random 3000rpm rev limiter

[legonutter]

the engine in my merc is a 2001 2.7 cdi 5pot and at random times after start up it engages a 3000rpm limiter without even throwing a code? is this a boost or maf sensor issue?

 

[carat 3.6]

Are you sure there are no fault codes stored?

 

[bob6600]

What are you reading the codes with? It does sound like the MAF but guesswork without codes or further inspection. Needs STAR session to prevent throwing parts at it. Check BlackC55s sticky for what to check

 

[legonutter]

No codes stored and it resets to normal if you turn it off and on again

 

[whitenemesis]

What code reader are you using?

Is the 3000 rev limit in all gears?

 

[legonutter]

i havent had a chance to plug her in yet but nothing is coming up on the dash and res its in all gears

 

[carat 3.6]

i havent had a chance to plug her in yet but nothing is coming up on the dash and res its in all gears

Even though the engine management light isn't on, it will still store fault codes in the ecu.

 

[legonutter]

Thanks I am getting it plugged in on Saturday

 

[edtzxr]

Sorry just a random thought the rev limit is when the car is moving? I know that mercs will not rev over 3000 when stationary

 

[bob6600]

Sorry just a random thought the rev limit is when the car is moving? I know that mercs will not rev over 3000 when stationary

Mine does, infact there is a STAR test that requires the car to be revved and held at around 3500 rpm

 

[carat 3.6]

The rev limit when not moving is 4000rpm, it wont be that. 3000rpm is the limp mode.