cfahamilton

97 Civic Hatchback, D16Y7 engine (I also have an identical 98 model that I have been swapping parts from to help diagnose the problem.)

I know that the more info you have the easier it is to help me so I hope you’ll bear with me. It’s a long story so I’ll start at the beginning.

The first trouble was a sudden stall while traveling on the freeway (it may have happened when I had the clutch in to shift gears). After coasting to a stop the car would not restart. I popped the hood and the engine felt very hot. I hadn’t noticed the temp gauge being too high before, but it seemed like it had overheated. I got back in and turned the key and the needle went well above normal. About an hour later, when it had cooled, I opened the radiator and found the coolant at normal level. I drove home on surface streets keeping a close eye on the temp gauge. About 5 miles in it started stalling again when I had the clutch in coming to a stop. The temp needle was at the normal warm position and it would restart easily but wouldn’t stay running. I parked in the shade for about 40 minutes to let it cool. I then drove a few blocks to a chain auto store and had them read the codes.

Codes:
P0420 - catalytic system efficiency below threshold (This code was already there for a few weeks since shortly after I replaced the O2 sensor because I got a different code. I had checked the tightness of the sensor b/c it suggested a leak near the sensor as a possible cause, but it was tight.)

P0441 - EVAP emission syst. small leak/no flow condition (This code was new.)

I managed to get the car home but had to keep the idle up to prevent it from stalling after the car fully warmed up.

Attempted fixes:

I replaced the EVAP system purge control valve with a known working part but there was no change. Then I realized it could be the classic main relay failure when it gets hot. I replaced the relay and took it for a drive. It started fine but once warm the symptoms were even worse. Not only would the idle drop to nothing and often stall when the clutch was in, but now there was very little power, it felt like it was missing on one or more cylinders, and it was making a lot of rattling and clacking noises as if the valves or something else wasn’t right.

I started checking ignition system problems next.

Spark Plugs: clean, good condition, gapped correctly **white deposits on all 4**
Plug Wires: inspected and in excellent condition, later swapped with distributor
Distributor Cap: clean, no red dust, cleared build up from interior contacts
Coil: swapped with known working unit
Igniter (ICM): “ “ “ “
Distributor (entire assembly): “ “ “ “

Compression: All 4 cylinders 160-162 psi and held compression well


At this point I researched the white plug deposits more and realized that this was a symptom of running lean so I started checking the fuel system.

Fuel Filter: replaced with new part
Fuel Pump: swapped with known working part
Fuel Pressure Regulator: “ “ “ “
Main Relay: “ “ “ “ (as stated earlier)

Again there was no change at all with the symptoms: Further online research suggested it might be a vacuum leak.

Vacuum Lines: visually inspected, all firmly attached and no cracks in hoses
Vacuum Leak Test: used propane flowing through rubber tubing applied to all vacuum lines and joints - no change in idle. Putting the tube into the throttle body would cause the engine to stall. (I did this to verify the flow and effect of the propane.)

Air Filter: not visibly clogged, ran same with filter on or off
Throttle Body: removed and cleaned
IACV: removed and cleaned

At this point I have done everything I can think to do. Nothing I have tried has made any difference in the symptoms. The car continues to start easily every time but develops a low and rough idle fairly quickly that seems to get worse the warmer the engine gets. The car makes a lot of racket when accelerating whether under load or when parked and revved. It continues to have low power and feels like it is missing. Once warm, it stalls out whenever allowed to idle.

If any of you have any suggestions about what else might be causing this I would greatly appreciate your input.

Thanks.

BTW, I’m a newbie on the forum but I’ve been driving and doing my own maintenance on Hondas (mostly civics) for 25 years.

cfahamilton

125 views and no comments? No one has any ideas?
Since my first post I swapped out the entire distributor assembly including the plug wires - still no change.

I am thinking about checking the TPS sensor, timing (to see if it the belt slipped) and changing the O2 sensor (even though it is only a few weeks old). Would any of these components explain the symptoms I am getting?