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New K24 / 18G Conversion throwing code...

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So I had a K24/18G conversion done with 1 bar waste gates, turbo intake hose kit installed (not boost), diverter valves, exhaust, 5 bar FPR, stock air box, K & N filter and Softronic tune...

Car is fine driving around normally and is even good upwards of 1.1 to 1.2 bar.

BUT... if I try to drive it hard from down low, WOT in say 3rd gear, the boost kicks in massively and then it all of a sudden dumps boost, and the CEL light comes on and the gas pedal no longer functions. Engine is still running but wont allow for any gas input and the CEL screem says drive to dealer. Turn the car off and back on and everything is fine...CEL is still on but car drives fine normally.

Hooked up Durametric and the code is P1508 Torque Comparison Function Monitor - Signal Implausible (Porsche code 408)

Cleared it and it was fine...

But now I'm afraid to open it up WOT...

I've done some searching and some people say that the MAF is bad... but that doesn't make sense because it didn't throw a MAF code. And I figure with electronics they either work or they don't.

Then others say the DME is bad... and that didn't make any sense either because if it was bad why would it continue to work and only glitch under high load, high boost. It doesn't have any CEL's at all till you WOT under high load condition.

Anybody else running higher boost (cfm) have similar problems?

Is the stock MAF not able to handle the additional air flow?

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Just a guess, but if you may be getting a knock sensed. When you have pre-detonation, doesn't the car go into a safety boost mode or something? I would just start by making sure you have some high octane gas. I always add 2 gal of Toluene and can boost to about 22psi in 100+ heat in Tucson w/o problems. Toluene will not hurt your fuel lines at that level, or hurt your cats at all. May be worth a try. I can't think of anything else, unless you have low fuel pressure or something? Hope that helps.

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That's kinda pushin the raggety edge for boost pressure on 93 octane.....1.2 bar that is. 1.0 should not be a problem. Do you know the heat rating on your spark plugs? Have good fuel pressure? Clogged cats can cause some funky issues too....Just thinking. Hmmm. A bad MAF can give bad readings if it is too dirty. May just spray that down with some carb cleaner if the sensor looks black or dirty. I have heard that does not always throw a code for some reason.

Edited by BOOSTTT
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you didn't mention anything about the spark plugs. How many miles has been since you changed the plugs?? I had similar experince after I reflashed my ECU with Softronic tune. It turned out the be the plugs. Please check out my post

I hope it helps :-)

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Sorry for your issues, but I have also experienced this. The problem actually is fuel related. Even with the 5bar fpr, you are not getting enough fuel for the system. You will need to tune it back a bit or get new fuel rails.

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  • 2 months later...

Update: ( just in case someone else gets this problem)

Reason for the P1508 Torque Comparison code after installing K24/18g hybrids..

Massive boost leak on one of the intake air runners leading directly into the motor. In my case it was the first cylinder, closest to the front of car on the psgr side...not easy to get to.

Had to replace the small rubber hose and the worm clamp, and had the shop strap the intake runners down just for a secondary precaution.

No problems since...

But on a 2nd note... If anyone is interested in the K24/18 swap, dont go the 5 Bar FPR route. Im not sure whom came up with this but the 5 bar FPR can't keep up with the fueling needs.

I was maxing at 1.2 bar of boost and my injector duty cycle was 100 to 125% with the 5 bar installed.

So i went back to the 3.8 bar FPR and had larger injectors installed and now at 1.3 bar boost my injector duty cycle is 75%

Hope this helps someone...

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Almost forgot...

As far as ECU tuning...

Avoid Softronic... (my humle opinion)

I had a Softronic tune on the oem turbos and it was fine.

After the k24/18g upgrade i had to pay Softronic for another map...

That map was way too rich (cold smell fuel out the exhaust constantly)

Tried to contat Softronic a few times to remedy the problem and I always felt like I was annoying them or getting in the way. I guess they only have 1 person over there that does the tunes? A few times I contacted them, that ONE guy was on vacation in Europe and I would have to wait.... Huh? Really?

So I cut my losses and ditched their sub-par program and shelled out more coin for one of MarkSki's tunes at 911Tuning.com.

I must say, Mark is the man! He's the Yin to Softronics Yang... He was polar opposite from them, always available to help, even on 4th of July holiday weekend he was answering my questions and helping me out.

Their map is perfect too. Afrs are in the sweet spot and the timing is perfect.

Their customer service is 2nd to none...highly recommended!

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  • 1 month later...

I wouldn't say sub par as many companies use Softronic for their mapping, you should ask Markski about Softronic. An intake leak or non meter air will also cause the car to run rich and the most noticable at Idle. This will then cause the AFR's to be off , timing indirectly as the fueling is not correct and other fault codes etc.

Edited by marine8541
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