Air Intake System rebuild questions
 

Greetings GasSavers!

Just bought a '92 Civic VX and this forum has had invaluable advice for the myriad issues mine seems to have (all-in-all pretty solid but *quirky*)

Armed with Helms, advice from these archives, and a little luck I will be tearing down the entire air intake system to try and eliminate variables.
This will include:
EGR; EACV, IAVC, throttle body, intake manifold, injectors and whatever else I haven't listed that's related. I will be doing mostly cleaning and reconditioning of the existing parts.

While I feel confident I can do this my questions revolve around my lack of *specific* experience in doing any of this.

Helms points out a plethora of gaskets, o-rings and the like that they say should be replaced when doing this work but...

(the real question ;)
...how many of these parts can actually be re-used (assuming they aren't damaged in the process) AND which will I most likely need based on your collective experiences.

I'd like to arm myself with the right repair parts without spending gobs or having to wait for things to be shipped because I overlooked something.

Hope that's a specific enough question. Let me know if I need to clarify.

Thanks in advance!!

What problems are you experiencing? Gaskets can be reused if they are not damaged. O-rings are likely hard and brittle.

Rebuilding the intake manifold is a pretty straight forward ordeal. It's not expensive to get all new o-rings and gaskets fo the intake manifold, so all new ones are the way to go. Usually you can get an upper engine gasket kit from the parts store which contains al the necessary gaskets.

Thanks to you and TomO.

The problems I'm having are like several of the other threads: 1) Miss under light load-NOT subtle i.e. like a bucking goat 2) fast and fluctuating idle 3) general poor fuel economy

I've only had the car a couple weeks so lots yet to investigate and problem solve but I have found a disconnected TPS, crappy and underinflated tires, bad rear camber, heavy rims, wrong spark plugs, misaligned body panels most of which I've fixed and have led to a *reduction*!!!! in fuel economy (43 to 35) Grrr. I've reset the ECU after engine fixes, and it has a new 5 wire O2 (LAF) sensor.

Next on my list is to check timing belt and compression (But it's CCOLD outside -whimper :P

So, I'm suspecting fuel mixture/distribution issues and want to at least eliminate gunked up parts from the equation before throwing new ones at the problem.

Will be investing in a timing light, vacuum gauge, fuel pressure gauge, compression tester. These are all tools I should have had a long time ago anyway.

So, any words of wisdom are welcome particularly about common problems/things to look out for when doing this kind of work. (Helms manual makes it all look so simple but I'm a realist ;)

Cleaning the IACV (Intake Air Control Valve), decarbonizing the motor and cleaning the EGR system (the whole system) can be done without even buying a new gasket for anything with the exception of getting new metal slugs from Honda to replace the slugs removed during the EGR system cleaning.

Are you still throwing any codes (CEL on)?

{1} Good to know. Because I was looking at nearly $60 in gaskets and o-rings with 1/2 of that going to the injectors alone. All those damned little things add up! Looks like I can lose the intake manifold gasket; map sensor o-ring;EACV filter and o-ring; throttle body gasket and EGR gasket?
Well, maybe keep the EACV filter just for good measure.

Would you recommend then, replacing all the seals/o-rings on the injectors regardless? ($32)

{2} That's the damned thing... no CEL. Checked the ECU (correct unit), CEL Light works (ignition on), jumpered ECU with no CEL. Runs better than it did now that the Throttle Angle sensor was hooked up but took a big hit on fuel economy as a result. Still bucks like a goat.

Next step would be to test the TPS (Throttle Position Sensor)
Sorry I didn't have time to do a nice little write up, but I'm in a hurry to get home so I just grabbed something from H-T.

Idle bounce seems to be caused by a vaccum leak most of the time, or a number of very small vaccum leaks, to fix my idle bounce I've adjusted my idle speed by turning it down, replaced the lower PCV hose gromet were it goes in to the oil seperator under the intake manifold, this was hard to do but with a pair of needle nose vise grips and a long screw driver I got the old shrunken stiff one out, and a new one installed.
I checked my injector o-rings, and they all appeared to be soft and fit snug like they should, but if you find them to be loose, then of course replace them.
you can find other vaccum leaks by useing a hose as a stethscope to lisen to each hose and fitting.
I also stoped using 0w30 oil and went thicker and found the my idle bounce is nearly gone.

That's interesting that you mention that. This has something very lightweight and doesn't smell natural (i.e. synthetic -came this way and is clean so didn't change it.)

Do you think too lightweight might be fooling the pressure sensors? or...?

TomO: No worries and thanks! Will be checking this soon.

Welded EGR ports?
 

Well, got the mess unbolted and noticed some interesting things and have a bunch more questions.

The EGR ports are welded shut. Was this normal for a '92 or was this worked on before?

Injectors have black sludge around the outside of the tips (centers look spotless) and they have a very subtle rattle when shaken. Is this normal?

Throttle Angle sensor had a broken gasket. This shouldn't have caused problems should it? Seems like it should only need general sealing from the elements, or...?

EACV and Throttle Body have been worked on before. TB had gasket goop and EACV was too clean.
There is a 4mm hex bolt on the side of the EACV and since is was worked on before, could opening that chamber have caused any problems? Should I check this?

Bottom of EGR Valve is gunked but the diaphram seems good and holds vacuum (sucked on it)

These all seem like really minor issues to me. Could any of these situations cause the 'Bucking Goat Syndrome {tm}' as is being discussed on other threads?

That is normal for the intake manifold for the VX. If you pull off the entire intake manifold and soak the EGR runners in brake cleaner/decarbonizer you can bypass having to remove the plugs, but IMHO it's best to do the work to get the plugs out.
Not sure if the rattle is normal but it is common to have a sludgy buildup around the tips of the injectors, tehy should be cleaned.
Do the bolts holding the TPS on have a groove cut into them or have a regular head on them? If the do, it means the TPS hase been replaced/tampered with. Would be best to fix/replace the gasket and test/adjust the TPS in order to make sure it is working properly.
Get a real gasket for the TB and clean off all the goop.
The chamber should not have been opened for any reasons, but if someone did open it up and screw around it could've potentially ruined the IACV.
Did you see the diaphragm pull up on the rod and pull the pintle out of the way on the bottom of the EGR?
All of these things combined can great an amplified effect of the normal amount of light bucking when the VX switches between lean burn and normal combustion.

Take a look at the attached photo. No plugs to pull -actually welded with blobs of molten aluminum. With the welding spatter, I suspect this was done after the originals got pulled and instead of tapping and risk getting shavings in the IM, they spot welded 'em shut.

I cleaned the IM quite well and it wasn't terribly dirty in the first place, so hopefully not a problem but was curious if this welded issue will cause any problems.


{1} Injectors have been cleaned and look good
{2} The TPS has been removed before, I'll check its functionality after reinstall
{3} TB Gasket already ordered
{4} IACV... I'll reinstall and hope its OK but will put it on the front burner for future problem solving.
{5} EGR seems to be working correctly. The little center plunger moves with the diaphram an seems to have a good seal. New gasket here as well

Thanks for your Help and I'll be posting future updates here. Keeping my fingers crossed this at least helps!!

It's hard to tell from that picture if the blobs over the EGR ports are the originals or done after the fact. But regardless, it seems that you've cleaned things up well enough that it shouldn't be an issue at this point.

Looks like you've got things down very well and are on the way to having a great running VX. Way to go and looking forward to your results!

When you check the TPS, make sure the voltage change between .5 and 4.5 V is smooth. I kinda suspect the TPS has a dead spot... When you hit that spot, the reading would drop and the ECU would go into throttle-closed fuel cut mode. The lurch associated with power suddenly being cut would cause your foot to move the pedal ever so slightly, pushing the TPS out of the dead spot and restoring power. Rinse, repeat.
As for the TPS gasket, it may hold vacuum but I'm not entirely sure.

Update>>>
 

Finally got the parts and got her back up and running.

The improvement is significant! Tho, still a few things to nit-pick about but I'll deal with those after I run a tank and see the effect on FE.

For the benefit of those that may be watching this thread I'll give a list of my problems; what I did; how things changed and what I'd still do if FE doesn't go up noticeably.

Original Problems:
1) Stumble / Miss under load; random miss under light load (cruising speed) a.k.a. Bucking Goat Syndrome
2) Fast idle; Surging idle
3) Poor fuel economy

What I did:
1) Took off the Intake Manifold(IM) and everything attached to it.

2) Tore down all parts and cleaned *thoroughly*-I can't stress this enough; there are a lot of nooks, crannys, ports and such to clean. Tedious but needed. I used solvents, dental picks, cotton swabs, air gun, etc.

Notably the EGR ports on the IM. Mine were welded shut so no way to get to them but to use solvent, air pressure, and a dental pick. Also the EGR pathways on the IM and don't forget the one on the engine block (mine were pretty crudded up on both. Used a dental pick and vacuum cleaner for the block).

Also the TB has several ports (tiny) that need to have free flow.

3) Replaced o-rings and gaskets to everything but manifold air pressure(MAP) sensor, electronic air control valve(EACV) (or IACV, I use these interchangeably), Throttle Angle sensor(TPS), Pressure regulator, purge solenoid as these looked good or weren't critical for vacuum (the TPS gasket)

Just for clarity I replaced Injector seals, IM gasket, throttle body(TB) gasket, exhaust gas recirculating(EGR) valve gasket, intake air temp thermistor o-ring(TA)[! seems this should stand for 'Throttle Angle' but doesn't. Confusing. Stands for Temperature-Air].

Also replaced any vacuum hoses that even *looked* not new. But really, most of these looked very recently replaced.

4) While the IM was out I also dealt with a coolant leak (new o-rings for connector pipe), put in a 195 deg thermostat, cleaned the 'black box' for the crankcase vent system; the stiff (PVC material I think) hose for the PCV (don'tcha love acronyms!) seemed good as did the PCV 'elbow' so just cleaned those as well.
A new fuel filter and crush washers for fuel line.
> Adjusted Valve Lash - several valves were off.
A general cleaning of the area for easier troubleshooting in the future.
Took a look at timing belt and it looked like it was in the correct position

How things changed (for the better, thankfully):
1) Bucking Goat Syndrome has been virtually eliminated. Left with a vague, nebulous 'bumbling' that could be normal, could be EACV, vacuum issues, could be bad shocks, tires... Guess I'm saying it's subtle, random and not worth pursuing (assuming my FE is good). Trying to describe it better would be to say it's like driving over a cushy soft but pebbly road despite the road being smooth. Sorta gentle random bouncy. Weee! Gotta love adjectives! ;)

2) Throttle response (sans air cleaner) is wonderful. Like a new car. Put the air cleaner system back on and there's a mild lag -seems normal to me tho.

3) Had a surging idle problem after re-assembly (this was very noticeable and rhythmic 200-300 rpm). Did a half-assed job setting idle and nearly right. Idle still sticks around 1000-1100 at times (random) but this was at night with electrical load. Otherwise right in the 600 rpm range. Still need to tweak this.

4) Fuel economy is now 75 mpg! (dreamy *sigh*). Have yet to actually find out how all this helped but if I say it, it will happen! right? right? ;)

Things to pursue/ suspect items, etc:
1) EACV. This was cleaned before by previous owner(s). They could have damaged it. Idle is not perfectly smooth yet and pinching the PCV hose causes a drop in idle. May be faulty, may be fine but will keep an eye on it.

2) TPS. Have yet to measure voltage. Need good Digital Multi-Meter (DMM) and don't really want to cut into insulation to test it. Also don't have test harness to check it by the ECU. Will eliminate this from the variables by putting a new one on ($11 on ebay -on the way) I figured, what the hell. If it works great, if not, no biggie.

3) Timing, compression, vacuum, fuel pressure tests. Tools for testing these things are in the works. Based on throttle response and 'ear' the only area I think could use further exploration is vacuum.

4) O2 Sensor is new (per previous owner) so was not replaced but I looked at it and cleaned off some very mild carbon with a clean, dry toothbrush (Carefully!!!)
Since the car runs well now, I don't suspect this as a problem BUT it does have the 'blue wire issue' that I've read about in other threads. Since I've seen no definitive answers to this issue, I'll assume it to be fine, based on performance.

Some questions about above post
 

Decided to break these off from the above post for clarity...

2 questions:

1) Bad valve lash-
If I understand this correctly, having the clearance too small (tight) will lead to the rocker arm keeping the valve down for too long, yes? How would this affect engine performance?

2) Compression question: The old plugs in the car (ZFR5F-11) looked awesome [but changed them to ZFR4F-11 per forum recommendations]. Based on the fact that they had NO oil fouling or carbon fouling, is it reasonable to assume that compression is probably decent? It's running on something thin like 0w-30w or 5w-30w so it would seem like if rings were worn, I'd get some blow-by. Yes?

Having the clearance too small will result in the valve not closing completely. Putting aside the compression leak that would cause, the valve could overheat and warp or crack. The valves dissipate heat through their seat (the ring where it seals against the head), not the stem (the part that extends up to the spring and rocker). If the valve doesn't close solidly against the seat, it can't dissipate heat.

Excellent. Good to know, thanks! Hopefully there has been no damage. The smallest clearance was in the .003-.004 range on some of the intakes and .005-.006 on the exhaust. Some of the others were off (too much) by almost .004. Not a very good job. While I am new to adjusting valves, I used to do FPI's (first piece inspections), measuring tolerances for manufacturing, so I'm fairly certain I did a good job (hopefully!). Triple checked everything. I pushed down on the back of the rocker to eliminate backlash. This seemed right anyway.