HELP.can't stop hitting BRICK WALL at full boost!

[insanedsm2403]

Het what's up everyone.I recently got a 90 tsi awd its all stock exept 3inch turbo back with external dump,supra fuel pump,2g injectors and regulator,autometer boost gauge,turbo xs boost control,and palm m130 datalogger.I can't upload any logs on here because my computer was stolen but I will gladly post any info neccesary to diagnose the problem just let me know what to put up.now I have my boost set at 10-11 psi and I have new plugs ngk bpr6es I believe,new wires,I changed the coil with a known good unit,I changed my mas as well.driving below full boost is nice and ill floor it and it starts to go,untill I hit full boost and at about 3700rpm it gets stuck for a second then starts missing and poping and sometimes will set of around 4-8 counts of knock if I try to stay on it.if I back off maybe 30% throttle it will start to go again untill about 4500 and gets stuck again.I'm out of ideas and would apprecite any help.posts will be responded to asap.thanks a lot


Ps.did boost leak test and found two at inj seal and tb shaft seal.both fixed yesterday.

 

[insanedsm2403]

Just got in from putting a 92 fwd turbo ecu in the car.I switched pins 6 and 14 and the car seems to run a little better.only went around the block will post again after I take it on the highway tonight.

 

[insanedsm2403]

Well I made some progress with the 92 ecu but I still get stuck at a certain piont.the car is pulling a little harder and further in the power band than it used too.2 questions.on my datalogger I have mmcd 1.5.how can I tell if I am running lean or rich?which values should I look at other then knock to know if I have to add or reduce fuel.secondly,does anyone think adding a s-afc will help.I have one I can throw but I'm not sure if this will help or add more fuel to the fire and make my problem worse?either way I need to find a reliable way to log if I'm running rich or lean.any help will be greatly appreciated.thanks for everyones time.

 

[habitatguy187]

Well I made some progress with the 92 ecu but I still get stuck at a certain piont.the car is pulling a little harder and further in the power band than it used too.2 questions.on my datalogger I have mmcd 1.5.how can I tell if I am running lean or rich?which values should I look at other then knock to know if I have to add or reduce fuel.secondly,does anyone think adding a s-afc will help.I have one I can throw but I'm not sure if this will help or add more fuel to the fire and make my problem worse?either way I need to find a reliable way to log if I'm running rich or lean.any help will be greatly appreciated.thanks for everyones time.

What are your fuel trims at? ltft, mtft, and htft. If they are under 100% then the car is pulling out more fuel than stock, which is fine, depending on how low the percentage is.


BTW: what rpm can you rev to now until it starts cutting out?

 

[insanedsm2403]

If you are reffering to fto2 I have a log with a max of 171.8%.it doesn't say high low mid but that was at 23.8% tps.that graph tends to stay even but I have spikes going into the higher then 100% more then I see lower then 100% spikes.idk if this helps any but I must confess I am a noob in this datalogger thing.oh and now if I rev up at part throttle I can get to about 5k.if I floor it it will now hit 13psi,hold it for a second,and then starts missing again.

 

[habitatguy187]

If you are reffering to fto2 I have a log with a max of 171.8%.it doesn't say high low mid but that was at 23.8% tps.that graph tends to stay even but I have spikes going into the higher then 100% more then I see lower then 100% spikes.idk if this helps any but I must confess I am a noob in this datalogger thing

That would be saying that the ecu is adding 71.8% fuel over stock, not good. Doesn't sound right either, the fuel trims should be on the same page on mmcd as the fto2.

 

[insanedsm2403]

Ok just figured out how to use them.let me warm up the car ill take it on the highway and get right back and let you know my numbers

 

[cody92talon]

i would go back to thinking bout the computer. mine had this same problem except mine made it to 4500 before cut out, an yeas i could get it to go a little farther if i let up on the throttle a little. my computer ended up being bad even though i had no burned smell or no leaking caps. i would try an get a hold of another ecu an try that

 

[insanedsm2403]

Just got back from my highway run.idk if this came from my ecu swap earlier today but my tps was working just fine.now I notice its staying at 0.0% all the time on my logger!ran a ecu code check and got 14 tps and 25 barometric sensor.don't know if this has any to do with my problem.my fuel trims never left 100% on high low or med.sadly enough my trims didn't log at full throttle on my graph.it seems it started graphing them once the tps takes a dump or whatever happend to it.

 

[insanedsm2403]

Just got back from my highway run.idk if this came from my ecu swap earlier today but my tps was working just fine.now I notice its staying at 0.0% all the time on my logger!ran a ecu code check and got 14 tps and 25 barometric sensor.don't know if this has any to do with my problem.my fuel trims never left 100% on high low or med.sadly enough my trims didn't log at full throttle on my graph.it seems it started graphing them once the tps takes a dump or whatever happend to it.also car does feel faster at half throttle but full throttle in third revealed my full boost/full throttle problem is still there and just as bad as before.

 

[habitatguy187]

Your fuel trims probably didn't have time to update if you've reset your ecu lately, you need to read this - The Essential Primer on the Diamond-Star Engine Control Units - Table of Contents

Also the barometric sensor is located in the mas if I remember correctly, which could definitely cause your problem.

 

[TimIacobucci]

Have you checked the plugs yet? Where they black or no?

I'm not trying to either back up dsmfa9nutter specifically here or call you out in anyway. I understand not wanted to spring for an adjustable fuel pressure regulator after spending money on other things that did not fix the problem. But if his explanation about the pump overrunning the regulator is true looking at the plugs would be a simple check regardless of data logs.

Also you are judging the 1g fpr anecdotes by a 255, as I understand it the supra pump puts out even a bit more than this so the problem would be that much worse. Much of the stock fuel system seems to be right on the edge of capable for the intended stock boost and turbo, when you modify things it is easy to get a mismatch and fueling problems.

 

[insanedsm2403]

Actually I noticed on my graph the mafs signal goes up and down kind of reminds me of when I was getting on and off and on and of the gas.but my barometer is at a steady line on the bottom of the graph and it goes between 0.07-0.14 all the time.I wouldn't think it shouldn't be laying dead the whole time with all the other activity going on?

 

[insanedsm2403]

Will check plugs in the morning.I have to get up stupid early too to change my b/s belt.its squeking like a bi*** and I'm not moving it till I change it.

 

[TimIacobucci]

I was thinking about fuel supply stuff and dug around for an old link with lots of good info if you are interested in looking at it.

Century Performance Center, Inc. :: Fuelish Tendencies - Understanding Fuel Pressure and Volume

I thought it was interesting how relevant the information might be, look at the intro.

A fuel system is just that - a system! All the pieces must work together. The current trend is to run a pump that is much bigger than should be required to compensate for deficiencies within the system. Simply buying and installing the biggest pump you can find will not be enough if the rest of the system is poorly thought out or sloppily implemented.

Here is an article specific to dsm fueling.

SteveTek Labs Research: High Flow Fuel Delivery System

Even if this turns out not to be the cause of your problem now it surely will be a bottleneck in the future and it's good info to know.

What is sort of funny is that it seems to me the only reason that I and others can seem to get away with too big a fuel pump without upgrading the rest of the system is because we have struck a balance where the extra output of the pump does not overcome the capacity of the stock regulator and return line because it is so restricted by the stock feed line!

I believe the order of inadequacy of the stock fuel system goes about like this. Fuel pump > fuel pressure regulator > feed line > return line. Someone more knowledgeable please correct me if I am putting out any inaccurate information here.

 

[TimIacobucci]

I really don't mean to keep harping on this topic but you have me going on a research hunt. I have read plenty about fuel systems before but not so specifically for dsms.

Anyways here is another link you might want to look through.

RRE Instructions

That supra pump flows allot more than a standard 255. You also have to look at the higher pressure #s, with the stock fpr being boost referenced the flow will drop allot as the boost comes on. Most pumps (like the stock one) drop off hard at higher pressures (maintaining the balance with the restrictive regulator) , this supra pump does not. It pulls higher numbers under boost than the high pressure 255.

 

[insanedsm2403]

Wow I never knew how much a supra pump puts out.thanks a lot for those links.well at least its not stupid loud for nothing!looks like ill be afpr hunting.will let you know how my plugs look.going to change my b/s belt now.

 

[Hardin]

Check the gap of the plugs and you can also do a boost leak test. Boost leaks can lead towards all types of stupid problems.

-Hardin

 

[insanedsm2403]

Just got back from working on the car.glad I decided to look at the b/s belt because it was so brittle I broke it with my hands.I ended up leaving the b/s with no belt since I plan to pull this motor and give it a nice rebuild this spring coming up.I checked my plugs and they are a light brown sort of sandy color.not too sure what this means.rechecked all the gaps all are at .28

 

[habitatguy187]

You didn't change your timing belt while you were in there?

 

[insanedsm2403]

Timing belt only has about 350 miles on it.I did a few searches on barometer malfunction affect but no matter how I would word it,not much would come up.anyone know if this can be my cause for my full boost problem?

 

[insanedsm2403]

First off I want to thank everyone who tried to help on this thread whether right or wrong.it will be helpful to others in the future.If anyone can tell me how to put "resolved"next to the title I would appreciate it.Now for the last week I have been taking my plugs out once a day to see what was going on.they where a sandy color but started turning white as the week went on with only a tiny spot of black at the tips.from this I concluded that my problem was a lack of fuel.so this morning I decided to take out my fuel pump and put in a fresh wally 255 I had laying around.this was my first time doing a pump in a awd and I must say,this was the easiest pump replacement I've ever done.well I get the old pump out and ewwwwwwww.all kinds of crude in the filter and all in the inside of the pump.I compared it to my wally 255 and guess what?it was no supra pump in there,it was a wally 255.the two part numbers matched to the t.I threw in my new pump and filter and the first thing I noticed on startup was no annoying whinning from the pump.nice and quiet.I looked at my fuel pressure and knew right away that I was headed in the right direction.it had jumped from 27.5 at idle to 40psi at idle.I take her out for a spin really not trying to get my hopes up.I get to a nice stretch,get up to 2nd at 3k rpm and floor it.holy shit!for the first time ever I could here my wastegate staying open because of the open dump at 15psi and she was pulling.so quickly I missed 7k and shifted at 7600 rpm.I could not stop smiling until I parked the car about a half hour later.my problem ended up being a old crusty wally 255 which I guess are hard to completely kill because they flow a lot,so they will run your car just not keep up at boost.and it whines like crazy because its going to hell I guess.once again thanks to everyone who put some words into this thread.gota go do some boosting!later

 

[habitatguy187]

Very glad that you kept going and figured out your problem, have fun!