P0300 Random Misfire with 6 bolt

[T is for TURBO]

Okay, So I recently completed a six bolt swap into my 96 TSi. The car runs GREAT pulls hard at 15lbs... However, If I drive at a fairly consistant speed, I will get a Random misfire CEL. I know this is common as I'm using the green lid CAS. But my question is; The common random misfire CEL with the six bolt swap; is it really misfiring or is it just a phantom CEL?

The reason I ask this is because my car is actually misfiring. It boggs down, and I get no power. If I restart the car, its fine, or if I slow down and bring my RPMs down, it will go away. Once I park the car, I clear the CEL and it will stay off until it happends again.
I haven't had a chance check the plugs, wire, coil pack, or transistor, as I just got the car on the road yesterday... I know I have boost leaks, so Im sure this is could be contributing. If I switch to a black lid CAS will this help? or do you think its more related to the plugs, wires, coil, transistor, and boostleak issue?

Thanks!
-Shawn

 

[chetvram]

If you know you have a boost leak than you are constantly running rich from it. Might want to pull your plugs and see what they look like.

 

[T is for TURBO]

will do... Just gotta wait for it to cool down now... I just drove about 20 miles with no CEL... but Im sure that doesn't mean anything...

 

[blackGSX2g]

Thats how random misfire is, mine did that off and on too. I have the black top CAS but still got the misfire off and on every now and then until DSMLink. It got annoying enough for me to just keep the old Palm in the car to clear it when it popped up.

 

[Jordanbutter]

I notice the samething with my car, I noticed it seemed to be related to having the turbo spool just a bit and then slowly letting off the gas allowing the turbo to despool with out blowoff. Also might just be coincidence but my friend and I swaped AFC head units and my old one threw that cel in his 2g almost right after install.

 

[Smokin80]

Magnus's tech article has a way to make the engine stop checking for random misfires with out dsmlink but other than that im not sure that you can get rid of it. I just did a 6 bolt swap last weekend and i have had no problems but i have dsmlink.

www.magnusmotorsports.com

just click on the tech articles and go to 1gina2g.

Smokin

 

[The_one]

I have the same problem but my car is a stock 2g with a 1g (90-92) CAS. I will put back the 2g CAS and let you know if it solves the random misfire or not.

 

[T is for TURBO]

Well, apon inspecting the plugs, I noticed that they I'm running a bit lean. So, my first two things I'm going to do (as soon as I can get in my driveway, since my road is torn up for construction) fix the remaining boost leaks, and redo my base timming. I accidentally put the 7 bolt crank pulley on instead of the 6 bolt one, so i didn't have a timming mark to shoot the light at...
This thing is pissing me off, It ran like total crap today, so I have to get to the bottom of this!
Ill keep you updated...

 

[the_red_pooch]

Probably not this easy but I had the exact same problem with my 6-bolt in my 96 GST. Put in some new NGK BPR7ES plugs and i have been trouble free since. But I had the exact same problem with the misfiring after you held the rpms steady for a bit, like on the interstate at about 3000-3300 rpms so I'd push in the clutch and let the car idle down and it drove perfect again once I got back on it. Just my experience, good luck to you.

 

[T is for TURBO]

Probably not this easy but I had the exact same problem with my 6-bolt in my 96 GST. Put in some new NGK BPR7ES plugs and i have been trouble free since. But I had the exact same problem with the misfiring after you held the rpms steady for a bit, like on the interstate at about 3000-3300 rpms so I'd push in the clutch and let the car idle down and it drove perfect again once I got back on it. Just my experience, good luck to you.

Funny thing is, I just got of the phone with a friend of mine and we were discussing the plugs. I have NGK BPR7ES plugs, and he suggested going to a BPR6ES plug. Anyone have any thoughts on this?

 

[T is for TURBO]

Thats how random misfire is, mine did that off and on too. I have the black top CAS but still got the misfire off and on every now and then until DSMLink. It got annoying enough for me to just keep the old Palm in the car to clear it when it popped up.

Can you explain to me how DSMlink gets ride of the random misfire? I was on the understanding that you could use DSMlink to just stop the ECU from checking for it so it didn't throw a CEL... Thats also how I thought the POT mod worked. Am I correct when I say that DSMlink and the POT mod don't actually get rid of the random misfiring problem (the studdering, lack of power ect...) or am I completley wrong? Sorry for my stupid questions, I can do all the wrench work, but I'm still learning the "tuning" aspect here.

Thanks!
-Shawn

 

[T is for TURBO]

AHHHH! it just keeps getting worse!
And now, so far I have hit fuel cut 4 times... I can't really even get into boost anymore with out fuel cut, or some sort of bogging. Its obviouse that the boost leaks just keep getting worse, along with the studdering and bogging. The P0300 CEL comes on more and more often... And the worst part is, I can't do anything about it right now ### I have no place to try to do a boost leak test, or adjust the timing!
Thanks for all your suggestions so far, I will keep you all updated when I get a chance to start tinkering with it...

Edit: Also, I forgot to mension. Everytime I get the random misfire and it starts to bog, my A/F gauge pegs out at lean. Is this because I am fireing on less than four cylinders and the flow of air is too high?

Thanks.
Shawn

 

[fwdturbobov1996]

Funny thing is, I just got of the phone with a friend of mine and we were discussing the plugs. I have NGK BPR7ES plugs, and he suggested going to a BPR6ES plug. Anyone have any thoughts on this?

What are your plugs gapped at?

Going to a colder plug should be needed when you plan on running higher boost ( 20+ psi ) or nitrous.

Ive ran the 6es up to 20 lbs and had success with it. Around 21-22 lbs I was experiencing problems and switched to the 7's and didnt have a problem.

 

[T is for TURBO]

What are your plugs gapped at?

Going to a colder plug should be needed when you plan on running higher boost ( 20+ psi ) or nitrous.

Ive ran the 6es up to 20 lbs and had success with it. Around 21-22 lbs I was experiencing problems and switched to the 7's and didnt have a problem.

I gapped them at .28

So do you think it would be a good idea to go to 6es?

 

[Tevenor]

If the misfire is indeed from the 1G CAS, there isn't too much you can do except maybe try to adjust the cas and see if it helps. The issue is that the signals for a 1G cas are far less precise than a 2G sensor and therefore much "sloppier" than what the 2G ECU expects to see. It interprets this as the engine misfiring.

 

[T is for TURBO]

If the misfire is indeed from the 1G CAS, there isn't too much you can do except maybe try to adjust the cas and see if it helps. The issue is that the signals for a 1G cas are far less precise than a 2G sensor and therefore much "sloppier" than what the 2G ECU expects to see. It interprets this as the engine misfiring.

Thanks for the explanation! I've been looking for a black top CAS, so hopefully that will help a ton... Now I just have to find the rest of my boost leaks. I found a HUGE one last night by the LICP. But what is really pissing me off is that I replaced all the injector seals, O-rings, and insulators, and it's STILL leaking by the insulators... Any opinions on this? should I pull them out and soak them in ATF?

 

[the_red_pooch]

He is right about the plugs. If you plan to stay around stock boost levels then go with the NGK 6es. I just replaced mine for it and I didn't want to buy plugs twice since I'm planning on an engine build up through the winter for about 25-28 lbs so I just went ahead and got the 7's ahead of time that's all. I had mine gapped at .28 also.

 

[T is for TURBO]

Okay, While the forums were down I was able to get the car running right again.

This is what I did:

After I got the car running after the swap, I put steering fluid in the power steering resivior instead of ATF which is supposed used. Along with that and a lot of air bubbles in the steering lines, I was getting A LOT of noise and vibration in the engine bay. This, I feel was causeing the random misfire (as I know noise has an effect on the CAS signal)

After I bled the power steering and put the right fluid in, the noise and vibration went away, so did the P0300. I mean, it didn't completely cure it, but it occured MUCH less often. Instead of 5 or 6 times a day, I would only get it about 1 or 2 times a day.

But since then I now have a black top CAS and I have only gotten the code 2 times in the last 4 days.

Also, I have fixed most of the boost leaks, (only a few small ones now) and the car pull HARD!

However, Im still running a bit lean. I just have to figure that out...

Thanks for all you help!

-Shawn

 

[blackGSX2g]

Can you explain to me how DSMlink gets ride of the random misfire? I was on the understanding that you could use DSMlink to just stop the ECU from checking for it so it didn't throw a CEL... Thats also how I thought the POT mod worked. Am I correct when I say that DSMlink and the POT mod don't actually get rid of the random misfiring problem (the studdering, lack of power ect...) or am I completley wrong? Sorry for my stupid questions, I can do all the wrench work, but I'm still learning the "tuning" aspect here.

Thanks!
-Shawn

DSMLink has a box to check where it will disable the ECU from even looking for RM without putting any of the other inputs out of spec. The POT mod is kind of a ghetto way to do it. The ECU needs 'normal operating conditions' before it starts looking for RM, the POT mod just allows you to adjust the baro wire signal to bump it out of spec. Personally I'd rather just unplug the TPS before I mess with the baro wire mod, but DSMLink is the best solution in my book.

 

[b4christ15]

DSMLink has a box to check where it will disable the ECU from even looking for RM without putting any of the other inputs out of spec. The POT mod is kind of a ghetto way to do it. The ECU needs 'normal operating conditions' before it starts looking for RM, the POT mod just allows you to adjust the baro wire signal to bump it out of spec. Personally I'd rather just unplug the TPS before I mess with the baro wire mod, but DSMLink is the best solution in my book.

Not to hijack a thread, but when I get my car back this friday, I was wondering if I could unplug the TPS to help with misfire for now? There aren't any bad side effects to doing this is there?

 

[T is for TURBO]

DSMLink has a box to check where it will disable the ECU from even looking for RM without putting any of the other inputs out of spec. The POT mod is kind of a ghetto way to do it. The ECU needs 'normal operating conditions' before it starts looking for RM, the POT mod just allows you to adjust the baro wire signal to bump it out of spec. Personally I'd rather just unplug the TPS before I mess with the baro wire mod, but DSMLink is the best solution in my book.

Thanks for the clearification!
-Shawn

 

[SixBolt_16G]

iVE had a the same problem for a while now.. When the temp drops below like 50 degrees i notice that it does it more... and for some reason i keep throwing an idle control code and not a random misfire code.. when that code pops up.. then it starts with the random misfires.. DUring the summer i disconnected my BOV return hose and vented just for kicks andthe light didnt come on at all the rest of the summer...Mechanical nightmare.. go figure..