Please help me tune my 3.2 Turbo Conversion

[lr172]

A little more testing tonight. I put the stock chip back in for a reference and at the 60lb fuel rate, I get pretty much low 12's were I would expect it.

Therefore, at 3500, I floor it (quickly getting me to 5 PSI boost) but don't activate the full throttle switch and I run 12ish on the stock chip and high 13's on the Proto chip. If I run long enough (~5K) it drops to 10 (end of range on gauge). good pull runs very nice before falling off the cliff to 10).

If, at 3500, I floor it and press the full throttle switch, I go quickly to the low 10's and eventually fall to 10.

It feels as though near 5K the Motronic is jumping into the full throttle map or otherwise significanly richening the mixture.

Maybe I will try lowering the BEGI to get the full throttle map to 11 and just keep out of boost on part throttle.

Hopefully I can speak with Todd about remapping this.

Larry

[lr172]

More progress tonight. Not sure why I didn't do it before, but I never pulled the O2 sensor. When I did this, things got a lot better. Turns out my air bleed for the Mixture setting was also a bit rich. More air through this passage also seemed to help.

I am now runnig fairly good. I am in the low 12's and will dip into the low 11's as well. Near redline I will still drop to 10. Both the part throttle and full throttle are similar now. The odd thing is that my FPR is running only 45 PSI at 5 Pounds of boost (I think stock FPR goes to 38 at load). Todd said 60 PSI for 5 pounds and Jerry was running 65 PSI for 8-9 pounds. I am still not sure why my system is running so rich. I guess I'll have to wait until Todd gets back from vacation before I can progress much further.

I also tested the AFM with voltage tonight and it tests out perfect.

Still confused, but at least it is driveable now.

Stay tuned.

Larry

[911st]

Originally Posted by 911st

If the chip still uses the O2 Lambda function the O2 should not be pluged in druing any of the tunning.

Some more thoughts.

I think factory spec for a Carrera's fuel pressure it 2 to 2.5 bar which is 29.4 to 36.75 ps (bar times 14.7)i.

5 lbs of boost is should require about 35% more fuel (5/14.7).

Thus, on boost would expect should be something like (29.4 x1.35=) 39.69 lbs to (36.75 x 1.35=)49.6 lbs of fuel pressure. That is something between 40 to 50 PSI.

That is at normal AFR's. We typically run about 10% richer for cooling on boost.

Thus about 44 to 55psi.

That is if you do not lose efficiency's for some reason like a poor exhaust. With no intercooler one might expect less so the fuel pressure expectation mightt come down from that.

Just a guess as I have never done this before.

[911st]

ps ; My chipped 3.2 pulls 215rwhp. 1.35 times that would be about 290rwhhp or about 340fwhp plus or minus depending on other attributes that can effect efficiency (exhaust/intercooler...).

Now I want one.

[lr172]

Interesting thoughts. No you've got me thinking. According to bentley. the fuel pressure should be 36-39 with no vacuum (i.e. WOT under load. Therefore, by your calcs, I should be requiring 55+ to be at 11 AFR.

Your comment about efficiency has me thinking. What if there is something wrong with my VE (voulmetic efficiency)? That might explain why I am running so rich at such a low pressure; I'm just not pumping the air through the engine, eventhough I am on boost. A resticted exhaust is certainly a possibility.

I have stared at my intake tract for an hour and can't think of what may be leaking. I even tightend the manifold nuts dring the conversion.

During the intstall, I pulled the chain case to replace seals. I don't think the timing could be that off, as I ran it NA and it felt the same as when I started. I'll have to think about this some more. However, a lower than normal amount of air going through the engine could certainly explain the rich AFR's on lower than expect fuel delivery.

A lot of the guys that do this run headers (SSI). Todd's system is set up for SSI's as well. I wonder if the stock headers are keeping the flow down and thereby reducing the fuel requirements. If that is the case, I definately need headers.

EDIT: As I think more about this, a restricte exhaust would also explain why I go even richer around 6K. I am really begining to thimk I may have a problem there or with VE in general.

Thanks for the insight.

Larry

[jbrinkley]

it took me a while to get the pressures right, I'd drive up the freeway in fourth gear while logging, and then pull over and replay the log. If lean in the middle I'd turn in the top screw on the begi and try again. If lean or to rich on the top I'd turn the side screw.
eventually I had it at low 11's all the way across.

[911st]

The issue in the exaust is usally in the muffler. A J pipe system is not going to hurt you in the upper rpm.

I would forget about the pressure readings and concentrate on the AFR's like jbrinkley is suggesting.

[lr172]

Thanks guys. I have concentrated on AFR's and have gotten near the best I can. In order to get to what I posted above, The center screw is out so much the I am <40 PSI with the vacuum signal line disconnected and my brass set screw is fully open with the restrictor in place. I am pretty much at the end of the range with the FPR. I don't think it can deliver much less fuel than it is now. Right now I need it to rise a bit less than it is and I am out of travel on the screw.

I will work a bit more on this today with a closer eye on the fuel pressure gauge.

Becuase my fuel consumption appears so different from other's experience, I need to better understand why this is. Why do I get 10's at 45 PSI fuel pressure while others get high 11's at 60 PSI? Somehting just isn't right here and I would like to get to the bottom of it. It really makes me wonder if I will get the full potential of this system if I don't figure it out. During my test runs, I am not "feeling the front come up" as others have described. Granted, I am only a .4 BAR boost so far, but I don't want to leave anything on the table becuase I didn't read the signs.

Jerry, did your car have stock exchangers or SSIs?

[lr172]

Originally Posted by 911st

The issue in the exaust is usally in the muffler. A J pipe system is not going to hurt you in the upper rpm.

I would forget about the pressure readings and concentrate on the AFR's like jbrinkley is suggesting.

I installed a new magnaflow 2.5" free flowing muffler. I would expect this muffler to handle 3.2 liters and 350 HP. Maybe not. I still wonder if the headers hold it back.

[jbrinkley]

I had SSI's.

sort of confused, you have both adjustment screws almost all the way out and you're still getting weird afr numbers?
if this is the case something is wrong.
at six psi you should really feel the difference in your car.
something's gotta be out of whack, plumbing, fuel line restriction, air train to gauges and begi, signal lines under the butterfly. What about the black rubber 90 that connects the afm to the throttle body? did you have this off and check it out real well? I had a recent one at the time that split parallel with the throttle body right at the lip where it connects to the throttle body.

you sure you're getting boost? Not trying to be a dick, just thinking.
I'd bet a fair amount of money it's a plumbing thing, fuel leak, or restriction inline. Fuel filter?,,, **** I don't know.
take a bunch of pictures if you can, of everything, and post them.

new full throttle switch in?

there's no CAT on your car right?

[911st]

Originally Posted by lr172

I installed a new magnaflow 2.5" free flowing muffler. I would expect this muffler to handle 3.2 liters and 350 HP. Maybe not. I still wonder if the headers hold it back.

I know of one tunner that makes 650hp with the stock HE & J pipe. That should not be an issue. There is some low end response that can be had with lower volunm headers.

Your muffler is not causing you a problem, thus it is very unlikly your issue is exaust related.

You seem to be be having issue with your adjustable FPR or somthing else.

[jbrinkley]

I'm reading the thread again, what about lag time in the WB display. You hit 5k rpm and it goes rich?
one test, from full boost let your foot off the pedal, see how quick the gauge goes to 19.xx
maybe your afrs are going down all the way up, but it doesn't show till 5k? also do this in fifth gear to get the maximum time to observe. any other gear happens too fast.
this is where an analog electric gauge would be handy for the fuel.
it's probably something simple you're just missing.

[jbrinkley]

check this plug on your afm, it will blow out eventually. weird things happen.

[lr172]

More progress yesterday. I am embarassed to say that I think I have figured a good chunk of my problem. My air filter is currently sitting right on the turbo for now. My muffler output also points this direction (driver's side) and I did not install the tailpipe, as I still needed to finish up the wastegate output/tie in.

When I installed the tailpipe yesterday, my idle AFR stabilzed a lot. I think that I was sucking in exhaust and this was messing with my numbers. Once stabilized, I realized that the mixture was now backed all the way out while adjusting for this condition the other day. Once I got this sorted out, I got much more consistent results.

I still have some issues, but I have a better platform to work off now. Last night I re-plumbed my fuel pressure gauge to the test port on the rail, so I can get a better picture throughout the acceleration range. I am also finishing up the the w/g plumbing before I do more testing to ensure I am not sucking exhaust while on boost.

Last night's testing required that I put quite a bit of pressure on on the center screw in order to pass through 0" in the 13's(45 PSI @ 0"). However, on boost AFR's were good, but I am still falling to low 10's near redline, but not falling below 10. I am near the end of travel on the screw, but not there yet. I don't want to read too much into this till I get the down pipe on and try again.

Oddly, my part throttle low RPM (off boost) is reading in the 15's with the O2 sensor dis-connected, but low 14's connected. Something is not quite right with fuel delivery and I'll need to examine this a bit.

Once I get the exhaust squared away and the throttle switch installed (coming today) I will do more testing over the weekend with hopefully some more data.

Thanks for all of your guidance through this. I'll takes some pictures tonight. I examined the rubber elbow pretty well, but cannot find any cracks. A leak between the AFM and the manifold certainly seems to be a the top of the list for problem candidates, but for life of me I cannot find a leak. I have put propane all over that area at idle and it is not leaking under vacuum. I do realize that it could be leaking under boost though. I'll pull it all apart tonight when I replace the throttle switch and see if something looks wrong.

[lr172]

Originally Posted by jbrinkley

check this plug on your afm, it will blow out eventually. weird things happen.

That plug is intact. I will look more closely to see that it is secure. Also, I do not have a cat. Good idea on the w/b. It snaps back to lean pretty quick. I have thought about lag, but just don't know whehter I should be trusing the gauge or not. There are times (like snapping off throttle) that I reacts very quickly and other times that I expect a change that I don't see. The fifth gear test is a good idea. This should slow things down quite a bit and make it easier to diagnose.

Thanks,

Larry

[lr172]

SUCCESS!

Got the exhaust all buttoned up and going out the tailpipe where it belongs and away from the intake. Need a little fine tuning, but pretty much in the 11's at full throttle / boost through the RPMs. The part throttle map is a bit lean for my liking, but shouldn't be too hard to go full throttle while on boost. I am now crossing 0" at 40 PSI and full boost pressure is 65-70 PSI but I'll slowly bring that down a bit as I still get 10's at redline. It is now behaving as I expect and as others see. Just some more fine tuning over the weekend.

Another lesson learned about taking short cuts

I thought that I still had a problem at first, as I was way lean on boost. I pulled the O2 sensor (oddly I needed this yesterday to keep from going lean) and everything fell into place. Note for the next guy, this is requrement!

Thanks so much for your help and support guys. I really appreciate the time you spent thinking about this and giving me suggestions. Absolutely invaluable. Now I can go out this and pay attention to how it feels. Too much time concentrating on the gauges and behavior to really notice or compare.

I promise to snap some photos, but have been too focused on getting it right.

Larry

[911st]

Larry,

Most excellent!

Was it just getting the settings on the adjustable FPR right or was it somthing else?

[lr172]

I was sucking the exhaust into the intake. The muffler output, without the tailpipe, was leaving a bunch of exhaust in that cavity by the bumper and it was getting sucked into the intake of the turbo. The was messing things up because there was not enough oxygen in the intake air. I just figured that the wind from driving would force fresh air. The blackish color of the filter yesterday tipped me off that the exhaust was getting sucked in.

Worse yet, the wastegate exit was pointed right at the filter. This likely meant I was sucking in exhaust under boost when I thought the air from movement would have taken away the exhaust from the muffler. This would explain why I had more stable AFR's in fourth gear. The wind was forcing more fresh are into that area.

I had tried every combination under the sun on the FPR, I knew that wasn't it; At least not by itself. I truly should have known better and should have recognized the odd ball AFR number being attributed to it.

[mxessin2]

Are you using a stock fuel pump on this build?

[911st]

Never would have guessed that one without pictures. Even then?

Very good.