Madmax670

The Good News: So today I finished installing my HKS Twin Power. I love it, everything is smoother, I would even say that driving is eaiser!

The Bad News: The problem that I have been having over the past couple of months persists. First gear pulls fine, but when I get into 2nd at WOT at about 4k RPM's the car starts jerking slightly and the RPM's seem to jump up in spurts. For example, it may go quickly to 5k then slow down when going to 6k. The car feels like a dog like this.

It seems like the engine is making good power but it is not getting to the wheels. There is no reason that it would be the clutch, it only has 20k miles on it. I cannot explain this and I would really appreciate some help!

Mods:

Blitz FMIC
Non-Sequential conversion, running around 14 lbs.
Bosch Fuel pump
1300 secondaries
9.5 lb flywheel
Fluidyne
Twin Power
No P/S or A/C
Full 3" exhaust, no cats RB Duals
PFC w/ datalogit + Tech Edge

On rebuilt engine with about 20,000 miles, stock ports.

rynberg

That's because you were trying to use the Twin Power as a bandaid!

What are your AFRs in the rpm ranges you are having problems with? Boost stay constant? How is the timing in those ranges? Have you replaced your ignition coils? Fuel pump working properly? Fuel system in general working properly?

potatochobit

iTrader: (1)

sounds like a wastegate problem

Madmax670

I just did a mapwatch in second gear at WOT for three runs, I will attach them, if someone could analyze them i would really appreciate it.

rynberg

Is your wideband reading right? High to mid- 12s under boost? What are the PFC target boost and rev limiter settings?

Marshall

Whats up with the o2 sensor?

Madmax670

rev limit is @ 8100, what settings is "target boost" in? How do I even know if my wideband is reading correctly? I calibrated the readout from my wideband to the fc edit software, i did a watch and the reading on the software is within .2 of the reading on the wideband readout.

rynberg

Your AFRS are too lean, at least they're leaner than I would like my car to run at on pump gas....

Boost control settings are under the Settings 1 tab. If you are exceeding the target boost entered in that section, the PFC will fuel cut on you. Just something to rule out.

Madmax670

what number should i tune to and if it were fuel cut wouldnt the car just completely die and stop? It would not be fleeting, correct? Thanks a lot for your help again rynberg.

TTBullet

i have same issue, today i got new ignition coil from racing beat. i'm going to test it tomorrow, i'll let u guys know.

jpandes

Yeah, You are running way too lean. You should be targeting 11.2ish under WOT under boost. I'm thinking that you are damn lucky that you have some setting that is saving your *** (and your motor) by kicking-in fuel-cut or retarding timing.

Check out the chart of your run(attached). Your knock readings are climbing in lock-step with your boost. That is bad!

Do yourself a favor and stay out of boost and get some tuning help... Here's what I did: I added so much damn fuel that my car COULD NOT lean-out and blow. And then I did numerous runs and datalogged them and SLOWLY removed fuel until I reached the approximate target AFR's. I am not and expert tuner, and my car could seriously use some fine-tuning from a veteran FD tuner. But at least I know that my fuel maps are safe(316 rwhp & 274 ft/lbs. @ 13-14.5 psi)

I uploaded a spreadsheet of MY target AFR's.


We could help you more if you uploaded a .dat.

rynberg

Here is a thread containing some of MANY excellent posts Chuck Westbrook (cewrx7r1) has made about tuning and ideal AFRs....also download the single turbo tuning guide written by Brian Davies (Wargasm). It is available in the single turbo forum.

I would start to suspect an ignition system problem. My mechanic recently had a customer where the leading ignition coil worked fine under cruise and light load but failed under heavy loading...you may be experiencing a similar situation.

Problems like this can be very complicated or hard to diagnose, perhaps a trip to a good FD shop is in order.

Madmax670

First of all, I really want to thank you both for helping me not pop my motor.

Here is my .dat, let me know what you see, I have read through wargasm's guide more than once and am still familiarizing myself with the tuning process. Thanks again guys.

I do have a-spec in town, but I have not been hearing good things as of late about them so I am hesitant to go there.

Keep in mind that I did not tune this car.

http://www.sendmefile.com/00077161 < the file

rynberg

I'm far from an expert but there aren't any glaring dangerous problems in your .dat file that I can see. The timing certainly is WEIRD in several places, and you should clean up several cells of negative split in the vacuum ranges. The timing is also not very smooth in some places but shouldn't be dangerous.

You need your ignition and fuel systems thoroughly checked out. You also need more fuel added to the higher boost areas...mid 12s at 10 psi on pump gas is leaner than you want to be IMO.

Madmax670

Is there anything I could do to verify that my fuel and ignition systems are working properly, maybe a fuel pressure test or something along those lines. I like to avoid having people mess with my car, at least if I screw it up I feel a little better about it.

jpandes

From looking at your .dat file. Your Knock warning is "on" and the threshold is set at 60. After looking at your logged runs you are hitting 60+ knock readings. I think that is why your car is hesitating(a good thing).

Rynberg is usually right about things right about things...

Your fuel system may not be delivering enough fuel... Have someone check fuel pressure, Injector flow rates(I have read that bored-out 1300 Secondaries have failed before.)
Or your maps are too lean.
Have you added any "flow" mods to the car after it was tuned?

I would suggest taking to rotary expert, and no one else.

Madmax670

I will definately do some tuning, and I like to think I am pretty savvy with my car. I went for a ride with another member on the forum and he said to check the igniter, for some reason I do not think it a fuel issue, but I will make sure to check both issues.

If anyone else has any feedback, I would greatly appreciate it!

Madmax670

now i feel like an idiot, replaced spark plugs, runs like a champ

jpandes

I'm glad that your car runs well again. However, I'm curious as to how your car ran leaner with bad plugs. Wouldn't bad plugs cause your AFR readings to be richer?

I mean: bad plugs = less spark = incomplete burn = richer AFR's in the exhaust... Do your new AFR's check out?

POS7

How long was it since your last change?

Madmax670

Well, i also got a new map from Chuck Westbrook, that helped a lot as well, I still have some fine tuning to do as far as the AFR's go. I saw 17 AFR's when cruising at about 2k rpm, scared me a little bit, which I should be, shouldn't I?

I had the same thought you had jpandes(I mean: bad plugs = less spark = incomplete burn = richer AFR's in the exhaust... Do your new AFR's check out?), it did not make sense to me either, all I know is that I no longer have any bucking and i spin all the way through 2nd gear.

The last spark plug change that I know of was about 1.5k miles ago, maybe a bad batch?