My 78 seems to be doing a lot of popping in the exhaust, it's not a backfire it's more of a going down a hill in 3rd gear popping????? but it also seems to be doing it as I'm driving at a steady speed. I have no loss of power when accelerating but it does almost feel like it's cutting out or missing. It also makes the putting noise at idle.
Any ideas?
exhaust popping??
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So Cal Mark
Re: exhaust popping??
a few possibilities; overly rich mixture will cause popping on decel, defective diverter valve in the air injection system, exhaust leaks, exhaust system with no back pressure.
You've described several different scenarios; popping at idle, popping on decel, popping at cruise, misfire or cutting out but not on acceleration.
I'd go through the basics first; set dwell and timing, test spark plug wires and plugs, check fuel mixture, check air injection operation, check for any exhaust leaks.
Is the exhaust system stock? replacement muffler?
You've described several different scenarios; popping at idle, popping on decel, popping at cruise, misfire or cutting out but not on acceleration.
I'd go through the basics first; set dwell and timing, test spark plug wires and plugs, check fuel mixture, check air injection operation, check for any exhaust leaks.
Is the exhaust system stock? replacement muffler?
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rdrtech
- Posts: 41
- Joined: Mon Jul 10, 2006 3:18 pm
- Your car is a: 1982 Spider
- Location: Saskatoon, Saskatchewan, Canada
Re: exhaust popping??
When I first got my fiat two years ago, it did exactly the same. A quick adjustment of the Throttle Position Sensor (TPS) fixed it very quickly.
Carl
Carl
Carl
1980 Fiat Spider 2000 FI (wrecked)
1982 Fiat Spider 2000
1980 Fiat Spider 2000 FI (wrecked)
1982 Fiat Spider 2000
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Makita
- Posts: 57
- Joined: Sat Feb 09, 2008 11:30 am
- Your car is a: 1984 Pininfarina
- Location: Finland
Re: exhaust popping??
My Spider did the same. Idle was very poor and there was popping in the exthaust. So, I cleaned throttle flap and body with WD-40 and pressured air. Did the TPS adjustment, replaced spark plugs, plug wires, distributor cover, rotor and pick up coil (?).
Now the engine idles fine and I can adjust it.
Now the engine idles fine and I can adjust it.
http://www.nic.fi/~makital1/spider/
Pininfarina Spidereuropa -84
Fiat 850 Coupe -66 (project)
Alfa 156 2.0TS -98
Pininfarina Spidereuropa -84
Fiat 850 Coupe -66 (project)
Alfa 156 2.0TS -98
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manoa matt
- Posts: 3442
- Joined: Thu Oct 26, 2006 4:28 pm
- Your car is a: 1978 Fiat 124 Spider 1800
- Location: Honolulu, Hawaii
Re: exhaust popping??
I agree with Mark check the ignition system first and make sure everything is working. Also make sure you have good grounds at the coil bracket to body. Good condensers on the dizzy. And ground wires from the rear cam tower plate screw to the firewall on each cam tower. That should eliminate the misfiring at idle.
Is your catalytic converter functional, or has the core been punched out/empty? That will amplify the popping sound.
No throttle position sensor on a 78 carb. The thing to adjust is the fast idle diaphragm. This should cure the popping on deceleration. On the front of the carb near the engine are two hoses coming straight out towards the front. The lower hose should go to the white/cream plastic electro valve on the drivers side fender. The one more rearward. A hose should come out of the back of that electro valve and go to a fitting on the intake manifold. Where the hose is connected on the carb should be a diaphragm with and adjustment screw on top. To adjust, get the car to operating temp and cycle the accelerator linkage a few times. Pull the linkage to get the rpms up to 2500 then push and hold the test button between the two electro valves. With the button held down let go of the linkage and the rpms should drop to 1550-1650 and stay there while you hold the button. Let go of the button and the rpms should drop back to idle 850 rpms. The adjustment screw should be turned out to increase rpms.
Check that you have all accelerator/throttle and pedal return springs and that the linkages are not sticking or binding.
Is your catalytic converter functional, or has the core been punched out/empty? That will amplify the popping sound.
No throttle position sensor on a 78 carb. The thing to adjust is the fast idle diaphragm. This should cure the popping on deceleration. On the front of the carb near the engine are two hoses coming straight out towards the front. The lower hose should go to the white/cream plastic electro valve on the drivers side fender. The one more rearward. A hose should come out of the back of that electro valve and go to a fitting on the intake manifold. Where the hose is connected on the carb should be a diaphragm with and adjustment screw on top. To adjust, get the car to operating temp and cycle the accelerator linkage a few times. Pull the linkage to get the rpms up to 2500 then push and hold the test button between the two electro valves. With the button held down let go of the linkage and the rpms should drop to 1550-1650 and stay there while you hold the button. Let go of the button and the rpms should drop back to idle 850 rpms. The adjustment screw should be turned out to increase rpms.
Check that you have all accelerator/throttle and pedal return springs and that the linkages are not sticking or binding.