| Author |
Message |
Nick Scianna (Nick)
| | Posted on Wednesday, February 28, 2001 - 9:41 pm: | |
The thermotime switch that is located between the intake runners is the one that controls the cold start injector. |
Herbert E. Gault (Irfgt)
| | Posted on Wednesday, February 28, 2001 - 9:17 pm: | |
The expansion tank switch has nothing to do with the cold start injector. It controls the fast idle and timing retard when the engine is cold. Some people loop the switch to fool the engine into thinking it is already warmed up and stops the extremely high cold idle speed that the early model 308GTIs are designed with. |
kelly vince (Tofosi1)
| | Posted on Wednesday, February 28, 2001 - 9:10 pm: | |
I forgot to add that I can start the car when hot everytime. I disconnect the cold start fuel injector. Nick, told me that means it's the thermal time switch. The local Porche dealership has one for $62.00. I going to pick it up next week. My main concern is why would the prevouis owner have looped this sensor on the radator explansion tank, and if could be why the car did not start when hot. I know it's getting plenty of gas, you can smell it. It fluded. definitley. |
David Prall (Davidpra)
| | Posted on Wednesday, February 28, 2001 - 12:59 pm: | |
Kelly,
These CIS systems are often misunderstood a bit. Malfunctioning cold start / enrichment components such as the Cold Start Valve, Thermo-time Switch and Warmup Regulator will not prevent the car from starting. They will simply make the fuel mixture excessively rich or lean.
I've experienced hot start problems on 308's before and 9/10 times it is due to heat soaking of the ignition system components. Two prime suspects are the leads from the crank sensors and the Digiplex ignition modules. Both sit in close proximity to the exhaust system and can become overheated and malfunction. The first thing I would do is visually inspect the wiring to the crank sensors for signs of excessive heat. Another simple check is to manually cool the ignition modules while the car is hot and not starting. Have the access panel unfastened ahead of time, and then flip it upside down and lay a couple of cold packs (the flexible ones used for first aid, for instance) on the modules for a few moments to cool them -- then see if the car starts. Another common gremlin is the spark plug leads. These fail through thermal degradation and often early signs of failure include intermittent shorting when the engine is hot.
If all this checks out, you might go back to the FI system. A very easy way to rule out both the Thermotime Switch and Cold Start Valve is to wait until the car is hot (radiator fans have switched on at least once), turn the engine off, disconnect the electrical plug on the cold start valve (blue, Bosch, 2-pin), and see if you still have the hot start problem. If the car starts, one of those components is defective. If that's the case, let me know, and I'll elaborate on how to check to them individually. |
Nick Scianna (Nick)
| | Posted on Wednesday, February 28, 2001 - 2:15 am: | |
Hi.Typical Hot start problems and diagnostics on K jetronic 308's.If it is hard to start or fails to start when warm it could be[A] the cold start valve leaking or operating continuosly.Test cold start valve and thermotime switch.[B]fuel pressure incorrect.test pressures.[C ]Air flow sensor plate rest position incorrect.Inspect and adjust according to correct spec.[D] Insufficient residual fuel pressure.Test pressure,possible fuel pump check valve,most likely accumulator in 308. Pull the breather line at the end of the accumulator,if you get fuel out of it,that's probably your problem.Also known for warm up regulator problems and fuel distributor problems and faulty or leaky injectors.The beauty of the CIS system in the Ferrari 308 is that the fuel metering unit,the combined air flow sensor and fuel distributor is a self contained,hydro mechanical system.Unless the system is worn out or has been tampered with or contaminated,usually by water,accurate air flow and fuel metering is pretty much guaranteed.It is just inefficient compared to todays standards as the air flow sensor flap is slow,also K jetronic fuel injectors are delivering fuel continuously not cycling on and off.I am just going on,I will stop.Hope that helps some of you guys out there.The K jetronic man. Nick Scianna. www.nicksforzaferrari.com |
kelly vince (Tofosi1)
| | Posted on Tuesday, February 27, 2001 - 8:27 pm: | |
Dave,
I cannot start the car for one hour after it is turned off when hot. i've been told it is a therma timer got the bocsh part number. Since this cold start switch has a loop in it, could it be why I cannot start when hot? |
kelly vince (Tofosi1)
| | Posted on Saturday, February 24, 2001 - 10:48 pm: | |
Yes, it is fuel ingected.The front one is disconnected and is looped back. The back one nearest the fire wall is 2 vacuum lines. |
David Prall (Davidpra)
| | Posted on Saturday, February 24, 2001 - 8:57 pm: | |
If you're talking about a USA injected 308, one is a temp switch which cycles the EGR system, and the other is a temp switch which controls the cold start ignition retard function. |
kelly vince (Tofosi1)
| | Posted on Saturday, February 24, 2001 - 6:55 pm: | |
One is electrical and it is disconnected and looped back, the other one has two small hoses. |
|