Cylinder Not Firing

SON240sx Automotive
1

I know that a lot of you guys know the car, and you guys know more about common SR20 problems than I do, so I need some help.
For the purposes of the thread, I’ll call the cylinder at the front of the car #1, and the cylinder at the firewall #4.
S14 Blacktop, AEM Standalone, 256 Cams, 9:0 CR, 740CC HKS injectors.
Any questions, post them up.

I picked up the S14 from the shipping company yesterday with no issues.
The battery was dead, but it started fine with a boost.
I drove the car home, not driving aggressively at all, with no issues.

After about an hour, I went for another drive.
After the car heated up a bit, I basically did two short pulls in 1st and 2nd from a roll. I didn’t push the car very hard, just enough to feel some boost.

After 2nd gear, I heard the car not firing correctly, it did the typical Boxster engine sounding thing. I got out and checked the coils (in the dark), and #3 seemed loose, so I pushed it back in and tried to drive off
again.

The A/F ratio now was dropped to about 10, so it was running super rich.
The fuel wasn’t getting burned through the engine.

That didn’t help, so I pulled into a lot with lighting and tried some more things. I saw that the 10mm bolt that holds coil #3 down had been broken off, so that’s why it was loose, no worries.

I unplugged the coil and the engine ran worse. I unplugged them one at a time, and #4 (closest to the firewall) seemed to be the bad coil. I decided to go home where I had more tools.

When I got home, I swapped a few of the coils around, and all of the coils were fine. So a bad coil is not the issue.

It was about midnight, so I swapped a few plugs around to see if it was a bad plug. All the plugs were fine, not a bad plug.

I bypassed the HKS Ignition Amplifier and no change.

As I unplugged coil #4 it made no difference to the way the engine ran, so the problem is in the cylinder closest to the firewall.

I pulled the AEM and the harness looked fine, it wasn’t loose and no wires were obviously broken.

Today after work I checked the spark with a spark tester, and the spark going to the cylinder is fine. So spark is not my issue.

I replaced the plugs while I was doing it, and they were all fully black, so I figured they might have been a contributing factor.

The plug in the cylinder was wet. I figured at this point that the injector may be stuck in the open position, dumping fuel down on the cylinder, and not allowing the spark to ignite it. I figured that at some point, it would have fired if it were getting spark, so it’s very strange that it’s got spark but is still wet??

I did a compression test. (9:1 CR pistons)
#1 - 140psi
#2 - 140psi
#3 - 140psi
#4 - 120psi

That’s uneven, but it would still run like that, no?
I definitely didn’t push the car hard enough to do anything serious, it has to be something stupid.
There are a number of things that could contribute to that, including the walls being washed down with fuel, and the engine barely running in the past month or so.

So the cylinder has spark, it has fuel and it has compression.
The car is running super rich, so I assume the fuel is not burning in that cylinder.

I tried to load an old tune onto the AEM to see if something might have went out of whack with the tune. That didn’t help at all. I loaded the original tune back to the AEM, and still nothing.

The cylinder is getting fuel dumped on it, and it’s not burning it.
So basically right now, I have to figure out if it’s an electrical issue or a mechanical issue.

  1. Is it the injector, stuck open.
  2. Is it the wiring that fires the injector.
  3. Is it the AEM unit, I don’t know much about it.

I tried pulling some parameters & such on the AEM while it was running, but like I said, I don’t know much about it yet.

Before I tear off the intake manifold, I would like to get some insight.
I don’t want to pull/install the IM a bunch of times to test the injectors if I don’t have to.

Is there any way that I can do some diagnostics with the AEM software?
Does anyone have some insight/help that would get me any further?
Is there an easy way to pull the injectors?

2

That was one fuck of a read lol

We have had many cars come in for problems similar to yours. Whats your oil look like? Smell like? In that whole kaboodled mess you did not once mention engine oil.

If it is full of fuel. Change it. Your washing the cylinder walls like that which is no good. She will probably run just fine after that.

Let me know.

3

Oil didn’t smell of gas, and looked fine.
I haven’t had much experience with that, but a buddy of mine smelled it and said ti seemed fine. It was changed before going on the truck.

I just drove up the street (After I wrote this thread from the car), and it has a hard time even getting around. I tried to build some rpm on the straight street in 2nd gear, and it has nothing above 3K.

It’s a MAP setup on the AEM, and not a MAF.

4

P.S. Thanks for the read, I need to find out why it’s washing the walls.

5

Also, when I started the car up tonight the oil pressure was jumping around with the rough idle. Right around 50psi, jumping around maybe 5-6psi.

6

sounds like a fuel delivery problem now. Oil pressure jumping around is normal with an unstable idle.

fpr any good? MAP reading correctly? Timing set? Maybe jumped a tooth? could be a million and one possibilities.

7

The thing is, it only affects the one cylinder, so I don’t think it’s a bad FPR, MAP sensor, etc.

It could be a timing issue, I need to find a way to troubleshoot those things.
The tune now shows 10deg timing advance, an older tune is showing 29deg.

The thing that get me is I can pull the coil right out of #4 and I get the same idle as with it in there. I need to narrow it down to something that wouldn’t affect the other 3.

8

cracked porcelain on the plug?

9

drop some oil in #4 cylinder and check if the compression goes up …

10

All new plugs.

Will do tonight.

11

It may sound like that injector number 4 needs to be flow tested? You may be correct in that it could be stuck open. Pull the rail and injectors out of the cylinder head and test each injector spray into a small cup when you try to start the car. Of course, kill the starter relay and ignition.

12

Also, moisture is a sign of coolant in the engine. Dump some of your engine oil to check if you have coolant in it. If that is the case, you may have a coolant leak or headgasket leak in that area of the engine, especially since there is a small amount of compression lost.

13

what injectors are they

14

sounds like an injector is staying open.

15

When I say “wet” I mean there’s fuel on the plug.

They’re 740cc HKS injectors, its in the original post.

I didn’t want to pull the I’m and rail etc. If I didn’t need to, but looks like ill be doing that tonight.

16

run the engine, and unplug each injector, find out which injector makes the biggest difference. its probably just the injector

17

I swapped injectors with another cylinder, and the same cylinder is giving me problems.
So it is not the injector.

I have good coils, good injectors, good plugs, good compression.
It must be wiring???
I unplugged the injector while the car was running and I heard a loud “tick, tick, tick”, so I killed the car and didn’t unplug any more.

Here are some shots of the lower intake manifold.
The slot for cylinder #4 was crystal clean, while the others had oil and crap all in them.
This tells me that the injector is in fact washing out the IM and cylinder, but if it’s not failed, then it must be the wiring keeping it open?

ACTUALLY, My Blackberry won’t send the pics, so I’ll post them later.

Here is some data that I got using AEMPRO, I just watched all of this while the car was running, and this is what it stopped at when I tuned the car off.
Notice that there are two BLANKS for Fuel Inj #2 Open and Fuel Inj 1 Pulse.

Fuel 1 - Off
Fuel 2 - Off
Fuel 3 - Off
Fuel 4 - Off
^^ These didn’t come on at all

Fuel Inj 1 Open - 15.91
Fuel Inj 2 Open - BLANK
Fuel Inj 3 Open - 18.62
Fuel Inj 4 Open - 0.53
Fuel Inj 1 Pulse - BLANK
Fuel Inj 2 Pulse - 2110
Fuel Inj 3 Pulse - 2115
Fuel Inj 4 Pulse - 2110

Coil 1 - Off
Coil 2 - Off
Coil 3 - Off
Coil 4 - Off
^^ These flicked on, maybe one every 3-4 seconds

Ign 1 charge loc - 0.06
Ign 1 firing loc - 0.82
Ign 2 charge loc - 18.05
Ign 2 firing loc - 18.82
Ign 3 charge loc - 6.05
Ign 3 firing loc - 6.82
Ign 4 charge loc - 12.05
Ign 4 firing loc - 12.86

I e-mailed Dan at u2NDyno and he said that the AEM is not a good tool to troubleshoot or do diagnostics with. I couldn’t get AEMLOG to log anything for me, as I haven’t read up on it yet.

Where do I go from here?

18

I just ran the car and tried unplugging the other injectors…they just caused the car to drop idle a little bit.

When I unplugged injector #4, it was almost as if someone was hitting the IM with a hammer. “Bang, Bang”…WTF???
It only happens when I unplug the injector…

19

To be fair, my comments were in relation to mechanical issues. ECU data can be very very helpful is the diagnosis of some issues…but not all.

20

Sorry Dan, didn’t mean to offend.
I’m just fishing for some info here, and I was trying to include whatever relevant info that I could.