Bucking under boost (log)

red_devil · Dec 9, 2017

My car out of nowhere has got a very violent bucking issue during spool up. I've checked for boost leaks but my tester keeps popping off at anything over 20psi. It seems to hold fine when it does stay on. The way the car runs it feels like it has a massive boost leak as its very harsh, but after the car has been ran a while it seems to go away. Maybe my maf is starting to die? Included a log just in case I'm missing something. Looking at my WB its spiking all over the place. Plugs and wires are less than a year old.

greddy_1700 · Dec 15, 2017

I cant see the log at work unfortunately, but my car did something similar, and it was the plugs and wires. They werent too old either, but changing them cleared everything up.

Another cause, which also happened to my car, was a deadspot in the TPS. Under about 80% throttle, the car would buck violently, but at full throttle it was fine. Replaced the TPS and it fixed that as well. (but again, I cant see the log so I dont know what your throttle position readings are).

red_devil · Dec 17, 2017

The issues seemed to be a damaged injector wire on cylinder 1. My log didn't really show anything to indicate it, but I assume it had issues on spool up and not at cruise due to the injector working harder.

19GSX92 · Dec 22, 2017

Not sure if this issue was resolved but I had similar symptom's when my car would sit for a while. After researching I ended up going with a cooler plug I went from NGK BPR6ES's to BPR7ES's the 6's were only a couple of month's old. Not sure what plug's you are running.

Derek232 · Jan 4, 2018

I may have read this wrong but it sounds like the car could be running really rich in boost. it wouldn't let me look at the log so I couldn't see the AFR's.

red_devil · Jan 6, 2018

Thanks for the replies. The issue was a loose injector wire on cyl 1. I replaced all 4 connectors as they all looked worn and weak. Since I did a wire tuck under the IM it added a bit of stress to the wires bending down below the runners. New connectors with shrink tube or liquid tape to give them some support and stop movement should stop it happening again.

Derek232 you may need to do a firmware update to view logs.

The Top DSM Community on the Web

Bucking under boost (log)

red_devil

Attachments

greddy_1700

red_devil

19GSX92

Derek232

red_devil

Similar threads

Latest posts

Build Thread Updates

Vendor Updates

Latest Classifieds