Topic 'Re: Engine stalling when Brake Booster line disconnected' in forum 'Automotive' - dslreports.com

Re: Engine stalling when Brake Booster line disconnected

Thu, 30 Aug 2012 10:02:46 EDT

cdru posted :

I do this on my Jeep every 3,000 miles.

You do a Seafoam treatment every 3000 miles? Good grief. Why not fix the problem instead of treating a symptom?

Re: Engine stalling when Brake Booster line disconnected

Tue, 28 Aug 2012 11:02:52 EDT

annoyingrob posted : Just for clarification, there are two methods for measuring air on fuel injected vehicles. Mass airflow sensors (MAFs), and Manifold absolute pressure sensors (MAPs).

A MAF based engine will run poorly with a large vacuum leak as the engine is sucking in un-metered air. The motor will run leaner and can die out.

A MAP based engine will run just fine, only faster with a large vacuum leak. The MAP sensor is located in the intake manifold and measures the manifold pressure. A vacuum leak into the intake manifold just increases the intake pressure which the ECU will read and compensate for. Because you're bypassing the throttle and injecting air in after, it revs higher, it's just like pressing the gas a little.

That's where the discrepancy between online instructions are coming from, where some say it will run worse, others say it will run better.

Re: Engine stalling when Brake Booster line disconnected

Fri, 17 Aug 2012 10:11:17 EDT

alkizmo posted :

said by MooJohn:

On cars with a mass airflow sensor, it may run better if you disconnect the sensor.

That worked! It was so easy and simple.

But I have a vacuum leak at fuel injector #3 so I'm not going to do the seafoam treatment until I fix this :(

Re: Engine stalling when Brake Booster line disconnected

Sun, 12 Aug 2012 17:42:43 EDT

alkizmo posted :

said by Beezel:

Wouldn't the Sea Foam spray be better suited for this than trying to pour liquid?

The spray and liquid can be used together.

I spray the throttle body through the air intake boot and soak the intake valves and cylinder tops with the liquid through the vac line.

Re: Engine stalling when Brake Booster line disconnected

Sat, 11 Aug 2012 23:15:11 EDT

MooJohn posted : Nah, it's easier to let the hose sip a little at a time from the bottle. The spray would be too diluted.

Most Dodge/Chrysler products have a MAP (pressure) sensor and not mass airflow. That makes it easier for them to keep running when the hose has been removed.
--
John M - Cranky network guy

Re: Engine stalling when Brake Booster line disconnected

Sat, 11 Aug 2012 22:20:11 EDT

Beezel posted : Wouldn't the Sea Foam spray be better suited for this than trying to pour liquid?

Re: Engine stalling when Brake Booster line disconnected

Sat, 11 Aug 2012 22:11:23 EDT

Network Guy posted : I do this on my Jeep every 3,000 miles. The engine revs up, not down, when I disconnect the brake booster line. As I slowly pour in the Seafoam the engine will try to die to which I either rev it using the throttle or I'll back off the Seafoam.

Re: Engine stalling when Brake Booster line disconnected

Fri, 10 Aug 2012 22:40:39 EDT

alkizmo posted :

said by MooJohn:

It's tough to keep the engine running with such a large vacuum leak. Keep a finger over the line so it isn't losing so much vac.

Then tip the can of Seafoam into the line ever so slightly. You want it to sip in the liquid, not gulp it. Make sure it pulls in far more air than liquid.

On cars with a mass airflow sensor, it may run better if you disconnect the sensor. The car will then run on a set of known tables that may keep it idling better while you do the job. This can set a CEL which should go away when the sensor is re-connected when you're done.

Okay so it is normal.

Your tips are good, but my dad's ever so retired that he loves to have an excuse to hang out and do guy things :p

Fingering a hole while sipping juices sounds tricky (And oh so wrong out of context).

Thanks for reassuring me I didn't have an already existing major vacuum leak that when combined with the brake booster leak made it stall.

Cars are sure fun!

Re: Engine stalling when Brake Booster line disconnected

Fri, 10 Aug 2012 22:27:22 EDT

MooJohn posted : It's tough to keep the engine running with such a large vacuum leak. Keep a finger over the line so it isn't losing so much vac.

Then tip the can of Seafoam into the line ever so slightly. You want it to sip in the liquid, not gulp it. Make sure it pulls in far more air than liquid.

On cars with a mass airflow sensor, it may run better if you disconnect the sensor. The car will then run on a set of known tables that may keep it idling better while you do the job. This can set a CEL which should go away when the sensor is re-connected when you're done.
--
John M - Cranky network guy

Engine stalling when Brake Booster line disconnected

Fri, 10 Aug 2012 21:37:30 EDT

alkizmo posted : So I was following the instructions from Seamfoam's website
»www.seafoamsales.com/how-to-use-···ent.html
See - Cleaning Deposits - Fuel Injected Engines

That guide, nor MANY other guides on that technique, mention needing someone to keep the car alive.

Basically at start up the RPMs jump as usual but plummet back to zero.

I tried putting something to hold the gas pedal down for stay around 2000RPM, but no matter what, the engine WILL stall after holding the RPM for a couple of seconds. The gas pedal needs a new nudge every few seconds.

That's not normal as far as I "understand". In fact, one guide said that the RPM would INCREASE when that vacuum line is disconnected.

Again, this is another of my threads with a symptom to inquire as to what's wrong ;)

////// And now to call my father to ask for assistance tomorrow night on: "Seafoaming a 12 years old 120k miles car - Attempt #2"