Mspeedpro

iTrader: (1)

My daily driver is a 1986 Honda CRX. It is not the most immaculate car in the world (needs body work and new paint) but it runs well, killer mpg, has only 150k miles and was inherited from my late grandfather.

First thing I did was totally detail the interior and throw on some seat covers, looks sweet!

Smelt a fuel leak and found a really simple problem, an o-ring at the end of the fuel rail needed replacing. Gas mileage is now 26 mpg city! WOOT WOOT.

My next problem to tackle: rough idle. The car idles EXTREMELY rough when stopped at a light. Fluctuates between 500 and 2500 rpm... The needle literally goes up, down, up, down, up down. If I depress the brake pedal the car adopts an extremely SMOOTH idle just at 1300 rpm.

Vacuum leak? Why does pressing the brake pedal 100% alleviate the idle problems??

Thanks all.

dynamho

Automatic?

Mspeedpro

iTrader: (1)

Nope, 5 spd manual. Sorry thats important data.

Also, its a CRX SI... not as important, just wanted to brag. LOL

rglbegl

86 was still carburated, right? Or was the SI given fuel injection?

If it is Carb . . get a carb rebuild kit. they are cheap and easy to do. It will also help the mpg a tiny bit.

If it is FI ( fuel injected, not forced induction ) get a cleaner.

If depressing the brake smooths it out, either drive with the brake on all the time . . . or it just means that a lttle electrical load make the idle go up. If it has power windows, try to put up the window when it is already up. This will cause about the same electric load as the brake pedal.

Or it is just the emmissions system. start cleaning emmissions parts.

dynamho

I was going to suggest a MAF sensor cleaning, but the brake part confuses me. It seems to be affecting the idle by electrical loading.

XDEEDUBBX

My Daily Driver Is An 88 Automatic Crx..got It At 150k As Well...=)

Mspeedpro

iTrader: (1)

My crx is not carberurated so I assume it is fuel injected.

There are no power windows in the car.

As far as cleaning the fuel injection system or the emission system... are either of these addressing the weird fact that the idle is corrected when i step on the brake pedal? overall the car runs really smooth and drives well, so id rather not start messing with too much needlessly.

Hopefully the issue of the break pedal being depressed is symptomatic of something very specific. Additionally, how hard I press the brake pedal affects the idle. I have to press on it relatively hard for it to smooth the idle out. Beyond this level of pressure, the harder I press on the brake pedal makes the Tach fall lower and lower... until when im REALLY pressing it down hard the idle is steady but too low...

Ring any bells?

scarroll

Sounds like it could be a vacuum related problem, vacuum state being altered by the brake booster being applied...

JB_Rotary

+1 I would start by checking all of the vaccum lines going into and out of the brake booster

Trekk

It sounds like an air leak. I haven't seen the 86 motor in a very long time but I'd say, check and replace every Vac like that is comming off the manifold. Should be very cheap and easy if its anything like the 90+motors. If I remeber correct the brakes have a vacume line that runs to the manifold, but I have no idea what for.

You could also buy or rent a vac tester and just hook it to the motor easy and see if it has consisnt vac. Pepboys used to sell a cheap 1 for like 10$ that was made for a gauge pod. You could also test this with a boost gauge.

scarroll

Check the vacuum lines running to the brake booster for leaks. It could be a leaky booster but I would check all of the usual / cheap suspects first.

Like replacing the pcv valve (3-6 bucks) (I would do this anyway)
Checking the throttle body, intake gaskets

Mspeedpro

iTrader: (1)

Thank you guys, I snagged a manual on the car at half price books for $2 so i will scope it out and take a look. This is my first car to really fiddle around with so I will return within a few days with findings / concerns.

RevTo9K

The 86 SI was, in fact, fuel injected. I had an 86 CRX DX which had what Honda described as a 3-barrel carburetor.

I put like 36,000 miles on that car in the two years I had it. Indestructible. At 111,000 miles the clutch was STARTING to slip.

Good luck with your idle problem.

Trekk

When I was in high school my friend had a crx like that. Another friend and I would sneak out of class and pick up his car and walk it across the parking lot and hide it in another spot. We even took it out and put it on the pitcher mound of the baseball field.
That was funny stuff, those cars are very light.

Mspeedpro

iTrader: (1)

Two people lifted and carried a crx?? Id like to see that!

dynamho

I find that hard to believe. 2 people carrying? Each of you would have to lift more than 1000 lbs. each. The CRX Si is roughly 2175 lbs.