Clogged Catalytics

[GraybeardAv]

GM cars of a dozen years ago had TBI, Throttle Body Injection. May still have, AFAIK. Instead of an injector at each cylinder intake, it has a single injector in the throttle body, curiously enought. The earliest EFI, on VW & Mercedes, had a throttle valve, and injectors on each intake. Fuel flow was controlled by a manifold pressure sensor that was a variable inductor. It was good, but the MP sensor was expensive.

Later EFI, about 1974-84, had a large vane that was moved by airflow through the throttle valve, and that was called AFC, Air Flow Controlled injection. It uses the same injectors as the MPC. In fact, the injectors in use today are almost identical to the ones on the 1966 VW.

Whenever an AFC equipped engine would backfire, it would damage the airflow sensor, souring customers and delighting mechanics.

As you know, the Mass Air Flow sensor upstream of the throttle valve is a hot wire that measures by the cooling effect of the air flow. That thing is very sensitive, and will cause grief when it gets dirty or contaminated. CRC now sells a special cleaner spray for MAF sensors. It leaves no residue. It didn't seem to help with my P171/P174 codes that came on at the same time, indicating a MAF problem. I'm in Illinois right now, and state law won't places like Autozone clear the codes.

If you opened the intake and squirted throttle body cleaner downstream of the MAF, then no harm should have come to it.

Did you look inside your cats when you got them out, or did the shop give you an "exchange price" for them?

GB

[mark v]

My owners manual said 87 Octane.

[BryanF]

the motors in a windstar do have a throttle body, but not throttle body injection . i believe it is tuned port injection (TBI), where each cylinder has it's own fuel injector where fuel is injected into the intake port of each cylinder. as opposed to throttle body injection, where fuel is injected into the throttle body by a single injector, to be dispersed evenly into each cylinder from there.

[midnight rumbler]

I do appologize, I meant 87 octane not 89, not sure where my head was at.

And yes, I know the GM Vehicles had two injectors in most if not all of the 305 and 350 motors as I have had both.

As for the cats, I kept the system and the mesh screen appears to be fine.

I do not spray the mass air with anything but the special cleaner for this due to the sesitivity of these units, always spray throttle body cleaner in any throttle body as they gum up after awhile

The van appears to have more power after the initial swap of the new cats.

Not sure yet if this is the fix or solution to the problem

[mark v]

What special cleaner are you cleaning the Mass Air with?

I have never ever cleaned any Mass Air in any Vehicle I have ever owned.

Some Ford Throttle Body's are coated and can be permanently damaged if cleaned, I always just wipe mine out. They also rarely need to be cleaned.

Sounds like you are doing maintenance on things that dont need to be maintained as much as you think. Who told you to maintain these parts as much as you do?

FYI my Windstar has 119,000 on the original Mass Air and has never been cleaned, My Throttle Body was cleaned once and I just wiped it out.

[microsfoftxpuser21]

best to use 87 all the time and 89 once every 3 months or evey time u do an oil change to help with matience u should read wut i have in all data very helpful

[mark v]

It is never a good idea to use a different grade of fuel. Every 3 months or so run 1 bottle of Fuel Injector Cleaner if necessary, I do this about 1 time a year.