My 1990 Honda Accord finally gave up with 430,000 plus miles on it(or I gave up on it) it still runs well but too many other problems to consider repairing. So I bought another 1994 Accord EX,
I usually do all my own repairs and maintenance on my vehicles but after reading up on the VTEC engine, I am worried that the problem I am having may be more than a simple tune up or timing adjustment.

It seems to struggle when accellerating. and when the RPM reach about 3500 it seems to miss and the accelleration becomes sporatic and rough. Then it starts to "ping"
Is this a problem with the VTEC or could it be a simple repair?

Just got back from the test drive after replacing the intakepipe between the air filter housing and the intake manifold. While I was inspecting the car I found a large hole in the pipe that I'm sure was fouling up one of the sensors because of a lack of air pressure/vacuum. Installing a new pipe solved the problem. Now the car accellerates as expected.

I still haven't found a logical place for the vacuum line.

 

I'd check the timing first thing.
Then check the basics, plugs valve adjust, air/fuel filters.

Vtec 101;
http://members.troublecodes.net/hondadude/vtec.jpg

 

OK, I was going over it some more this afternooon and found a vacuum hose that was plugged by placing it over the threaded rod on the battery hold down bracket. I unplugged it while the engine was running and noticed a very slight change in the way the engine idled (not much).
I took the car for a spin and noticed a slight improvement in accelleration. It still pings and it still gets rough at about 3500 RPM. I also noticed that the air duct from the filter housing to the intake manifold is broken. Just before the filter housing the air duct splits off and attaches to a strange looking box via a hose clamp. It is broken at that point. There are several vacuum lines attached to the air duct assembly so I wonder if the overal vehicle performance could be affected by the break in the line (let alone the intake is no longer receiving filtered air...gotta replace it pronto).

 

Check and set timing as Hondadude suggests as first step.

No EGR flow can cause pinging. Check whether there is a vacuum supply line to EGR or to EGR solenoid valve. Someone may have disabled the EGR system. EGR does not usually cause drivabilty problems so you may have mulitiple problems. Good news is the VTEC is pretty robust. I've never read of anyone having severe problems. It's off when you're at low engine speeds w/ the 94ex so it should not be an issue.

 

Any ideas where that misplaced vacuum line is supposed to go?
I found it attached to the battery hold down bracket. I searched the engine compartment for a missing hose but had no luck.
Thanks for the input. I will check timing.

 

Check where the other end of loose vacuum line is attached and check the vacuum diagram on the hood, or download a vacuum diagram for your model. See following link for a manual. http://www.hondahookup.com/manuals/

good luck

 

If it is near the battery, the air resonator box is a likely culprit for the vacuum line to plug in to. It is that box that you mentioned that the intake is plugged into on the bottom.

You will have to take out the air filter to get the connection, and its a bit of pain to get connected.

 

OK, I checked around the air resonator box, I checked under the filter housing, I even pulled the box off the car but found no connection. I checked the vacuum diagram on one of the suggested shop manual downloads and can see that there is supposed to be a hookup on the resonator box but there isn't one on mine. Is it possible that the PO replaced it with a different box? (I am beginning to suspect that this car was in a wreck).

 

Just got back from the test drive after replacing the intakepipe between the air filter housing and the intake manifold. While I was inspecting the car I found a large hole in the pipe that I'm sure was fouling up one of the sensors because of a lack of air pressure/vacuum. Installing a new pipe solved the problem. Now the car accellerates as expected.

I still haven't found a logical place for the vacuum line.

 

What/where is the other end of vacuum line connected to?

There is an intake control solenoid valve on the pax side firewall that has a vacuum line supply attachment. It also has a departing vacuum line that attaches to a vacuum actuated intake control diaphragm on the air intake duct.

good luck