JohnD2024

I just bought a 2006 MDX with 165k miles. The dash was lit up like a Xmas tree. All cylinders misfire, ABS, VTM-4, VSA, TPMS, p1077, p1078. Parked at idle the car is rocking back and forth.

Put in new plugs and coils. (The old Denso coils looked new. NGK plugs looked well used.) Now misfire down to cyls 1, 4 and 6.

Compression test showed most cylinders had about 125/130 psi except cylinder 4 which was low at 80 psi. Did a wet compression test on cylinder 4 and it came up to 120 psi. So it's probably stuck or worn rings, right, not the valves?

After some googling around I found out these engines can throw all cylinder/random misfires because they need to have valve lash adjusted. So I did that next.

Since I had the intake off I pulled the fuel rails to check out the injectors. I noticed that the cylinders I was getting misfires on had newer injectors. The other three looked like they had the original OEM injectors.

I checked resistance on all of them. The newer aftermarket ones showed 10.2 ohms. The OEM ones showed 12.5 ohms. When I applied 12V to them from the car battery, they all sounded like they worked. But I thought it was odd that I was getting misfires on the cylinders with the newer aftermarket ones only.

I took the injectors inside the house with the idea that I could try cleaning them. When I applied a 9V battery to them, the aftermarket ones would activate but the OEM ones would not. So now I'm wondering if the aftermarket ones may be injecting fuel too early, before the triggering signal reaches 12V. Or does that matter?

I just ordered 6 refurbished OEM injectors on eBay which should come during the week.

At that point, I thought the misfires could have been caused by the valve lash being off, the aftermarket injectors or the low compression on cylinder 4.

The exhaust valves were all too tight. Most intake valves were OK, some were slightly loose.

After I replace the injectors with OEM, if I still get misfire codes, I am thinking sticky or worn rings.

Whoever worked on the car before me threw 6 new coils and 3 injectors at it to try to fix the problem but didn't want or know to try a valve adjustment.

At this point, I could put the intake back on to see how it runs and if the valve adjustment fixed the misfires. But I don't want to spend the time putting it on and then having to take it off again to replace the aftermarket injectors if it's still misfiring. Also, the weather outside is not so nice this week.

If it's still misfiring after replacing injectors, I am thinking doing an engine flush and adding an engine restorer to bring compression up on cylinder 4.

If all that fails, my last resort is to replace the piston rings.

The ABS, VSA, VTM-4 lights I'm hoping were all caused by the one bad ABS sensor that I replaced.

I checked and cleaned the PCV and EGR valves. They were OK. The intake and throttle body were clean.

I replaced the IMRC valve assembly and I don't see p0178 anymore. Still get the p0177.

What engine cleaner and restorer work well?

Am I overlooking anything that could be causing the misfires?

I don't see smoke or smell unburned gas at the tailpipes. The car doesn't overheat. It drove smoothly when I test drove it.

JohnD2024

Fuel injectors arrived with one injector DOA. Resistances were 10.5 ohms. So I put them in and one of the old aftermarket ones.

No more misfires on the scanner. Engine runs much smoother but I still can feel it's a bit uneven from cylinder 4 low compression.

Trying to do a piston soak on 4. I put 2 Oz of Berryman's in this morning. 6 hrs later I turned the engine over at the crankshaft. I used the oil dipstick to try to check how much was still in there and it came out dry. Added 2 more oz berrymans. Put the dipstick into the cylinder and it was still dry. So I think it's either draining out right away and not soaking or because of the angle of the piston I need to put more than 2 oz in at a time to cover the whole piston.
In the morning I will take a compression test. Then I will run the engine 5 minutes to warm it up and get whats in there circulating and on the rings. Then I will take another compression test. Then I will add 1 or 2 tablespoons of oil in the cylinder along with more berrymans so that maybe it won't drain out so fast.

No more ABS and VTM-4 light. VSA and triangle light was still lit up. P1077 and P1078 both gone. I think someone had the IMRC actuator off and reinstalled it with the fins in the open position. I reinstalled it with the fins closed.

I turned off the VSA light by doing a procedure I saw on youtube.

The only light I have on now is the TPMS light, which I will leave alone for now as I dont need it to get through inspection.