A too-rich mixture can cause this symptom. I was doing a repair job on my Corolla recently which involved a half-dozen starts with the ignition disabled toward the diagnosis, each one injecting a little more unburned gas into the engine. When I finished the repair and attempted to start the engine it sputtered like crazy until it finally burned all that extra gas. After that it ran normally. Add to that spark plug fouling, and suspected O2 sensor involvement, seems your shop is thinking the same thing.
Changing the O2 sensor wonât directly fix a start up problem btw, b/c the O2 sensor isnât used during start up, and not after start up until it warms up anywhere around 1-5 minutes later. But a faulty O2 sensor could cause the engine to run rich and foul the spark plugs. I highly doubt most Fiat 500âs are worn out after 33 k miles, thatâs a myth. The problem is that the computer systems are not co-operating with the diagnosis, and the blame on that belongs both to the carâs designers who made the system overly complex, and the folks who buy the car, who demands lots of gadgets and gizmos. Suggest to let the Fiat experts figure it out once they arrive on the scene.
If your goal is to avoid this sort of problem going forward, on your next car purchase focus on cars that sell a really high volume, Corolla, Civic, that kind of car, and from those choose cars that do consistently well in the Consumer Reports reliability ratings.
Thank you for the reply George. At present Fiat National has sent the dealer a more complex diagnostic tool for internal engine data collection. The sad thing is that before we turned the car over to the dealer, the problem only occurred once at start up for the day. Start attempt number 2 was perfect and the car ran fine for the day. Now, after the dealer changed the plugs and the O2 sensor the car struggles to start as before, but once started sputters terribly. The way the car was BEFORE the dealer, I could have driven into any dealer and traded the car. Now the car is un-trade-able. This Fiat was my wifeâs doing. We have had bullet-proof Toyotaâs (our 91 Previa bought new went for nearly 500k trouble free miles over 22 years of service.) The Previa will forever be the cheapest vehicle we ever owned. The engine had nearly new compression numbers after all that time. The engine was transverse mounted. not sure if that matters, but the engine was sure trouble free. My wife âlikedâ the look of the Fiat 500C in white/red, but looks don;t help the car go.
If that always happens, the dealership shop should be able to figure it out. Eventually. When something like that only happens intermittently, then it can be very difficult for a shop to diagnose. So even though it doesnât seem like it to you, Iâd say the shop is moving the diagnosis is the right direction at least. The engine will run correctly with the right amount of gas, air, compression and a healthy spark in all 4 cylinders. Those are all measureable quantities. The shop needs to begin the measuring process one by one.
I own an early 90âs Corolla, still using it as a daily driver. Performance and reliability remain a constant. Only about half as many miles as you got on your Previa though. We hear similar stories about these cars here frequently. Early 90âs Toyotas, definitely one of the sweet spots in automotive history.
I like the look of those cars too. Remember the old saying âhappy wife, happy wife lifeâ? If thatâs the car she likes, then I expect your shop will be able to eventually fix what ails it. Donât give up.
The more the merrier I say. 