Vacuum System Effecting The Emissions On 7a-fe Engine.

[Konrad C]

My car struggled to pass the MOT, and with a bit of investigation it seems that the vacuum was not regulating the valves in the inlet port properly.

I inspected the system and the vacuum pipes seem fine. I then disconnected some of the pipes and checked the vacuum actuator on the inlet manifold by hold it in a different position and cover the port with my finger. The actuator held, then returned quickly when I uncovered the port. So far so good. If that had leaked, new manifold!

Next I looked at the vacuum tank. It seemed fine but I just found test procedure which I will try later. I blew into it but to confirm operation I need to blow the other way.

The final item is the vacuum solenoid valve (VSV), but I could remove it. I checked the Haynes manual and there is a removal process so I will try that later along with the vacuum tank.

The car runs well, so if these items are faulty, then hopefully the replacement parts should cure the vacuum issue.

I looked at the MAP sensor and when I unplugged it with the engine running, the engine stopped. Not a good test but at least it works.

Now to source the parts.

[Konrad C]

I have learnt a couple of things since the first post.

I forgot to plug back the throttle position sensor on the throttle housing, and this causing the ECON light not to illuminate. The car drove fine. Plugged back and all is well.

Secondly I may not need to get any of the vacuum parts. I disconnected the vacuum pipe at the inlet actuator, the held the lever against the stop then reconnected the pipe. The lever stayed close to the stop when I released it. Then I started the car and the lever moved against the stop. I shut off the engine and it still against the stop.

The first set of photos with the switch in what may be the wrong position:

The next are after the little fix I did:

I think a long while ago I may have disconnected the vacuum pipe whilst sorting the linkage. You may notice the little clip from speaker fixings to stop the linkage disconnecting. I have seen queries about what position the lever should be in so this may be the answer.

So those with the similar engine, take a look where the control lever is with the engine of and on.

[TAvensisNF]

what is the round cylinder part that is displayed in the photos? I am looking for this part but dont know what it is officially called. TA

[jcps001]

It's a vaccum actuator, I believe. They're not sold separately, they come with the part itself (older turbos, egr, etc.)

[flash22]

That is the lean-burn vacuum valve (controls the flaps in the intake) Toyota list it as part of the manifold, plenty of pics just no one listing the part

edit, you may have to take another part and adapt it to fit

like 17061-46010

https://www.drive2.ru/l/547722543084077357/