z3 fuel trim 1 and 2

tazmanic

Dedicated Member
British Zeds
Joined
Apr 3, 2025
Points
29
Location
herne bay
Model of Z
2.8
Hi from taz, i have 2000 2.8 z3 intermitent fuel trim 1 and 2 for a while some days nothing others several times a day. didnt like to drive as worried about damage to engine. treated myself to a smoke machine. OMG what a bit of kit. first of big split underside of pipe maf to intake see pic.had a drive a few days later same fault but i would have fuel trim 1 for a few days clear it then fuel trim 2. Then i tried the smoke machine again but into vac system bit awkward. blank on ev valvesplit replaced still fault put smoke through from vacuum pump side came out all over the place. replaced all vac hoses bmw still do a kit but last one is the one that goes into the fuse box never have found these without smoke box only £60 save a lot of money a week no faults sorry to ramble hope it may help some one.
 

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@tazmanic @Neilb62

The hose that runs into the fuse box is so that it can run to the rear of the car alongside the front to rear wiring loom.
If you pull the left side boot trim open you will see the other end of this hose going into a little solenoid thats located there the hose provides a constant vacuum with engine running the solenoid is opened and closed by Ecu to operate the flap on the Exhaust rear silencer.

Stephen.
 
Many thanks i havnt gone beyond the fuse as all is working but odd set up. as we would say in the RAF if it aint broke dont fix it. ive now got a few friends wont there car SMOKED lol see if any leaks certainly cheaper than bmw cheers taz
 
Hi from taz, i have 2000 2.8 z3 intermitent fuel trim 1 and 2 for a while some days nothing others several times a day. didnt like to drive as worried about damage to engine. treated myself to a smoke machine. OMG what a bit of kit. first of big split underside of pipe maf to intake see pic.had a drive a few days later same fault but i would have fuel trim 1 for a few days clear it then fuel trim 2. Then i tried the smoke machine again but into vac system bit awkward. blank on ev valvesplit replaced still fault put smoke through from vacuum pump side came out all over the place. replaced all vac hoses bmw still do a kit but last one is the one that goes into the fuse box never have found these without smoke box only £60 save a lot of money a week no faults sorry to ramble hope it may help some one.
Interesting read. Where did you buy the smoke tester from?
 
Interesting read. Where did you buy the smoke tester from?
here is link more than i thought but so easy to use. i made an extension cable couple of croc clips as z3 battery in boot and wouldn’t reach took just a few mins to set up do test wonder how much bm would charge. you can get specific oil but i used baby oil works bril cheers taz
 
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