Knock in 1st gear
 

Around the time my 14B ws dying I noticed heavy knock in first gear and continually lessening knock as the gears got higher (43-1, 20-2, 8-3, 0-4&5 or similar). I replaced the turbo with a B16G and got a 2G manifold. For the most part things got better. For some reason I'm still seeing knock in first gear. Anytime I even come close to boosting I can feel the timing being pulled. I haven't been running it hard in that gear, but even in partial boost/partial throttle I'm seeing 20-something counts of knock. I get little to no knock in other gears.

:confused:


*edit* It may be related to a problem I've been having where the O2 sensor reads 0.03 or 0.05 sometimes at idle, but seems to cycle fine otherwise. I changed O2 sensors with the turbo (one came with the new one). I had the same O2 sensor issue before and after the change.

Re: Knock in 1st gear
 

Awww, come on guys. I need a little help here. Pretty please. :)

Re: Knock in 1st gear
 

O2 sensor is not related to knock counts.

Have you had your car tuned? That would be a good place to start.

Re: Knock in 1st gear
 

Completely lacking in tuning hardware right now. Just bought an evo 8 fuel pump and injectors. Will be looking for an AFC right away. Until then....

I don't think this has anything to do with tuning though. It just started recently without any major changes. I mention the O2, because it does it at partial throttle as well, when the O2 actually means something to the ecu.

Unless I'm running rediculously lean I think it's a false reading, because it starts at anything above 0psi or even slightly in vacuum.


It's also worth mentioning that my mileage dropped about 5-6mpg around the same time, but I think that's just due to pulled timing.

Re: Knock in 1st gear
 

It would help if you tell us what has been done to your car.

Have you tried diagnosting it yourself first? What all did you check already?

Re: Knock in 1st gear
 

So you have Evo 8 fuel pump and injectors in your car and nothing to tune with, correct??

Tsk tsk tsk..

Re: Knock in 1st gear
 

Oh yes, and it seems to me that this is a new car?

Re: Knock in 1st gear
 

If the last post is correct, then you are quite rich, which would lead to the knock in the lower gears. You can knock from being too rich, which would be the case with bigger injectors and no tune.

Re: Knock in 1st gear
 

What are the mods on the car?
Rich "knock" and lean "knock" can both occur. One is more of a cylinder miss-fire the other can be detonation. Both are very bad for power and longevity of the motor.
"knock" per gear could also be a load change or possible drivetrain noise.

Re: Knock in 1st gear
 

No, I have ordered the evo 8 fuel pump and injectors. The fuel pump will be going in as soon as I get it, but the injectors will wait until I get some fuel control.

The car is a 91 TSI AWD. Big 16g, 2g manifold, 3" exhaust, boost controller set at 14psi, rewired stock fuel pump, egr and vacuum lines removed and capped, FMIC (a few small leaks, but nothing major). I can't remember everything right now that's going on in the engine bay. No major changes. Compression is low, but stable (110 to 120) which allowed me to run 17-18 psi on my 14b with no knock whatsoever.

I have tried to figure it out on my own, but have come up short. When it was knocking through the lower gears (most in first, but lots through third) I thought it was my dying 14b causing it. The knock was reduced when I changed the turbo, but I'm still having problems. The problem is it started without any major changes being done by me and I can't think of what would cause this condition.

So to reiterate the symptoms: Knock starts at any boost in first gear at both partial and wide open throttle. Rises to mid twenties at least which causes timing to be pulled heavily (car feels very doggy). I may be getting a little knock in second as well. Third on up runs smoothly with no knock until I start running out of fuel.

Re: Knock in 1st gear
 

Your compression should be right around 160. Id look more into that. :(

Also I would fix any of the boost leaks, you would be amazed at how much air is escaping when your doing 18 psi. Also, if you are still on your 1g mas, you might be over running it too, since you are leaking boost too. Or your 1g mas might just be faulty.

What are your injector duty cycle at in 3rd?

Also, your fuel pump could be dying out too. So I would consider replacing that, if it hasnt been already. It is a 10+ year old car.

Have you checked your base timing? If your knock count is going up that high the timing may have been advanced. If you haven't, check it and make sure it is back to factory specs.

Re: Knock in 1st gear
 

Is the Evo 8 fuel pump extremely cheap or something? That is one of the first things we swap on the Evos. Going to a Walbro 255HP on the Evo makes a world of difference in tuning those cars. With a couple bolt-ons you can into problems getting eough fuel under boost with the stock pump.

Re: Knock in 1st gear
 

I plan to rebuild it. I was going to do it around Christmas, but since it's been stable since I've owned the car (well over a year) I've decided to wait until spring.

I was leaking at a couple welds on my piping. I ground them down and fixed most of them. I still need to pressure test for the rest, but it's much better than it was. The problem started long after the install of my FMIC so I know the pipes arent the cause. (Though for good measure I will check all of my couplers)

The MAS issue is a good one. I shouldn't be over running it, because I'm not boosting much, but it may be bad. I hadn't thought of that, but I had similar issues when one went bad on me a while back. Good time to find a 2G MAS.

When I last checked my injector duty cycle the spring in my boost controller was too stiff and I was boosting 15-16psi. I was getting 110% by 6,500rpm. I have since replaced the spring and am running more conservative boost. At 17lbs on my 14B I was hitting 100% around 7,000rpm.

Fuel pump will hopefully be replaced within a week with an EVO unit so that should cure any fuel pump issues.

Checked base timing 5 or 6 months ago. It was a couple degrees off. I set it. Haven't checked it since. I'll grab my timing gun next time I get to my folks place.

Re: Knock in 1st gear
 

Yes, it's very cheap. I paid $30 shipped for a low mileage one. They flow about the same as a Walbro 190, but are supposed to be much quieter and better quality. I was going to go 190, but I've heard good things about the evo pumps and will run it at least until I can afford a good FPR and 255.

Re: Knock in 1st gear
 

If the EVO pump truely flows the same as a Walbro 190 then its a good match to your current setup.

Re: Knock in 1st gear
 

Definitly get a 2g mas. You may not be boosting much, but when the mas draws in air, some of it is going to leak through boost leaks, then the mas is going to draw in more air again to replace the boost that is leaking. Which ends up in your mas over running. This also makes you run richer too, because the mas is counting air that isnt getting sucked in by the engine, but rather being dispersed into the atmosphere via boost leaks, and your ECU doesnt know that, so its reading more air, which means its going to send more fuel. This also then raises the injector d/c to a higher point than it should be, and causes the fuel pump to not be able to support this much amount of fuel that is needed. So all of this is going to account for your car to go FDRTHRTHAEFGARHGFDVXVBAR!!!

So...

FDRTHRTHAEFGARHGFDVXVBAR!!! = Knock

Well, atleast thats what I came up with, lol.

Re: Knock in 1st gear
 

I don't believe the MAS is being over run. The problem started before the turbo upgrade and after the FMIC install. But if the sensor is going faulty it may be having the same effect. I thought the IDC's were high and it would explain the loss of mileage.

Do you think that a 2G MAS and EVO injectors (supposedly act like 580-590cc) would be too rich to run for a couple weeks until I get an AFC? Or am I better driving it as is until I have the whole package?

Re: Knock in 1st gear
 

Hmm.. If the IDC is higher than it should be then you are running rich from leaks. Boost leaks = bad gas mileage. Since you are using more fuel than you need.

Umm I would wait until you get an AFC to tune with before putting in the injectors. But the 2gmas should be fine with the stocker 450's?

I ran my car once with 450's and a 2g mas with no AFC for a month and didnt notice anything different. But thats just me, dont do what I did. Unless someone else on the board thinks it'll be fine

Re: Knock in 1st gear
 

The 2G MAS is not a good match for the stock 450cc injectors on a 1G. If you are going to run a 2G MAS untuned on a 1G then get 550cc injectors (or something close such as those EVO injectors).

Although harsh, here is the best advice you'll be given all day: Cut the bullshit and trying to be a cheap-ass and mod your car right. If you can't afford to do it right then don't do it at all; you'll only end up costing yourself more in the end and run the risk of destroying your car in the meantime.

Re: Knock in 1st gear
 

What am I doing cheapely or hurting my car with? I try to do everything as safely and completely as can be. Are you talking about having to wait until my next paycheck to buy an AFC? Honestly, I've gone hungry to make sure my car is running well so I don't know what you're talking about.

Re: Knock in 1st gear
 

Just an update. Injectors and fuel pump are here. Will be picking up a MAFT setup tomorrow and putting it in either wednesday or friday. (work and classes every other day).

I'm not sure, because it's been too damn cold to get my logger to work properly, but I think the O2 is junk and I my TPS hasn't been passing 95% and causing poor issues. The MAF is still a possibility as well.

So I will be:
Replacing fuel pump
Replacing injectors
Replacing MAF with GM unit and MAFT
Tuning
Pressure testing the intercooler piping and rewelding and leaks.

Hopefully all this will solve whatever my problem is and leave me with a few extra ponies to boot! :)


BTW, the guy i got the injectors from (owner of xtremeboost.com) said he had them flow tested and they flowed something like 75cc over stock. Does this sound plausable and if so what would be a good ballpark setting for the MAFT at stock fuel pressure?

Re: Knock in 1st gear
 

I'm coming in a bit late on this, but have you replaced your knock sensor yet, or check to see if it's leaking at all?

FYI, I've maxed out my evo's fuel pump on the stock turbo, stock cams, with full exhaust and upgraded i/c and i/c piping. Nice call on the maf-t, that will be a good option for ya!

Re: Knock in 1st gear
 

No, haven't done anything with the knock sensor. I'm pretty ignorant about them. It's on the firewall side of the block right? Any advice with this would be much appreciated.

I've seen flow charts that say the evo pump will do about the same as 190, but if I ever max it out I'll put in a 255 and FRP. Hopefully it will flow enough to keep things happy for now. ~20psi on an B16g would be nice. I'll be conservative until I get all my kinks worked out. (assuming that ever happens, lol)

Re: Knock in 1st gear
 

Yup, search a bit for pics and whatnot. It's on the firewall side of the block, just under the intake manifold. If there is drippy residue leaking out of it you want to replace it. I think I have a pic somewhere of mine on my 1G...

Re: Knock in 1st gear
 

Ahh here it is. Notice the leaky residue directly below it.

http://www.scheides.com/albums/dyno-...0717.sized.jpg

I had a hell of a time finding a pic of this when I had to replace mine, so I thought I'd just do the internet a favor and keep one around. :)

Re: Knock in 1st gear
 

Cool, thanks. I'll check to be sure that isn't leaking or loose as well.

Re: Knock in 1st gear
 

Sounds like your problem should be fixed, or atleast you ran out the many possibilities. :D Hopefully that baby's gonna run good after that. Let us know how it goes.

Oh yes, and I will also pray for you, since the weather is really cold. Haha.

Re: Knock in 1st gear
 

Oh yea the 02 has doesnt play a role in any of your issues. Or atleast, when my 02 went faulty it didnt.

Re: Knock in 1st gear
 

I know if it goes out it shouldn't as the ecu will just run in safe mode. I think it may be giving false readings which are throwing things off. Who knows. I'm replacing that as well just to be sure.

And yes, it's freaking cold out. I did a little work yesterday and it was frigid! I had soldering to do, but the solder would barely melt in the cold.