1G Misfire on Cylinder 3 and 4

[mac 108]

Completely stock 1G turbo

Car developed a severe misfire and loss of power. Seems to be running on only two cylinders.

Plugs on cylinders 1 and 2 read fine. Plugs on cylinders 3 and 4 are black and gas soaked. While the car is idling, you can remove the plug wires on cylinder 3 or 4 and there will be no change in how it runs. Removing one of the plugs on cylinder 1 or 2 will cause the engine to die.

Stock heat range NGK plugs have less than 1000 miles on them. I have replaced the plug wires and tried 3 different coils. Compression is uniform across all cylinders at about 150 cold.

What's my next move? This car ran great then developed this problem out of the blue without warning.

 

[pauleyman]

Open the ecu and look and ignition transistor as possible problems

 

[delval2011]

Sounds like a electrical problem. Check all your wires and connections maybe something came lose.

 

[josh2000]

if you know someone with a dsm 1g ask if you can swap coils to see if thats the problem.

 

[mac 108]

Open the ecu and look and ignition transistor as possible problems

ECU looks clean. The caps were replaced a few years back by the guys at ECMtuning. I know that there still could be a problem, but it has been serviced. No smells, no burns, no obvious ECU damage.

I only have spare M/T ECUs and my car is a stock automatic GSX.

Thoughts?

I have replaced the plug wires and tried 3 different coils.

if you know someone with a dsm 1g ask if you can swap coils to see if thats the problem.

C'mon, dude.

 

[mac 108]

Tried an M/T turbo ECU, exact same symptoms.

Car will start, but it dies immediately if you try to move it.


So far I've changed/tried:

Spark plugs
Coil
Spark plug wires
ECU
Compression test was about ~150 cold on all four cylinders.


I'm stumped. Could it be something like the CAS or the ignitor under the coil?

 

[gsxeclipse102]

I would try swapping a power transistor first. If that doesnt fix it your wiring may be damaged

 

[enriquez2000]

I would also say do a compression test.. coils fire 4-1 and 2-3 so i would suspect them to miss in those pairs if it was coil related.

A small possibility could be those injectors being stuck open and washing out the cylinder. You could try swapping plug wires for 1 to 4 and 3 to 2 and see if the miss follows the swap.

 

[gsxeclipse102]

He already stated he performed a compression test and did spark plug wires.

 

[enriquez2000]

He already stated he performed a compression test and did spark plug wires.

I see the comp test now... but i dont see he did anything than remove plugs.. he needs to move them to see if misfire follows

 

[josh2000]

sorry bro did't read that part that you already did the coil swap

 

[mac 108]

I am so dumb and I should know better by now. Decided to do a BLT. Massive boost leak from the injector seals and PCV hose. New parts on the way.

BLT first every time!

 

[boostdawd]

I don't believe a massive boost leak test will cause this but I may be wrong. Let us know what happens when u change out the seals.

 

[mac 108]

I don't believe a massive boost leak test will cause this but I may be wrong. Let us know what happens when u change out the seals.

You were right


Now the car will actually run, but it's still running on only two cylinders. I can remove the two plug wires on the passenger side and there is no change in how it runs. Going to compression test this afternoon and I also have a new ignition module to try.

Could it be anything else? Crank sensor perhaps?

 

[Marchev]

Swap injectors 3 and 4, with 1 and 2 and see if the problem follows the injectors.

Also swap the power transistor, like stated already, in case you haven't done that yet.

 

[mac 108]

That's on my list for this afternoon, compression test and swap that part. Will update with my results

 

[GPLaserRS]

Swap injectors 3 and 4, with 1 and 2 and see if the problem follows the injectors.

I second this! You mentioned that the plugs that weren't firing were soaked in gas it sounds like injectors are stuck open.

 

[mac 108]

Looked back through the thread. This project has been on the back burner so long that I forgot that I've already done a compression test.

Looks like switching injectors and the ignition module are next.

 

[mac 108]

Found this from post #2 in this thread http://www.dsmtuners.com/threads/if-cam-angle-sensor-is-bad-will-i-get-a-spark.427803/

"My CAS went bad, but mine is a 95. I don't think that makes much difference when referring strictly to the cam signal. When it went bad I would get spark on 2 cylinders, and the other 2 would flood. Generally, if the cam signal is bad, that is the case, though I can't say it is ALWAYS like that... It just seems to be the most common symptom. I am running a 1g CAS now, and all I can think of is that maybe the wheel inside is jammed, or possible that the crank signal is fouled up. Open it up and make sure it isn't full of oil too. I have a friend with a 1g that had one fail due to oil getting by the shaft seal and fouling the inside of the sensor up."

I'm going to try a spare CAS first.

 

[boostdawd]

Swap out the injectors for known working ones or swap with cylinders 4 and 2. U can even take a screw driver and place it on the injector to see if it clicks.

 

[mac 108]

Worked on it tonight. Swapped the CAS and ignition module/ignitor whatever it's called.

Still no change. I did notice that the two passenger side cylinders are getting weak spark. It was dark, so when I pulled one of the spark plug wires from the good driver side cylinder, there was a strong arch onto the valve cover that you could see. On the two passenger side cylinders, there was clicking, but no arch. Seems like it's getting weak to no spark. I also tried a different set of plug wires and a different coil pack with no change.

I'm running out of ideas. What else can I do? I'd be surprised if two of the same parts were bad that I've tried using.

To recap:
Running on two cylinders
2 Passenger side (looking from the front of the car to the back) cylinders are not firing properly
Getting fuel
Weak spark on the two bad cylinders
150 compression across all 4 cylinders
New spark plugs

Tried swapping the following:
CAS
ECU
Ignition module
Coil pack
Spark plug wires

 

[boostdawd]

I know u said u have weak spark but try swapping the injectors like we recommended see if the problem cylinders change. Was it running fine before? When did it start giving u issues? Also, the ignition module u referred is that considered the power transistor?

 

[mac 108]

The ignition module I am referring to is part # MD149768

 

[boostdawd]

Ok so it's the same part. The issue your having may lie in the wiring. Maybe it's time to pull the harness out and check for brittle connectors, frayed wires. Electrical issues. Gotta love em

 

[mac 108]

I'm going to double check connectors for corrosion and fit. Also going to see if I can find my other CAS and ignition modules to see if maybe a different one will work.

This car has been very reliable until now. I don't get it.