rbsurfer

I was having a problem with my car surging and bucking under full throttle only in first. I replaced the ckp sensor and it is still doing it but only in first when full throttle. I've searched everywhere with no answer my car starts and runs perfect but will not let me mash it in first any other gear is fine.. does anyone have an idea replaced all plugs and wires also

Old Geezer

iTrader: (3)

What led you to change the CKP sensor, in the first place?? Code[s]?
Have you logged it when this happens?

rbsurfer

I was getting a ckp code so I just replaced the sensor and also checked the wiring

Old Geezer

iTrader: (3)

Still need the data log to help pinpoint the problem[s].

rbsurfer

What pids do you want me to include in the log?

rbsurfer

ckp issues 2 did not die.hpl
ckp issues.hpl\

here are 2 logs one the car bucked hard and shut off and threw another p0335 ckp code the other it bucked a few times and i let off i dont wanna break anything any help would be greatly appreciated.

rennat_2006

iTrader: (10)

Log your throttle position sensor. I bet youll find it is loosing voltage at wot when it happens

rbsurfer

And what would cause it to loose voltage? I'm pretty sure its in the logs I posted also

rennat_2006

iTrader: (10)

The contacts inside of it are bad and its making the pcm think it isnt actaully at wot.

rbsurfer

But it only does this in first gear? That doesn't add up?

rennat_2006

iTrader: (10)

Ive seen stranger.

Just had this same problem with a 2000 s10, would fall on its face and buck like twice while cruising at 40ish in 3rd.

You need to log the tps voltage.

rbsurfer

ok ill try to log the voltage

rbsurfer

Just replaced the ckp again and now its only in second ?? But not every time?? Any ideas

rbsurfer

OK so replaced the plug and wiring all the way to the ecu and still messing up!?!? Has anyone ever heard of e67 ecus just failing randomly

soundengineer

iTrader: (16)

its not the CKP sensor

No crank position sensor = no running engine



bucking is a function of either Air, Fuel , or spark...
many times its an issue with too much or not enough air in the throttle follower table
sometimes related to a bad TPS Sensor because the Throttle follower table uses the tps signal
it can also be caused by a bad IAC motor as it can also create airflow issue, but you would typically have other issues as well, like idle control issues

rbsurfer

So why would it start all the sudden ?

soundengineer

iTrader: (16)

looking at your log, it looks like you have a sudden drop out of signal on all sensors....
so you might have a bad or intermittent ground on the ECU

its not big enough to completely kill all signal...but everything in your datalog shows a drop...

I had a customer with a similar issue where the vehicle would just run like crap and then kick back to fine....
finally it just died on him and he couldnt get it to run again...
by a lucky changce I happened to accidentally touch the ECU to a bare spot on the chassis and it fired right up and ran perfect....
the ground in the harness at the ECU connector was broken
so we tied a ground onto the ECU case and hit it straight over to the battery, and he hasnt had any issues since