Honda D Series Forum banner

1 - 11 of 11 Posts

·
Registered
Joined
·
5 Posts
Discussion Starter #1
Okay guys, so I have a 1999 Honda Civic D16Y7 1.6L NA 5 Speed Manual -
HUNDREDS of dollars later and I am still chasing this problem. I really need someone smart on this one. I have an idle issue that I just can’t figure out whatsoever. I start the car and it idles good then it travels up and down right after you give it gas. The only check engine light is for an oxygen sensor due to the aftermarket exhaust. Sensor 1 Bank 2.

I have replaced:
Idle air control valve. (Brand new)
Radiator (Brand new)
Flushed and bled the cooling system after a good pressure test.
New plugs, wires, cap, and rotor.
New intake manifold gasket.
New OEM fuel injectors.
New MAP Sensor. [Brand new]
New TPS. [Brand new]
New fuel filter.
New coolant/vacuum lines.
New tight good clamps everywhere.
Tried a different throttle body from a junkyard no fix with oem sensors.
Sprayed the entire engine down for a vacuum leak several times, nothing.
Tried another ecu from a d16y7.
Seafoamed/cleaned the manifold off the car.
New throttlebody gasket.
Proper coolant mixtures.
Torqued every exterior bolt to spec.

I am STUMPED and my mechanic is as well. Any help would be greatly appreciated. I absolutely love this car and would love to give it the attention it deserves if I can get it running right enough to drive
 

·
BATSLOMAN GIVES NO FUCKS.
Joined
·
4,403 Posts
"problem with a crank sensor breaking down, the sensor would behave normally when the engine was cold but once the engine got hot the sensor began breaking down under load and causing many of the symptoms you describe. This was overlooked by many mechanics as the engine ECU had not identified the sensor as bad, and after all how could the car run with a bad sensor right? Once it was put on a scope with the engine hot the sensor break down was obvious. Not sure if your crank sensor is inductive pulse or hall effect but if you can get it scoped or even just swap it for a known good one then at least its ruled out. At this point you need the help of a decent tech with good test equipment as all the best will in the world from us is no match for good face to car diagnostics guy that knows his stuff! ?"

source
 

·
Registered
93 Civic HB SI
Joined
·
724 Posts
The world needs more oscilloscopes :)

This is a clip from another thread I replied to, he was having similar symptoms as you describe. He cleaned his IAC and FITV, and readjusted this screw and his idle issue was fixed. You'd be surprised at how many technicians don't know about this bleed air control screw:

"2. Try lowering metered air by adjusting the TB bleed air screw, this one:



Your TB may or may not have a cap over this screw, hiding it. Turning it in closes the bleed air passage, loosening it opens it. Try turning it in a bit and see if surge stops. Go slowly, no more than 1/4 turn at a time, then blip the throttle valve and let the engine come down to idle. See if it still surges. Keep going and trying again to see if you can control the idle. If you end up bottoming out the screw or are past 2 full turns and you are still surging, check the FITV and IAC components and/or additional uncommon vacuum leaks."

Has your mechanic, just for shits and giggles attempted to clamp off the brake booster vacuum line? I've had brake boosters leak vacuum from inside the car. Spraying around the intake and engine bay does not show this leak, but pinching the booster hose with a pair of needle nose vice grips or hose clamp pliers can identify if this is an issue.

Here is a link to that thread, as I included other pieces of diagnostic areas your mechanic may not have tried yet:


The D16Y7 TB bleed screw looks like this:

20200311_230001.jpg


It may be under a small metal cap, kinda like a mini freeze plug. Just pop that cap out with a screwdriver and light tapping from a hammer, and the cap will come off.
 

·
Registered
Joined
·
5 Posts
Discussion Starter #4
"problem with a crank sensor breaking down, the sensor would behave normally when the engine was cold but once the engine got hot the sensor began breaking down under load and causing many of the symptoms you describe. This was overlooked by many mechanics as the engine ECU had not identified the sensor as bad, and after all how could the car run with a bad sensor right? Once it was put on a scope with the engine hot the sensor break down was obvious. Not sure if your crank sensor is inductive pulse or hall effect but if you can get it scoped or even just swap it for a known good one then at least its ruled out. At this point you need the help of a decent tech with good test equipment as all the best will in the world from us is no match for good face to car diagnostics guy that knows his stuff! ?"

source
I shall give this a try! Fortunately enough I work at a parts store so I will replace the crankshaft position sensor as soon as possible. I have played with the idle screw on top of the throttle body with no luck as well. I did forget to mention that in my original post. Thank you guys for being so nice and inviting. I’m happy I have joined this forum. ?☺?
 

·
Registered
Joined
·
5 Posts
Discussion Starter #6
UPDATE:

I went through and retightened my intake manifold bolts. While spraying brake clean I noticed an idle change at the center of the gasket where there is a channel with an Allen screw behind it? Tightening the bolts stoped this leak. I did not notice a major change with the issue. I kept spraying and right above the iac it seems to change as well? I put a new rubber gasket and torqued the 4 bolts down when I put on the new IAC. Still stumped. Tried a distributor from a junk car too. (D16y7) still having the same issue. Crimped off the booster, noticed no difference aswell.
 

·
Registered
93 Civic HB SI
Joined
·
724 Posts
Well, IAC can only supply the engine with air allowed through the hole in the throttle body right above the throttle plate.

With the engine at idle, stick your finger/thumb over this hole to try and stop the air flow.

If the car dies, you probably don't have a serious vacuum leak, and IAC should be capable of correcting for such a small leak if it did exist.

If the car DOES NOT die when you plug that hole, then you have a vacuum leak significant enough to keep the car running, it's getting air from somewhere.
 

·
Registered
Joined
·
5 Posts
Discussion Starter #8
Drtalon123,

I plugged the IAC hole while it was surging with my finger it brought the car down to a nice steady idle but would not die. Would it be a good idea to keep this whole plugged while I have someone spray around the tb?
 

·
Registered
93 Civic HB SI
Joined
·
724 Posts
Drtalon123,

I plugged the IAC hole while it was surging with my finger it brought the car down to a nice steady idle but would not die. Would it be a good idea to keep this whole plugged while I have someone spray around the tb?
Yup, sounds like a plan. Your on the right track. Can you confirm you still have the stock D16Y7 intake manifold and throttle body?

If you do, then you have no FITV (Fast Idle Thermo Valve), so you don't have to worry about that supplying air to the intake.

If you plugging that hole didn't kill the car, then also try putting your entire hand over the TB opening and sealing it shut. I'm curious if the TB dead stop adjustment could be out and your leaking air past the throttle butterfly valve? If doing this kills the car, then you will need to adjust the dead stop.

If the car still runs with TB completely closed off, its obviously getting the air it needs to run from somewhere! You'll find it soon enough :)
 

·
Registered
93 Civic HB SI
Joined
·
724 Posts
Also, I know you've said you brought it to a shop for diagnostics. Did they ever at any time try smoking the intake with an EVAP leak detection smoke machine?

Every reputable shop will have one of these tools, and they are incredibly powerful tools when it comes to allowing for visual locating of intake/exhaust leaks.

The base line procedure to properly smoke an intake is to cap the TB off entirely, then feed the smoke machine through an intake vacuum port and let it fill with smoke and the regulated air pressure it passes in. ANYTHING that leaks will leak wispy white smoke that is highly visible in most cases, its then up to you to determine if the area leaking SHOULD be leaking or sealed. Just FYI, it is normal to have small leakage around the throttle body shaft, this is unavoidable. For best leak inspection environment, the air around the car does need to be very calm for the smoke to stay visible. Flashlights and/or UV inspection lights and goggles are your friend here :)
 

·
Registered
Joined
·
5 Posts
Discussion Starter #11
WADA BOOM! We found er boys.

So when I purchased the car it had a high idle (2000) and a check engine light for the throttle position sensor. After purchasing and installing the TPS I could not get it into calibration specs. After finding the plug had a bad connecter many of parts later. (Idiot) I immediately purchased one. I was diagnosing backwards. I had criss-crossed the red and green wire to the wrong parts of the connecter because the new connector came with black wires. I was in a rush and never got around to re-specing it. I was reading 0.56 closed and 2.00 WOT. (Lmfao) Got the TPS properly calibrated and took her for an hour rip. No idle issues. No surging. No bucking/hesitation. No overheating. I appreciate all the help and knowledge guys. It truly is a blessing to know that good honest people exists on these forums. Now that I feel like I have essentially fixed everything that wasn’t wrong hopefully we shall get a good life from this d16y7. ? You win some, and you lose some but I still ultimately feel like I won. As for my “mechanic” he gave an honest effort, but maybe Honda’s aren’t his cup of tea. Needless to say, we will stick to the forums before seeing him again.
135966
 
1 - 11 of 11 Posts
Top