Good afternoon

I recently obtained a 94 accord 5mt f22 and I'm having the funnest time trying to get the idle to mellow out. originally it would idle at 3-4 rpm and just stumble hard. When it is cold the car idles and runs fine. However once it reaches operating temperature and under load it will idle rough, misfire and buck really hard. and sometimes stall. first thing i did was check for vacuum leaks with brake clean. I didn't find any, so I hooked up my smoke machine to the line that runs to the brake booster before the valve and had no leak ( I opened up the oil cap to make sure the smoke was entering the system which it did).

So i started doing some digging on here and a couple other honda forums and found that the egr could be clogged and seems to be a very common issue. So I took the rail off replaced all the orings for the injectors since i was right there, pulled the plate and cleaned it, along with cleaning and vacuuming out the stuff that was in the manifold. Put it all back together and the car ran worse. checked again for leaks and nothing. So I jumped over to the throttle body and noticed that the idle screw was set all the way out, I finally got it to a decent idle and it runs fine.

However once I put some load on the car it starts acting up again. I noticed that the map sensor would not shut the car off if I pulled the plug off so I replaced the map sensor and the car idled very well. Then I could hear the fact that the IACV was on its way out (we all know that sound) and once again, any load caused the car to stumble but not as hard and it stopped stalling out. I checked the plugs and they were fine. cap and rotor are brand new. wires are new import direct. I was going to do a leakdown and compression check but I wanted to see if there was any other recommendations before i did that.

what really boggles my mind is when the car starts acting up and stumbling, if i pull the connector for injector 3 or 4 or the spark plug wire for 3 or 4, the car will hesitate and then catch its self, however if I try the same things to cylinder 1 or 2 NOTHING happens.

I've built a few Turbo hondas, some toyotas, and lots of Subarus (currently own a 630whp forester) so I know my way around, but in this case I don't know what else to try. pls haaaaaaaaaaaaaaalp.

-Mig

EDIT: forgot to mention that there is no CEL illuminated or stored.

 

So I did the compression check and the 1-4 were 110 115 90 110. To me this is too low. Someone tried to tell me that because we are 4500 ft in elevation (+/- 200 feet depending where in the city) that these were normal numbers. Now I know that BS. So the car ran fine for about 2.5 hours even with load. However the car stalled again and would not restart. My coworker was adamant that it was the coolant temp sensor (surprise, it wasn't) and then that it was the ignition control module (pointing to the wrong part). I said it was the fuel pump or something with the fuel system since it is throwing a 16 code and a 41 code now. all the injectors are seated properly and the connectors are secured., Any other input?

 

If you can pull an injector or plug wire for a cylinder and it does not affect the running of the engine, then that cylinder is not working.
Verify the plugs are not worn, properly gapped, tight, as well as not oil fouled in the well and the spark plug boot is properly seated as well as the spark plug wires are also in good order.

You do have to apply a correction factor for air density the higher in elevation you go. Every 500'.
In your case the correction factor is .88 for 4500', thus your compression numbers are; 125-130-102-125.

When doing a compression check, the throttle needs to be wide open with no obstructions(verify air filter is not plugged).
Nominal should be 178psi(156.6 @ 4500')
Minimum should be 135psi(118.8 @ 4500')

#3 is definitely below minimum.

Have you verified the valves are correctly adjusted? If they are too tight that will allow them to hang open when they should be closing/closed, which would cause a loss of compression and misfire issues.

 

Mike Thank you for the reply.

The plugs were brand new iridium plugs (bought just 2 days before we received the vehicle. the gaps were all at .044" which is right from my research.) one was just moist from oil so I replaced the spark plug tube seals and the valve cover gasket since I had pulled the cover to check timing, ran the car and no new oil on plugs. wires, cap and rotor were brand new as well.





well I knew about the correction factor but even so i figured these were still to low of numbers, and with #3 being so different I figured we needed further testing. I did not check the valves for adjustment, but I did do the leak down 1-4 was 4% 4% 6% 5% so well within tolerance, which I would no valves need any adjustment (although if you suggest it I'll happily do it). I had another friend who also builds hondas (more frequently than I), come by and see if I was doing something wrong and he also came up with the same numbers and did the same trouble shooting.

We also replaced the fuel pump as I had a similar problem with an RX8. When it would get to temp the pump would get hot and shut off. replaced the fuel pump on the rx8 and it worked right away and properly. however this was not the case here. does anyone have a vacuum diagram? I can't seem to find one outside of the emissions diagram. unfortunately I dont have the shop manual.

TIA
-Mig

EDIT: the car is popping code 16 and code 41. I can't imagine the car running this crappy due to a bad o2 sensor. seems that code 16 is a more rare code. when the car stalls/loses all power it throws code 16. The injectors are all getting signal when the car runs. when it stalls it will crank but not turn. however if we shoot some starting fluid into the intake it will fire right back up. This leads me to a fuel issue still, but I cant figure it out

 

Are you able to scan the o2 sensors to see if your fuel trims look decent? A bad o2 can make a mess, even a lazy o2 can cause weird issues.

 

With the engine cold, verify lash is correct for intake/exhaust. Usually exhaust is what becomes tight. Engine may run fine when cold but when warmed up the lash may be just enough to cause the valve to hang open.
At the end of the intake plenum(opposite of the TB) under the Boost Chamber is where the main engine harness ground is attached, verify that it is a clean and tight connection with no damage to the ground.
Also verify your wiring harness is undamaged. If multiple electrical issues are showing up(codes), verify that it is not due to damage. Loose grounds can have you chasing for phantom codes.
Verify that the injector itself is getting power. One of those injector noids would be handy to verify actual power output to the injector. Then verify the injector itself is working. It should have a resistance of 1.5-2.5Ω

 

I did check the injector harness with the noids, all which had power. I found the problem. at the fuel pump relay, one of the black with yellow wires (2 were going to the same pin) was loose. someone had jumped into harness before. that was what the problem was. After I soldered and fixed the wires, it ran perfectly, even after warn up. still running great right now.
thanks for all the help you guys.

 

Way to go! I love when people take the time to dig in and figure out those niggling issues. Loose wire, bane of my existence.

 

Thanks man. This thing was a pain in the ***. I ended up selling it to one of my friends (which ultimately means i'll somehow work on it again haha). Now I get to wait on my taxes so I can put my Monster Forester back together.

 

Hey guys brand new to the site not sure how it works but im gonna jump rite into it lol. I got a beautiful 2001 accord ex coupe v6 and my temp gauge was not working so I replaced temp sensor and still nothing. I hooked a wire from pin 26 out pcm (red/white ect wire) and hooked into #2 on gauge connector (yellow/green) and it works now but I still have the original break or a short and it is now giving me a high idle and showing code 86. my question is my car does not have a coolant temp sending unit and I see the wire going to the gauge from the pcm is pin 24 (yellow/green) but on my v6 that spot is blank. the only thing I thought of was coming out of the #26 (red/white ect) and I got the gauge to work by doing that. Is that the correct wire for my car that goes to the temp gauge from the pcm? and does anybody have the wiring diagram for the ect sensor to the temp gauge so I can try and just trace the original wiring problem down so I can remove my wire I ran? thank you so much.