TT chip and octane

[Steve Wood]

yes, still learning and the chip does not go to open loop idle until the next start as per the above instructions

try the other maf?

[Shimy87]

Away camping with family. Will swap it this week.....the one in the car now is brand new?? I also have another new one that came with car, will start with mine as I know it works right

[Steve Wood]

Hope you're having fun and the mosquitos are not bad wherever you are!

This situation is more complex because you are at about half throttle according to the tps.  Power Enrichment came on at an lv8 of 140 which seems to be a bit high to me but it was on before the knock retard started altho I am going to look at that point again.

In PE, maf air flow and lv8 tend to control fueling as I recall but I think Eric still uses the tps at that point as well.  It's been so long since I had a maf on my cars that I have not been interested in such.  The SD chips like I have calculate a theoretical air flow using the MAP sensor as I recall.

If the maf sensor is reporting an air flow that is too low compared to the actual flow going thru it, then your chip is going to give it too little fuel and you will be lean.  Your logs show it to be lean and I assume that is why it is pulling timing.  

Now, the question is, too little fuel, or too much air getting into the engine without being measured?  Seems to me it would have to be one helluva air leak after the maf to make it go that lean.  The usual leaks don't have much effect under boost.  It would seem to me it would have to be something like a hose pulling off the turbo inlet to allow it to ingest enough air to do that (or off the maf outlet)  So a leak between maf and turbo.  Be sure those connections between maf and turbo are solid.

As you took the ic off your car, we cannot compare logs under similar conditions at the moment.  I suggested trying to run at higher throttle opening for a shorter duration to see if stayed lean at wider throttle opening... as well as swapping the maf.  I am pretty sure it stays lean because you were having the apparent same problem when you first tried stepping on it before swapping the ic.

[Steve Wood]

btw, your tps is going above 4.25 at wide open throttle, correct?

[Shimy87]

No mosquitoes yet!!!

Checked all connections before and were solid there. Like an idiot I did not check my IC for leaks when I swapped them....assume d it was solid but you know the saying about assuming things. 

WOT does get above 4.25 but barely and you need to be serious about how your stepping on it to apply enough pressure to get it there. I have tps set at .42 but think I'm going to try to get it set at .44. .....trying to get a bit more at WOT to assure computer reacts accordingly

Also second guessing my translator settings as I can't check them now, will make sure thats right.

Thanks Steve!!

[Steve Wood]

The tps is fine.  long as it is between .36 and .46v, everything is good.  On the top end, it needs to be 4.25 in order to program the chip.  It makes zero difference in performance if it is 4.25 or 4.9.  

The leak would have to be before the turbo to really make a difference, I think.  After the turbo, it would not be sucking air in except under no boost condition.  Once you got into boost, it would be blowing air out the leaks instead of sucking air in.  If anything, I suspect that would make it rich and it is definitely lean from the O2 readings

[Shimy87]

swapped in another 3.5 inch MAF I had, set translator to base setting for that maf, no adding or subtracting fuel at idle. took it out and after warming it up did a short WOT blast. boost is only set to 10 lbs. file attached. this maf didn't get to 255 during this run. tomorrow if I have time I will get the one out of my car and see how that one reacts.

at warmed up idle this one will run about 800 O2 but the every now and then have a quick drop to almost zero and then right back to 800. also at cruise if you let off gas to coast to a stop sign the O2s drop to the bottom of the graph and stay there until you touch the brake or gas, then they move round again???

[Steve Wood]

Okay, first we have to be careful comparing maf air flow to boost.  The first is how many grams of air are passing thru the sensor where as boost is resistance to air flow.  Therefore a car with stock heads, cam, and a small turbo may require 18 psi of boost to see 255 on the maf numbers.  But leave the boost setting where it is and install heads and big cam while keeping the same turbo and settings, and you may see 255 g/s while the boost drops to 14 psi.  Adding an inter cooler that has less backpressure and you will also see a drop.

My guess is that you would probably see 255 on the maf around 18 psi with your current arrangement.  200 seems to be the right number for 10 psi of boost if I were to guess which I just did.  LOL

LV8 and power enrichment happened around 106 which is close to what I was expecting.  Now did the improvement in maf flow come from the throttle being wide open, or did it come from the other maf.  I have no idea.

The knock retard did not resemble actual detonation.  It looks like the ecm was hearing something via the knock sensor and jerking a little timing each time it heard it.  In my experience, real detonation continues to increase the timing retard until you let off the gas instead of rippling the retard as was happening here.

If I were to happen to be right, then I would be looking for a source of noise.  sometimes, it would be a knock sensor that was overly tightened (hand tight is about right), perhaps a tired sensor, or a too long belt that is allowing the tensioner pulled to kiss the ac compressor clutch pulley, a downpipe touching the back ear of the a arm, or the pinch weld at the bottom of the firewall.  Or a bad tranny mount or a worn out hanger on the rear of the test pipe which is allowing the exhaust to "rattle"

In essence, I don't know if the maf improved things or it was the increased pedal.  My cars tend to not knock at light throttle when the boost is coming on.  Not sure what my cars do is truly relevant.

As far as the idle goes.  It may be that the o2 sensor is hot enuf to maintain the idle.  O2 readings seem to drop as the exhaust cools down at idle and run higher when the car has been driven that on a cold start in the shop that allows it to warm up.  I know that Eric uses both coolant temp and O2 activity to command simulated open loop idle...I think I know that.  Something like that may cause it to fall out of open at times...I'm not sure.

given the magnitude and appearance of the timing retard, I would be tempted to add a couple pounds more and try it again.

[Steve Wood]

oh, yeah, it's normal I think, for the o2s to fall when you let off the gas.  That fuel injection trying to save gas and probably reduce some emissions.

I did notice that the O2s at wide open throttle were dwindling a bit as boost was maintained.  Still looks like fuel was not being maintained...a s in reduced pressure.

It was much higher like it should be at the beginning of the run

[Shimy87]

Thanks Steve. I did to a longish 5 lb pull at about half throttle and had a few small ( less than 1) knock spikes but they were there and gone so I think it was false.

The tranny was rebuilt in the car but never used before I got it. It is the hardest shifting car I have ever had. I adjusted the tv cable and that helped alot but still to harsh. Going to loosen the cable one more click to see if that helps but still shifts at the correct points.. maybe that's some of what its hearing.

Most of the usual suspects for stuff hitting causing knock have been checked.. i might try removing and reinstalling the knock sensor. Is there a torque spec for it?

Will try increasing boost after these adjustments to 15 lbs and give it a rip.

[Steve Wood]

Book says 14 ft lbs. I use hand tight. You might program 3 gear fueling to 135

[Shimy87]

Thanks again. 

[Steve Wood]

Kinda sounds like the maf was reading low. These cars may be more magic than technology driven⁸

[Shimy87]

Seems thay way sometimes..... it was a brand new MAF that was not working well and the old used one seemed to help alot

[Steve Wood]

Maf reading used to be the first thing we checked...but we have tended to assume the translator has eliminated that problem.  Lately, we seem to be more maf problems again, it seems to me.

Powerlogger makes it far easier to get to the root of the problem.  Altho, I admit that I was thinking about the problem after looking at the logs and went back to check the maf after I first look...popped into my mind the second go round.  Of course, lotsa things pop into my mind these days LOL