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Discussion Starter #1 (Edited)
misfires, blinking CELs, and no throttle response - UPDATE

Well, not all at once, but all that has happened in the last two days along with my brake lights getting stuck on. That was an easy one though.

2004 1.8T tip, 44,7XX miles

Thursday evening - Leave work, driving down the street. As I start to come to a stop pulling into a left hand turn lane, the car starts to feel a tiny bit rough. At first I thought it was just a rough road surface, i couldn't really tell, and the tachometer wasn't doing anything wierd. Just as I thought to myself "Well, if something was wrong, the CEL would come on." (And the CEL has never come on) Sure enough, just then the CEL comes on, blinks 3 or 4 times and goes off. Car runs just fine after that. Got it scanned this morning, no codes. Already did the 40K service including plugs around 40 or 41K miles.

Friday afternoon - making a left hand turn at slow speeds, as I try to acelerate, I press the pedal and nothing happens, the car just coasts. Thinking the worst I pulled over, but the car didnt stall, no lights came on. I pull back onto the road and everything is fine, except my brake lights were stuck on. (I fidgeted with the pedal and they went off. Not a big deal)

Now I dont know if these are related or not. The first item is my biggest concern. Assuming it was a misfire I dont know what could've caused it. Im thinking random anomaly, MAF, throttle body, coil pack, or spark plug wires. The "misfire" only happened once and there was no code so theres no way to tell if its the latter two.

So, Thursday's episode was enough, but Friday really spooked me. I think I had the momentary lack of throttle once before and assumed the "drive by wire" system was just momentarily confused. With outside temps between 38 and 41 degrees, the occasional, indecisive, blinking "snowflake" on the screen, and its accompanying chime, today freaked me out as I was already on edge with the rest of it. :crazy:

Maybe the car is just being fussy with the recent onset of cold weather?
 

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Hmm, sounds fimiliar to me.. I had my coil packs changed to the newest ones and new NGK plugs and have been running smooth as ice since.. Make sure if you do get the Coils changed that they do all of them at once.. Although I was getting misfire codes after the CEL flashes.. Strange if your CEL flashes there should be some code telling you why.. DO NOT IGNORE THE CEL!!! A cheap fix could turn into a very $$$$$ if you do..
 

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Since you said that the brakelights were stuck on it's probably a faulty brakelight switch causing all your problems. On the drive by wire models when you are braking a signal is sent to the ecm which won't let the engine accelerate until the brake pedal is released. I would replace the brakelight switch.
 

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blinking Cel mean misfire, more then likely a bad plug or coilpack, if you can have someone Vag it you may be able to tell which cylinder its on, or with the engine running disconnect one coilpack at a time, when you find the cylinder that does no affect the motor(worse), there is your problem.
 

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blinking Cel mean misfire, more then likely a bad plug or coilpack, if you can have someone Vag it you may be able to tell which cylinder its on, or with the engine running disconnect one coilpack at a time, when you find the cylinder that does no affect the motor(worse), there is your problem.
Wouldn't a bad coilpack or spark plug throw a code? He said no codes showed up when he had it scanned. Still think a new brakelight switch will cure the problem. This issue has come up before and that has turned out to be the problem.
 

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Wouldn't a bad coilpack or spark plug throw a code? He said no codes showed up when he had it scanned. Still think a new brakelight switch will cure the problem. This issue has come up before and that has turned out to be the problem.
I was just reading the title, didn't actually read his whole thread, your right thought is does sound like its related to his bad brake switch,
 

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You'll definitely have to change your brake light switch, so I'm thinking do that first and then see what happens. I had to replace mine recently and the car ran terribly when the original one failed, like I was dragging a very large anchor behind the car. I guess this is limp mode? I would get down to a dealer today, if you can, and purchase a new one. Mine was about $25. Good luck.
 

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Discussion Starter #8 (Edited)
Ok, so if I understand correctly -

A faulty brakelight switch could have caused Fridays "loss of power" issue. makes sense. However, after the car didnt accelerate, I pulled over with my foot on the brake, sat there, then pulled out into traffic, and the car accelerated normally. It was then that someone pulled up and told me my brake lights were on. If the diagnosis of "brake engaged = no acceleration allowed" were true then I shouldn't have been able to accelerate into traffic right? Of course I was in stop and go traffic so it could have gotten stuck on more than once. It did feel a bit heavy, like the brakes were engaged. I thought maybe the pedal got stuck down or something. Of course it was raining and traffic was slow, so I wasnt going to push my luck in terms of speed.

Im still not sure how a faulty brake light switch could cause the first problem. (CEL, misfire...) However, my foot was on the brake when it happened.

I'll call the dealer on monday. My fear is that the car will be driving fine and there will be no code stored so they wont find anything. Maybe I can at least get them to change the brake light switch. I'll have to see.

EDIT - Just went out for a spin. car drives well, no brake light issues, no CEL, throttle response is fine. It did seem a bit "heavier" than normal though. Maybe Im just paranoid. However, the transmission seems to like getting up to 5th gear by 40mph. If Im driving around town in high gear, at a lower speed and consequesntly no boost, I guess it's going to feel heavy. I know the tiptronic is "adaptive" and I have been in a LOT of heavy stop and go traffic lately, plus I have been playing with the tip in traffic, experimenting with shifting into lower gears rather than braking. So it's probably just a bit confused.
 

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If you are still under warrenty the dealer should replace the brakelight switch just because the brakelights were on when you weren't braking and maybe that will cure the loss of power etc. Let us know how everything comes out.
 

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You would like sport mode. It makes the downshifts sooner under light throttle pressure. Dealer should cover the brake light switch.
 

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Discussion Starter #11
Yes, Im under warranty. Im taking it in on Monday after work.

I do like sport mode! :) I did the key/gas pedal method this afternoon and the car was more responsive. I think it had become sluggish with my driving habits the last few days. Unfortunately it doesnt last long when you start driving slowly.

I'm hoping Chris, or someone, brings a VAG COM to the next garage day so I can get it permanently enabled as the "default" programming.

It's like a poor mans chip...
 

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Discussion Starter #12
You'll definitely have to change your brake light switch, so I'm thinking do that first and then see what happens. I had to replace mine recently and the car ran terribly when the original one failed, like I was dragging a very large anchor behind the car. I guess this is limp mode? I would get down to a dealer today, if you can, and purchase a new one. Mine was about $25. Good luck.
Im thinking when the car thinks the brakes are on it wont apply full power. OTOH, if the brakes ARE on, you wont get full power, because the brakes are on.

I think the actual "limp" mode is when power is cut and the "EPC" light comes on.
 

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Discussion Starter #13
I'm taking the car to the dealer on Monday evening.

I guess I've been concerned since Thursday, since the CEL was blinking, even though it did it only for a few seconds and went out. I know you arent supposed to drive on a blinking CEL, but I'm guessing if it goes out, there are no codes and no warning message of the MFD screen its ok to drive for a few days until I can take it in.

Also, would a VAG-COM or actual VW scan tool be able to do a more thorough scan for codes compared to a generic OBD-II scanner? I find it odd that the CEL went on but no codes were stored unless they immediately cleared.
 

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the vag-com is more thorough then a generic obd2 scanner. in general though, if you have a CEL light, then the obd2 should be able to read the codes.
 

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Discussion Starter #15
Well I've driven several times since then and nothing has come up.

It felt like it was "vibrating" a bit more today, but the idle was fine, and I could just be paranoid. The seeming onslaught of recent issues combined with my recent stupid jack mishap has me a bit freaked out.

It drove well today and seemed happy. We'll see what the dealer says. I'm hoping they wont gripe about my lowered suspension although I don't see what that would have to do with it. I haven't touched the engine mod-wise.
 

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Discussion Starter #16 (Edited)
Update!

UPDATE!

The good news is that they're replacing the brake light switch under warranty even though they found nothing wrong with it because I told them it had left the brake lights on more than once.

As for the Misfire/CEL issue - HERE'S THE INTERESTING PART - I was told that the misfire codes (P0300 and P0301) was due to the wrong plugs. Apparently they tested the coils and they were fine. I was told if the coils were bad it would have sent a "hard fault" (CEL constantly on) and not a "sporadic" fault. Now I just replaced the plugs less than 5,000 miles ago using NGK PFR6Q (Audi/VW part number 101 000 063 AA) plugs. I told him I checked the part numbers with the Bentley and ETKA and he said (according to the tech) that VW specs Bosch plugs. When I went to pick up the car we talked some more about it and went to ask the parts dept. The Parts guy said that aside from a few early 1.8T's VW has always used the NGK plugs and I had the right ones. We tried to figure what else could be causing it and were stumped.

So I'm stumped. I think I just noticed it feels like the car vibrates very slightly while idling when my foot is on the brake (only) but maybe Im paranoid? Other than that it drives fine.

They also pulled P0456 (Evap canister) but it tested and passed.

To their credit they did help me out on the brake light switch and the SA was very patient with my constant questions, but Im still curious what's going on...
 

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^^^^^^^ Bump - any ideas regarding the mystery misfire?
I haven't had this problem mind you, but maybe it would be worthwhile to pull the plugs one day and see how they're looking, maybe one is fouled, and to carefully double check the gap?

Surprised to hear them thinking that the bosch plugs are the OEM, that's kind of disturbing don't you think?
 

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Discussion Starter #20
yes, considering it was the dealer. And really, I've always found them to be pretty good. Not only that but I took the car in on Monday evening and they couldnt get to it that night so I got it back around 11:30 and brought it back the next day (tuesday) and got it back that night. The good thing is the dealers parts and service depts are open from 7AM - midnight; M-F.

The parts guy said the early 1.8T cars used Bosch, and I think some other VW engines use Bosch. When I went looking for plugs I saw Bosch listed as a choice, so Im sure they use them for some engines, just not 1.8T.

Since the tech thought I had the wrong plugs, he pulled the plug out of the cylinder than misfired. I assume that he would have checked it to see if it was fouled. I checked the gap before I put them in. Guess I will take a look this weekend. I need to drain a little bit of oil anyway. :rolleye:

The misfire came from cylinder 1 - which one is that exactly? The one closest to the firewall or the one closes to the front of the engine bay?

I'll check the hoses. I will also do a throttle body cleaning in a few weeks.
 
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