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Discussion Starter #1
Just trying to work some of the kinks out of her. I have a very interesting knock problem. It's not getting very high, 4 at the most but mostly just 1 or 2. I just want it gone. Anyway, it mostly only happens if I hold the throttle at a constant point, and it occurs most if I hold it to where I am showing 0psi on the boost gauge (aftermarket). What is really interesting is I can somewhat control how many counts of knock I get. I can hold it at 0psi and make it knock all day long. Most of the time I am in 3rd gear at around 30-40mph when I hold it at 0psi. I have searched quite a bit and read something about a low load-high throttle knock thing, but I didn't find any cases where there was a solution found. On the contrary, if I put the throttle all the way to the floor and haul bootie at 12psi through all of the gears, I have absolutely no knock at all. I would think that if it was a fuel issue, it would knock at 12psi rather than 0psi. I have concluded it is not phantom knock because of two reasons: 1) I can make it knock as many times as I want by holding the throttle at a certain point. 2) I have cruised around town at 30mph in 4th gear and stomped on the gas to sort of "shock" the drive train. I have done this repeatedly and will not get any knock counts.

I have a boost controller set to ~11-12psi on 9bs. Stock fuel system. Fuel filter was replace ~5k ago.
I have vacuum tested multiple times and I am not leaking anywhere except my boost controller is leaking a little. I have ordered another one, but I don't think it is the problem. I won't know for sure until I swap it. The boost gauge reads ~20vac at idle and is steady.
Since I am 1st gen, I swapped ECUs. (Kinda the first step for anything wrong with the 1st gens. Lol.)
I have replaced the MAF.

I will be honest, I don't really know what the logs mean. I can get you guys logs if you tell me what information you need.

If this helps:
I have read that my air temps don't get much over 130, and I have gotten many knock counts with air temp at <100. My water temp is around 190 degrees F. Valve stem seals are not a problem-I replaced them ~3500 miles ago and there is no smoke, not even a puff after idling extensively. My turbos are not pushing oil. My O2s are wonky. I really don't know where they are supposed to be at except rich and lean. As far as where they are supposed to be due to how the car is running (MAF, TPS, whatever) I have no clue. My mid and high fuel trims are static at over 100%. My low trim stays constant at a given value below 100% (It seems to change with logs, but stays constant within a log.) O2 trim is all over the place.

Additional info: (I'm not sure if these are related or just more issues.)
If I start the car after letting it sit for a while, it runs fine at idle. But if I blip the throttle it will kind of sputter and then resume idle. It usually takes a minute or so for it to stop doing it, but the time does vary.
I have noticed that if I blip the throttle while in the engine bay, my Blitz BOV "sucks" in air, closes, and then the engine will rev up. If I rev it pretty high, then let it go, it will vent the air into the atmosphere like it is supposed to, but when the revs drop, they will go below idle speed, the BOV "sucks" the air in, closes, and then idles at normal speed. Is this normal?

Sorry for the novel. Lol. Just trying to give you guys as much info as possible. Thanks in advance!
 

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Discussion Starter #2
I got some logs for you guys. I actually seem to have gotten these logs on a bad day (or good, depending on how you look at it lol) because I hit a 6 knock count:( Again, I don't know much of what I am looking at, but my front O2 doesn't seem to be doing much of anything. Can anyone confirm this? If you guys need more info or whatever just let me know. Thanks.

The important parts are mostly toward the middle or end of the logs.

Log with knock: 2000-01-16_16_22_41
Log without knock, WOT: 2000-01-16_16_25_35
 

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I took out both of my O2 sensors and put the one from the rear in the front and the one from the front in the rear to plug it, but obviously it wouldn't reach the connector. I was able to see that I get about the same readings from the front bank with different O2 sensors. My front bank is running lean, about 15-20% during normal driving and 10% during WOT. Because of the lean condition of the front bank i'm pretty sure that is where my strange ass knock is coming from. I have confirmed that it isn't the O2 sensor. I swapped out the injectors and had the same result, so its not those either. What would cause only one bank to run lean?
 

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I took out both of my O2 sensors and put the one from the rear in the front and the one from the front in the rear to plug it, but obviously it wouldn't reach the connector. I was able to see that I get about the same readings from the front bank with different O2 sensors. My front bank is running lean, about 15-20% during normal driving and 10% during WOT. Because of the lean condition of the front bank i'm pretty sure that is where my strange ass knock is coming from. I have confirmed that it isn't the O2 sensor. I swapped out the injectors and had the same result, so its not those either. What would cause only one bank to run lean?
A clog in the fuel rail after the input line (not likely) but I would guess a bad ECU.
 

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Wouldn't a clog in the fuel rail make both banks run lean though? It seems as if my rear bank is perfectly normal and my front is crazy lean. I have swapped ECUs and had the same result. I have read that an exhaust leak can trigger false knock but I don't understand at all how. I suppose that could maybe make my O2 reading seem lean if the leak was before the O2 sensor. Even if the exhaust leak was the cause of the bank to be lean, it wouldn't explain how I can make the engine knock whenever I want. Its just so damn weird.
 

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I've thought about it going out but the knock corresponds with my lean condition. I also have thought about the race gas. Idk how that would tell me why my front bank is going lean though. I just don't know where to begin.
 

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Wouldn't a clog in the fuel rail make both banks run lean though? It seems as if my rear bank is perfectly normal and my front is crazy lean. I have swapped ECUs and had the same result. I have read that an exhaust leak can trigger false knock but I don't understand at all how. I suppose that could maybe make my O2 reading seem lean if the leak was before the O2 sensor. Even if the exhaust leak was the cause of the bank to be lean, it wouldn't explain how I can make the engine knock whenever I want. Its just so damn weird.
Not if it is in the bend of fuel line leading to the back bank of cylinders!
The factory piece already has a pretty odd kink in it.

Should be easy to check.

Edit: your problem is reversed. Never mind.

I would think that a bad knock sensor would affect all cylinders since it does not differentiate between cylinders. The engine is either knocking or it is not. I am not an expert on how the ECU responds to engine knock but only leaning out one bank of cylinders seems and unlikely solution that would be programmed.

I would go back to the basics. Check for leaks around the injector seals, both on the manifold and the injectors. Check for fouled plugs, bad wires, bad center coil on the front bank, run ohm test as per manual to make sure they are in spec, and check for any nicked\sliced wires in the harness leading to the injectors (especially around the coolant filler neck and the bend in the harness just at the edge of the battery).
 

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Discussion Starter #10
It seems like most of the stuff you said to check is spark related rather than the air:fuel ratio. Would a fault in the actual spark cause it to run lean? Like only igniting some of the mixture in the cylinder? I have been running some crappy Autolite wires for the last 1k miles. The ONLY reason I bought then was to troubleshoot a sputtering problem. I didn't have the money or time to order some quality wires so I just bought those as a temporary thing. I just bought some MSD wires from Monochrome and they should be here in the next few days. A couple of days ago when I pulled the plugs out they weren't white like I was running lean. If anything they are black, which means I am running rich. But that just doesn't make sense.

I worked on the car a little today and I let the car cool down and then started it up and ran and sprayed the manifold, where the turbo meets the manifold, and the precat with soapy water. There weren't any bubbles coming from anywhere, but it heated up pretty quick. As far as I can tell, there isn't an exhaust leak.

I should get my boost controller and MSD wires in the mail in the next few days. Since I have to take off the plenum to replace the wires, I will go ahead and swap the knock sensor out at the same time. Hopefully that will make a difference.

Thanks for the suggestions. I'll try that stuff out whenever I get a chance, probably in a couple of days.
 

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It seems like most of the stuff you said to check is spark related rather than the air:fuel ratio. Would a fault in the actual spark cause it to run lean? Like only igniting some of the mixture in the cylinder? I have been running some crappy Autolite wires for the last 1k miles. The ONLY reason I bought then was to troubleshoot a sputtering problem. I didn't have the money or time to order some quality wires so I just bought those as a temporary thing. I just bought some MSD wires from Monochrome and they should be here in the next few days. A couple of days ago when I pulled the plugs out they weren't white like I was running lean. If anything they are black, which means I am running rich. But that just doesn't make sense.

I worked on the car a little today and I let the car cool down and then started it up and ran and sprayed the manifold, where the turbo meets the manifold, and the precat with soapy water. There weren't any bubbles coming from anywhere, but it heated up pretty quick. As far as I can tell, there isn't an exhaust leak.

I should get my boost controller and MSD wires in the mail in the next few days. Since I have to take off the plenum to replace the wires, I will go ahead and swap the knock sensor out at the same time. Hopefully that will make a difference.

Thanks for the suggestions. I'll try that stuff out whenever I get a chance, probably in a couple of days.
Actually, I was trying to emphasize that an air leak around the injectors or damaged wire to the injectors was the probable cause. Ohm testing would be my first priority since it is the easiest to perform. Then pull the plenum and fuel rails and inspect them for air leaks\bad seals.

I doubt it is a knock sensor. Would affect both banks, IMO.

I was less convinced you had a spark issue until you said your plugs look like they are fouled with fuel. Unburnt fuel is seen by the O2 sensor and would indicate to the ECU that you are running rich and it would respond by leaning out the engine.
]
I am not an expert on TT's but if you have two O2 sensors, and one is reading one bank and the second, the other independently, than I am "leaning" more and more to a possible spark issue. I am not sure how dual O2 sensors work in the TT's though so I would verify my assumption.

But, bare in mind, that O2 slipping by the injectors can also create a lean condition. The injectors dump more and and more fuel to compensate but it causes the O2 sensors to read rich if unburnt. A vicious circle for the ECU.

Either way, unburnt fuel is getting to the O2 sensors and the ECU is trying to compensate.

I would not be surprised if you find both conditions an issue thereby causing a trouble shooting headache like this.
 

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Discussion Starter #12
That is a very interesting theory. Makes a lot of sense too. The last time I looked at my fuel trims they were pretty far over 100%. That could be killing my plugs. I don't know much about what all of the logging means, but from what I understand, that means the ECU is adding more and more fuel, making me run rich.

Now there's one question: Is the stock ECU capable of leaning out one bank?

How do I go about testing the resistance of the wires and what wires should I test?
 

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That is a very interesting theory. Makes a lot of sense too. The last time I looked at my fuel trims they were pretty far over 100%. That could be killing my plugs. I don't know much about what all of the logging means, but from what I understand, that means the ECU is adding more and more fuel, making me run rich.

Now there's one question: Is the stock ECU capable of leaning out one bank?

How do I go about testing the resistance of the wires and what wires should I test?
Here is a link to the service manuals. They have all the information you need to troubleshoot the injectors and the rest of your car.

3SX Performance - Service Manuals Backups 3000GT / Stealth - Mitsubishi 3000GT / Dodge Stealth Parts

I am not sure if the ECU can lean out one bank or not. I do not own a TT but you might want to ask a TT expert. That is my theory since they have two O2 sensors (one for each bank).
 

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Service manual. Duh:)

I took it out for a drive last night after installing the new boost controller to tune it and I was knocking like CRAZY. I mean, the highest I would get would be like 6 but everytime I hit boost I started knocking. And the situation slightly changed. I now knock at WOT. Fantastic. I really need to get this sorted out but 2 jobs, college, and a VR-4 don't really mesh. Lol. Luckily I have my trusty SL if shit really starts hitting the fan.

On the plus side, I made it to school without it knocking once. :) Of course the highest intake pressure I got was -8 psi (vac).
 

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Well it's taking a while for my spark plug wires to get here. I'm beginning to think my neighbor got them... Anyway. I have been experiencing a misfire during startup sometimes, and I am beginning to think it is related. Earlier I went to move my car and it would start, idle like crap with misfires for about 2 seconds and then die. Almost like it was getting no fuel at all. It did this 3 times and the 4th time I started it, I had to give it a LOT of gas to keep it alive. After about 5 seconds of pulsing the throttle on and off, it was fine. This is the worst this particular problem has gotten. I think that one of the injectors isn't getting enough signal or fuel. I still haven't checked the harness because I planned on doing the spark plugs and wires and checking the harness all at the same time.

Another one of my theories; tell me if this makes sense or if I am crazy:
I have NGK iridiums in right now at stock gap which I believe is like 0.044 (not sure though). I did some reading up on what spark plugs and gap to use for a BPU VR-4 (what my car is +/-). Most everyone recommends NGK coppers (BKR7E) gapped at about 0.035-0.38. This means my gap right now is way to large. The misfire happens mostly on a cold start, meaning the plug is cold. Now, once the car gets a few sparks and a particular cylinder starts warming up a little, the heat will make the spark plug slightly expand, closing the gap a little and then it is able to fire. Basically spark blowout on startup I guess. Is this a valid theory or completely stupid? Lol.
 

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Well it's taking a while for my spark plug wires to get here. I'm beginning to think my neighbor got them... Anyway. I have been experiencing a misfire during startup sometimes, and I am beginning to think it is related. Earlier I went to move my car and it would start, idle like crap with misfires for about 2 seconds and then die. Almost like it was getting no fuel at all. It did this 3 times and the 4th time I started it, I had to give it a LOT of gas to keep it alive. After about 5 seconds of pulsing the throttle on and off, it was fine. This is the worst this particular problem has gotten. I think that one of the injectors isn't getting enough signal or fuel. I still haven't checked the harness because I planned on doing the spark plugs and wires and checking the harness all at the same time.

Another one of my theories; tell me if this makes sense or if I am crazy:
I have NGK iridiums in right now at stock gap which I believe is like 0.044 (not sure though). I did some reading up on what spark plugs and gap to use for a BPU VR-4 (what my car is +/-). Most everyone recommends NGK coppers (BKR7E) gapped at about 0.035-0.38. This means my gap right now is way to large. The misfire happens mostly on a cold start, meaning the plug is cold. Now, once the car gets a few sparks and a particular cylinder starts warming up a little, the heat will make the spark plug slightly expand, closing the gap a little and then it is able to fire. Basically spark blowout on startup I guess. Is this a valid theory or completely stupid? Lol.
Misfires can be caused by a lot of things, most of them we have already touched on. Getting the spark plugs replaced with coppers will save you money and will force you to change them more regularly. I know, more work but it will help you stay on top of fuel related issues (these cars run rich anyway and early fouling is common) , bad wires, vacuum leaks, EGR carbon build up. etc.

It is fairly common for misfires to clear up once an engine warms up but to draw conclusions from this behavior would be premature.

Check your ignition first, then check your injectors\fuel system, check for vacuum leaks, maybe run some chemicals to reduce the possibility of carbon build up.

I would even be tempted to stick in a fuel pressure gauge just to make sure it is not an erratic fuel pump.

Start with the less expensive hardware solutions and easier labor tasks and escalate from there.

Don't think of this as a pain in the butt, but more as a free lesson in engine diagnosis.

:D
 

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I know. That's the price I pay for having a 3S. I'll see if I can get a fuel pressure gauge because I think that will be a very useful tool for now as well as the future. Just giving you guys an update to see if the problem stuck out like a sore thumb. Lol. I'll be able to dig into this once the spark plug wires come in and maybe I can figure this out.
 

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Keeping you guys updated. Just got the wires in today. Unfortunately I wont be able to swap the plugs and wires until next week. I have a linear algebra test Thursday, calculus 2 test Friday, and a physics test Monday:eek:

Spark plug peoples: How does a .038 gap sound on my NGK coppers (BKR7E)?

On a side note, I dropped off a spare plenum to get powder coated today. :D I got there and realized the front valve cover I brought was from a stealth:( I'll just have to make another trip over there to drop off the one on my car. If all goes well, I can do the plugs, wires and plenum at the same time:) The powder coating will cost less than $100 for the plenum and valve cover btw.
 

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Well. Think I found the problem. There is TONS of oil in my intake. The gasket spaces between the ports to each chamber are covered with oil. The oil on my finger is just from wiping one chamber of the plenum. Interestingly enough though, there is practically no oil in my intercooler hoses, y pipe, or throttle body. The only place I was able to find oil in the intake tract was the bubble coming from the MAF. There is oil in the bubble around the small hose that connects it to the rear valve cover. Why would it be sucking in oil from there? And what's even stranger is my oil level is full and has been since my last oil change and I did not overfill. Any suggestions?
 

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You're building up pressure in your crankcase I think. PCV is probably bad. Did you give it the rattle test yet?

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