153 to 173 ECU

[jlevie]

Use carb spray like the old days. Smoke testing is for late model 2000-up models.

Carb cleaner or similar will work on leaks close to the head, provided that you can wet the entire surface where a leak can be. And the leak has to be fairly large to suck in enough of the fluid to noticeably change the engine speed. In other words you have to hit a fairly large leak directly with the spray. So big leaks at the injectors, breather hose fittings , top part of the intake manifold gaskets, top part of the throttle body gasket, or brake booster fittings can be found with spray. But that isn't even half of the possible leak locations. And since several small leaks (which you can't detect with spray) add up to a major leak, you need a test that can find every leak, regardless of where it is or how big it is. Which means a smoke test. If a pro has access to a smoke machine (and the good pros do) you will never see them try to check for leaks with carb cleaner.

Every E30 that I have ever checked with a smoke machine has had at least one leak, somewhere.