2G Odd/random misfire.

[TSIflyer95]

Okay guys. I went the distance and bought link hoping it would fix my problem of an intermittent misfire.

Well some of you guys had told me that it was probably the CAS.

I have a 6bolt swap in the car.

1g rods, 2g pistons, bc272, bc valvesprings and retainers, acl bearings, blah blah blah.

Well, I got link installed and have been messing with the tuning. BUT upon some casual driving for data logging, the car just started to miss like it used to?!?!?

I did click the box in link to choose "Using CAS non 95-99"

So I guess it isn't the cas. The only thing I can think of is that it has something to do with some wiring issue somewhere. I had a S-AFC on the car, I removed it upon installation of link.

The misfire will happen and stay until I shut the car off and restart it. Sometimes I go all day, other times I'll go 5 minutes and start missing.

I would greatly appreciate the help. This is the ONLY issue I am having. The car is running moderately happy minus the misfire.

Also, I am sitting here looking at my DTC checks in link, and there is no code for a cylinder misfire!?!?!

Only a code for the EVAP purge malfunction
Manifold differential pressure sensor malfunction
and o2 sensor heater circuit malfunction

Thanks guys!!!

 

[RogueTalonTSI]

Heat and vibration wreaks havoc on coils and transistors. Does it miss at idle also? If it does try a cylinder drop test by unplugging one injector at a time and take note of the cylinders that don't change the miss. If the cylinders are on the same coil try replacing that coil.

 

[TSIflyer95]

It only misses at idle when the miss starts if that makes sense.

I'll be driving, it misses, then if I let the motor slow down to idle it will continue to miss until I shut the motor off and restart it.

I did check my dtc's again in link and it is now throwing the "random misfire code" code 0300

But it only happens when I am driving the car. I have idled for 10 minutes and it won't miss. Only when driving.

Anybody have any idea what this could be? It seems to do it only after I boost the car. If I drive and stay out of boost it doesn't seem to happen.

 

[Grescht]

Make sure you check the box in link to ignore cyliner misfire. It comes from putting an eprom in your car. If you check that box it should go away. And btw. The onlyway to fix it besides putting a petentiometer on a wire (which wire it is escapes me) that goes into the ecu, is to buy link and use that DTC ignore function. So you did right by buying link. Hope that solves the prob.

And the reason it doesn't happen at idle is because the ecu has to see closed loop in order to throw the code. So if u baby the car and never get the ecu to switch to closed loop, you can hold off how long it takes to set in. But mine kinda always did it inevitably within 30 mins of driving.

And also leave that "use non 95-96 cas" box checked. It inverts your cas signal. For your cas swap with the 6bolt.

And if all of that stuff above doesn't work, then check your signal wire to the cas. There's that one wire that likes to break and mess stuff up.

 

[TSIflyer95]

Make sure you check the box in link to ignore cyliner misfire. It comes from putting an eprom in your car. If you check that box it should go away. And btw. The onlyway to fix it besides putting a petentiometer on a wire (which wire it is escapes me) that goes into the ecu, is to buy link and use that DTC ignore function. So you did right by buying link. Hope that solves the prob.

And the reason it doesn't happen at idle is because the ecu has to see closed loop in order to throw the code. So if u baby the car and never get the ecu to switch to closed loop, you can hold off how long it takes to set in. But mine kinda always did it inevitably within 30 mins of driving.

And also leave that "use non 95-96 cas" box checked. It inverts your cas signal. For your cas swap with the 6bolt.

And if all of that stuff above doesn't work, then check your signal wire to the cas. There's that one wire that likes to break and mess stuff up.

I will definitely see about changing that. Would you happen to know about where the box is for ignoring the misfire? I don't recall it.

And if the works. I'm going to marry you.

 

[Grescht]

Its on the dtc tab in link. There's a big box at the top that shows current dtc's, and another big box below that that checks the status of the evap system and stuff. In between those two big boxes are a series of small checkboxes all labled separately. There is one for misfire, o2, and a few other things. Lemme see if I can get a screen shot for ya.....

Checking that box Enables the ECU to check for codes. So Un-check it and you should be good. (the boxes should all be checked automatically)

When the car actually misfires, does it feel like it runs great until it happens? and then as soon as it misfires, it feels like someone cut on a "misfire" switch. and its all like blahhh pop pop blahhhhhh pop pop. hahaha

Hope this helps bruh.

 

[TSIflyer95]

UH-MAZING! Thank you my friend. I just unchecked the box and am about to take the car out.

And yes that is exactly what it feels like. I'll be cruising, then its like you just pull out 1 or 2 of my plug wires.

And for the record, you are now my favorite person on this forum.

 

[Grescht]

Well?

 

[TSIflyer95]

You are my hero!! I drove the car all over the place today to test it. No problems whatsoever!!!

Although, after doing some more tuning I had a HUGE knock show up under boost. I thought I had it all about gone but this one was like 8-9• spike. Very short time but it was there.

But Anywho. Now that there aren't any major issues with the car I can fine tune!! Thank you again!!!

 

[Grescht]

No prob man. Do me a favor and mark the thread resolved and you can also leave me feedback saying I helped. Happy boosting.