Why doesn't my car pull hard?

[1stgensleeper]

OK i got a 92 Talon, Its got a walbro 255, and a K&N drop in, i got the boost turned up to about 13 (it spikes to 14 or 15 but that really doesn't bother me) when my car is cold and/or it just feels like it, at WOT it boosts up to 13 psi but the car pulls like its running on 2 cyllinders, the engine sounds fine and everything appears/sounds like its perfect the car just doesn't pull hard (it basically pulls like theres no turbo at all,But my boost guage reads 13, and its an aftermarket boost guage not the stock one so yes its accurate), then i can shift to the next gear and put the throttle down and it pulls like normal pushes me back into my seat.......(and i win the race anyways ) this also usually only happens at WOT so i find myself accelerating at like 75% throttle so i dont have this problem because my car is probably quicker at 75% than if i go WOT and it has this problem. I don't currently have any way of datalogging but my assumption was that its my ECU pulling alot of timing but then why wouldnt it do it in every gear every time, and i never run below 93 octane so i don't even get why it should pull timing at all

 

[GVR4592]

You need an adjustable fuel pressure regulator and a datalogger, without those there's really nothing you can do.

 

[1glaserturbo]

Your pulling timing. Rich knock is occuring, and your running the car into the ground. Stop while your behind.

First off, why do you have a 255 without any aftermarket Fpr? That's just...dumb. Second off, get a logger, and something to tune with. (SAFC, DSMLink) You get the picture.

Don't do anymore runs at WOT or your car won't last much longer.

 

[1stgensleeper]

first off what the hell is rich knock, why is it occuring and i was told by a buddy who is an avid DSM'er (hes got a 2g stroked butchered MAgnus coil onplug.... 700AWHP) that a walbro without an AFPR is the best way to go, beside like rewiring the stock pump or any of the other shortcut ways of fuel system upgrades and my AFC is on the way it will actually be at my doorstep tomorow morning and will be in my car tomorow night

 

[1glaserturbo]

That 255 is overrunning your stock fpr.

Rich knock is caused when there is way to much fuel for the airflow. It is causing your car to knock due to premature detonation and pulling timing.

Maybe you should get a logger as well....will tell you exactly what I just did.

 

[Dred]

Rich knock is what happens when you're flooding your combustion chamber w/ too much fuel. This is happening in your case, because you put a 255lph fuel pump w/o any kind of aftermarket fuel pressure control. Your fuel pressure is higher than stock, but the injectors are stayin open for the same amount of time as stock. Basically, if before you were gettinx X amount of fuel a Y IPW with Z fuel pressure, and for arguments sake, the 255lph creates 1.5x more fuel pressure, you are now injecting a 1.5X amount of fuel instead of what you need to be injecting. Hope this makes sense. Get a logger and an AFPR to get the base fuel pressure to stock.

 

[GVR4592]

Rich knock is extremely overrated. I highly doubt his engine is experiencing it. I've ran my engine in the low 9:1 range(not purposely) and have never seen any indication of rich knock. There's a guy that posted a Dsmlink datalog a while ago and he was in the same area 9:1 A/F and there was no knock, but there was no power, the car felt like crap.

I just re-read the original post and I was wondering if you're getting a check engine light?

 

[1stgensleeper]

no check engine light

 

[Ultimatedsm]

I ran a 255 with a stock FPR, and my car pulled pretty decently. However, getting an aftermarket AFPR makes tuning a lot easier. I noticed when I had the stock FPR it ran rich on idle to about 3000 rpm, after that it was fine because the boost kicked in. It wasn't pig rich, but a little richer then you should have it.

Anyway, you are experiencing a boost leak. Do a boost leak test and I am sure it will solve your problem once you get them cleared up.

 

[1glaserturbo]

Rich knock is extremely overrated. I highly doubt his engine is experiencing it. I've ran my engine in the low 9:1 range(not purposely) and have never seen any indication of rich knock. There's a guy that posted a Dsmlink datalog a while ago and he was in the same area 9:1 A/F and there was no knock, but there was no power, the car felt like crap.

I just re-read the original post and I was wondering if you're getting a check engine light?

I've been experiencing quite a bit of rich knock with my 550's and 190, tuned it down and am running very nicely as of the other day. Unfortunately the transmission is on the ground behind the car, so I can't pull any logs for ya

Either way, if my tips don't help, good luck


Chris

 

[Ultimatedsm]

I've been experiencing quite a bit of rich knock with my 550's and 190, tuned it down and am running very nicely as of the other day. Unfortunately the transmission is on the ground behind the car, so I can't pull any logs for ya

Either way, if my tips don't help, good luck


Chris

You have something different going on. He has 450cc injectors with a 255LPH, the 255 can outflow the fuel injectors no problem. So the fuel injectors are the restriction there. You have 550's which can easily flow much more fuel then the car was suppose to get. It is odd to get rich knock with stock 450's.

 

[1stgensleeper]

thanks for all the info, ill run a boost leak test in a couple min when i get out to my shop, and whats a good and decently cost effective AFPR i may as well buy one now so on mon when my AFC gets here and i get on the Dyno i can turn the boost up even more and have a little fun.....oh and also what fuel pressure should i run for 13-16 pounds of boost, is stock fuel pressure good or should i up it a little bit?

 

[Ultimatedsm]

Base fuel pressure is good enough for now. It is a good start when you tune. Aeromotive makes the best in my opinion AFPR. Trust me, you don't want to cheap out here or you will be sorry with inaccurate fuel pressure. That can cause tuning issues.