1998 Q45 - should I junk it?

[duck_3986]

Hi,

I love my Q. I'm the 2nd owner (first didn't maintain it well for 62k miles), had it for 13 years and have put 117k miles on it.

Yesterday it suddenly ran rough. No code for a few hours, then I got "random engine misfire". Pulled coils one at a time and found one where the engine idle didn't change when I pulled it, so I then pulled the plug....oily w/ some caking, unlike the others which were dry and light greyish.

I replaced the plug and the coil.....and I know, I should have tested the coil first. Turns out the coil works fine. I did a compression test. That cylinder is about 100psi, the cylinder next to it was 140. I assume I have a bad head gasket (I do see oil seeping) or a bad ring or a bad valve.

Anyone tackle a head removal on the right side of the engine? With 179k miles, I'm not willing to spend $2k+, which my mechanic friend says it would probably cost.

Does the Q have adjustable valves?

If I decide to get rid of the car, I figure it's either sell it for parts or donate it. Anyone need a parts car? The transmission is perfect, with only a 100K on a factory rebuild, and I've regularly changed the fluid w/ Mobil 1.

Thanks for the help,
Don in New Hampshire

[elwesso]

How do you know the coil is working? Did you swap it to another cylinder?

I doubt the head gasket is bad, the oil leakage is most likely coming from the valve cover gaskets, not the head gaskets.

100PSI compression should be enough to at least make the cylinder fire.. Spec on the compression is about 180 with 140 being the minimum. When you did the compression test, did you take all 8 plugs out or did you just take those 2 cylinders apart? If you dumped oil into the cylinder and it made the compression higher then you know the issue is the rings.

At 180k miles the engine should still be pretty healthy... On my 94 Q, I did a compression check on all 8 cylinders and I still had almost brand new spec compression on all 8, both hot and cold! My car has been well maintained but driven HARD...

[duck_3986]

thank you very much for the reply.

I bought a new coil, installed it and rough idle/misfire was still there. Then I did something I should have done to start with....I took the old coil, put a plug in it, connected that cylinder's electrical connector and grounded the plug. With the car at idle it was sparking just fine.

So with both the old coil and a new coil, the misfire continued.

I didn't take out any plugs other than the bad cylinder when I did the compression test. Then I took out the plug next to it....that's the one that read 150.

I'm probably jumping to conclusions, but if I have spark.....and I believe I have fuel because I can smell the car running rich, then I'm assuming I have a cylinder/valve/ring issue.....and believe me, I'm so hoping I'm wrong because I just sunk money into new snow tires, rear brakes, two new Oxygen sensors and some exhaust repairs. Also, I really do love the car.

Is it possible the injector is flooding the cylinder? Has that been a problem others have experienced? When I took the new plug out to do the compression test, it was wet with fuel.

I didn't put oil in the cylinder because I figure if I have bad rings, valves or head gaskets, it's probably not going to be something I would have fixed.

Thanks again,
Don

[duck_3986]

I just did an ohm test on a few injectors. They're at 11 (including the one on the "bad" cylinder). I also did a screwdriver "listen" test and could clearly hear the "bad" cylinder clicking away at idle.

I had driven the car 10-15 miles on a new plug in that cylinder, but with the injector unplugged. It was pretty black/carboned up....not sure if that means something, like oil getting into the cylinder.

So I left the injector unplugged and put a dry spark plug in and started the car. I want to see if, after idling for a few minutes, if the plug would be wet. It wasn't.

Then I plugged in the injector and pulled the plug after a few minutes of idling. Was still dry.

I plugged in my scanner and the bank 1, oxygen sensor 1 is reading .63 at idle. Bank 1, sensor 2 is .92

Bank 2, sensor 1 is mostly reading .07-.09 with occasional bounces up to .5. Bank 2, sensor 2 is .8

Bank 2 is the right side of my engine, where cylinder 1 is located and it's where I'm getting the misfire code.

I'm guessing my oxygen sensors on the right side/bank 2 side are getting those reading because of raw fuel passing by.

[elwesso]

Don, by only taking out the one spark plug and doing a compression test isn't really telling you the true compression. A compression test needs to be done with all 8 plugs out and the throttle opened all the way...

The fact that it suddenly is running rough wouldn't seem likely that the "low" compression on that cylinder would have anything to do with it. It would take a long time of that cylinder misfiring (running rough) for it to wear out that much faster than the others.

Injectors really aren't very problematic on that generation Q, so I wouldn't suspect that. The most likely cause is the coil. I would still be interested if you moved the coil to another cylinder if it followed it. Seems unlikely since you got a new coil (from where?) and it made no difference.

Coils have a tendency to fail very intermittently, making tracing these issues very difficult.

Have you ever replaced all 8 plugs with NGK laser platinum? You don't want to use any other spark plugs in that engine but the NGK's, NO EXCEPTIONS.

Personally what I would consider doing is if you're concerned about the internal health of the engine is take all 8 plugs out and do a proper compression test, and if they haven't been replaced recently, go ahead and put new plugs in it. If you do have one cylinder that's on the low end, dump some motor oil into the cylinder and see if the compression goes up, if so you have bad rings.

The valves on the Q engine are not adjustable. Valve lash is automatically adjusted by the HLA's (hydraulic lash adjuster)..

[duck_3986]

I'll do a proper compression test, but can I ask why it would matter to have the plugs out of cylinders on the other side of the engine?

I'll also try swapping coils from another cylinder too. Both the new coil and the coil I though was bad both were visually sparking at idle when put a plug in it (out of the engine), connected the wire pack and grounded the plug.

I had NGK plugs in it for about the last 90k miles, which was the last time I swapped them out. The engine has run like a champ with good mileage, so I know those plugs, although not the laser ones you mention, did well. There was only one plug that was fouled and in really bad shape...cylinder 1. I've tried both a new NGK and one of the NGK's that had been in a cylinder that was running fine. No change in the stumble.

Any thoughts on why the new plug, with less than 20 miles on it and the injector disconnected would be all black/carboned up?

Thanks,
Don

[elwesso]

The reason the compression test won't come out right is because the engine has to get to the maximum speed the starter can crank the engine, and if half the cylinders are still allowed to have compression. All it really means is that you won't actually be getting accurate numbers to determine if something is actually wrong. The spec is basically 140-180PSI, so if one cylinder is lower than 140 then you know you have a problem.

Another thing you could try just for fun is a fuel pressure test. The O-rings on the older Q injectors have been known to give people problems occasionally, so it's possible that fuel could be leaking past the injector? Seems unlikely but easy to test. All you need to do is hook a pressure gauge up past the fuel filter, let the system pressurize, and then make sure if it holds pressure. if it doesn't hold pressure, it's possible that fuel is leaking out. I agree with you that the plug shouldn't have been carboned up with the injector unplugged.... if there's fuel leaking into the cylinder, that would explain the carboned up plug and also why the compression may be low on that one cylinder, due to the fuel washing away the oil.

I still think the first thing to do is the compression test just to be sure you know what you're dealing with.

[duck_3986]

I did a proper compression test and now find the cylinders, including the "bad" number 1 cylinder are all 150+

I did the number one cylinder several times and it's at 150-160 psi.

I had driven the car 20 miles with that fuel injector unplugged, prior to doing the compression test. When I pulled the plug, which was clean when I put it in, it was very carboned up....deep black, velvety looking carbon all over it.

so if there's no fuel going to the cylinder, and compression is good, any thoughts on why all the carbon?

Could the egr valve be sending too much exhaust gas to just one cylinder?

Could the egr pipe that I hear sometimes gets clogged affect just one cylinder?

The other plugs continue to look fine and seem to be running well....and if I floor the car, pickup is still quite strong....so I'm guessing the other 7 cylinders are producing decent power.

I'm baffled at this point....I have spark, compression and fuel....I don't get it.

[elwesso]

Well the good news is that you're still within spec easily, so the engine is still in good health.

Did you try swapping the coils and seeing if the misfire follows the coil? Again, coils have a tendency to fail in a funky way, so usually it's hard to distinguish between a good coil and bad coil.. I guess maybe what I might try and moving the coil AND the spark plug to the bad cylinder and see what happens. Again, I don't really suspect an injector issue... I think you might have spark, but maybe not "enough" spark. Besides, injectors usually work 100% or they don't, rarely do they operate sorta half-arse...

If you move the coil and spark plug to the #1 cylinder and you still have an issue on that cylinder, I might suspect an issue with the connector on that coil pack.

I highly doubt it's anything to do with the EGR at all.

[Q451990]

I'd swap all of the coils left to right and see if the problem moves from one bank to the other. If you can confirm that, and you're going to keep the car for a while - the ultimate solution is to just replace all eight coils with new confirmed Hitachi or OEM coils, factory or NGK specified plugs, and be done with it...

Heath

[duck_3986]

I've now tried 3 coils on that cylinder (2 swaps from other cylinders, 1 a new coil) and the problem still persists. Plus, why would there be a carbon build up on the plug when there was no fuel going into the cylinder (during the 20 miles I had the injector disconnected).

I guess it could be something to do with the wire harness, but at idle, with a plug out of the block but still in the coil and grounded, I can visibly see it sparking. Yet the car at idle with the same coil and plug has the stumble at idle.

My battery could be low, but I have to assume the alternator should be feeding plenty of power to the coils, even with a low battery.

I'd rather not go out and buy a new battery just to check that. Maybe I can plug in my charger and start the car, giving the battery some extra juice while at idle.

[Q451990]

Sounds like what happened on my first Q with injector failures. Maybe your injector is physically blocked, but electrically ok. In my case the I had two injectors fail... I don't remember if they'd ohm ok or not... I think they did, but they weren't flowing. At that point I don't know if I knew to ohm test them back then... this was back in the late 90s when we had good fuel here.

Either way, I replaced injectors, had visible spark with my carboned-up spark plug on the corresponding spark plug - but it was too weak to fire the cylinder correctly. After cleaning the plugs with a toothbrush and gasoline (not the recommended way, but it worked) they would fire.

My main point here is that visible spark is not necessarily good enough spark to fire the cylinder.

Heath

[duck_3986]

Good point, but I'm getting a very rich exhaust smell when the injector is plugged in. I was thinking it was more likely that the cylinder was getting too much fuel, but then again maybe the oxygen sensor is making the other cylinders run rich to compensate.

I just wish I didn't have to pull the entire plenum to remove the injector.

[elwesso]

I suppose it's possible that an injector could be bad like that.. Would seem unusual that something like that would get past the fuel filter to cause an issue, but crazier things have happened...

Unfortunately it sounds like this is the next step. This is not something I would put off for a long time because running rich like this will eventually destroy your catalytic converters...

My thought though is that is if you unplug the injector and it's still like this, that must mean it's leaking.

[duck_3986]

I just pulled the upper intake/plenum (the part on top of the runners that the throttle body attaches to.

I found the rubber gasket had wet, seemingly fresh oil on it. Does engine oil run down the enter of the plenum? If so, do they ever develop a leak inside....which would allow engine oil to go into the cylinder, which may be causing my plug fouling mystery.

I took some pictures. I'm pointing w/ my finger to the very front part of the plenum where two rubber hoses meet at a circular connector at the middle of the plenum. These leaked oil when I pulled the plenum off the motor. I assume that's where the oil flows into the plenum.

I also drew pointer to the wetness on the gasket.

I bought a new injector to plug into cylinder one, but I can't seem to get the two screws out. They're almost stripped. any tips?

is it possible to pull the fuel rail up out of the intake, with the injectors still connected, and pressurize the system to visually inspect for leakage? Or is this a bad idea?

Thanks,
Don

[duck_3986]

forgot the pictures in my last post, but I can't figure out how to get a picture posted. sorry for my ignorance, can someone tell me how to post a photo here?

Thanks again

[duck_3986]

Found the problem!

I got the plenum off and pulled cylinder 1 fuel injector. There was a broken piece sitting in the port.

Put a new injector in, buttoned everything up and she runs smooth as silk. No more rich fuel smell, no more rough idle and no check engine light.

I put about 400 miles on the car with it dumping fuel into my exhaust. Do you think I've ruined my catalytic converter on that side?

I did just change the oil. I'm sure the oil was diluted with gas.

I'd like to post a picture of the broken piece if someone can help with posting photos. I tried cutting and pasting, but that didn't work.

Wes, thanks for helping.

Don

[BadQ45t]

A smog test machine will tell you if you fried your cat or not. What state do you live in? In CA every other year you have no choice but to get the test done. If it runs fine I wouldn't replace a cat until you have to.

[elwesso]

If you email me the pictures I'll post them for you. [email protected]

Congrats Don, you had the first reported failure of an injector on a Y33 (97-01) Q that I've heard of.

[elwesso]

Here's the picture..



Anyone's best guess what that is? I have a feeling that whatever is in there wasn't affecting the injector, and just the injector itself was bad.

[liteemup39496]

looks like a pintle cap cover for the injector. ive run cars with and without them but that could certainly be causing your fuel to be pooling and not properly be atomizing into the intake tract. pull it out and A) retry original injector or try a new one you should see a difference.

ive actually had issues with my vh swapped s13 that the coil pack sub harness would stock getting a good connection to that coil pack and would run on 7 cyl. drove me crazy for a few weeks till i found the issue and corrected it.

[duck_3986]

I did put a new injector in and after 700 miles now, the car's been running great! I just hope my catalytic converter holds up on that side. I was definitely getting a lot of raw fuel dumped past the cat for about 500 miles.

Since I swapped several of my new plugs into the "bad cylinder" while troubleshooting, I'm just going to pick up 8 new plugs.

I plan to use NGK, but are the laser iridium or laser platinum really worth the extra money? NGK also offers a V-groove plug that's less than half as expensive as the laser ones.

[elwesso]

I plan to use NGK, but are the laser iridium or laser platinum really worth the extra money? NGK also offers a V-groove plug that's less than half as expensive as the laser ones.

Yes they are, anything other than the OEM plugs have known to have issues in these engines.

Try ebay, you can usually get the PFR5G-11s for under $60 for 8.

[paranoidjack]

hey, 1 yr, 2 yrs, 3 yrs...when the time comes for you to get rid of it, call me first. I'm in MA and need a 2nd parts car for my '00.

Glad you got it figured out! This forum is indispensable and has saved many Q's.

Merry Christmas!