Knock at 15psi with 16g and stock FP

[Talek]

Ran a log with tunerstein on my laptop the other day and was registering a noticable amount of knock at WOT > 4.5k RPMs or so. I have a 1g tsi with an evo 16g, ported tb and o2 housing, 2.5" straight thru exhaust, 650cc injectors, gmaft tuned relatively rich over default for that size of injector. Stock cooling aside from UICP. But, my fuel pump is stock. I tried replacing it with a 255 walbro, but no matter how hard I tried I couldn't loosen the bolt on my stock fp.

So my question is, am I running lean from the crappy stock fp causing knock? I don't have many places around here where I can go WOT multiple times in 3rd+ gear so it's tough for me to log repeatedly to tweak/test. Oh, and if anyone has any tips about how to get this friggin old FP out, feel free to post.

 

[Spades]

So my question is, am I running lean from the crappy stock fp causing knock? I don't have many places around here where I can go WOT multiple times in 3rd+ gear so it's tough for me to log repeatedly to tweak/test. Oh, and if anyone has any tips about how to get this friggin old FP out, feel free to post.

your logger should indicate whether your leaning out or not. As for removing the fp, some people used line wrenches, but i used a regular vice grip

 

[oldman420]

You need the 255 to power those larger injectors, but if you can't do which i'm sure you can. Look into a re-wire kit to get that stock fp if you dont feel like replacing it but i guarentee you need more fuel. How many miles on on engine, maybe it's also time to look into a new fuel filter if it has never been replaced.

 

[Talek]

98k miles. I do have a rewire kit laying around here somewhere...

 

[oldman420]

Your filter should be good, do the re-wire and get back to us. You may need a new pump but the re-wire is cheap and easy and may do the trick.

 

[KiNg MaRtY]

Some fuel system cleaner can also do wonders

 

[Talesin]

Our fuel filters just about never go bad... they have a very good design. It's good to change them out, but that's unlikely to be the reason for low flow, if you swap the filter at 120K or so. My previous one was never changed (original part from '90!), and there was no noticeable difference after putting on a fresh OEM one.

Which 'bolt'? The fuel line fitting? One of the nuts holding the FP sender assembly into the fuel tank? Be careful when lifting the FP assembly out, not to tear the rubber gasket between the FP assembly and the tank. Slides down over the six studs, and it can get hung up on the threads. If you mean the Phillips screw on the bottom of the assembly itself, the PROPER SIZE screwdriver (not too small/pointed, not oversize) usually seems to be able to crack it free.. it's on there REALLY tight. Most give up and use a pair of vicegrips to break it free a quarter turn, then just unscrew it with a regular driver after that. If you mean the wiring inside, some use nuts to hold the wires on the pass-throughs, and some are rivetted on (on the underside, all are rivetted on the top).

Also note that you WILL NEED an AFPR for a Walbro 255. It's not an optional part. The stock FPR cannot handle the flow, and will severely overrun.

 

[dsmsucks]

I would say that the stock fuel pump is not pumping enough fuel to the injectors. I bet thats whats causing your knock. For that stuck bolt I would soak the joker with wd 40 for bout a week!

 

[kenamond]

Next chance you get for a 3rd gear pull, log O2v. If the O2v look good, it may have nothing to do with your FP. 15psi on stock FP with no rewire may be pushing it, but 4.5k is still fairly low rpm.

 

[Talek]

Thanks for the replies. It's actually a 190lph, I forgot, it's been awhile since I messed with it. I've done all the work on my car myself so far, but I may just take it in to have the fp installed... If I remember correctly, it's the fitting for the fuel line that was being a pain, it was stripping so I stopped messing with it. Maybe I'll just try the rewire but if I already bought the fp, blah.

I have an AFR gauge but it's never worked. Might be defective, idk, maybe I just screwed up when I was tapping the o2 wire, but I'm 99% certain I got it hooked up properly. It lights up but only shows one green light at the max end of the "rich" side. There's no way my car is running THAT rich all the time. It does fluctuate when I turn my car off though...

On my next day off I'll just go out into the country somewhere and run some logs, tweak the boost. Then I'll figure out the FP. I still have an FMIC core laying around that needs some piping and install too... Ugh.

 

[Talesin]

Even an un-rewired 190 can still overrun the stock 1G FPR (partly due to the lower pressure that 1Gs run at stock, partly due to part design).
And the rewire will help no matter if you stick with the stocker or put in the upgraded pump... stable, strong power will let it operate as intended, and give you maximum flow from whatever you put in.

Those cheap 'A/F Ratio' gauges are worthless, pure ricer lightshows, other than to tell you if your front O2 sensor is still cycling properly. If I were in your shoes, I'd grab my logger and check to make sure (should be cycling between near 0v and somewhere over 0.6v at idle.. VERY lean, as intended), and replace it if it's hosed. Dead O2 sensor (front O2 on the 2Gs, 1Gs only have one to start with) will result in poor fuel economy, among other things. For proper tuning you'll need either an EGT (the rough tune way), or a full wideband O2 setup (the right way), in addition to some kind of fuel alteration control of course.

 

[DECODER22]

Get a real wideband, AEM UEGO - $222 shipped from Egay, cant beat that price! Also rewire your fuel pump, its cheap and easy and should do the trick. And BTW, tuning and driving is dangerous, get someone to drive so you can tune, or get someone to tune while you drive, that way you dont total the car and yourself with it

 

[Talek]

I wouldn't tune it myself while driving, I'd log it and tweak after. The maft I have should allow me to adjust the afr well enough without needing another form of engine management. Buying a real wideband is definitely a good suggestion... I was also considering just finding a shop with an AWD dyno and get it tuned professionally. I'm competent enough for bolt ons and some slightly more advanced stuff but I don't know if I could tune it aggressively enough to get good performance without risking damaging something.

 

[Talesin]

So long as they know how to tune a MAF-T and have done it before, or you're paying flat-rate instead of hourly. The MAF-T is not the best tool to tune with, even if it's better than nothing. If you have the option, definitely get it dyno-tuned if you just have a MAF-T and no WBO2. With DSMLink and a WBO2 piped in on one of the 'spare' inputs, you can tune it yourself just on the road, and get almost as much a result as proper dyno-time, but more reliable for driving around town (as opposed to the perfect-conditions of a dyno).