328 Stalling at hard stops - what gives?

You might post this in the Tech section above. Also if you fill out your profile people would know if there's a nearby Ferrari tech would could help.

Was the car cold, warm or hot when this happened? I can't speak to the altitude issue, but it wouldn't surprise me if a component in the FI system needed adjusting or replacing. I haven't had this issue in my 328, but in my old Fiat X1/9 I had an issue with the Bosch FI airflow sensor that produced exactly what you describe.

Also, is your idle set to ~1000 rpm? These cars idle faster than the generic modern Honda, etc.

 

Could be a problem with the power brake booster/system. A vacuum leak in the system will cause the engine to stall due to overly lean mixture under breaking/stopping at a light, whatever. Just slowing down won't do it because the engine RPM remains high enough for the vac leak not to matter. This is a common symptom of a brake sys vac leak and though not the ONLY possibility, is certainly worth checking.

 

Based on the diagnosis by Mike996, and if it were my car, I'd disconnect and plug the vacuum hose on the brake booster to isolate the problem. It could be the booster leaking vacuum air internally or maybe just a loose/cracked hose.

BTW, if you choose to try this yourself then be warned that you will have no power brakes with the vacuum hose disconnected.

If you're handy with tools then you can buy a vacuum test kit at any of the auto parts supply shops.

 

If the float level is too low, at a sudden stop fuel sloshes to the front of the tank and the orifice in the center of the tank which supplies gas to the needle goes dry momentarily stalling the engine. I do recall this happening to me...about 50 years ago.

Now if the 328 only had a carburetor.


All seriousness aside, I see substantial differences in idle performance (stumbling & stalling) during ethanol months.

 

How long has this been going on? I.e. have you just purchased the car? If the idle is set too low this will happen, as I can well attest to (and an easy fix)! But you say it idles fine so... As Bullfighter points out, could be an injection problem, too. I had a similar situation with my 328. Though it wouldn't completely stall out, the rpm's would dip decidedly low upon deceleration and then kind of bounce back up. My mechanic checked my vacum hoses and all was okay, and since I had just put gas in the car, we determined that it was possible that I got a bad tank of gas and/or that my injectors could probably use a cleaning. As far as the gas is concerned...apparently if one allows their car to run very low, adding gas at that point can sometimes dredge up some sediment/residue from the tank and clog the injectors a bit. I treated the car to aome new gas and injector cleaner and that helped quite nicely But I had the injectors cleaned anyway on my next "visit and that really did the trick. But...alas...there are many fine gents on this site (made quite obvious by this thread) that are FAR more knowledgeable than I, so heed their advice!

My best,

Scott

 

just have car tuned for your area....you are running too rich now that it is at 7000 ft. Set it for proper emissions readings and idle speed for 7000 ft instead of sea level where you got it.

 

Swearing in Italian is actually good for another 5-10 bhp.

 

Wondering if you ever solved the problem. Same issue here....

 

Had a similar problem. Found the hoses to the auxiliary air valve were cracked. Replaced them and problem solved.

 

I'm going to be inspecting all the vac lines today and hope to get lucky!

 

I'd also check all your plug wires for continuity & make sure its firing on all 8....

 

All plug wires as well as distributors brand replaced last winter so should be OK there. Thanks.

 

All good, FWIW I just found a broken wire - less than 8500 miles on the set.

Also check the Vac line that goes from the plenum back to the ignition box in the rear - you will have to remove the LHS arch liner to check it all. Mine had a big tear in it some years ago where it had rubbed through - caused chaos with the fuel mixture at idle & also killed the vacuum advance.

 

Also check the electrical plug on the top of the Warmup Regulator for corrosion and possible non-contact.

 

Ordered some new hoses. Found one cracked but not enough to screw things up. Will pull all old hoses for complete replacement.
Also installing an air/fuel mixture gauge so I can tune this thing correctly.