Hi

I installed the K4 turbo in my car some time ago. When I would step on the throttle it would adjust the timing I believe due to running to lean. I learned not to step on it for quite some time. Recently I installed larger fuel injectors with a new fuel pressure regulator. Now when I step on the throttle I'm getting misfire codes (which I was not getting before installing injectors/regulators). Since the misfire started after I installed the new injectors I'm not sure that I have bad coil packs. I'm curious if anyone has ideas on what I should check. I did install new NKS spark plugs. Do I need to gap them tighter/wider for running more boost?

Thanks!

Russ

 

If you are chipped, you need to run them at .28 Is your misfire code directed at one specific cylinder? If so, when swap out the coilpack with an unaffected cylinder and see if the code follows the coilpack.

 

.028 not .28 biiiiiiiig difference....

 

^ Agreed. I'm guessing you mean K04... What are the plugs gapped at? Are you tuned for the K04 because if not, that could be the source of your misfires. Are you using a stock FPR?

 

Someone correct me if I'm wrong, but I dont believe you can just toss in bigger injectors without the proper ecu tune. I dont think there is a way for the ecu to know what size injectors you have installed and will be dumping in way to much fuel because of it.

too much fuel -> overly rich a/f mix -> fouling sparkplugs -> misfire.

 

.028, my bad. point zero two eight...yikes, could you imagine .28 gap?

 

Thanks for the responses. A bit more information:

Yes - K04 turbo
Chip - TAP stage 1 (bought long ago before I learned there were better)
FPR - I installed a 3bar regulator. I originally installed the larger injectors for running to lean with the K04 turbo. When I did I was getting running to rich errors in the computer. I did some research on the injectors and found that they need to run 3bar. I believe I found stock FPR is 4 bar which makes sense why it would run way to rich. I wasn't sure if a new chip is required for larger injectors. I figure the computer would adjust the pulse times based on the O2 sensors. However, I may need a different chip for the K04? I installed the TAP chip long before I installed the larger turbo.

I'll try swapping the coil packs as I'm getting mostly cylinder 3 misfire. But I did see one random misfire code in the group of errors. The car accelerates nicely under about 1/2-3/4 throttle. But when going full throttle it starts chugging.

Also, for the plugs I am gapped at .028. Is that wider or narrower than stock. I can't remember.

 

Thanks for the responses. A bit more information:

Yes - K04 turbo
Chip - TAP stage 1 (bought long ago before I learned there were better)
FPR - I installed a 3bar regulator. I originally installed the larger injectors for running to lean with the K04 turbo. When I did I was getting running to rich errors in the computer. I did some research on the injectors and found that they need to run 3bar. I believe I found stock FPR is 4 bar which makes sense why it would run way to rich. I wasn't sure if a new chip is required for larger injectors. I figure the computer would adjust the pulse times based on the O2 sensors. However, I may need a different chip for the K04? I installed the TAP chip long before I installed the larger turbo.

I'll try swapping the coil packs as I'm getting mostly cylinder 3 misfire. But I did see one random misfire code in the group of errors. The car accelerates nicely under about 1/2-3/4 throttle. But when going full throttle it starts chugging.

Also, for the plugs I am gapped at .028. Is that wider or narrower than stock. I can't remember.

 

You are 100% correct. You can not just throw on larger injectors because the car is running lean. If the injectors are too large the ecu will not be able to pull back enough fuel. Also if the car is a pre 2000 the car will be running way too rich at WOT because thats when the ecu just uses the fuel maps and the MAF readings to tell the injectors to spray so much fuel.

This is exactly why a K04 setup needs K04 tuning to run correctly. The K04 tunes have fuel maps that have been adjusted for larger injectors or for a higher 5 bar fuel pressure. The fuel curve is also changed since the K04 will flow a little more air. Plus the fact that the WG is slightly different causing the K04 to run at a slightly higher boost level then the K03 when running on a K03 tune.