Need help bad! Don't know whats going on...

[4G63dsmpwr]

I recently picked up another DSM (90 TSi AWD). When I bought the car, the wastegate arm was busted, and the car would just keep making boost until you let off the throttle. It wasn't the actuator - it was the small flapper inside the turbo

I installed a new manifold, 14B with 30k on it fully ported, and that went really well - no leaks, no broken manifold studs, nothing - very clean install. I used all new gaskets wherever possible, everything.

I got my logger setup I ordered and began logging my car. I have a boost controller for the car, but its currently not installed. Totally stock boost (holds steady at 9 pounds) I made a few passes. The results were awful:

At WOT, I was seeing O2 voltage ranging from .76-.84 . I know this is EXTREMELY lean, and I also logged crazy amounts of knock. Usually between 12-20, however sometimes as bad as 30!

I don't understand... The car is setup totally stock right now, there isn't anything changed. So the stock fuel system should be able to provide enough fuel... The car has 170k on it also. I was thinking maybe a boost leak? Or maybe a new fuel filter (would that cause such huge problems though?) I'd imagine at 170K miles, the fuel system is pretty tired.

I'm not really sure, but anyone that could help me locate the problem, it'd be greatly appreciated! I'll check anything out, the car is sitting out front, and I have access to a bunch of tools and everything. I know these cars pretty well, but can't figure this out.

Thanks alot for the space!

 

[iowaTSIfWd]

I would really recomend a pressure test on intercooler piping. You can find this in the htt://www.vfaq.com Also i know that you really cant judge lean or richness on your o2 volts. Our cars only use the o2 for cruising (low throttle position LTP). The o2 reading is actually not even taken into account in WOT. But 30 counts of knock is definalty telling you that you are extremely rich (rich knock), extremely lean, or there is a leak of some sort (which would really mess up your Air to Fuel ratio). And it always a good idea to change your fuel filter or what not when you get condition like you have.

Also, do your lifters tap alot to? I found that when i had my old FWD the tapping was really pulling my timing. This might he your problem hence your high millage. Also a knock count is alot different between first and second gen. 1g knock count is like 10 count to every 1 2g knock. Im really not sure on that but 5 counts of knock is to much for me on my 2nd gen. Hopefully that helps!! Your best bet when logging is to just look at the timing and your knock count. Hope that help!!!

Oh one more thing what was your timing near redline? it should be anywhere from 15-18 degree of timing.

 

[SpeedFreak03]

A dirty fuel filter can certainly cause a lean condition, change it ASAP. Is timing being pulled when you have high knock counts? I'm thinking bad O2 sensor (try swapping with another car if possible, then buy another one if it works), or maybe leaky ECU caps? Let us know what happens.

 

[4G63dsmpwr]

Guys I really appreciate all the suggestions! Some more info:

I do have LOUD lifter tick. I had a 92 - and it had lifter tick, but not as loud as this car has it! Why would this cause a problem as far as creating knock? I've spoken with a few people also, and the asked me if I could audibly hear the knock (a pinging sound?) and I've never heard such a thing, only the louder lifter tick.

I also forgot to mention this, but my fuel trims are as follows: LOW: 95% (normal) and MED: 119% and HIGH (119%). I also have a 90, which have less fuel adjustment, and 120% is the MAX (so my ECU is doing all it can)...

I'm going to do the following ASAP:

I'm going to do a pull with the car, and let you know what my timing was like. I'm using MMCD, is there anyway to upload my logs here so you guys can see everything?

Do an intake leak test via VFAQ instructions.

I have already purchased a new fuel filter, and will install tomorrow.

My friend also has an 02 sensor for sale - only has about 5k miles on it, I'll buy it from him if the two previous remedies don't fix the problem. Is there a difference between the 90, and 92 02 sensors?

I really appreciate all the help! I'd really like to square this problem away, so I can start modding! Thanks again for all the help.

 

[iowaTSIfWd]

Let us know about that timing. Also about the lifter tick. I know with my awd (i have dsmlink so i can check knock) i get some mechanical knock when i shift at the track. Just to show you that the knock senor is pretty sensive. The knock sensor picks up the lifter ticking as actaully knock and will pulling time a certain degree. Oh and this is also called Phantom knock. You might want to take your lifter out and clean them ( really isnt that hard i have done it a few times) or just replace them with 3g lifters. That should be the last thing you do because i does take awhile. Your o2 sensor might be bad are you getting horrilbe gas millage? that is usually a sign of a bad o2 sensor. Let us know!! good luck I also have an o2 senor from a 1g (90-94 will be the same only the 2g will be different) that i will let go cheap if you really need one.

After reading over this again to proofread it. Im really thinking that your problem is the lifters. Just as explained your lifter tick is LOUD which will definaltly pulling that timing and produce knock. Just my 2 cents

 

[4G63dsmpwr]

I really appreciate all the help...

I'm gonna make a pull when I go out this morning, and post the results here.

Let me know if this makes any sense: After you mentioned that the lifter tick might be the problem, I disconnected the wastegate actuator arm (so the car doesn't build any boost, only 1-2lbs if that). This way, the lifter tick would still be present, but the boost (and need for extra fuel) wouldn't be. I can do a 1st through 3rd gear pull, zero knock with the wastegate actuator arm disconnected from the turbo... So the problem is only present when there is boost...

However, even without any boost, only mayb the 1-2lbs that it still builds, I still have really low O2's. On my last DSM, I used to tune for .90-.92 O2 voltage, at WOT with only a couple of pounds of boost present, the O2's were between .80-.85 .

I'll make a pass ASAP, and see how much timing I have around redline. Will post my findings as soon as I leave this morning.

I have been gettting pretty horrible gas mileage. I think about 200 to a full tank of 93 octane. My friend has an O2 sensor, with about 5k miles, and he wants to sell it for $50. Is that how much you'd be looking for yours or..?

Thanks alot for all this help!

 

[Syndicate13]

1G O2 values will be a lot lower than 2G values. You say you used to shoot for .92-.94 on your old car, was it a 2G? This entire section following is pulled from RRE's website www.roadraceengineering.com

Interpreting O2 Sensor Voltage Readings:

Every car is different when it comes to your tuning settings. The O2 sensors were never designed to be accurate to with in .1v For the most part these numbers will help but you can not compare numbers as gospel with someone else's. O2 sensor voltage decreases with increased heat. As you make more and more consecutive tuning runs, the O2 sensor voltage you see will decrease a bit even though your air/fuel ratio is remaining constant.

At idle and part throttle you want to see the voltage cycling up and down between .2 and .8 roughly.

Typically, your O2 voltage will cycle like this:

.2-.8-.3.-.8-.1-.6-.2-.8-.3-.8-.4.-.9..2-.8-.2-.8.1-.9.........up and down, up and down, up and down........

When you go past 40% throttle the voltage will be set at what ever you have the AFC set at. This is the same for full throttle.


2G 95-99 Turbo

On 91 octane gas you will want .94-.95v If you are at a higher altitude then lower voltage is OK.
On 92 octane gas you will want .94v
On 93-94 octane gas you can get away with .92v

When the O2 sensor heats up after several runs, the voltage out put will drop off a little. What was .94v will drop to .92v. This is normal.


1G 90-94 Turbo

The O2 voltage will vary a lot more from car to car. Your numbers can vary from these easily by as much as .05v. 1G cars have more grounding issues and 90s in particular will read leaner (lower voltage) With a 1G car the compression is lower too so you can run leaner before getting knock that retards timing.

On 91 octane gas you will want .89 to .91v If you are at a higher altitude then lower voltage is OK.
On 92 octane gas you will want .88v
On 93-94 octane gas you can get away with .86v

The same applies to the O2 Voltage when the O2 sensor heats up, it will drop some.

 

[4G63dsmpwr]

Thanks very much, very informative read. I run 93 octane, and they mention .86v being not that bad, so when I'm hitting .76 its still really lean, but not as bad as I thought.

My last car was also a 1G, but had a JDM VR4 motor in it with 8.8 compression, and 510 injectors, so it was sort of a different setup then I'm dealing with here...

I did a 1st gear through 3rd gear pull, and results are as follows:

RPM 02 READING KNOCK TIMING

1ST:
2500 .74V 6 19
4562 .82V 24 22
7125 .80V 22 13
2ND:
5218 .78V 15 13
6343 .78V 27 16
6750 .78V 33 12
3RD:
5218 .80V 8 23
5968 .74V 32 15
6593 .78V 40 9

Sorry if its a bit messy, hope you guys can get the information from it...

As you can see, very lean. I disconnected the actuator arm from the turbo for the time being, so I don't accidentally boost, and run this way.

I'm getting tons of knock, really low 02 readings also, even for a 90 I think.

Thanks for all the help, I'm off to Autozone to pick u a compressor fitting, and pressure test the intake system. I also have a new fuel filter to go in.

Thanks very much for everyone's time!

 

[4G63dsmpwr]

Hey whats up everyone, just wanted to let you guys know that I installed a new fuel filter - that was not the culprit.

Tomorrow I'm going to pressurize the intake system, and hopefully, I find a boost or vacuum leak somewhere, thats causing my car to run so lean.

Thanks for all the replies guys, I hope I figure this out real quick!