4800 rpm. Any ideas? My first thoughts: Broken throttle position switch (no wot signal) I only hear one click turning the throttle through full range. I think it should have 2 Fuel pressure regulator not working correctly Vacuum leak What do you think? Also no high speed idle at cold start. Any suggestions are welcome. This is a 4 valve injected 308
Did this behavior begin abruptly or has max RPM been gradually decreasing? Is the max RPM the same regardless of engine load, same 4800 RPM max whether accelerating in neutral or on the road in gear?
No, the idle switch has an audible click, but the WOT switch is a (soundless) pair of contacts (closed by a cam) that allows over-travel: Image Unavailable, Please Login Have you put a timing light on it to confirm/deny you aren't losing a bank of ignition? Also, is the warm idle unchanged (i.e., it's still the same as it was when it would rev over 4800 RPM)?
If it occurred gradually, it could very well be muffler or cat breaking down internally/clogging as was suggested earlier. I've worked on cars with mufflers or cats so badly clogged that the engine could only idle - no power available above that.
What happens when the engine reaches 4,800 RPM , is there some sort of a misfire , or lost of power ? This happened to my 3.2 Mondial when the new Bosch Fuel Pump I installed was from a Mercedes 280SE . Idling and power was perfect but when it reach 5000 RPM misfiring and lost of power . When I installed the proper Bosch fuel pump for the Mondial problem solved .
I had the same problem with both my 208 turbo: it happened around 5500 rpm in one and around 5000 rpm in the other. Solved with a full service to the Bosch fuel distributor: I was told that the membrane there is inside makes a frequency resonance due to age hardening. Both happened when they were around 33-34 years old It was like hitting the a rev limiter Ciao
No high speed idle is likely an AAV stuck closed. You can loosen it up by spraying a lubricant inside, and work the valve back and forth with a screwdriver. This would not cause the lack of revs problem. I would check for proper fuel pressures there.