Help please! Massive knock in 1st gear!

[4G634ME]

Okay, I'm really goin' nuts. My car ('91 GSX, JDM engine w/ 75,000 mi) seemed to be running a bit weird all day, especially in first gear. Having a hunch that timing was being pulled, I checked for knock on the Pocketlogger.

For some reason, I am getting serious knock (40+) under heavy throttle in first gear and ONLY in first gear. Even at the same engine speeds in other gears I get absolutely nothing! Runs perfect!

Can you guys give me a hand with this? I'm really really nervous.

Is this the so-called 'Phantom Knock?'

FWIW:

14B
Walbro 255
Stock injectors
17 psi
AFPR
Manifold leaks (broken studs... waiting for turbo to arrive to put 2G on)
Boost leak (intake test)
Other mods under profile

Gonna go down to 15 psi for now, see what happens. Gotta go, wife is demanding we go to dinner.

Thanks guys....

Jason (off the boost for now)

 

[AWD_ENVY]

I seen that you have an AFPR, but which one. What is your base fuel Pressure....

Se if it will knock on the highway... fether the gas so the Boost gauge reads "0". See if you get knock at that point.

 

[95talontsi]

have you checked to see if the knock sensor is faulty.

 

[4G634ME]

Hey guys, thank you for trying to help me. I'm still really worried.

It's knocking at REALLY weird times now. Like just driving down the freeway at 60 mph I show nothing, then after accelerating to a steady 63 mph I get serious knock. This morning, I got knock in every gear until fifth. Then sometimes, absolutely nothing. More often than not, I get really bad knock. Strangely enough, I usually get nothing under full throttle in 3rd, 4th, and 5th... partial throttle results in knock.

I thought the AFPR was a Spoolinup (it looks exactly the same as mine) but I found a receipt from the previous owner that says it's a 'CRB' (abbreviation on the NAPA receipt). I'm not quite sure how to adjust it (or if it even needs adjustment, for that matter). My base fuel pressure (I assume this means at idle) is 45 psi, according to the gauge, which is mounted on the fuel filter (firewall). Is this normal? Strange thing, it doesn't seem to vary a whole lot when the rpms are brought up. Normal?

No idea if the knock sensor is bad or not. Is there a way to tell?

Thank you guys SO much for helping me with this. I'd really like to avoid a visit to Satan.

BTW, back down to 14.5 psi (for now). Want to get this sorted out before I drop in the new toys and all.

Jason
(Praying the DSM Gods will wait till I get my backup car back from the shop before they decide to do anything harsh!)

 

[AWD_ENVY]

This sounds like what my problem was.... Fuel Pressure.

I could drive at any speed and as long as I would keep the partial throttle to read "0" on the boost gauge, It would Knock 40+. If I went WOT the knock would start to go away. It also wouldn't knock if I let up on the throttle(boost gauge in vacuum). In addition, got knock EXTREAMLY bad in 1st gear. Base fuel pressure should be at 38Psi. Adjust your FPR(with the vacume source disconected) to between 38-40. When Mine was having the problem, I was at 48PSI base pressure. You also might want to check for a boost leak to rule that out as well.

 

[fast4wardTSi]

45PSI !?! Wow man, that's a lot of fuel pressure for your setup. If you're on the stock turbo and running 14.5 psi boost with the Whinebro 255lph pump, you are running way too much pressure. I wonder what your O2 is reading when this knock occours? If it is above .92, you are way too rich. I would definitely turn down the fuel pressure and if that doesn't work, check to see if the knock sensor is going out. When they get ready to die they get really hiperactive.

 

[4G634ME]

Again, thank you for the help. Two questions:

1. How do I check to see if the knock sensor itself is going bad?

2. How do I turn down the Fuel pressure? The gauge is on the fuel filter, which (obviously) is before the AFPR. The guy gave me an additional spring, which I believe he said is used with it for adjustment. Not sure. Would making adjustments on the AFPR change the readout on the gauge even though it's before the regulator?

Another thing... seemed like the pump was a bit whinier than usual yesterday. Might have been me though.

BTW, the PO was running at 17 psi, which might explain the higher base fuel pressure.

AWD_ENVY... sounds almost identical. FWIW, I know I have a boost leak, as well as an exhaust leak. Just waiting for the turbo to get here to throw all the new toys in.

Are directions available anywhere on how to adjust the fuel pressure? I've never done it before (remember, bought the car a month ago with this stuff already installed), so I'm kinda lost.

Any help is appreciated.

Jason

 

[4G634ME]

Also... my o2 voltages are absolutely nuts. All over the place. You name a number (.12, .35, .97, .00, etc.) it goes there.

I worry all of this may be related to the leaky manifold (unreliable o2 readings), possibly faulty o2 sensor, boost leak, etc. It's just that this all happened totally out of the blue... like something actually broke.

Replacing the manifold, turbo, o2 sensor and housing in 6 days. Just waiting for the turbo to arrive. UPS says the 12th. Hopefully the broken manifold studs don't give me too much trouble coming out.

'Nother question... how bad am I hurting her by driving (few miles a day off the boost; wife needs to get to work) with the knock? Does the ECU pull timing enough to negate the effects?

Jason

 

[Enigma_Man]

Allright, this is totally a guess, and theoretical in nature, so don't take it as "what to do" But if your O2 sensor went (as judging by your wacky readings, mine's dead and does the same thing) The car would run very rich, even if it was perfectly stock (the ECU sees dead O2 sensor, and runs on the rich/safe fuel maps, I think mine is doing this, it's "boggy" gets poor fuel mileage, and at idle, I can hear it sputtering a little). In addition to that, your base fuel pressure is very high.

So, the combination of all these things is making for a wicked rich idle/part throttle condition. Which might explain the knock (people have said too much fuel can cause knock too).

That's my thoughts, anybody agree?

-Jesse

 

[4G634ME]

Oops... double post, my apologies. Darn dialups! Want my T1 back!

Jason

 

[4G634ME]

Originally posted by Enigma_Man
runs very rich, it's "boggy", gets poor fuel mileage, and at idle, I can hear it sputtering a little).

Apologize for the delay in reply... had to fly to Jersey for a few days. Still there, borrowing computer.

Jesse! You are da man! This completely and totally describes my situation! It is definitely 'boggy' (no doubt also caused in part by the leaky turbo and manifold), it gets ridiculously bad fuel mileage, and nevermind sputtering, mine is friggin' burbling like a V8 at idle! Which, I admit, I've kinda grown to like at stoplights.

I fly back in tomorrow night, and the turbo should arrive sometime during the day (wife will be home). Assuming I have all the gaskets and miscellaneous items, the turbo, manifold, o2 sensor, o2 sensor housing, and EGT/boost gauges will all go on the car Tuesday! I can't wait!

Oh, and I'll go ahead and turn my base fuel pressure down to a more reasonable 38psi.

One last thing though... is there a method to check whether or not your knock sensor is going? My 'idiot light' knock sensor does not correspond with the information the Pocketlogger provides.

Again, thank you guys for all the help.

Jason

 

[fast4wardTSi]

If your car knock at idle, and all the black goo has ran out of the back of the sensor, it's probably bad.

 

[hdswanny]

yup, yup, look for the icky goo just below the knock sensor.