88 Accord LXi, AT, 225K miles. Starts great in the morning, but after about 10 minutes of driving, starts to run rough at idle (stoplights and such). Sometimes, I'm forced to keep idle at about 1200 rpm to keep it from stalling at the light. If it does stall, it won't start for about 30-45 min. Same thing happens if I shut off the motor voluntarily (i.e. getting gas). The engine will turn over, but not start. My gas mileage has been very poor, also.

When it does this, I have confirmed that I'm getting spark at all 4 cylinders by using a timing light on each cylinder. I am confident that I'm getting fuel, as I can smell the gas after several minutes of starting attempts. After waiting for about 30-45 min, the car will start and I'm on my way again.

I will also note that I have a very slow coolant leak (about 1 pint every 6-8 weeks). I haven't noticed any spillage on the ground, but haven't seen any of the common signs of a head gasket problem, like water in the oil or signs of coolant vapor in the exhaust.

I've replaced the following, in this order (yes, I know, diagnose first, then replace, but I'm desperate):

Ignition Module
Fuel Main Relay (the one under the left side of the dash)
Air Control Valve
Fast Idle valve

No luck. I am starting to suspect one or both of the following:

1. Vacuum leak.
2. Head gasket.

My questions:

1. What's a good vacuum leak test? There seems to be about 1/2 mile of vacuum hose under the hood and a visual inspection of the hoses found no leaks, but I'm not confident that I didn't miss something. What's a good test for detecting vacuum leaks?
2. What's a good head gasket test? Every blown head gasket I've had showed the obvious signs. This seems more subtle.


Thanks to all in advance!

 

ok back in the day we seen so many pcv valves fail and would do the symptoms like you described simple test is pinch off the pcv hose you weill be able to see it near the injectors.

 

I have the same problem with my 95 Honda Civic with a D16Y7 motor that I bought for a friend.

I cleaned out the IACV replaced it. It worked fine when I tested it. RPM's didn't bounce around. Next day same ****, I am soo pissed. I suspect I have a vacuum leak as well. Today I bought some Seafoam and poured it through my vacuum line. Let it sit off for like 5 minutes. When I turned it on and revved the car a little bit of white smoke was coming from the throttle body area.

Throttle body, Distrubutor & Cap & Rotor was replaced, Just did a new tune up, spark plugs, wires, filter. Oil change just done NO miles on oil change, oil filter. What the hell!!

Made a thread at the Civic section but no one seems to answer like people at the accord section.

I will subscribe to this as well.

Dude when you are at a stoplight do the RPM's drop to zero and the car shuts off. I have the same issue. I have to feed it to keep it from not dying.

 

Yes, I do. Also slow to accelerate. Idles fine at at stoplight, but turns green, I hit the gas, and it sputters. It's done both.

 

the most accurate way to confirm any h/c's in the cooling system is use a 4 gas and check the cooling system for h/c's. open the rad cap make sure the coolant level is low maybe the level is to the core and then increase the rpm's a bit to get the vapor flowing and look at the machine and see how many h/c's are in the system more then 50 plus is a sign of h/c's .
i didn't see if you checked the system for any dtc's stored i know the distributors in the lxi were known for going bad.


Modified by dtapia at 11:43 AM 10/4/2008

 

What are h/c's, h/dc's, and a 4 gas?

I actually had a mechanic suggest the distributor, but I didn't believe him (thought he was just trying to sell me a distributor). If it is the distributor, wouldn't I not have spark at the cylinders? Can a distributor be faulty and still have spark?


Modified by fbjunkie53 at 12:24 PM 10/4/2008

 

oops i ment h/c's
anyways h/c's are hydro carbons
and the 4 gas is a smog machine or exhaust gas machine if you know someone at a smog or auto shop that has one then that is the way to check.

 

so any update on ur find ?