2G: Slight Misfire at Idle, Running Rich, Failing Emissions

ryshinazy · 08-18-2012, 11:05 PM

I have been trying to get my 1995 GSX to pass emissions. It is failing for HC (hydrocarbons) and CO (carbon monoxide). There is a slight misfire at idle (no MIL) and it runs rich once it gets into boost.

I have already checked the timing. I smoke tested the intercooler piping and intake (Fixed small leak). Replaced spark plugs NGK and wires. Did a compression test (140 for all cylinders). Replace O2 sensors.

Any suggestions on what to test next or what could be causing it?

I read all the other threads about this for 2-3 hours and did not find a solution that is why I am posting one specifically for my issue.

WES_393 · 08-18-2012, 11:16 PM

While smoke tests are good for finding vacuum leaks, you need to do a boost leak test as well. The biggest problem I see is your compression numbers, which are about 5psi from the service limit. Such low compression number could be a major cause for the poor emissions. So if your compression tester is accurate then it's likely time for a rebuild.

ryshinazy · 08-19-2012, 08:52 AM

Quote:

Originally Posted by WES_393

While smoke tests are good for finding vacuum leaks, you need to do a boost leak test as well. The biggest problem I see is your compression numbers, which are about 5psi from the service limit. Such low compression number could be a major cause for the poor emissions. So if your compression tester is accurate then it's likely time for a rebuild.

I just had the cylinders bored new pistons, rods, rings, block resurfaced, valve job, and head resurfaced 5,000 miles ago so the motor is freshly rebuilt.

I just realized I forgot to have the throttle open when I did the test.

I suppose I will retry it tomorrow and see if it changes the numbers.

ryshinazy · 08-24-2012, 10:05 AM

I am assuming the Habor Freight compression gauge I used is not very accurate because when I did a leak down test the percentage was very low. I pulled the EGR valve and it is sealing properly. I tested the fuel pressure regulator and it wasn't holding vacuum so I replaced that and the fuel filter.

So after cleaning the egr, replacing plugs and wires, all the intercooler couplers, fuel filter and fuel pressure regulator it still has a slight miss at idle and failed emissions again. Except this time it failed for HC and NOx instead of HC and CO.

Talon virgin · 08-24-2012, 10:28 AM

I'm not too certain about the 2g motors, but i was having roughly the same problem with my 90.

I was told in a previous post my Cam position sensor/synchro was bad. I replaced it with a junkyard takeoff and my problem cleared up. went from 18mpg to about 26
though i kinda cheated the emissions test with denatured alcohol

ryshinazy · 08-24-2012, 11:52 AM

Quote:

Originally Posted by Talon virgin

I'm not too certain about the 2g motors, but i was having roughly the same problem with my 90.

I was told in a previous post my Cam position sensor/synchro was bad. I replaced it with a junkyard takeoff and my problem cleared up. went from 18mpg to about 26
though i kinda cheated the emissions test with denatured alcohol

Well I just tested the wave form of the cam sensor and it looks to be within spec, then I tried flipping that positing piece inside with no change.

I tried putting octane booster in and it did not help.

On the topic of fuel mileage on my last tank, where I dumped some fuel during the fuel pressure test and replacement of fuel filter and fuel pressure regulator, I got 23 MPG and on the previous tank where I burned all the fuel I put in I got 26 MPG. So this issue is quite puzzling.

ryshinazy · 08-27-2012, 07:02 PM

If anyone wants to physically see what it is doing here is a video I just made:

95 Eclipse GSX rough idle/ failed emissions

I plan to keep posting on this thread until my issue is fixed whether it be from someones advice on here or my own findings because I hate when I find a thread that is the exact issue I am having but it is never resolved!

Talon virgin · 09-01-2012, 11:12 PM

[QUOTE=I plan to keep posting on this thread until my issue is fixed whether it be from someones advice on here or my own findings because I hate when I find a thread that is the exact issue I am having but it is never resolved![/QUOTE]

damn... im not sure dude
im running through possibilities in my head, and they coincide with those youve diagnosed.

I would try a boost leak test as Wes suggested
Boost Leak Testing

thearkatek · 09-11-2012, 08:44 PM

Hey did you figure this out yet? I am having the same problem. I had major boost leaks, but I have fixed them all and this is still happening. Really sucks when your in traffic

ryshinazy · 09-11-2012, 08:56 PM

Quote:

Originally Posted by thearkatek

Hey did you figure this out yet? I am having the same problem. I had major boost leaks, but I have fixed them all and this is still happening. Really sucks when your in traffic

no still nothing. i brought it to the emissions place to have it tested and they said the cat didnt work and that's all they could figure out. then the guy said to put it all back you stock, yeah right. so i really need an idea of what to test next

kidmet · 09-12-2012, 01:53 PM

Quote:

Originally Posted by ryshinazy

no still nothing. i brought it to the emissions place to have it tested and they said the cat didnt work and that's all they could figure out. then the guy said to put it all back you stock, yeah right. so i really need an idea of what to test next

Did you check your timing? Maybe you jumped a tooth. A Cat prob will cause other (emission related) problems too. Did you ever do a boost leak test?

ryshinazy · 09-13-2012, 02:27 PM

Timing was the first thing I checked. I never did the boost leak test because I only have an issue at idle, not driving and not under boost, so I only did the smoke test.

ryshinazy · 09-18-2012, 07:00 PM

May have finally figured something out. It started misfiring really bad so I brought it in the shop for my Master Technician friend to look at. He started checking the wiring and then he touched the wired going across the intake manifold that go to the injectors, crank sensor, ac compressor, etc the idle went up and stopped misfiring. So tomorrow I will be tearing into the harness and checking for broken wires.

greekgodchaos · 09-18-2012, 07:08 PM

I just had some seriously bad stumbling and misfiring that was caused by a faulty Injector Resistor Pack, you might try testing it while you are in there. After I swapped it for another replacement, runs smooth as butter. It also may be your coil pack is gone bad.

ryshinazy · 09-18-2012, 07:12 PM

Quote:

Originally Posted by greekgodchaos

I just had some seriously bad stumbling and misfiring that was caused by a faulty Injector Resistor Pack, you might try testing it while you are in there. After I swapped it for another replacement, runs smooth as butter. It also may be your coil pack is gone bad.

Thanks I will try checking that Injector resistor, the coil should be good because the wave for for the spark looked good.

greekgodchaos · 09-18-2012, 07:22 PM

Also make sure your plugs are in the right order going to the coil: 4123, that will also cause some messed up idling. Have you ever cleaned your factory MAF? If so, you shouldn't have, because MAF cleaner states it is not for Karmen Vortex MAF's. Um, also make sure all of your exhaust manifold bolts are tight and you don't have any exhaust gases escaping from the bottom of the exhaust ports on the head. Double check you do not have any leaks underneath your intake manifold as well, that is a common spot to miss.

ryshinazy · 09-18-2012, 07:33 PM

Quote:

Originally Posted by greekgodchaos

Also make sure your plugs are in the right order going to the coil: 4123, that will also cause some messed up idling. Have you ever cleaned your factory MAF? If so, you shouldn't have, because MAF cleaner states it is not for Karmen Vortex MAF's. Um, also make sure all of your exhaust manifold bolts are tight and you don't have any exhaust gases escaping from the bottom of the exhaust ports on the head. Double check you do not have any leaks underneath your intake manifold as well, that is a common spot to miss.

All that stuff looked good when I checked it but thanks for the advice

ryshinazy · 09-26-2012, 08:51 AM

So I got a few things fixed. I found a bunch of hack job splices taped up that went to the cylinder 2 injector and crank sensor. I ran new wired and soldered them and wrapped them in heat shrink. I also found that the gasket between the header and turbo was blown out on the back side. After fixing those few things it is running better but still not exactly perfect but it will due for now.