Not Starting

[925benjie]

Recently removed and cleaned maf sensor, icv(idle control valve), egr and throttle body on a '92 es300 due to sluggish idle. After i put them all back together, i attempted to start the car with no luck. Recheck all connections to make sure but the car would not start. The only way the car would start is if i unplug the maf sensor connector but only for a few seconds and it dies. Tried to plug it back while it idled but it shuts down as soon as i plug the connector. Anyway of testing the maf sensor if it's good or need replacement? Looking for any feedback. Thanks.

[landar]

Yes, there is a method of testing the "maf" (it is actually a "vaf" in your '92...Vane Air Flow). The solder connections inside my vaf were loose and I had to resolder them. I think I have the shop manual for your car if its a 92 ES300. Are you getting any codes at all?

Here is a tutorial on how it works, in general. -> http://www.autoshop101.com/forms/h34.pdf

[925benjie]

No codes at all. Just doing some routine cleaning because of the idle when this thing happened. Anyway, I removed all the parts from the air filter to the throttle body again and will attempt to put them back probably this weekend. Thanks for sending me the tutorial, very informative. I will look into the vaf sensor a bit more this weekend probably take it apart or so. Will post an update when i get to it.

[landar]

Apparently those solder connections inside the MAF/VAF are very sensitive and we just pulled the external connector and yet (somehow) managed to pull the inside solder loose. Must be the age of the part. 20 years.

[925benjie]

Great news! I put everything back together this past Sunday afternoon except the vaf/maf sensor so i could take a closer look. I did a visual and component check and noticed that the measuring plate was stucked in closed position. Tried to push it with my finger from the air filter side area with a slight pressure but no movement. I went back to check the diagram from the tutorial that Landar sent me and how it should work and that the measuring plate should move with a slight force so air can flow thru the intake. Tried to push it again with a little bit more pressure this time and the darn thing opened. For some reason the return spring that controls the opening and closing of the measuring plate did'nt work. Took it all apart except the circuit part (connector) and cleaned them with a can of CRC maf sensor cleaner and paying more attention to the plate area and put them back together. Pushed the measuring plate again to make sure it opens and closes like it should. Also, checked the electrical connection and soldered parts to make sure. Installed the part and got the car started immediately the first time. Because of the measuring plate stucked in the closed position, there was no intake air flowing through the system so signal to the ecm was affected including the fuel pump and injectors.

[landar]

Yep, a stuck plate (vane) will do it. You did a very good job of troubleshooting and fixing. And you saved yourself a bundle.

[925benjie]

I thought about changing the whole vaf/maf assembly by shopping on eBay but decided to work on it with the help of the tutorial you sent me. Thanks again.