bbbc78

Ok here is my problem. I my car most of the time will start with cyl 7-12 off. This happened after i replaced my coil pack that had a couple of bad coils missfiring. My car turned off on me and i pulled a crankshaft position sensor code. Sensor has been replaced and still my car runs on passenger side only. This was not the case before the coil swap. I also swktched out the transformer in the middle of the engine. When the car randomly does run on all 12 it runs great. Boost works and no cel. Then start it back up later and back to the same problem. The missfires show up on das before the car is even started sometimes after being cleared of course. I feel like something is forcing it into limp mode but i cant figure out why changing the coil pack would do this. Either can my mechanic that i have it at currently. Any thoughts would be greatly appreciated since I dont want to keep throwing parts in no real direction.

Here are our thoughts so far
Ground to the pack
02 sensor
Ecu

No codes come up for any of those though.

Welwynnick

Were the plugs changed when the coil pack was changed?

Could you put the old col pack back in, and see if you can get back to where you were before?

Nick

bbbc78

Yes new spark plugs were put in. I didnt gap them but they are the laser iridium ngk. I would think if it was the plugs it wouldnt run fine without misfires randomly. I have put 2 different packs from v12icpack.com and 2 voltage regulators. He actually came to my house to make sure it wasnt the parts.

I also forgot to mention that my ic pump is working and checked after coil install.

Welwynnick

OK. What's the part number of the plugs?


Nick

bbbc78

Ngk laser iridium Ifr6q-g (5648)

kraut56

my 2002 NA V12 has for each coil pack a rather hefty ground wire to the most forward bolt holding the coil pack down (i.e the ground is not via the block, but via the harness). You may want to check that this ground has no resistance or corrosion.

I am not aware of any engine limp mode other than the transmission limp mode due to faulty transmission speed sensors.
good luck!

bbbc78

After testing wires it seems there is resistance in one of the grounds the shop says. I will hopefully find out today if this solves the issue. I still feel like there is a sensor telling that bank to shutdown but ill be happy to be wrong if i get it back running on all 12 cyl today. Fingers crossed.

bbbc78

Well i didnr get a call saying to come pick up my car thats fixed. Im assuming the ground idea didnt fix it. Does anyone have experience with this issue?

bbbc78

Ok well it lookslike im going to revive this thread. It helps to read and see this misfire history hopefully. After i switched the Voltage transformer all was good... for about 4 months (600 mile). Now my right side is dead 1-6. Changed the right coil and vt again and spark plugs and valve cover while i was in there. No luck.
Car starts on 12 and shuts down 1-6cyl in seconds unless i keep my foot on the gas and keep rpms up. Then i can get it to stay running on 12 for a bit. As soon as i put it in drive it shuts down right bank.

yes i have star. Yes i have checked 02 sensors in star. Seem to be ok while running on 12. Took it to the shop in oct. They went through wiring harness and replaced coil 2 more times. Checkedfuel pressure. Had ecm sent to east coast and tested. They finally gave up.

now i droppedit at the dealer. They think o2 sensors shorting. I said ok but now they also think whole wiring harness.

so then i showed them i can make it run on 12cyl if i keep the rpm up. I asked since its the same 02sensors and harness they think is bad then why does it run on 12 with no codes with the gas pedal pressed. They are going to get back to me they said.

any ideas? Other codes were p410 secondary air and i have an abc system pressure low after the system is pressurized and then i let it sit for about an hour. If i let it sit overnight its fine until i turn it off for an hour and restart. This happened after i changed my accumulator in front driver wheel well.

any suggestions are greatly appreciated. Ive driven this car less the 1k miles in 15 months and spent $6k.

tusabes

Welwynnick

Was it?
What?
Where?
When?
Who?
How?
Why?
Nick

tusabes

bbbc78

Yep all plugs gapped and checked twice. It acted the exact same after changing plugs and after re checking gaps. Plugs are definitely no doing it. I get the car back tomorrow and im gona switch o2 from left to right and see where we stand. Ill update then.

bbbc78

Picked up car from dealer. Report says 02 sensors found stuck at 20mv right and 78 mv left. It then says they disconnected both and missfires were not present. I got home and disconnected them both and then one at a time and i still got the bank to drop. It seems to happen as soon as i put it in drive. Sometimes i can get it to stay on 12 for a bit but as soon as i drop it in drive it drops the bank. It will do it in park most the time too but its instantly when i put it in gear. Still thinking o2 sensors i will swap left to right after it cools. Does anyone know the 02 socket size off the top of their head before i go get one?

Racin_fool

if you can access them with a wrench, its a 22mm.. same size with a spark plug socket (22mm) if you need to get them off that way.

wallyp

Otherwise known as a 13/16".

Sensors can be tough to remove. If you are sure that you will be replacing them, you can just cut the harness off (of the old one only!), which will allow you to use a box-end wrench/spanner or a standard socket. Reinstalling is then done with an open-end wrench, or with the special socket with a slot in the side.

Welwynnick

It does sound like a tough one. Lambda sensors are a bit complicated, and you can't really say they're OK from any sort of single spot measurement.

Modern 3-way catalysts for gas engines run by simultaneously oxidising and reducing the exhaust gases (which sounds like a contradiction). The unwanted exhaust constituents are carbon monoxide (CO), unburnt hydrocarbons (HC), and oxides of nitrogen (NOx).

In cruise and idle, the engine runs close to stoichiometric by using closed-loop feedback from the lambda sensors. However, the mixture is continuously oscillated between rich and lean several times per second in order to provide a supply of both oxygen AND carbon monoxide in the exhaust together (if the mixture was spot-on, there would be just water and carbon dioxide, which cannot oxidise or reduce the unwanted exhaust gases).

The lambda sensors will detect this oscillation if they're working OK, and you can see the oscillation on a good OBD2 code reader. You need to be able to see this oscillation to diagnose lambda sensors, and you'll see it best on a real-time graph. Lambda sensors normally last quite a long time - say 100k miles if they're treated OK - but oil, anti-freeze, lead or fuel additives will screw them up. As they get older they get slower :-) and can't react quickly enough to display the mixture oscillation by the engine. If you cannot see several cycles per second between rich and lean when monitoring the output, then it's a sign that the sensor is worn out.

Finally, lambda sensors usually exist in pairs - a control sensor and a monitor or diagnostic sensor. The control sensor sits upstream of the catalyst, or on the catalyst itself, and this is what controls the engine mixture. The monitor sensor sits downstream of the catalyst, and is just there to make sure the first one is working, and this is the simplest cause of the CEL light.

If the sensor really is bad, then the mixture will be out, and there will be a CEL light and some OBD2 mixture warnings. However, it can get old and weak and need replacing even if the mixture is controlled adequately.

Replacing the lambda sensors isn't a big deal, though the V12 isn't easy to work on, of course. They DO NOT have to be expensive. They're a commodity. Some are three wire, but most are four wire, and you can use most sensors on most cars, as long as the connector is the same, which they usually are.

So there's little harm in replacing all the lambda sensors, especially if they're old, but it might not be the fix. Kind of like replacing spark plugs on an engine that isn't running right, and it still doesn't run right, but it's worth trying anyway.

Having said all that, I would start with looking at some of the simple things like the air filters and fuel filter, if you haven't done so already.

Make sure there are no leaks in the intake system.

Does it make any difference to the engine running when you put your foot on the brakes? There are quite a lot of vacuum & pneumatic pipes under there...

Nick

Welwynnick

Does it make any difference whether the engine is hot or cold?

bbbc78

No difference when using the brake. It does seem to stay workin on 12cyl in park a little easier after driving it and its warmed up. Fuel filter was changed with oem when i started this thread along with air filters. So its been about 18 months. Only 1500 miles probably cause its been in the shop the whole time. I dont have a shop to work on it so im really hoping someone here is smarter than sds. It wont give me anything but the damn 7 misfire codes. 300-306. O2 sensors are going to get switched tomorrow... no time with work lately.

ItalianJoe1

I'd still suspect a coil or VT issue. There just aren't that many other parts of the system that can do that. Nothing else will disable the whole bank like that without setting other codes.

I'd be checking for proper grounding of all the ignition system and the engine itself. If a ground wire is loose or in poor condition it can cause these types of issues that are impossible to troubleshoot with normal diagnostic testers.

bbbc78

Yeah i agree. My mechanic already went through and re soldered the gorounds in the harness that run on top of the engine. Everything tested fine but we had nowhere else to go. Its been 3 different (2 new) coils on right side and i have an extra vt from clark ( v12icpack). He actually lives about an hour from me. No change with any of that... still same.

ItalianJoe1

Have you tried a new transformer?

bbbc78

Well i put a new one on in april of last year which solved my left side problem. Then in oct i tried the new fused vt from clark after replacing the coil the first time. When the last vt went out it seemed to always start on 6 cyl. When i switched it with clarks whiched worked on his car... i got the exact same issue as i had. Starts on 12 then drops right bank after a few seconds unless i keep on the gas and it always drops right side when i put it in drive. All the voltages check out from dealer and indy shop from the vt also. I like the ideas. Keep them coming please. When my vt went out last time i had a code for it too.

driveability

Hello,
What a nightmare !!!! I would start the engine letting it idle and at the same time start tugging all the wiring harness listening very carefully to any engine changes. I would also tap/slap different sensors and computers. I would wiggle the wires individually. The entire bank dropping out is fault likely related to
that circuit that shares across that bank. I would see if the injectors are getting the voltages one would expect to see. Power 12 to 13 volts. On a side note make sure your charging system is working along with the battery health. Make sure there is no obstruction in the air intake for that bank. You do have an intercooler
on that bank along with a turbo system. Maybe run the engine with the air filter, turbos out of the way. Run it without the air filter and intercooler off. see if anything changes ?? Might need to secure another vacuum source for the MAP sensor. i would concentrate on the engine harness and connectors for sure.Wondering about the injectors ? the fuel rail on that side of the engine ???
John

captearlg

How old is the gasoline? Since you have been working on this for 18 months, you may have fixed it several times and not known it due to old gas.
The crap with ethanol in it that they call gasoline has a shelf life of ONE WEEK TO ONE MONTH.
I had similar problems and drained the gas and replaced the filter and added new crap er gasoline and it has been good but I do add Stabil to the crap.
Earl