Sputtering at lower RPMs

[activekcc]

I have an '81 Fiat Spider 2000 FI with 160K miles.
Yesterday the car ran pretty well - 75 degrees outside.
Today it's 87 degrees and the car sputters and coughs when under each gear shift load. Meaning, from a stop to getting going, it sputters and coughs until the RPMs get higher. Same thing happens at each change of gears. It also happens when I'm at speed (any gear) and push the peddle to the floor, unless, the RPMs are already high.
While in gear and moving, there is no sputtering or coughing, unless it's at a lower rpm and I step on the gas; in any fashion.
It idles fine with clutch in, or in neutral. It also reves up just fine in neutral and sitting in the driveway.

Thoughts?

Thanks
KC
clark_kerry@msn.com

[So Cal Mark]

sticky AFM flap, but I could list many, many items that can cause it. It would be helpful if you did at least a cursory inspection under the hood and post what you've looked at and found otherwise you'll get advice ranging from a faded back window to stale air in the tires

[narfire]

Yeup many ideas....Sticky injectors, sticky afm flap, spark plugs, spark plug lead arcing, inside the afm is an arm that swings as the flap moves on a strip and this strip can get worn over time requiring the pins to be moved about 1 mm to a fresh bit of the strip. clogged fuel filter...
Chris

[KevAndAndi]

I'm a big believer in sending the AFM to an outfit like Fuel Injection Corp. for a complete refurbishment and recalibration. To spend $150 or $200 every 160k miles doesn't seem unreasonable. The AFM is the source of many FI woes, and it's nice to have that eliminated as a potential cause of problems. It is possible to improve the function of the AFM as a DIY project, but that's a false economy, IMHO.

[activekcc]

OK, Mark. I looked under the hood, started the engine and waited a bit. I found the problem. There was a water/coolant leak. It was enough to fill two spark plug depressions. In the recent past, I went from rubber hoses to silicon. Not a great idea. They get very soft when they heat up. But I wanted blue or red colored hoses in the engine bay.
Chris, spark plugs look great. They're new about 6 months ago. Plug wires are new as well. Apparently, if you touch the distributor and the valve cover and rev the engine up, you'll get shocked? That didn't feel good. Oh, I'm getting a new fuel filter too, just to be safe.

Kevin. I like your idea if sending the AFM away. Who would I contact to get that started?

Thanks for the help gang.

Look for my upcoming problems with re-doing my front suspension; control arms, springs and shocks.

[narfire]

Look for my upcoming problems with re-doing my front suspension; control arms, springs and shocks

Nah...these cars don't offer any problems....
Great upgrade, thing to do. Most of these cars don't have break neck performance but when the suspension is done with the lowering springs, a set of Koni's and a 1" front sway bar, the car is an absolute hoot in the twisties. Consider the braided steel brake line as well.
Chris

[activekcc]

So, my lowering springs and shocks came in today. Yayyyy! But after looking at my bushings, I've decided to purchase new upper and lower control arms with all new joints and bushings installed. Oh, I also replaced the entire braking system with copper lines and braided lines, new booster and master cylinder. Same calipers and disc though.

[KevAndAndi]

KC,

Here's a link for Fuel Injection Corp. Give them a call.

https://www.fuelinjectioncorp.com/products/air_flow.php