i wanted to post this here so im not continuing to post in the half power sticky thread anymore....that problem went away with the new hpfp.

after 42 days of driving with no half power mode and new hpfp, i jump in the car to haul *** to orlando for dinner with family at the airport and now the stupid car is missing and backfiring under hard accel. if you go more than half throttle, once it hits about 3000 rpms, it starts popping and backfiring out exhaust like you hit the rev limiter. let off a little and its fine

the car is fun to drive when it rarely acts right....but man im getting tired of working on this thing

i have no codes with the torque app except a p0420.... catless DP

my inpa quit working in that 42 day time span some how...cant get it up and running so far

i have been thru everything on this car trying to get rid of the dreaded half power mode....that has had multiple causes while i was chasing it.

every time i figure out whats causing the issues, 2 other things break

i have walnut blasted twice since the summer of 16. last time maybe 5 months ago

new plugs 15k ago, all new coils as well.... 3 took a dump just from being removed from car to get at plugs

new valve cover, new turbo recirculation valve

adjusted wastegate linkage to remove most of the slop it has...

tested wastegate actuator.... is good

new vacuum pump and lines dec 2015

timing set replaced at dealer before i bought it

im going to pull intake saturday and look at intake valves again

going to go to autozone tomorrow night to get codes if i cant fix my inpa before then

im also going to attempt a fuel pressure leak down test with the torque app tomorrow, not sure it will work tho

any suggestions?

 

does your k+dcan cable have a switch on it?

recheck the timing and check the vanos solenoid.

 

no switch on cable

worked fine like 2 weeks ago. shut down laptop, no one has touched it since.

booted up to check codes, inpa initialization error 28

im at a complete standstill until i figure out how to pull the codes, and or test the fuel pump and the vanos

my torque app wont let me check the fuel pump, it shuts off the gauges on realtime info when i turn the car off

my autozones scanner wont pull the codes. im going to a different store tonight

 

try to put the cable at the same usb port like the first time. worst case scenario, reinstall it.

does the car start fine and smooth and at idle too?

 

my laptop only has the one usb

ive uninstalled the drivers, adapter, and programs and reinstalled exactly as before, no help

before thanksgiving, the car was randomly going into half power mode, was hard to start sometimes

then that weekend, it would start and die like 10 times before it would run. checking the fuel rail pressure with torque app showed it was low

i put a new factory hpfp and fuel pipe on the weekend after thanksgiving

starts right up, first try every try. idles fine

up until this weekend, it was running fine, no missing of any kind, just doesnt make as much boost as it used to. wastegate is toast

8-12psi on boost gauge.... maybe 14 every once in a while.

i know i need a new turbo, but thats a separate issue( i think anyway)

i just checked my fuel pressure. it is 95psi or 6.5bar with key on. 700psi at idle, and goes back to 95 psi when key is turned off. but i have no way as of yet to check it for leakdown. my app stops working with key off.

going to advance auto parts right now to see if they can pull codes on a mini

 

no codes again

 

update, i got some help with INPA.

found out my windows 10 pro defender was keeping the software from communicating

not sure how or why it worked initially, then quit?

turned off windows defender, restarted computer, works fine

so the only codes i have with INPA are p0420 and p0141

both from catless downpipe. Torque APP reads p0420 every other drive and occasionally reports p0141

car is still missing. i havent done anything else to try to find the issue

i have near white out conditions in my garage here in florida...its like 50 degrees

i dont operate in these conditions unless its absolutely neccessary

after the cold front passes, i am going to throw new plugs at the car to see if it helps

 

spark plugs.... f my life

i read some hundred more threads, learned how much plug gap can effect performance at high boost

decided to pull my plugs and check gap....was .045 thou

bought some new bosch plugs supposedly gapped at .028...did not check them. IMHO its kinda silly to pay 10-12 bucks a plug for a few micron thick coating of iridium and then ruin it touching it with a tool.

put them in as gapped by bosch, test race

no misfires, good power again

if you are following this thread or searching for missing and backfiring under boost or over 3000 rpms try this

pull your plugs no matter how old, visual inspect for deposits, and if they look good, check the gap before you re-install them. is its a turbo car and the gap is over .030". gap them, re-install, and test race. if the problem is solved, go buy some new plugs

thanks for all replys to this thread for trying to help

 

Thanks for the update, yep gap is critical and you should always check the gap again if new and pre gaped as they can get bumped in shipping.