[CannuckCorradoVR6T]

Okay, there is an overwhelming amount of information on the "bucking bronco" syndrome, so I thought I would start a poll.
Let me say this. I do not want to spend $1000 in parts to figure out my problem, this is why I am doing a poll - attack the problem with statistics. Only people who have had this problem should participate in the poll.
update: Brand new bosch maf=still bucking.
The car:
93 Corrado VR6 Turbo. OBD2with C2 chip . 10psi.
original coilpack
original fuel filter and pump
original sensors
new plugs
Neuspeed wires < 2 years old

Symptoms: the car bucks violently with about 20% throttle - and I do mean engine mount breaking violent, there is an O2 sensor code, but whent he codes are cleared, the bucking causes no CELand no other codes. The wideband reads lean when the symptoms occur (this could mean not enough fuel, or missfires)
Scenario: Two days ago, I swapped my coilpack with a used one I had laying around to see if it would cure a slight hesitation problem. It didnt cure anything, nothing changed at all. One day later, the bucking started -so I changed the coilpack back to the original. The bucking still persists.
Please select what you think would cause CV shattering engine buck.


Modified by CannuckCorradoVR6T at 6:40 PM 11-12-2006

 

[CannuckCorradoVR6T]

Re: Violent Bucking Bronco Poll! People with real solutions apply within (CannuckCorradoVR6T)

Lunch bump http://****************.com/smile/emthup.gif

 

[VW_IS_life]

Re: Violent Bucking Bronco Poll! People with real solutions apply within (CannuckCorradoVR6T)

I have the same problem with mine, but Im not FI, 93 corrado motor, mk4 headgasket, schrick cams, new wires/plugs/maf/o2 sensor. It started doing it right before my thermostat pooped the bed. I was running a low-temp t-stat and the motor never got fully warm. It ran 160*F even in summer. ran rich like crazy, and soon before the t-stat stuck close on me, the bucking became worse and worse to the point it was really undriveable. when the t-stat stuck close and the car started to overheat one day, I turned the heater on to bring down the temps, and I noticed the bucking problem was completely gone

i used to have bucking like crazy at part throttle, and when i hit the gas it would pop and backfire etc.. since the t-stated f-ed up , I had to leave the heater on when the temps would get up there, but I could adjust it so that the temp would stay right under the trigger point for the low temp fan switch, and the car ran A LOT BETTER, mpg went back up, driveability was much improved.
so if you have a low temp switch, I would recommend looking into that.

 

[moze304]

mine is at the shop right now for similar problem....especially when start cold....car idles ok...hit the gas an get to 2000 car starts buckin cuttin out....once it gets warm it still does it...but if you step an the gas an can get through it to 3000 rpms its fine after that...its been at the vw shop for about 2 weeks now they're still tryin to figure it out...its one of those problems that if pretty much any part on the car goes bad it could make it run like that....it threw a code for the engine speed sensor...they put new one in...car still runs the same...anyone else had this problem??

 

[CannuckCorradoVR6T]

Re: (moze304)

Well, I unplugged the Maf, and the bucking calmed down somewhat. I guess that is the problem. I tried cleaning it with a little brake cleaner, but no such luck. Will a 2.0 Maf insert work?

 

[Vdubsolo]

Re: (CannuckCorradoVR6T)

Quote, originally posted by CannuckCorradoVR6T »

Well, I unplugged the Maf, and the bucking calmed down somewhat. I guess that is the problem. I tried cleaning it with a little brake cleaner, but no such luck. Will a 2.0 Maf insert work?

Yes it will.

 

[abt cup]

Re: Violent Bucking Bronco Poll! People with real solutions apply within (CannuckCorradoVR6T)

Check your ignition switch and also check the connection at the main harness.
I also had issues with bucking. It was 1st gear tire chirping bucking. I spent about 500 bucks replacing parts that did nothing. It ended up being a bad connection at the fan motor plug.

 

[vr6swap]

Re: Violent Bucking Bronco Poll! People with real solutions apply within (abt cup)

My Passat daily driver had a real irritating bucking / misfire at light throttle cruise, and wouldn't hold an idle when cold or with the A/C on. Was also running pretty rich, to the point where a tank of gas only lasted 275-300mi.
I cleaned the TB, replaced the 02 sensor, the coilpack, the coolant temp sensor, and the FPR (I didn't think the FPR was the problem, but I had an extra one). All this work improved it some, but didn't get rid of the light-throttle bucking.
After a few sessions of swapping parts / test driving / cussing, I got around to trying a known-good MAF, and that finally fixed it.

 

[maxslug]

Re: Violent Bucking Bronco Poll! People with real solutions apply within (abt cup)

Quote, originally posted by abt cup »

Check your ignition switch and also check the connection at the main harness. I also had issues with bucking. It was 1st gear tire chirping bucking. I spent about 500 bucks replacing parts that did nothing. It ended up being a bad connection at the fan motor plug.

I have the same problem. 3.0L VRT C2 30# OBD-II.
When I start off in the morning cold it bucks like crazy form 2000-2500.... if I keep it out of that range it's happy.
The interesting thing is I'm having problems with my fan control module -- my fan comes on high (setting 3 w/ac) when the engine is not that hot. I replaced the left-most temp sensor (brown or blue/white top) and that helped the fan from staying on forever after the engine is off, but still going into full-blast mode when it's not appropriate.
MAF is 120k miles / 10 years old -- so that could be suspect too.
-m


Modified by maxslug at 7:55 PM 11-4-2006

 

[vwmk1gti]

Re: (moze304)

Quote, originally posted by moze304 »

mine is at the shop right now for similar problem....especially when start cold....car idles ok...hit the gas an get to 2000 car starts buckin cuttin out....once it gets warm it still does it...but if you step an the gas an can get through it to 3000 rpms its fine after that...its been at the vw shop for about 2 weeks now they're still tryin to figure it out...its one of those problems that if pretty much any part on the car goes bad it could make it run like that....it threw a code for the engine speed sensor...they put new one in...car still runs the same...anyone else had this problem??

I have the exact same problem, I've tried a known good tps, throttle body, maf, speed sensor, isv. Plugs, wires, fuel filter, o2 sensor and coilpack are all new. I"m thinking maybe the sensor on the cam or maybe dirty injectors

 

[CannuckCorradoVR6T]

Re: (vwmk1gti)

Okay, I did a test with a known good maf sensor from another car
- problem solved- Now I just have to buy one of my own. The car still has some hesitation, but I chalk it up to old coilpack with maybe a little too much boost for being unintercooled/high compression. Thanks everyone.

 

[moze304]

Re: (vwmk1gti)

this sucks...the shops had my car for over two weeks trying to find problem...he had a couple people check it out....someone there "thinks" its the coilpack....someone else there"thinks" it could even be a bad computer....i'll give them a few more days...then i'm just gonna pick it up...thats the second shop its been to to try to figure out the problem...i don't know where else to go after that...will the volkswagen dealer be able to figure it out???...car i starting to become a pain in the ***!..

 

[SlowMotion]

Re: (Vdubsolo)

Quote, originally posted by Vdubsolo »

Yes it will.

i thought that only mkIV vr6 and 2.0 where interchangeble.
if that's not the case could you tell us which one will work with the MKIII

 

[abt cup]

Re: (moze304)

Quote, originally posted by moze304 »

this sucks...the shops had my car for over two weeks trying to find problem...he had a couple people check it out....someone there "thinks" its the coilpack....someone else there"thinks" it could even be a bad computer....i'll give them a few more days...then i'm just gonna pick it up...thats the second shop its been to to try to figure out the problem...i don't know where else to go after that...will the volkswagen dealer be able to figure it out???...car i starting to become a pain in the ***!..

The engine light will normally blink as the car is misfiring if the coilpack is bad. Maybe check the cam sensor.
The car will throw the engine speed sensor code if it is not running.

 

[moze304]

i'll run it by him....thanks.

 

[maxslug]

Re: (CannuckCorradoVR6T)

Quote, originally posted by CannuckCorradoVR6T »

Okay, I did a test with a known good maf sensor from another car - problem solved- Now I just have to buy one of my own. The car still has some hesitation, but I chalk it up to old coilpack with maybe a little too much boost for being unintercooled/high compression. Thanks everyone.

OK, chalk one up for the FAQ -- Bucking Might equal bad MAF.
I'll try to find a known good one and correlate this.
-m

 

[Oh_My_VR6]

Re: (hotshotz16v)

Quote, originally posted by hotshotz16v »

i thought that only mkIV vr6 and 2.0 where interchangeble. if that's not the case could you tell us which one will work with the MKIII

The housing diameter itself is smaller on the MK3 2.0's, but the insert/sensor is the same exact part and is interchangeable.

 

[95GTIVR6Speed]

stock clutch with boost?

 

[maxslug]

Re: (95GTIVR6Speed)

Quote, originally posted by 95GTIVR6Speed »

stock clutch with boost?

These are symtoms that are happening before the car is anywhere being in boost, low throttle, low rpm.
-m

 

[95GTIVR6Speed]

1st gear kinda revs fast even at 20% throttle. I dunno. If he has boost on a stock clutch that would be my guess.