Air pump and missing idle

[Mr_7]

hello just picked up my new fd today woohoo!

any way im just woindering what the air pump does it doesnt seem to be connected to anything and has a pipe next to it that above the air filters. it has twin hks filters, and on the end of this pipe next to it that runs to the back of the engine its has a hks little thing?

i ask as it has a horrible lumpy idle that seems to go when revved but wont boost any help please

i have piks but cant post them sos

[Jit]

the airpump doesnt do anything above 2500rpm....as i understand it, its there for emissions purposes and so shouldntt upset the idle?

The boost probelm culd be any number of things....do you have a boost gauge? Ive got a boost problem which i just cant shake off...it doesnt boost fully....

[Mr_7]

yes i do have boost guage fitted it seems to want to  at bout 2 k it builds to .5bar then  instantly creeps down to zero.

the air pump is on a clutch which seems ti disengauge at 2.5k does this mean that if i connect it back up into a loop system the idle might settle or will that do damage

[Jit]

connecting the airpump back up and seeing if it does anything wont do any damage....

So what youre saying with the boost is that it goes up to 0.5...and then slowly down....that sounds like less than 8psi...i read somewhere that if the first trubo doesnt acheiev 8psi, the second one wont come online....
Sounds like an odd problem tho...

[mrfitz]

The air pump is functioning correctly.

[Mr_7]

ok so the pump is working correctly eg it disengages at 2.5k but does any one else have this system open i mean not going any where should this be connected to a pipe that goes on the left back of the engine.

ok so how can i tell what turbo it is and also what would cause this

[TRex]

Why did you buy a car thats obviously not working correctly? :confused:

[Mr_7]

i bought it as i had it at a great price and i bought it as a non runner which is now running! i also have intentions of rebuilding it as im a technician by trade.

i just thought that as mercedes does not do wankel engines i thought i would ask some polite helpful people before jumping in at the deep end

[BlitzBoy]

Does it still have the cat?

[stuart wizy]

lumpy idle could be an air leak in any of your vacum pipes, a tiny air leak can cause uneven idle, check for leak from plenum to map sensor which is situated on the  bulkhead. also check that any  pipes havent popped of any of the check valves.(check valves are the green and white straight conectors on vac pipes)
Sometimes the map sensor can get clogged up with oil and give false readings if its a high mileage motor, mine did it on my last fd on tickover and it turned out to be loose wire and an iffy  pipe on map sensor.
Failing that do compression test.
If u have a boost gauge does it fluctuate on tickover or does it stay stable?

[Mr_7]

thanks very much guys yes iy still has a cat, il check for leaks today and the sensors il also do a compression test and post up the results later. not sure on the boost fluctuacting front il have a good poke round today