Ever since I bought my truck, I have been trying to fix my stumbling idle. I tested all the sensors, checked the codes and even tested all the sensors individuallly. I even went as far as changing some of them (like the O2 Sensor) even though they tested good. In the end, the truck still stumbled at idle.

I had also noticed that the truck would occasionally spit out a cloud of white smoke through the exhaust.


Yesterday, I noticed that the Transmission fluid was WAY low. I put in a quart of Tranny fluid... Still low

Put in another... low... yet another... then it was registering on the dipstick, but still a little low.

So I added a little more....

All of a sudden, I get a HUGE cloud of white smoke coming out of the exhaust. I couldn't believe how much white smoke was coming out of the truck. It filled the entire parking lot (and attracted the attention of everybody in the area )

After some checking, it turns out that the vacuum modulator on my transmission was bad. apparently, the diaphram was punctured and that was causing the vacuum line to the modulator to act like a straw and suck my tranny fluid into the intake Manifold.

I replaced the modulator ($14.00) and flushed out the vacuum line. Now everything works fine and my stumbling idle is gone. Not sure if the stumbling idle was being caused by the engine choking on tranny fluid, or by the vacuum leak of the broken diaphram, but either way, it's fixed.

 

SoFla David,
I haven't seen this happen in years.Thanks for the tip,and reminder.
Huffer

 

What truck and tranny is that on?

 

Man I got excited for a minute and thought my idle would finally be fixed. Lucky me I got a ****in manual. So close yet so FAR!!!!

Al

 

Had the same problem on a B4000 mazda. no smoke just loosing fluid with no visible leak. but lots of oil in vacuum lines

 

'88 F-150 351W C6 tranny


It was in my sig, but it looks like the sigs are gone?