3.3TT Motor idle rough/stalling JB4 + Limp mode

[MLRS777]

Running 3.3t, with BMS intakes, Denso spark plugs gapped to .22, running 93, map 1/2 only. The car has run fine for last 2 weeks after installing JB4, after a drive today that went fine map 1 and 2 no issues. I started the car tonight idled fine, put the car in sport mode and map 2. After driving for a few minutes driving 40mph or less when I came to a stop the car started to stutter, transmission seemed off and jerky, and the engine would increase rpm and decrease randomly and rapidly. Pulled off road and parked car the CEL appeared on dash. I read the codes and it showed P0237, says relating to my map sensor. I turned the car off checked for any connections loose/ smells and nothing from what I saw it was dark. I tried to start car idled rough then stalled, tried again car immediately stalled. I got out locked car and attempted to start again, car started idle seemed okay drive around 10 mins 0 boost limp mode, CEL on still, and car ran okay until I came to a stop, and the engine was sputtering/stuttering again pulled into driveway and turned car off. CEL is still present as well as the code. Hoping or wondering if loose connection, or something not seated or plugged in properly? I have work on Monday hope you will see this so I can try solutions tomorrow.

I’ll also add transmission seems to be shifting fine, and no prior issues with car only 15,000 miles fresh oil change Live in Houston, hot temps outside. Hoping for the best but honestly kind of nervous.

 

[Flynfishmedic]

Clear codes, JB4 in map 0, test drive and see if you have the same problems! Did you do the plugs yourself? Putting the car back to not seeing JB4 will help you isolate fuel, plugs, coil pack issues. If they are GTG then reinstall JB4 checking yourself as you go!

 

[MLRS777]

Clear codes, JB4 in map 0, test drive and see if you have the same problems! Did you do the plugs yourself? Putting the car back to not seeing JB4 will help you isolate fuel, plugs, coil pack issues. If they are GTG then reinstall JB4 checking yourself as you go!

Hello, well I drove in map 0 as well same issue persists, clearing codes does not delete the code or make CEL go away unfortunately. I had a reputable shop in Houston do the plugs for me same day JB4 installed few weeks ago. Thank you for reply and if any other tips I’d be happy to hear!

 

[MLRS777]

Hello, well I drove in map 0 as well same issue persists, clearing codes does not delete the code or make CEL go away unfortunately. I had a reputable shop in Houston do the plugs for me same day JB4 installed few weeks ago. Thank you for reply and if any other tips I’d be happy to hear!

 

[General_Vodka]

Hello, well I drove in map 0 as well same issue persists, clearing codes does not delete the code or make CEL go away unfortunately. I had a reputable shop in Houston do the plugs for me same day JB4 installed few weeks ago. Thank you for reply and if any other tips I’d be happy to hear!

Definitely need to check plugs and coils. And the coil wires. I had a misfire issue but it was just that I forget to plug a coil in all the way. Also what was the map sensor error for?

 

[Terry@BMS]

If you end up needing any technical support just email us, include a log and some install photos.

 

[MLRS777]

If you end up needing any technical support just email us, include a log and some install photos.

Thank you Terry and everyone, I’m driving in limp mode, what would you suggest If the code states it is a map sensor shorted to ground or faulty map sensor. That’s What the code states at least

 

[Flynfishmedic]

Any updates on your issue?

 

[MLRS777]

Any updates on your issue?
going

Definitely need to check plugs and coils. And the coil wires. I had a misfire issue but it was just that I forget to plug a coil in all the way. Also what was the map sensor error for?

the only code showing for the car is that P0237 - Turbocharger Boost Sensor “A” Circuit low/ also says could be shorted to ground. That’s why I believe I’m in limp mode with CEL and all boost disabled. Could the JB4 have cause that map sensor error or failure if that’s the case? Taking to the shop today after work they’re going to try and diagnose. I’m thinking it could be a melted wire but I don’t know honestly :/

 

[keplaffintech]

Hi @MLRS777 its been a while. Did you get your issue sorted? Would be good to post here so that anyone in future who has the same issue has a clue.

 

[timbo_slice]

L dealing with currently the same issue, car was running good and then all of a sudden rough idle and trying to stall. Got towed to nearby shop and found map sensor on jb4 and boost sensor are shorting to ground.

 

[timbo_slice]

Currently no resolve, unplugged map and boost sensor and OBD port car then seemed to warm up and run normal have not test driven yet. Inspected wires and motherboard no melted wires are apparent and motherboard doesn’t seem to be fried or shorted not sure cause or complete fix but will update.

L dealing with currently the same issue, car was running good and then all of a sudden rough idle and trying to stall. Got towed to nearby shop and found map sensor on jb4 and boost sensor are shorting to ground

 

[timbo_slice]

Currently no resolve, unplugged map and boost sensor and OBD port car then seemed to warm up and run normal have not test driven yet. Inspected wires and motherboard no melted wires are apparent and motherboard doesn’t seem to be fried or shorted not sure cause or complete fix but will update.

After diagnosing issue appears to be a bad motherboard, no apparent water or moisture damage but after swapping a separate board in car ran perfect as before. Runs good with jb4 unhooked, Ordering new board will verify once I receive.

 

[Royal]

After diagnosing issue appears to be a bad motherboard, no apparent water or moisture damage but after swapping a separate board in car ran perfect as before. Runs good with jb4 unhooked, Ordering new board will verify once I receive.

Did it resolve your issue overall? Have a similar issue with my jb4 on my forte gt have a limp mode first install reinstalled it and ran fine for a week then got a rough idle when in stoplights or parked when running map 1 or 2 and went away when in map 0, seems like it may be a bad motherboard.

 

[2SCARGO]

i have a misfire code P0303 replaced plugs and swapped coils. code still on only on #3 any suggestions on a fix

 

[Royal]

i have a misfire code P0303 replaced plugs and swapped coils. code still on only on #3 any suggestions on a fix

perhaps a bad motherboard?