Carbon Fouled Plugs / Leaking Injectors??

[tsi1991awd]

Pulled the plugs and they are fouled with carbon all over the tip. They aren't wet, but the cylinders have a strong fuel smell. I've been battling a hard start problem, this usually only happens after the car has been sitting for a long period of time...8 hours or so.

With the hard cold start and fouled plugs, these are symptoms of leaking injectors (leaking into the cylinders). There is no external leak anywhere.

My gas mileage has been suffering, performance seems to be lacking, I don't know where else to look. So I ask you all, could it be leaking injectors? I've already ran seafoam and injector cleaner to no avail.

 

[JusMX141]

Possible vacuum leak or fuel pressure regulator issue.

Vacuum is needed to drop the fuel pressure at idle so you don't fill the cylinders with fuel. If you don't get the problem figured out soon, the fuel you're dumping into your engine will pass (unburnt) into the crankcase, contaminate the oil, ruin it's film strength, and eventually wipe out your bearings and score the cylinder walls from lack of lubrication.

 

[tsi1991awd]

The thing is, it's not running rich. It idles perfect once it's started, which leads me to believe it is not a vacuum issue. I've gone over all the lines, I'm about to just cap the ones I don't need off to completely rule the issue out. It's just an issue that happens once it's been sitting for 8 hours or so.

 

[JusMX141]

Pulled the plugs and they are fouled with carbon all over the tip. They aren't wet, but the cylinders have a strong fuel smell.

My gas mileage has been suffering, performance seems to be lacking, I don't know where else to look.

The thing is, it's not running rich.

Ummmm....contradict-much?

If your plugs are carbon-fouled and you're losing fuel mileage, you're running rich. Most modern cataytic converters will dissolve the grey smoke and heavy exhaust smell to the point where you can't tell out of the tailpipe.

If you're absolutely POSITIVE there aren't vacuum lines leaking (this includes down at the evap canister under the battery), then you may simply need a new o2 sensor or some other diagnostic component. An o2 sensor can be bad without setting off a check engine light.

 

[tsi1991awd]

Ummmm....contradict-much?

If your plugs are carbon-fouled and you're losing fuel mileage, you're running rich. Most modern cataytic converters will dissolve the grey smoke and heavy exhaust smell to the point where you can't tell out of the tailpipe.

If you're absolutely POSITIVE there aren't vacuum lines leaking (this includes down at the evap canister under the battery), then you may simply need a new o2 sensor or some other diagnostic component. An o2 sensor can be bad without setting off a check engine light.

Sorry if I wasn't clear on what I meant...what I was saying was when the engine has been sitting, if I pull the plugs out there is a strong fuel smell. There is no smell while the engine is idling, or while driving.

And if the O2 sensor was bad, would that even cause it to be hard to start? The carbon fouling could have happened due to the plugs firing and not being able to start the car due to flooded cylinders, not rich conditions while driving. Gas mileage and performance could suffer due to the fouled plugs as well. Just throwing that out there.....

 

[BurnBarfield]

Did this ever get resolved, it sounds similar to my problem?

 

[DSM1G90]

Interesting, for I'm facing the same problem - hard start after sitting for quite the time - like a couple of days, esp. now with it being cold outside in our state and my car sits outside-no garage or carport to protect it from the elements.

Times are where I have to crank for 5 secs, get off the key, then repeat this procedure for a good 5 plus times until it finally catches like it was flooded and as mentioned above, will suddenly settle down to a very smooth 750rpm idle after being warmed up.

I have no vacuum leaks to mention of, yet need to check out the Ox2 sensor if that has died or such as also mentioned above. Have to dig out the Chilton's and see how to test Ox2 sensors - being that it really isn't hard to do..

At first, I was wonder on if the stock FP was going out, but if I can run freeway speeds and even get the revs up close to redline, I've been eliminating the FP thing due to the constant feed of fuel being present. I did change out the stock FPR thinking that it was going wicky on me, but it seems that wasn't the issue on my hard starts.

I've got stock 450cc (blues)injectors installed now, but do have some 510's(yellowtop) and wonder, if I do have leaky injectors, would mileagewise be affected with going up to these 510's? For during the summer, I was getting close to 30mpg with the bluetops and would like to keep that mileage since I travel freeway on the norm almost all week.

Thx-DSM

 

[JusMX141]

To install the 510's you WILL need an AFC or some way to compensate.

Once tuned properly, the 510's should yeild the same fuel mileage as the 450's. The engine's demand for fuel will not go up across the board....hence the necessity of the AFC. You'll need to "tune" your stock fuel curve to make use of the bigger injectors.

 

[Detective Coating]

My guess is that the OP's problem was a faulty FPR because of his issues. I have the same problem and leaning heavily towards my AFPR being the problem. I thought I had a bad injector but that was not the case because I manually checked to see if they were working and they were all good. I know I fouled my plugs out so bad that they were not igniting therefore leaving unburnt fuel in the cylinders. I got new plugs and it ran good but still had a FP problem so now I am going to replace my AFPR and hopefully that will fix it because I've replaced darn near everything else.

 

[brownfinger]

I'm dealing with the same thing as you guys. Thought it was fuel pressure related. Got a guage. It said my FP was 10 PSI too high. Replaced FPR. No fix, same problem. Finally got datalogger capability. For long periods of time (several seconds) there is no signal from the O2 sensor. Computer thinks car is lean, computer maxes out all fuel trims. Trims are stored in memory an used at start-up. Computer is then dumping ASSLOADS of fuel into the engine at start-up. Checked O2 sensor. It's OK, and so is the other one I tried it with. Same results.
Last time I Seafoam-ed, the masses of smoke pouring out from under my heat shield told me about the huge cracks I have in my exhuast manifold. Everyone I have asked tells me that those cracks will allow air into the exhuast, causing the O2 sensor to stupify the computer.
It makes sense; looking at my data logs, the only time the O2 sensor reads is when I really get on it-when the exhaust is thouroghly pressurized with gas. And before anyone else chimes in, yes the O2 heater circuit checked out OK.
I need to get away from the computer and find out about getting those cracks welded up. I need to drive to Chicago for Xmas, and my new exhuast won't be here in time. I'll try to let you all know somehow if this fixes it.
I'm starting to feel that maybe a lot of otherwise good cars have been junked or sold due to cracks in the exhuast manifold!

 

[JusMX141]

I just rebuilt the engine in a 1G N/T that had MASSIVE cracks in the exhaust manifold and it ran just fine after the rebuild. No rich conditions at all. I ended up replacing the manifold for the customer anyway (eBay had them brand new for $42 shipped), but the operating condition was the same with the new manifold as it was with the old one.

As far as a cracked manifold causing an extreme rich condition, I think this myth is busted.

 

[brownfinger]

I just rebuilt the engine in a 1G N/T that had MASSIVE cracks in the exhaust manifold and it ran just fine after the rebuild. No rich conditions at all. I ended up replacing the manifold for the customer anyway (eBay had them brand new for $42 shipped), but the operating condition was the same with the new manifold as it was with the old one.

As far as a cracked manifold causing an extreme rich condition, I think this myth is busted.

DUDE! I was out in my garage taking off my manifold when you wrote this! I got it off (1st time in 200000 mi, thank god for leaky valve covers!) and then came inside and read your post. I'm not glad to hear that maybe a new manifold won't make my O2 sensor read right, but I was just able to cancel my order for a $120 cheesy header. It would have shipped within hours. I ended up talking to some nice people who in Mumbai, India who canceled my order I placed over eBay from some place in California, selling stuff imported from China. Then I ordered the manifold you mentioned. Thank you!
The car has remained unmodified this long, it's easier to keep it that way: Especially for 1/10 the MSRP of a factory part.
As far as the O2 sensor/exhuast leak thing...Please God, I hope you are wrong. To recieve conflicting information shouldn't be new to any of us.
tsi1991awd...You need to get appropriate guages/meters whatever diagnostic thingamajiggies connected to stuff before you go assuming things are or are not OK. PLEASE take my word for it! I've dumped tons of loot into new parts that I didn't need. I even used all of the appropriate diagnostic thingamajiggies to accurately determine that the part was really, truly out of spec before buying a new one, and even then it still didn't fix my problem.
I got a B&M fuel pressure guage from extreme PSI for $30. Never guess your fuel pressure again! Cheaper than a test guage, and always hooked up.
If your plugs are carbon-fouled, it's running rich.

 

[JusMX141]

Don't buy one of those sh!tty Chinese tubular headers. Here's where I got the new manifold for my customer's car (in case anyone else was wondering):

eBay Motors: EXHAUST MANIFOLD mitsubishi ECLIPSE 90-94 auto 91 92 93 (item 370123010235 end time Dec-31-08 01:12:39 PST)

The part I got was a brand new Dorman part, which would've cost almost $100 at a parts store. The fitment was great, but I destroyed the old o2 sensor because they didn't have the o2 hole drilled deep enough for the sensor portion to protrude properly. Once I fixed the hole and installed a new sensor (the old one needed replaced anyway), everything was good to go.

Apparently this seller bought up all of the old Dorman manifolds that were slow movers and decided to unload them on eBay. It doesn't matter....I got a hell of a deal, and my customer was happy as hell that I saved him so much money!

 

[tsi1991awd]

Well my speculations were confirmed. When I pulled the rail (inlet hose and FPR still attached) injector number 2 had a constant drip. Two or so drips per second. Injectors 1, 3 and 4 were not as much but they did leave a little puddle on the VC after 15 or 20 seconds. I could push the pintles closed with my finger but they came back down.

Installed black tops and everything works perfect...changed the plugs as well. I'm assuming it did run a bit rich since the injectors were leaking.

Also took a look at the CTS and it checked out OK like always. But I noticed at the plug, the insulation was coming off of the wiring and I assume the wires were touching causing a possible short....fixed those wires and the car starts on the first try no matter what.

My battery was also shot to hell. Wouldn't hold a charge, got it tested and charged and tested again and it was definately bad. When I was cranking in the car, it had 5v. 12v otherwise. During the testing, it dropped to 8v after an hour of charging.
So the problem was a combination of leaking injectors, fouled plugs, faulty CTS wiring, bad battery

Hope this can help someone else out in the future.

 

[brownfinger]

Don't buy one of those sh!tty Chinese tubular headers. Here's where I got the new manifold for my customer's car (in case anyone else was wondering):

eBay Motors: EXHAUST MANIFOLD mitsubishi ECLIPSE 90-94 auto 91 92 93 (item 370123010235 end time Dec-31-08 01:12:39 PST)
The fitment was great, but I destroyed the old o2 sensor because they didn't have the o2 hole drilled deep enough for the sensor portion to protrude properly. Once I fixed the hole and installed a new sensor (the old one needed replaced anyway), everything was good to go.

You are just full of usefull information, jusmx141! Thank You! That's the exact manifold I ended up ordering, and O2 sensors are expensive!
We almost completely hi-jacked this thread, too.
Then, finally, tsi1991awd, you come back on with even more usefull information! Just today I came to the conclusion that my car is suffering from more than one problem. My fuel rail would have come off today, too, except the obligatory Xmas-ness sort-of commanded my attention.
You guys rock. Happy motoring, and merry New Yeeeaaaar!
P.S. gotta mark it 'resolved', don't ya?

 

[dsmfa9nutter]

Yes your battery would be dead, you used it to crank the car a thousand times before it would start.


Temp sensors people! Change them, that's more than likely the problem. They DO wear out and they cause hard starts. A dead temp sensor will tell the ecu that it's -50* outside. The ecu then DUMPS GAS into the cylinders, flooding the engine, making you crank it 50 times before it will start, and fouling plugs. These issues always show up when it starts getting cold out. It's a $35 part at autozone.

 

[tsi1991awd]

Yes your battery would be dead, you used it to crank the car a thousand times before it would start.


Temp sensors people! Change them, that's more than likely the problem. They DO wear out and they cause hard starts. A dead temp sensor will tell the ecu that it's -50* outside. The ecu then DUMPS GAS into the cylinders, flooding the engine, making you crank it 50 times before it will start, and fouling plugs. These issues always show up when it starts getting cold out. It's a $35 part at autozone.

No actually the temp sensor has been fine all along. Every time I tested it, it was in working order. The wiring also shows the correct voltage. It was when the plug was attached to the sensor that it twisted the wires, so to speak. Bare wires touched and the problem ensued. So if the sensor checks out fine, check the wiring next.

 

[darryloake]

if your running bigger injectors then you need some means of controlling them, i would not suggest a safc ### they are junk. unless you have some means of contorlling ignition timing too. even then all it does is mess with the amf signal so the injectors send less or more fuel.also if you have an aftermarket fuel pump u would need some way to return the fuel fast enough as a stock one really doesnt flow enough to compensate for a 255. i assume your running a maf setup, clean your maf with intake cleaner, get new plugs. are you running bpr6es plugs? from ngk becuase that is the temp plug that u should have if your going to a colder plug like a bpr7es this will cuase your burn to be less intense. the plugs being fouled is what is giving u toruble starting. your injectors most likely are not leaking unless they are old or you bought them used. first clean ## maf out of the car, change ## plugs run stock fuel pressure and if u still have torubles then get ## injectors flo tested or just buy new ones. hope this helps if u have quesitons ask. a mod list would be helpful to diagnose your problem pal.

good luck