Brakes Question

AlfaRomeo1750 · #1 (**permalink**) 06-29-2009, 03:35 PM

Hey Guys,

This morning my 164S's brake pedal felt normal but tonight when I drove home the pedal felt hard as a brick. The car stopped fine...but I am wondering what has come up. Thanks in advance ...Martin

**Alfisto Steve** · #2 (**permalink**) 06-29-2009, 05:26 PM

Be sure you don't have a hot brake(s) such as a L/R and R/F or R/R and L/F.

Usually if pedal does not move much master cylinder is the issue.

If really hard like no boost then maybe booster not working.

AlfaRomeo1750 · #3 (**permalink**) 06-30-2009, 11:35 AM

Steve,

Thanks for the reply... When I got in this morning I put my foot on the brake pedal, started the car and it barely softened up. So I am thinking perhaps that the brake booster is on its way out. Is there any other way to "Test" the booster or service checks to perform? I would hate to buy a new one, go through all the "PAINFUL" troubles of installing it .. and have that not be the problem.

ALSO,

While this is unrelated to the brake issue, I didnt want to start another post since I would ask you this question any way.

For a while now, I had been posting about intermittent stalling problems. I checked the fuel lines for leaks (Even in the trunk). I jumped the fuel pump relay and the car started normally. Full tank, empty tank didnt make any difference. So I am pretty sure that the issue is not in the tank or fuel delivery.

In the intervening weeks, I have been giving serious consideration to the idle control valve since on occasion the car's idle will "Race".

If I take the car on LONG drives I will have problem free driving for several weeks. However I have noticed that if I just use the car locally (4 mile drives or less) for several days I will start to have this low idle/stalling problem.

Last night I went out to run some errands after work and decided to take the 164 since the spider was already under cover. When I got back home, pulling into the driveway the car started to idle poorly and "Tried" to stall a few times but never did.

I went under the hood, disconnected the Idle control valve to see if there was any change. Simply put the car ran just the same with the ICV disconnected as with it connected.

HOWEVER, with the ICV connected and the Throttle position switch disconnected the idle raised to 1100 where it was previously around 500-600-ish. The idle was so low as not to even register on the gauge.

Plugging back in the TPS caused the idle to again drop. When I turned off the car and checked the switch for the signature "Click"... everything looked good. Within 1-2mm the switch clicked as I moved the throttle by hand.

Is there any way to test the TPS or ICV to see which is the culprit.. Do you think in your experience that I am on the right track? I mean the car at speed runs well, gives me little problems after long distance drives.

The only reason I think this may also be the ICV is because as I thought about it, this problem started just after I changed the spark plugs and had to remove the ICV to get my "Non Factory" tool back behind the rear bank.

Thanks in advance for your thoughts.

Cheers
Martin.

**ChazzyD** · #4 (**permalink**) 06-30-2009, 01:33 PM

It does sound to me like your IAC (or ICV if you prefer) valve is not working. I would clean up the contacts with Deox-it (or is it De-oxit?) and then do the same with all the injector connections. Worked miracles for such problems with my car. After doing that to mine, it has been running better than ever without stumbles, hesitations, etc. like I had before. I would also make sure the connectors are not getting pushed back into the connector when you plug them in and not making contact. To test the TPS (assuming it is already adjusted to click just right at closing): with the butterfly closed, between the bottom terminal and the middle terminal, you should get 0 ohm. Slowly rotating the throttle, using the same terminals, the reading should go to infinite before the butterfly has rotated for less than 1 degree from closed. You should get 0 ohms at full throttle using the top terminal and the middle one.
Charles

**Alfisto Steve** · #5 (**permalink**) 06-30-2009, 01:42 PM

Inspect inside IAC to be sure rotary vane rotates freely and is not binding. Spray clean with some carb cleaner if gummed up or binding. Do not try to open any farther by trying to increase small air gap in vane with power off. It opens completely the opposite way so roll vane and close that small gap to expose wider gap on other side.

With connector on turn key on and see vane move too.

Be sure wire terminals in connector not broken or unlocked.

**ChazzyD** · #6 (**permalink**) 06-30-2009, 01:45 PM

I would check the booster check valve and the hard plastic hose that goes up to the back of the intake, could actually be related to your idle problem. Check for air leaks in the hose (splits). You can pull the check valve out of the booster and check to see that it works as a one-way valve. Check that you have vacuum at the valve with engine running, you may need a helper to start the car while you plug it with your hand and check for vacuum.
Charles

AlfaRomeo1750 · #7 (**permalink**) 07-02-2009, 12:25 PM

Thanks for the replies guys... I will pull the ICV and let it soak in cleaner this weekend or early next week as time allows. How much of a headache am I in for with a brake booster ... I.e. getting it out.. and a new one in with as little bleeding as possible.

Cheers
Martin.

**Alfisto Steve** · #8 (**permalink**) 07-02-2009, 05:13 PM

NO NO NO don't soak it just spray some carb cleaner inside it and check rotary van for free movement and snappy spring snap back.

AlfaRomeo1750 · #9 (**permalink**) 07-02-2009, 06:01 PM

Steve, What you said ... okay.. no soaking... just carb spray...

AlfaRomeo1750 · #10 (**permalink**) 07-04-2009, 11:38 AM

1) Okay... so I am reasonably sure that the booster is going out because I had good soft/normal pedal pressure for a while this morning then all of the sudden it was hard as a brick again... so now the task will be how much of a pain in the A$$ will this thing be to swap out. Plus the fact that I pulled one of the vacuum hoses and almost got sucked into the engine when I put my finger over the hole to keep pressure.

2) As above I ranted about the ICV/TPS. Does any one out there know the relationship between the ICV and TPS. With the TPS unplugged, does it signal the ecu to think that I have a closed or open throttle?

Also, when the TPS is connected, and I open the throttle plate what effect does that have on the ICV vane? I am trying to understand the system a little better so that I know what part to target first on Tuesday.

Cheers
Martin.

PS. Happy 4th!