I did a smoke leak test on my d15b1 DPFI recently and found it has a vacuum leak at the throttle body just under the throttle position sensor. I replaced the throttle body base gasket and throttle body O-ring. Bolted it all back together and it is still leaking at that exact same spot. I took it down to a shop and they used some hondabond but it didn't fix the leak either. Now they are telling me I may need a new throttle body & intake manifold because the original ones may have warped mating surfaces. Has anyone else had this same problem and were you ever able to fix it? This is driving me crazy.

Thanks!

 

Nobody, eh?

 

What does a throttle body leak do? In my 89 hatch, I don't seem to have the power I used to have and though it was a problem with the air supply.

 

I didn't realize it was leaking at the TB until I got it smogged and the numbers were out of control. The car drives the same, but apparently it is running very lean because of the leak.

 

i ended up using exhaust sealant (the goop stuff that comes in a tube) and it worked wonders.

 

I have problems with vacum too. Well, i think i have...

Well, if i am pushing the brake pedal, the revs get around 1100, and than lower itself o 600, and than go up again to a 950. The sound of motor is very noisy. Motor doesent drink oil, no signs for mixing water/oil etc., IACV cleaned, throtle butterfly cleaned, new sparks, new spark cable, new radiator. D15B2 dual point

http://youtu.be/a4aG3KRAd9U http://youtu.be/ElGD34hVQuk



Those lines are from LPG instalation which isnt in use right now, it is completly closed till i fix this problem, computer has been reset.

 

with the engine running, you can spray some brake cleaner or parts wash around where you think its leaking, this should cause a noticeable change in idle. I've heard of vacuum leaks developing from the butterfly valve pivot points where they are set in the tbody housing, over time movement of the valve will wear the holes to the point where air can enter. i had a similar issue on my 88 but never found the actual cause; have since converted to mpfi. best decision ever. as for rpm drop when pressing the brake pedal, the power brake booster is ran off engine vacuum, this is not abnormal unless rpm drop is severe, in which case you may have a leaking booster diaphragm

 

I heard for that way of finding a leak. Will do it next week, and see what happens.

About rpm drop.. it is a self boosting rpm, after i stop the car, rpm goes from 750 to 1000-1050, and after 1050(lets say 1050) it immediately goes to 600 - and again goes high up to the point of falling to 600. It is a loop error. Hitting a brake it bounces fast above 1050 and falls to the lowest point. Brake is in some connection with that. I will clean IACV again next week, (FITV doesent exist on 1990 d15b2 dual point?), and try the brake cleaner method.

About diaphragm, if i pump the brake few times i can hear squeek sound of air somewhere below the pedal. ??

THX btw, sry for engl., i suck

 

your idle control valve might be no good also. to rule it out you can take the cover off the air plenum (black cover over tbody that says pgm-fi) and plug the hole going to the idle valve with a bolt or something, this will completely cut out the idle valve all together and keep the idle from loping. with this method it will take longer to warm up to temp. I ran mine like this for years. a bit of air noise from the brake booster is normal