Engine bog.

[Sandy L]

My Talon seems to bog under acceleration mostly when it is warm. I step on the gas and the rpm and boost go up but the car doesn't go like it should. Car is automatic. Every dealership I have been to can't find any fault codes and therefore cannot fix. This is getting very frustrating & expensive. Any help would be greatly appreciated.

[Sean Tran]

Sounds exactly like what happened to me.  It turned out to be a HUGE boost leak.

[Sandy L]

Sorry Sean, I don't know much about this. Where was the leak on your car? Was it a hose or something? I'm just trying to figure out where I should be looking.

[Sean Tran]

On my car it was the lower intercooler pipe.  Here's a link on how to make your own intake leak tester.  If you're not a DIYer, you can bring it to Lowell at L&R Racing in Coquitlam.  He'll fix it good

[Travis Merrick]

Mine does similar, when i initially step on gas it bogs down, but when I let go of gas and boost up again it spools and pulls great!

[Chris Andrews]

Travis, you could be experiencing phantom knock, esp. if what you are experienceing doesn't happen all the time.

I have done EXTENSIVE datalogging on phantom knock.  Here's what happens:

Cruising at 2.5-3.3k rpms.  Hmmm, want to go faster...
Stomp on the fun pedal
Knock-sum goes to 43, timing gets pulled, car feels laboured, doesn't accel
Take foot off, and stomp again,
Knock-sum goes to 0, timing advances, and car kicks ass.

I have found the best solution to this is an immediate downshift to get the revs up, and then floor it.

If this doesn't describe your situation, then ignore this.

My latest suspicion is that turbo lag is a factor in phantom knock...... but at this point I'm merely speculating.

[Travis Merrick]

Yes Chris that is exactly what is happening, if I shift down it pulls really hard, or if I let go or sorta "wave" the gas pedal it pulls fine, I thought it felt like my timing was being pulled, does anyone know a cure for this "Phantom Knock"?

[KevinBuckham]

The cure (mostly):

- revised lifters (I bought mine from Lowell)
- change your oil and use good stuff
- flush when you change your oil
- use a good oil filter (no FRAM crap)

This has significantly reduced my knock.  Once you do this the way to keep from cropping up a bit is to take the car to redline once a day.  This seems to build enough oil pressure to clear the sludge away from the lifters.

I'll bet it is most often lifters and oiling issues, followed by bad or overtightened knock sensors, and finally some *other* mechanical noise.   The *other* is generally not good unless you feel like a rebuild.



I would highly recommend changing the lifters, oil, and oil filter and datalog, datalog, datalog.

-Kevin

[Richard Nazar]

Does anyone know if the weather affects lifter tick? My lifters are a lot louder now than they were a couple of months ago...

[Travis Merrick]

yah im pretty sure it does, cause as soon as it has been getting cold out my lifters are crazy noisy!  but when the car warms up it seems to go away a bit, I think it matters how thick your oil is.

[Anonymous]

I totaly agree with you guys , I had the same problem on my 7-bolt engine until I went with a Mitsu filter.
After a couple days of driving it got less and less noticable.
I also heard that if your base timing is a little much it will cause low end knock in 3rd and up.

[George Myshlyayev]

so what kind of oil filters do you guys recommend then?

[Chris Andrews]

OEM mitsu