Bucking under acceleration
08-26-2018, 01:00 PM
#1
Rennlist Member
Thread Starter
Bucking under acceleration
I have searched and read several posts about this problem. I checked all of my intake hoses and I also just installed the LR silicone J boot (I had this issue before I got the new j boot).
But I still am getting bucking when I accelerate from 3k rpm to 3800. If I go WOT below that, I get normal acceleration all the way to redline. But if I'm cruising at 3k, then go 3/4 to WOT, I get bucking at 3800 or so. It's almost like it's the overboost or rev limiter.
Any and all help is much appreciated.
But I still am getting bucking when I accelerate from 3k rpm to 3800. If I go WOT below that, I get normal acceleration all the way to redline. But if I'm cruising at 3k, then go 3/4 to WOT, I get bucking at 3800 or so. It's almost like it's the overboost or rev limiter.
Any and all help is much appreciated.
08-26-2018, 02:53 PM
#2
Drifting
Sounds like a worn out potentiometer in your AFM or TPS. You can test them with an analog ohm meter. A digital ohm meter is not accurate enough when testing a potentiometer unless it’s an oscilloscope.
08-27-2018, 06:47 PM
#7
Rennlist Member
Thread Starter
I change my plugs annually and I put new 9mm wires on in 2012. They plugs/wires are connected nice and solid.
I'm not sure how to check the turbo system for positive and negative pressure leaks. How is that done?
I'm not sure how to check the turbo system for positive and negative pressure leaks. How is that done?
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08-28-2018, 09:15 AM
#8
Drifting
Five years on those wires might be the issue. It very well could be that easy. How many miles have you driven it in the last five years? I only mention that because electricity takes the path of least resistance and at 3000 to 3800 rpm’s is where the engine produces the most torque meaning the most resistance in the cumbustion chamber is happening. Take a look at them to see if there looks to be a vary small black spot on one or more of them where they could be grounding to the fuel rail mounts or anything else they could rubbing against.
08-29-2018, 12:44 AM
#11
Rennlist Member
I've had ignition missing/bogging from wires that look great and spec out on the ohm meter, so not sure there is any practical way to know if yours are bad other than trying new ones. You can try looking for arcs in the dark, but chances are they are fine until your motor sees a lot more load than you can get in a dark driveway... If yours are from 2012, it wouldn't be a waste to change them anyway.
08-29-2018, 06:43 PM
#12
Rennlist Member
Thread Starter
I looked at Automotion's and Lindsey's website and there seems to be a lot to choose from. I have an MSD ignition and a Blaster 2 coil (new coil as of last summer). Any recommendations on new wires?
08-29-2018, 11:28 PM
#13
Drifting
Isn’t there supposed to be a risistor on the power wire to the coil if you use an MSD Blaster coil? Maybe not if an MSD spark controller is in place. Also I believe any new plug wires are good but use resistor wires if you listen to the radio.
09-02-2018, 12:53 PM
#14
Race Car
I once found bad ign wires by fluke (pun not intended)
when the garage lights were off & it was dark, engine running & hood up.. I saw sparks on the wires.
Did you verify wire orientation is correct on cap?
when the garage lights were off & it was dark, engine running & hood up.. I saw sparks on the wires.
Did you verify wire orientation is correct on cap?
09-02-2018, 04:02 PM
#15
Rennlist Member
Back in the olden days --think typewriters, phone booths, and record players-- it was a common shade-tree diagnostic technique to pop the hood in a dark garage and look for sparks. Unfortunately, with our turbo cars, the wires start to fail under heavy load first, and generally do just fine in a dark garage while idling and/or revving with no load. Spenc -- see my other post about Clewett wires. Perfect for MSD -- great value and great wires!