EPC and CEL light on Ctapp MAF-less file (kinda long)

[JumboBlack1.8]

Well, I sent my ECU away to Tapp to get it reflashed with a Maf-Less and SAI-less file for my 71r, and I finally got it back yesterday. Well, after installing, resetting, and doing a throttle body adaption, the car gives me serious problems. It idled like ASS in my driveway (which I expected it to do) so I let it warm up and stabilize a bit. After it did, I dropped the hood.....and all of a sudden, the engine cuts out....????....then I restart the car with the hood closed, let the idle stabilize, and I figured it was okay......then, when I closed the drivers door, the engine shut off once again. I figured it was a battery problem, but my battery is keeping its charge fine according to the volt gauge

Then, once I got the car on the road, driving outside of boost felt normal until at around 2.5k rpms, the car bucked pretty violently and the RPMS dropped dramatically. Meanwhile the EPC and the CEL lights both flickered VERY briefly (not flashing, but like there was an electrical short). So, I quickly try to rev up the engine to keep the car going, but I get no response for about 5 seconds. So I pull over to the side of the road and shut the engine off. When I turn the engine back on, it started up fine. So I started to drive off, and it happened AGAIN. So I went straight home, and emailed Chris and he suspected it might be a bad coilpack. But, after checking my codes and logging blocks 115 and 20, he concluded that there was nothing noticeable....However, i'm not sure it is a coilpack, because my issues doesn't quite feel like a typical misfire. It feels like the engine is shutting itself off, which leads me to believe it could be the speed sensor. But I'm not sure how that could've gone out, because my car has been sitting for weeks while I waited for my reflash, and it was fine before then.

I've done research over on Audiworld, and some people with these systems have either a bad ECU, or a bad engine speed sensor....Anyone got any ideas?

[JumboBlack1.8]

Also, I should add that this doesn't just happen over 2krpms....it happens in ANY gear at ANY rpm....it is completely random

[k0mpresd]

and you have no codes?

[JumboBlack1.8]

None....its a damn mystery

[mike-2ptzero]

When ever the EPC light comes on while you are driving you will lose control of the throttle body, its does this for safety. It does not reset till after you turn the key off and then back on. you might be hitting a tq limit at part throttle and below 2500 rpm.

Suprised the ecu didn't throw any codes unless he wrote the codes out on the software.

[JumboBlack1.8]

No, I dont think I'm hitting a torque limit, but have yet to really accelerate.....this happens when I am midly building speed,....and sometimes, even just when I tap the gas pedal....and like I said, the light doesn't fully come on. It literally flashes for a split second, then goes away......but, even tho I'm not gettin any codes, the problem continues

Could it be a bad ECU? speed sensor? throttle body? Where should I start looking?

[Nebone]

There has been a few bad/damaged/not ideal CTapp ECUs floating around, especially after a reflash.

[mike-2ptzero]

No, I dont think I'm hitting a torque limit, but have yet to really accelerate.....this happens when I am midly building speed,....and sometimes, even just when I tap the gas pedal....and like I said, the light doesn't fully come on. It literally flashes for a split second, then goes away......but, even tho I'm not gettin any codes, the problem continues

Could it be a bad ECU? speed sensor? throttle body? Where should I start looking?

That is when it happens. I used to have this issue way back in 2000 with my K03 setup. It would happen just as I would hit the throttle at low rpms. The tq limiter is not just a peak number, it is ramped up and you might just be hitting the low end of it. I never had a problem at WOT or running thru the gears.

[JumboBlack1.8]

That is when it happens. I used to have this issue way back in 2000 with my K03 setup. It would happen just as I would hit the throttle at low rpms. The tq limiter is not just a peak number, it is ramped up and you might just be hitting the low end of it. I never had a problem at WOT or running thru the gears.

Interesting....i never even considered that. So, how did you go about resolving it?

[JumboBlack1.8]

There has been a few bad/damaged/not ideal CTapp ECUs floating around, especially after a reflash.

Any with this same problem?....I literally JUST got this from Chris, and he said it should be working fine....i really dunno what to do

[maxspeed]

what are you doing for boost control? if your making boost faster than the software requests, or the turbo starts producing more boost than should match the TPS that could happen (its what triggered the EPC light on my k03)

[mike-2ptzero]

Boost deviation usually just causes the ECU to close the throttle to 40% or less and then opens back up once the boost is controlled. He is running a GT2871r so I dont think over boost is going to be an issue below 2500.

[Poopie]

check your fuses?

[JumboBlack1.8]

I'll do that tomorrow.....any in particular that I should look out for?

[Poopie]

engine timing...i think 29, 32, 34.

i'll double check for you. that usually throws a code. Bassed had the same issue though with weird codes but has similar symptoms and a flashing epc light. He checked the fuses and said they were fine visually and with and ohmeter. Then he replaced the fuses and the problems went away.

[JumboBlack1.8]

Thanks a lot poopie! I was just thinking of gettin in touched with bassed to ask if he'd had any similar issues, but i'll try ur advice first

I'll give an update tomorrow

[Poopie]

ALSO!! Double check your softcoding for your drivetrain set up. I forget what it is...

maybe 16201?

[JumboBlack1.8]

The soft coding is where it should be....read 16201 like its supposed to....i was thinkin it could be the fuses earlier today, so i'm gonna keep my fingers crossed

[f15046]

I had a similar problem, not identical, but similar. Mine ended up being crankshaft sensor (rpm sensor).

[JumboBlack1.8]

what were your symptoms? Did u get any codes?

[f15046]

Symptoms were the car was hard to start, it went dead a couple times will coming to a stop. And the EPC and check engine light were on. Honestly i cant remember what the codes were. I ordered a new crankshaft sensor from ECS tuning, and that fixed it.

[maxspeed]

anything about a ram limit ring a bell codewise?

when you get in the car, and turn the key, without starting the car, does the epc illuminate?

[JumboBlack1.8]

Yes it does illuminate when I put the key in the on position....as do all the lights....but when the others go off, the EPC and CEL stay on....but I get absolutely no codes at all....

I didn't get around to changing anything today cuz I had to run to the weld shop to get my manifold and downpipe fixed....but tomorrow I'll be doing some Innovative wideband logs and some Vag-com logs.....are they any blocks that I should be looking at to narrow down this issue?