F355 Spider - New cats - high revs

[Ian355]

Is there anyone out there who can give me some advice? I have a 1997 F355 Spider which had the cats removed before I bought it.

The car was extremely loud, so after almost going deaf and getting complaints from the neighbours, I bit the bullet and had new cats put on.

However, the car now frequently idles anywhere between 1500 and 2000 revs - very annoying - especially in traffic. The car has been checked out for air leaks and verified that all sensor plugs are connected correctly.

Any ideas/suggestions/experiences gratefully received.

[phib]

Sounds like its "hunting"

I have had this issue on another couple of cars, in both cases it was the oxegen sensors that needed replacing ( as they were causing the car to overfuel)

Does it happen only only a 2000 revs ? I.e. if you dip the clutch at higher revs whilst moving does it settle down to 1500 - 2000 ?

One last cheeky question are you selling your old cat by pass pipes ? Only as I have been looking for a pair ?

Thanks
Phib

[ian_uk1975]

O2 sensors are a pretty-much a consumable item on 355's. Also, the O2 sensors are the only things that have any direct connection to the cats, so I'd say it's fairly likely that they're the culprit. Will most likely be hurting your part-throttle performance and economy, too. I think you should be able to test the sensors with a multimeter, but I don't know what the appropriate resistance values are.

[Murph7355]

Have you tried resetting the ECUs?

Disconnect the battery (hatch in the boot, circular knob) and leave it off for a bit (overnight should do it).

Reconnect it, then restart but don;t touch any of the controls. Leave it idling for 10-15mins.

Might not sort it, but worth a try as it's free.

[tony h]

call verdi, he can help

[GreigM]

My suspicions:

1. Mass Air Flow (Oxygen) sensor - try cleaning with electrical contact cleaner
2. Reset the ECU
3. Previous owner had the car mapped to take advantage of the de-cat, need to get it re-mapped back to original

[Ian355]

Thanks for all the advice. Tried resetting the ECUs but the car idles pretty much the same,so now ordering some new sensors, hopefully I should be able to fit them myself.

If that fails I will book it into ferrari for ECU reprogramming