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Installed BFI Stage 2 Chip, ran great for 4 days, now idle problems & rev hang

97K views 398 replies 27 participants last post by  dailygolfer 
#1 ·
I had a GIAC chip installed, and went over to the BFI stage 2. Once running, the car ran fantastic for about 4 days. I was really pleased that the rev-hang issues (revs hanging up between shifts) were gone (when I let off the throttle, the revs dropped quickly back to about 1050rpm idle). Then a problem developed suddenly where the rev-hang returned and when coming back to idle, the engine will float between 1500-2000rpm for a few seconds before returning to idle. The rev-hang is much more noticeable now than when the GIAC was installed. When cruising around 1500rpm, I can feel the motor trying to pull gently towards 2000rpm. Intake system is clean and no check engine light. When I put the GIAC chip back in, it seems to run just like it used to (same amount of rev-hang, returns to idle quickly). Re-install the BFI chip, and the problem is back, even after clearing the ECU via VAGCOM (just to clear whatever learning sequence it does). Thus far BFI doesn't have an explanation. There aren't any vacuum leaks. I took the cover off the idle control motor, cleaned it with contact cleaner, and nothing appeared visually broken in there but it's obviously not serviceable. The only thing I can think of is the throttle body needs to be replaced, but I don't understand why the problem doesn't show itself with the GIAC chip installed. I can only surmise that the BFI chip is actuating the idle control motor in a different manner and the original idle control stepper motor can't keep up?

I posted videos to exemplify the problem.

http://www.youtube.com/watch?v=Y6og6H0SHGA

http://www.youtube.com/watch?v=-AkaxO9lUYM

http://www.youtube.com/watch?v=_x6-QMbg7M8

http://www.youtube.com/watch?v=zFPj1mwtx3w

http://www.youtube.com/watch?v=np7fesgM2H4

What the hell is going on? I'm super frustrated because the car ran the best it ever had for about 4 days.. and now it's all gone to **** again grr.

-Patrick
 
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#66 ·
ive got a 98 jetta as well and have the same problem. ive got a 276 cam in there. the random rpms going up and down between 1500 and 2000 untill it eventually settles to 1050. also have a cel for running to rich and im also getting very crappy city mileage, yet amazing highway mileage. i know my maf is bad, kept cleaning it but the code keeps coming back, and i have a brand new vdo brand throttle body. any ideas? i noticed the crappy mileage when i went from my autotech chip to the stage 2 pem. from what i understand, the pem is like a fineley tuned machine that even the smallest kink will throw it off because it demands a lot from all the sensors readings.
 
#68 ·
i have been having all these problems that all of you are talking about (P0172,car shutting off during warm up cycle, also while driving :banghead: )
the code only came up whenever the chip was installed which is weird..
anyway, i sent out my ecu and chip over to c2 motorsports so they can check out whats wrong with it.
once i get an answer from them ill post it up on the thread.. maybe its the same problem for all of us who knows....
 
#71 ·
I live about 2 hours from BFI in NC. I could drive up there on a Saturday or something if they needed a vehicle with the exact same symptoms we all are having to try and get this resolved.
 
#75 ·
Just a quick question, has anyone changed the vacuum lines under their fenders? For the evap system on the left and the vacuum reservoir on the right? I haven't yet cause I haven't taken my fenders off yet. I have changed all other ones under the hood though.
 
#77 ·
Will do, thanks man! :D .
 
#79 ·
Can you ask them if they need a tester with the same symptoms? Don't know where c2 is located but I am close to bfi.
 
#81 ·
info from Chris over @ c2

ok so I just got off the phone with chris from c2 motorsports. He told me that chip I had ran fine as well as the ecu. He actually helped me out and gave me a deal of swapping my chip with a brand new chip for $50 to see if it will work or not. I told him about this thread that we have going on about all our issues and said he's gonna take a look at it to see what other issues are going on with it. As fas as people willing to drive over to c2 to show them there car with the symptoms he said that would be great that way they can figure out exactly what the problem is.

once I get the ecu back from them I'll try it out and see what happens.
I will be keeping you guys posted on this :thumbup:
 
#82 ·
how many of us are having problems with a stage1 chip and how many of us are having problems with stage2?
that way they can get a better idea.. its on a 2liter regardless

my problem is with a stage1 chip
 
#83 ·
Mine is with the stage 2
 
#86 ·
There aren't any tweaks to help out with the different cams? If not, that's very very useful information for those of us with vagcom's...after I confirm my motor is good to go for a cam upgrade I wouldn't need a reflash to put a cam in.

That would be awesome if I didn't have to plan for shipping downtime at all? :)

Kei
 
#87 ·
Fixed a small vacuum leak on my evap system. Also had the entire vacuum system "smoked" here at the automotive place where I work. No vacuum leaks found...And the car is still running rich and slight rev hang, lol. Also, ran the car for 4 days without the bfi chip and no cel, no rev hang and no richness codes found. Think there is something wrong with the chip?
 
#89 ·
Okay here's an update and some additional information:

News From BFI

Just heard from Joe at BFI that a new chip is coming my way to test, so I'll post results once that swap is completed.

History Lesson / Smog Check

The whole reason I got into the BFI chip in the first place was because I couldn't pass CA Smog and suspected the GIAC chip was contributing to the problem. My first test result is below:



The car had audible knocking at the lower RPMs under load, so I was speculating that the timing curve wasn't right with the GIAC chip, and could have been causing excess combustion temps and thus excess NOx. Thus, I changed over to the BFI chip. That's when I started this whole rev-hang discussion. Since the first test, I installed the BFI chip, changed the oil, replaced the TB, cleaned the intake system, new fuel cap, and put the stock 3bar FPR back in. The second test results are as follows:



As you can see, it failed NOx again, with worse results. The front O2 sensor is
 
#90 ·
Excellent information Patrick, I haven't had to take my car through inspection this year (not til next year thankfully).

I've been doing almost the exact same things as you (if not more :eek: ) in looking for this problem. Again this week I decided to go through again and replace every visible vacuum line I could see since I'd used some hose that wasn't originally meant for that exact purpose (worked great though). I bought a pack of hose, and went to town in th engine bay while waiting for my brakes to cool (replacing a rear wheel bearing).

After replacing all those lines including the long hose that leads down into the fender, I've still got nothing in the way of answers. I haven't bought more hose, and went under the car to remove the liner to replace whatever hose I see in there, but mad what a journey this has been.

Everything I've seen almost screams to me that it's a vacuum leak, but man I swear it's impossible for me to find one. I've sprayed carb cleaner, listened by ear, replaced lines, replaced gaskets, etc. etc. etc.

I almost hope that it IS something in the code that causes this...but then in my head it still wouldn't explain why I don't have the same power I had when I first installed the chip...my car is up to par with maintenence parts now, but wasn't fully up to par when I first installed it to test it. (the power left before replacing any parts so that's not it)

Still the only codes I get are the rich code (p0172) and the missing rear/secondary o2 sensor (p0141). I'd put another o2 sensor in there if I knew that would fix the problem, but that is the one that doesn't do anything other than check the catalyst efficiency...right? (one will be installed eventually, but not until I get a new high flow cat to put it in)
===============================================================

On another note, I hooked up my laptop with the vagcom again the other night to look at the maf readings at various rpms (full throttle) as well as look at the lambda values.

The max reading my maf sensor gave me was


Coolant 99.0C
Rpm 6,040
Maf 99.86 g/s
Air temp 31.5C

Those numbers look okay to me, but I'm not 100% sure what the maf reading should be (roughly) at that rpm on a chipped/exhaust car. I think I remember tdogg saying something about it needing to be ~82% or near that mark of what the engine power would be. I don't remember if that's at the flywheel or drivewheels, and I can't find the thread/message he said it in lol.

A quick search on the net shows someone saying that ~HP= MAF reading/0.8

That would put my engine power at...

99.72 124.6hp @ 6,040rpm
97.22 121.5hp @ 5640rpm
91.53 114.4hp @ 5120rpm
84.03 105.0hp @ 4560rpm

I'd love to know what tdogg thinks of those numbers (tt exhaust, test pipe, and chip are the only power adders). The car still returns to me roughly 30mpg mixed city/hwy using my usual 92oct.

Looking at the vagcom numbers it showed that the car was running very rich at idle when I was finished driving, showing correction numbers of roughly -19% at times though it would never stay that high for a long time. When driving around the values are very close to zero.

Thoughts...anyone?

Kei
 
#91 ·
Still the only codes I get are the rich code (p0172) and the missing rear/secondary o2 sensor (p0141). I'd put another o2 sensor in there if I knew that would fix the problem, but that is the one that doesn't do anything other than check the catalyst efficiency...right? (one will be installed eventually, but not until I get a new high flow cat to put it in)
...
The car still returns to me roughly 30mpg mixed city/hwy using my usual 92oct.
...
Looking at the vagcom numbers it showed that the car was running very rich at idle when I was finished driving, showing correction numbers of roughly -19% at times though it would never stay that high for a long time. When driving around the values are very close to zero.

Kei
I thought the BFI chip deleted the secondary o2 sensor? Yes I believe that rear o2 sensor is only a metric for catalyst efficiency. I don't know if these computers change map or go into a form of limp mode when the CEL is tripped, but the best apples to apples comparisons would probably be to clear up whatever is setting the code (o2 sensor in your case). It seems I'm the only one not getting P0172 code (or any CEL) as well. If the norm is for the BFI chip to cause P0172 rich condition, and I'm not seeing that code, that further leads me to believe a lean condition is causing my high NOx.

causes of lean condition i haven't explored yet:

low fuel pressure: My injectors were recently cleaned, but I've never changed the fuel filter nor checked the fuel pressure, there's no sensor data to log for FP is there?

other sources of vacuum leaks: uhh

I get 23-25mpg, but i drive hard, always on 91oct in cali.

gonna log some data with VAGCOM soon and put that on display too.
 
#92 ·
I had that rear o2 sensor code when I didn't have a rear o2 sensor bung install on my custom exhuast...Installed a bung and added the rear o2 sensor back, code went away so that has nothing to do with the richness code we are all getting with the bfi chip.
 
#94 ·
Let's get interesting...

Okay so I installed the stock chip again today to do some vagcom logging, and then immediately swapped back to the chip to log again under the same weather conditions.

The only variables are the two different chips (stock vs. c2/bfi), and the intake temperature being slightly higher due to heat from sitting to change the chips.

Stock gave me a high of 100-102 g/s in maf data going from about 5300-6000rpm (don't have it in front of me). Intake temps were 28.5C (83.3F) at the time of the test.

C2 gave me a high of 99 g/s going from about 5800-6100rpm (again not in front of me). Intake temps were 31.5C (88.7F) at the time of the test.

If you look back to the data I listed the other night, the max was still the same today as was then with the chip installed. The other night the intake temp was down to 30C still yielding 99.72 g/s at 6000rpm.

What is boggling my mind is that while of course the throttle response is better, and the lower rpm acceleration seems better (not huge but still noticeable)...the stock setup is yielding higher numbers over a broader rpm band...on 93oct (which shouldn't really help the car gain power anyway).

For whatever reason it seems as though besides the throttle response, the car isn't making any extra power where it should be. This would confirm that I'm NOT crazy when I said that the car feels quicker/different than stock, BUT not nearly as quick as when I first installed the chip at H2Oi last year.

Since that time the only real mods I've done to the car are adding the TT exhaust, and the 42DD test pipe while I save up for a new cat. (mine was starting to rattle) Still the ONLY codes that come up are the p0141 (2nd o2 sensor) and the p0172 (rich), but as it's been cleared swapping chips the rich code hasn't returned yet.

When the throttle is pinned during these runs the lambda values are at 0.0%. While cruising the values are around 0 to say -3% at roughly 2200rpm cruise. Look again at around 1800rpm and you can be 0 to -8% or so...then at idle (set at 960rpm) you can be from 0 to -17% or so.

My thought right now is that maybe there is a leaky injector or something...but this is the 2nd set I've tried since I got a set from a fellow vortexer to see if my stock units were just not working out. Car is still the same as when I was using the stock ones. (didn't have a vagcom at that time). If I need to, I don't mind buying new units...but I don't want to buy parts that may not be causing the problem.

Okay thoughts...cuz my head hurts right now? :screwy:

Kei
 
#96 ·
O
Stock gave me a high of 100-102 g/s in maf data going from about 5300-6000rpm (don't have it in front of me). Intake temps were 28.5C (83.3F) at the time of the test.

C2 gave me a high of 99 g/s going from about 5800-6100rpm (again not in front of me). Intake temps were 31.5C (88.7F) at the time of the test.

If you look back to the data I listed the other night, the max was still the same today as was then with the chip installed. The other night the intake temp was down to 30C still yielding 99.72 g/s at 6000rpm.


Okay thoughts...
Just an FYI...your chip has nothing to do with A) your MAF output readings and B) controlling your throttle position.

The MAF converts temperature into voltage to deliver load readings to the ECU. It's just a sensor sending a voltage...not controlled by your chip. The ECU chip adapts to the voltage signal, not the other way around. Any differential in g/sec readings has to do with temperature, relative humidity, and barometric pressure. OR how you happened to drive the vehicle during the test procedure.

The throttle position is controlled by your foot. Not the chip.

Also, hot-swapping chips like this, and then doing logs back to back, is not going to yield an accurate comparison. It takes a complete ECU reset (disconnect battery and discharge) and about 7 cold starts for a chip to fully adapt....and thats taking into consideration your driving style during those learning periods.
 
#99 ·
got the ecu along with the new chip back from c2 on friday but didnt get to open the package until tonight.
ill be swapping out the ecu tomorrow and let you know what happens. hopefully it fixes the problems
 
#100 ·
Patrick, I usually look at channels 1, 3, and 4 when I'm logging my car (use measuring blocks not basic). Those have the coolant temp, intake temp, maf data, rpms, throttle position, timing, and lambda/fuel data.

I'm very interested to see what results you guys get with the new chips. If you don't mind, let me know what the throttle angle is (channel 3 I believe) at wide open throttle. Mine value is roughly 78, just want to make sure that's about what it should be.

Kei
 
#101 ·
Updates?
 
#104 ·
thanks for the info tdogg..
im honestly just looking to see if the car is going to shut off or not after the warm up cycle. I just drove it now so i am going to wait for it to cool down a little before installing it
 
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