Hi. I have a 89 civic wagon D15b2. The engine runs okay at start up, then gets progressively worse at operating temp. It shows no ECU codes at all. It starts missing as if it is starved for fuel and eventually dies. All the sensors have been checked and come within spec upon OHM testing. I started out checking components that would not trigger ECU codes. It has a normal high idle at warm up. These are the things I have done.
1. Replaced the coil
2.Checked to see if the Cat converter is clogged.-- NO.
3. Checked the Fuel Injectors. -- Good within spec. I even changed them out with some spares.
4. Checked voltage at Map sensor. Good- Also checked vacuum. Holds vacuum
5. Checked for vacuum leaks. None
6. Checked and tested the idle control valve. Within spec. Apparently good.
7. Compression check. All four cylinders.- Good
8. Full tune up. Plugs/Dist. cap/ rotor etc.
9. Replaced fuel filter and checked pressure. 30 psi constant. Fuel regulator is good
10. Throttle body is in excellent condition.
I would like to know if it is possible to have a faulty sensor or component, but not trigger a ECU code. I am gravitating toward a bad map sensor or oxy sensor or even a bad igniter. Clearly this car has me close to committing myself. I'm a smart guy, but at the moment this thing has me whipped. To back up a bit, when I drove the car over the last month it would hesitate upon acceleration. Then it started missing and losing power at normal driving speeds. It eventually died at night and I lifted the hood and the Cat converter was red hot. I thought it was clogged and replaced it. It was not the cat. It is running leaner as you warm up the engine until it eventually dies and super heats the exhaust system. I know there is a simple answer here. Can a component be bad, and check within spec and not trigger the ECU. This type of problem is the hardest to diagnose. Can anyone help. Thanks, Richard

 

The ECU only reads voltage ranges from the sensors or on/off functions, so as long as the sensors are outputting the correct voltage ranges then they wont trip a code. For example, a vacuum leak at the map sensor would make the car run really rich, but the map sensor is still working correctly and the ECU will just assume a WOT position and likely not throw a code.

Have you replaced the fuel filter? Hows the fuel pressure regulator? Checked your mechanical timing? Ignition timing?

 

Hi again. I forgot to mention that I replaced the fuel filter and checked the pressure. The pressure was a constant 30 psi. The regulator is functioning normally The timing has not been altered as far as mechanical. Ignition timing is fine. Thanks, Richard. I knew I forgot a few things on the first post.

 

when your engine is dieing
can you keep it on by pressing the throttle?
when the rpms die down after its warmed up
what is it idling at?
should be 700 rpm from the factory, but 29 years later 900 rpm is the sweet spot at idle

if your rpms are ever lower than the 700 rpm range the engine will sputter
so id start by cleaning out the throttle body
and then adjusting the idle screw till you get to 900 rpm

let me know if that helped

 

Not to hijack your thread but I have a similar issue with my D16A6 however it occurs after a hot start and it clears up after about 1 min. But it acts as if there is a fuel starvation or lean condition. I am also looking at the igniter (have a honda part on order) or coil. I have replaced a bunch of parts as well. I would suggest you install a fuel pressure gauge on the fuel filter (I did). It allows you to rule out fuel issues.

One thing I am also looking into is the EVAP system. I am wondering if the the EVAP is purging either too much air or at wrong time (I think it should be purging during driving with the engine at a higher RPM.). Any way, I will be following your progress on this. Been very frustrating for me as well. Good luck.

 

Hi Arries 289.
I have checked the fuel pressure at the fuel filter and I get a constant 30psi. You brought up the EVAP system. I have limited knowledge on how it exactly functions, but I used my service manual to diagnose it. I followed it to the letter and everything seemed to check out until the last part. I took off the gas cap, and I was to check for vacuum at the bottom of the canister while raising the rpm of the engine to 2000 rpm. I was supposed to get vacuum, but didn't. I was late and I was burned out and I thought I did not do it right or that I was far afield from the real problem. Could a failing purge system cause my engine to start and run well and then start missing and running like crap and die after fifteen minutes. I am going back tomorrow and checking the major sensors again with new information not found in this poorly written service manual. Thanks for replying. Richard

 

Hi arries 289
There is a you tube video you might want to see on EVAP purge solenoid. The title is: Evap canister purge valve solenoid operation diagnosis and testing procedure. He talks about the solenoid being stuck in the open position causing the gas tank and canister vapor to pour in to your engine on start up. Worth watching. Richard

 

Thanks Richard. Was your fuel pressure at a constant 30psi even if you blip the throttle? The pressure should go up when you hit the throttle (to a predetermined set point). Example: my car will be at 24psi at idle and will go to 37psi during heavy accel. That is the fuel pressure regulators job. If your PSI is not moving that could be part of your problem. The EVAP system (on my car anyway) only purges if the engine temperature has reached 135F. That is why I am looking at it. But I also ordered a air temp sensor yesterday to add to the mix. Another part I already replaced that I have read can cause similar issues is the engine temperature sensor (for the ECU not gauge).