355 rev problem in traffic

How does the car drive under other conditions?

Also please take part in this poll;

http://www.ferrarichat.com/forum/348-355-sponsored-bradan/377706-355-owners-only-more-data-samples-needed-anonymous-poll.html

 

is it a 6speed or F1
do you see the slow down light flashing or stay on solid

do you see the slow down light on at time of ignition and then go off.
if you don't then the bulb has been pulled.
and Liklely potential your cats are overheating in traffic, and putting car into limp mode.

are you aware if the car has stock cats, high flow cats or test pipes.

I would not drive car until resolved, especially if it's a cat overheating issue and if sld bulb has been pulled.

 

Good advice. Start reading about SDL system.

 

Make sure the bulb for the slowdown hasn't been pulled as well. Ran into that one yesterday. Also have a 348 in wher the check engine bulbs had been removed. Fun stuff these DIY cars..

 

Same trick I have seen from Shops someone paid for the tech to pull that bull and charge them for the work of doing the real job. haha

 

Yup. Back in the day, the dealer was the worst one for it.

 

SDL has three thermocouples (TC) and three ECU's. One after each cat and one at the by pass valve area. When the TC senses a high temperature the ECU sends a signal to the main ECu and the one engine bank is shutdown. TC and or ecu's can go bad. You can read a few threads on testing voltages and swapping parts to figure out where the issue is. Not too hard once you understand the system.

My car had the bulb removed. The owners manual has a picture listing all the dash lights. I took a bulb out of another spot to troubleshoot the SDL. Ended up getting some spare bulbs from a vendor when I ordered some other stuff. Dash pod comes out by removing two phillips screws. I ended up with a bad TC, but replaced an ecu also. Fchat member DrBob makes TC's that are very good quality and more reasonably priced than OE. I got one from him. Hope that helps.

 

If you have straight pipes the SDL thermocouples are not installed and most likely just hanging there somewhere. If the TC have just been tied up out of the way that would be OK but you can still have an issue with the warning system that is triggering a SDL/limp mode. i.e., bad SDECU, faulty TC, unplugged component. The main ECU will see a 5V signal if you have a bad component and it will trigger a SDL result.

If your issue is a limp mode as a result of the SDL system then you need to diagnose and correct that problem whether you have the TC in use or not.

 

whispered into my ear.... these test pipes have bungs for TC:

Ferrari F355 Primary Catbypass Pipes - Fabspeed Motorsport

 

I am by no means an expert on SDL, but as DrBob said, since you are running test pipes, you need to look and see where your TC's are located. Are they mounted in the exhaust or just hanging? When it goes into limp mode is it always the same side? If so swap the TC's from left to right. If the problem swaps sides, then you may have a bad TC. Swap ecu's in the same way to see if one of them is bad.

I back probed my TC's and checked the voltages. I dont recall the voltages (DrBob) has posted them in other threads. The fact that it only goes into limp after running would be more TC than ecu, I would think. If the SDL light goes at cold then more likely ECU. Black epoxy ECU's are old ones that were known to fail. Green ones are supposed to be newer better ones. You should check those as well. Find out what you have and post.

 

to my understanding limp mode is triggered by too high cat temps.. triggering the SDL light to light up solid. as per manual pull over and shut car down.. etc..

given you have confirmed you have test pipes on and given you do not see the SDL at ignition, means the bulb is pulled..

as Drbob mentioned, there is something going on with your Thermocouplers and Cat ecus..whether they are connected or not.. something is triggering a signal to the engine ECU to put the car in limp mode, in traffic conditions or otherwise..

first step, is to get a bulb in the SDL ligh slot on the dash.. then you will see if its flashing or solid, when you start it up..etc

then check if you can see if the Thermocouplers are connected to the test pipes or not.

take some pictures and post them here if you can..

on a side note, as a general rule of thumb, 5.2 cars ( 1996+), will have issues with test pipes.

if you can get your hands on a set of used stock cats, would be better for you to diagnose/troubleshoot, this issue.. i beleive there is a set for sale in the sales section.

tyring to troubleshoot with the test pipes on.. will be more difficult and/or redundant..

 

Best way to diagnose and troubleshoot the sdl system is to tap the outputs from the SDECUs and determine what the voltages are that the car ecu is seeing. By doing that you will know where and what the problem is and then you can start replacing components that are creating the issue. It may be the ECUs, bad TC or wiring, pretty much in that order of culprits.

On a 5.2 there is only one SDL and so no right or left specificity. By using a DVOM and tapping the outputs you can instantly determine where the issue is and see the results of your troubleshooting without relying on driving around to see if you get a light or not.