[Exxxtacy]

I've been having a problem when I have my jb4 on map 1,2,5 and the car hits 15lbs it falls on its face and has a misfire. Once I turn the car off and then turn jt back on its fine. The misfire changes from cylinder to cylinder when it happens. Plugs were changed with oem bosche.

I took it to the dealer stock and that was a lose cause cause they couldn't make the misfire happen seeing it would only happen when the car hits approx 15lbs which doesn't happen stock.

Thinking maybe the map sensor is failing? The car runs no problems under WOT with the jb4 off on stock 5lbs. I cleaned the sensor off and tried it and that didn't help. Possibly it's failing under the amount of pressure? I don't just wanna start throwing money at random parts. Thought I would see what other people may think or if anyone had the same issue.

[mojobmw_e90]

Spark plugs, Ignition coil, fuel injector. From cheapest to expensive. I had a same issue. Replaced the oem Bosch with ngk step colder plugs and problem fixed. Seems to me that plugs last between to 8k to 12k depending on hard you drive the car.

[Exxxtacy]

Originally Posted by mojobmw_e90

Spark plugs, Ignition coil, fuel injector. From cheapest to expensive. I had a same issue. Replaced the oem Bosch with ngk step colder plugs and problem fixed. Seems to me that plugs last between to 8k to 12k depending on hard you drive the car.

Yeah I know plugs can fail sooner then most. I had them replaced not long ago due to a misfire but when I replaced them I found oil all over them which was the valve cover leaking which caused my misfire. This was before Christmas and ever since then I have had this never ending misfire.

[mojobmw_e90]

U can try getting race gas or e85. See if higher octane will fix it. This way you can eliminate gas being a cause.

Did you ever get the valve cover fixed? If it's covering the spark plugs in oil that sounds like your problem.

I had exactly the same issue. Get some better plugs and see what happens. Step colder is what I recommend and been running for over a year

[Exxxtacy]

Originally Posted by mojobmw_e90

U can try getting race gas or e85. See if higher octane will fix it. This way you can eliminate gas being a cause.

Did you ever get the valve cover fixed? If it's covering the spark plugs in oil that sounds like your problem.

I had exactly the same issue. Get some better plugs and see what happens. Step colder is what I recommend and been running for over a year

Yup I got it covered. I haven't tried better gas then 93. I'd be surprised if it's the gas since its been happening a little while now. I just turned the tune off and I don't have the problem but now I'm getting tired of not enjoying my car lol

[Hilly]

My car is sitting at the dealer right now being fixed as I type this. The issue I had seems very similar to you. Only on WOT my car would get a misfire boosting around 15psi. I thought initially that it was a bad coil or something and mentioned it to the dealer. Well they had a hard time figuring it out (took them around three days) but it was a bad low pressure fuel sensor. Will hopefully get the car back Monday and it "should" be good to go....maybe that is your issue

[924er]

Originally Posted by Exxxtacy

I've been having a problem when I have my jb4 on map 1,2,5 and the car hits 15lbs it falls on its face and has a misfire. Once I turn the car off and then turn jt back on its fine. The misfire changes from cylinder to cylinder when it happens. Plugs were changed with oem bosche.

I took it to the dealer stock and that was a lose cause cause they couldn't make the misfire happen seeing it would only happen when the car hits approx 15lbs which doesn't happen stock.

Thinking maybe the map sensor is failing? The car runs no problems under WOT with the jb4 off on stock 5lbs. I cleaned the sensor off and tried it and that didn't help. Possibly it's failing under the amount of pressure? I don't just wanna start throwing money at random parts. Thought I would see what other people may think or if anyone had the same issue.

What thoughts are u expecting to hear from ppl with no other data or codes. Misfires are treated by sparks/coils/injectors/HPFP etc. go read the misfire thread. I had the same problem as you where the car would only misfire when tuned.

I suggest I start reading codes and swapping sparks and coils. If that doesn't work get ready to spend $$ on injectors.

You said ur valve cover gasket is leaking too. I seen that cause misfires. Why not fix that ?

[Exxxtacy]

Originally Posted by Hilly

My car is sitting at the dealer right now being fixed as I type this. The issue I had seems very similar to you. Only on WOT my car would get a misfire boosting around 15psi. I thought initially that it was a bad coil or something and mentioned it to the dealer. Well they had a hard time figuring it out (took them around three days) but it was a bad low pressure fuel sensor. Will hopefully get the car back Monday and it "should" be good to go....maybe that is your issue

Hmmm interesting. Back when I had the misfire due to the valve cover gasket I thought of that being a possibly issue. I have a warranty still on the car which is why I never took it to them with the tune on so I didn't get screwed. Keep me updated on how it turns out for you.

[climax_e92]

Originally Posted by Exxxtacy

I've been having a problem when I have my jb4 on map 1,2,5 and the car hits 15lbs it falls on its face and has a misfire. Once I turn the car off and then turn jt back on its fine. The misfire changes from cylinder to cylinder when it happens. Plugs were changed with oem bosche.

I took it to the dealer stock and that was a lose cause cause they couldn't make the misfire happen seeing it would only happen when the car hits approx 15lbs which doesn't happen stock.

Thinking maybe the map sensor is failing? The car runs no problems under WOT with the jb4 off on stock 5lbs. I cleaned the sensor off and tried it and that didn't help. Possibly it's failing under the amount of pressure? I don't just wanna start throwing money at random parts. Thought I would see what other people may think or if anyone had the same issue.

I had the same problem for a year. It only miss fired 5 times in the last 10 months. Then after i switched from G4 board to G5 iso with 2 step, it miss fired 3 times this month. Always same cylinder 5. I just replaced the ignition coil with a new delphi one a the dealer for $43 with tax and it hasn't been an issue since. Car runs a lot stronger also through all the gears just by swapping that 1 coil. Hope this helps.

[Exxxtacy]

Originally Posted by 924er

What thoughts are u expecting to hear from ppl with no other data or codes. Misfires are treated by sparks/coils/injectors/HPFP etc. go read the misfire thread. I had the same problem as you where the car would only misfire when tuned.

I suggest I start reading codes and swapping sparks and coils. If that doesn't work get ready to spend $$ on injectors.

You said ur valve cover gasket is leaking too. I seen that cause misfires. Why not fix that ?

Well for one valve cover was fixed which I did say. Secondly there are no codes other then which cylinder is misfire WHEN its happening.

[climax_e92]

Originally Posted by Exxxtacy

Well for one valve cover was fixed which I did say. Secondly there are no codes other then which cylinder is misfire WHEN its happening.

Try swapping 2 coils around and see if the problem follows? Or just buy a spare ignition coil at the dealer. I have 2 extras. Cylinder 5 was always the one that would miss fire so after putting a new coil on that i haven't had a problem since.

[climax_e92]

Mine doesn't switch me to map 4 when it happened. I would get the engine light. I would have to restart the car to fix it before.

[Hilly]

Originally Posted by Exxxtacy

Hmmm interesting. Back when I had the misfire due to the valve cover gasket I thought of that being a possibly issue. I have a warranty still on the car which is why I never took it to them with the tune on so I didn't get screwed. Keep me updated on how it turns out for you.

I do have a tune on my car and also have a warranty (route 66). I only set it to 0 before I take it in and never had any problems from them. Maybe just lucky I guess not sure. Should get car back tomorrow.

[Exxxtacy]

Originally Posted by climax_e92

Mine doesn't switch me to map 4 when it happened. I would get the engine light. I would have to restart the car to fix it before.

I also don't get thrown into map4. Stays which ever map i happen to be in. When it happens I get the SES light.

[Exxxtacy]

Originally Posted by Hilly

I do have a tune on my car and also have a warranty (route 66). I only set it to 0 before I take it in and never had any problems from them. Maybe just lucky I guess not sure. Should get car back tomorrow.

I'm not that lucky. Those dude always found it. Maybe the "burger tuning" stickers don't help

[mojobmw_e90]

Originally Posted by Exxxtacy

I also don't get thrown into map4. Stays which ever map i happen to be in. When it happens I get the SES light.

This just points out to spark plugs. Does the car drive and idle badly after the misfire?

[Exxxtacy]

Originally Posted by mojobmw_e90

This just points out to spark plugs. Does the car drive and idle badly after the misfire?

Drives badly yes. Idling not sure. I never let it idle when it happens I turn it off right away. When I accelerate its bad and has practical no power.