R53 with built motor. Installed AEM AFR after primary O2 sensor. Pre-cat. Idle running 16.7
AFR. Wide open throttle pegs out over 18. When coming down speed on gear it finally hits 14 ish. Only happens when throttle is released. Any thoughts?

 

sounds like it's sucking air from somewhere it shouldn't.....I would suggest a smoke test on the intake system

Bryan

 

If you can't do the smoke test, try small squirts of starting ether at or near the usual suspect areas. A rise in rpm will point to the culprit. Could be something as simple as a cracked intercooler boot.

 

Smoke test done on intake and exhaust side. No leaks and holds pressure.

 

Double check you did the calibration properly, "all" those readings seem off, idle and running with moderate to light pedal should have you bouncing between 14.0 - 15.5, and pulling your foot off the accelerator should peg you at max for the gauge.

 

I’ll be testing wide band with the brake cleaner trick in a few hours. Thanks

 

Wide band fails. Stuck at 15.7. New wide band in order. Also noticed gas pedal has dead spot. Anyone have this problem? Pressing with foot feels normal. When I used my hand to slowly increase RPM, motor dies at about 1/8 of an inch downward pedal movement. Pedal assembly or throttle body?

 

New wide band installed. Running 16 AFR still but gauge is calibrated correctly. Still running lean. No leaks. New vacuum hoses. TMAP and MAP sensors have correct voltage outputs. O2 sensors have correct voltages. Fuel pressure at 55 psi and holds for hours after shut down. The only thing I noticed was a fluctuating timing retard. From 9 to 22 degrees. Never noticed that but it could have latency with signal. Any thoughts? Or do I have a bad tune?

 

While you didn't specify whether the 16 was idle or WOT, it still seems as if there's a problem with the gauge or sensor.
Only other thought would be that you might have a plugged CAT and it's effecting the readings because of back gasses.
With an AFR of 16:1 at WOT, your engine wouldn't last long at all, but I have seen periodic readings of 16:1 at idle, but they didn't last long.
My only suggestions would be to check the reading with the exhaust disconnected, or find a shop that has an exhaust sniffer that can check it at the end of the pipe with their equipment.

 

Just ran the car around the neighborhood and the AFRs finally hit 10-15. Only going 25ish mph but blipping throttle to around 4K. Then came back. On idle started to get 16s. I’ll have to take it on the highway and see what she does. Got stuck on jacks installing some Fotune Auto coilovers.

 

Troubleshot more into this problem. Still pops P0172. Running lean. Fuel pressure at 40 psi on idle. Revving engine changes nothing. Stays at 40 psi. Then when engine is shut off, pressure goes to 65 psi. Fuel issue? Fuel pump? Installed new fuel filter with no change in discrepancy.

 

Possible bad pressure regulator under the hood. Try taking the vacuum line off the regulator and see what the pressure reads then.

Bryan

 

Hose removed. Pressure increases to 52 psi. Bad FPR?

 

Probably not, the FPR adds fuel under the absence of vacuum, so pulling the vacuum line should have increased the fuel PSI.
Not to mention that it did change, if there was no change, then I'd be suspect.

But....
Can you check the fuel PSI at WOT, under a pull? (With the line attached of course)
If so, you should be seeing 57+ PSI.
- If not, it will be a sign of a vacuum/boost leak, fuel restriction or worn/failing pump seals.
- If it does give you 57+ then your fuel system pretty much checks out.

 

Removing vacuum from intake manifold and plugging were was did increase psi from 40 to 52. I revved engine with it connected and stays at previous
40 psi in neutral. I’ll have to try a pull in the road to see
what psi it shoots to.

 

Just did a smoke test. Intake side. Nothing. No leaks at all with throttle body taped up. Did smoke test from
tail pipe found small leak but after downstream o2 sensor where flange is. Don’t think it would affect a lean condition if it’s after the second O2 sensor. Also with FPR vacuum disconnected, the P0172 code went away. Looking in history, found some data for a few things.

B1S1 .890
B1S2 .885
STFT -30.5%
LTFT 8.6%
RPM. 3046

STFT should be lower right?
B1S2 shouldn’t match S1. Bad secondary O2 sensor?

Getting lost in all this data.

 

Yes, STFT should be a lot lower, maybe around 5% or so.....the ECM is trying to make some big corrections without any success.

Fuel pressure spec per the Bentley manual is 47.8 - 53-8 pounds.......I'm sure that's with the vacuum line off..I can't find a spec with the vac line on

Bryan

 

New numbers after WOT.

IDLE:
STFT -30.5%
LTFT 14.06%
O2 S1 0.880
O2 S2 0.880
AFR 17.1
FUEL 42 psi

2500 RPM holding:
STFT -5.5%
LTFT -4.7%
O2S1 0.085
O2S2 0.715
AFR 15.3
FUEL 50 psi

WOT run:
STFT -3.1
LTFT -4.7
O2S1 0.050
O2S2 0.115
AFR 18 plus. AEM gauge pegged out.
FUEL 52 psi

So after its warm and after a run, still running lean. Anything else I can check? Smoke check has been done on intake and exhaust. One thing I noticed was when I open the gas cap, a lot of venting went on. Not sure if its related.

Forgot to mention P0172 still popped. Also has a P2096 I am not able to delete.

 

There will be pressure inside the fuel tank if you open the gas cap after a long run, this is normal.

Curious, you say that it's a "built motor", what does this entail? Also, what injectors are you running?

Rear O2 will mirror the front until the cat lights off, I would not worry about the rear O2 until you get the front one reading properly. Until the STFT is down around -5 to +5, and fluctuating, no other readings are going to matter....the ECM probably isn't going into closed loop either

Bryan

 

FUEL SYSTEM 1 says “CL” on scanner. I assume it means closed loop.
Here is my build. Let me know if there’s anything that would cause this lean mixture.

Newly built motor.
CP pistons
Carrillo rods
17% pulley
Rebuilt/ported/polished factory supercharger
ATI crank pulley
Balanced/polished factory crank
RMW Big valve head
RMW shorty header
AEM wide band after flex pipe
550cc injectors
Newman 272/450
Ported intake manifold from Thumper
Forge top mount intercooler
DDM intake
Detroit tuned BPV
BKR7EQUP 4285 NGK plugs
Screamin Demon coil pack
MSD plug wires
RMW 550cc tune
AC removed
CSF radiator
All sensors are brand new

Thats all I got for the motor. About 10 hrs on motor. The rest is just accessories

 

Fuel PSI is a little low at WOT, but not horrible.
Honestly, those two codes almost lead toward a plugged CAT, p0172 - system to rich, but p2096 - post CAT lean..
Or
The p0172 could be causing the low fuel PSI and the p2096 if the car is trying to compensate for a rich condition.

I'm gathering that this was a canned tune for the 550's by the way you put it, quite honestly with that many modifications, the car should have a logged and custom tune, otherwise I'm afraid you may be chasing a problem that is strictly tune related, no matter how many parts you throw at it.

And don't do any more WOT runs without verifying the AFR, find a dyno with a sniffer to double check that gauge, 18 will KILL your engine quick, don't risk it. At the very least you'll know about the accuracy of that gauge.

 

DeatschWerks DW65v fuel pump on order. Not sure if pressure will increase with stock FPR but it’s already on its way.
Cat is welded and part of RMW shorty header. Header
was removed due to failed welds on flange so nothing is clogging cat unless clogged means something else.
Anyone can tune a stock ECU? I have the MyGenius to upload into OBD2 port but need a dyno tune to make sure numbers are good.
No more WOT runs for sure. Been trying to get this ready for track and I think I hit a speed bump.

 

After multiple starts, idles, and 2500 RPM holds, STFT sits at -30.5 on idle. AFR sits at 16.2 at idle. AFR at 2500 fluctuates from 14-17. Exhaust leak? Bad wide band for AFR gauge? It’s my second one. Bad location of Wide band sensor? Spark plugs? Need to check those to see how they look. Any recommendations of what to check? Once new fuel pump goes in I’m thinking a sniffer verification of AFR on dyno.

 

Somewhat fixed. New fuel pump fixed fuel pressure. Moved wideband sensor before flex pipe on header. Idles at 11-12 AFR and WOT 14’s. Still dies when blipping throttle.

 

It seems like Jan did the tune. Why not contact him? Seems like you have enough injector (550).

Idle AFR too low, WOT still too high. Numbers should be reversed.

If you are seeing 16 or 18 on a dyno, the car should run like crap and not sound much better. You are WAAAAY lean and you would be able to hear it.

Regards,
Jerry