9:04 am
Your car is a: 81Spider Pininfarina
Location: Canada

Re: Not idling, sputtering

Postby Observer » Thu Apr 05, 2018 10:02 pm

Had almost everything check as recommended, including AFM, with no luck at all. The car runs fine on the highway, but once I have to engage the clutch it stalls.

Question: Could it possibly be the clutch that is causing the car to cut out in traffic?

grrrdot
Posts: 224
Joined: Mon Jan 02, 2012 11:14 pm
Your car is a: 1967 124

Re: Not idling, sputtering

Postby grrrdot » Thu Apr 05, 2018 10:50 pm

Could it be a leaking injector?

Any trouble restarting hot?
If you pull the spark plugs after the car has idled for a bit what color are they?
The color will tell you if it’s rich / lean.

-G

Observer
Posts: 39
Joined: Thu Apr 12, 2012 9:04 am
Your car is a: 81Spider Pininfarina
Location: Canada

Re: Not idling, sputtering

Postby Observer » Fri Apr 06, 2018 5:47 pm

Thanks!

Injectors are fine and all plugs are burning normal.


Return to “Engine and Tuning”

Who is online

Users browsing this forum: No registered users and 20 guests