Freezeframe data for P0171 in a new engine
 

I have just put a new engine in an 04 192. All standard, no mods anywhere. I reused the ancillaries; new plugs/coils/leads; injectors cleaned refurbished and tested.
It starts easily hot and cold. Idle is erratic and it throws a P0171 code. I have cleaned the MAF, checked for leaks (none found).
The code says 'bank 1' - I take it this just means the whole engine - it doesn't monitor the 2 rotors separately does it?
Can someone interpret data? Does it give any more clues where the issue is? Is this list of things to check comprehensive? https://www.rx8club.com/attachments/...n-dtcp0171.jpg

Your airflow at 850rpm is 4.6g/s, which seems low, and your short term fuel trim is +25% which is extremely high, so it sounds like a vacuum leak. Perhaps an open vacuum line or connector somewhere?

It's getting extra air somewhere to show lean at +25% STFT.

Second option could be you got the injector connectors connected in reverse order, it's a common mistake that causes unpredictable behavior, but I'd check vacuum first.

Also your coolant temp is 97C? That's high for 28C ambient, unless you just came off a race track, is the car cooling properly?

Vacuum leak seems pretty sure, it wouldn't idle anywhere near correctly if injectors connections are messed up, hard to start, etc.

However, 97*C is 207*F, which is where the OE thermostat & PCM fan programming will hold the coolant temp after full warmup. The low speed fan on temp is 208*F as supplied from Mazda

Definitely a vac leak someplace....

Thank you all. :biggthump
I've been over it again with the brake cleaner spray, and think I've found it down around the distributor block for the pipes to the oil injectors. Need to take the inlet upper manifold bit off to get there. I replaced the old small hoses with new silicone tubing so I'll add some hose-clips/cable ties to hold them tighter.

Check to make sure the distribution block isn't broken...they tend to get brittle with age and crack open

Yep, the likely source unless one the tubes on it is off

Update:
Took off the UIM, checked all hoses and concertinas; checked vacuum distribution block - all intact. Solenoids working OK.
Put it all back together and got a P0410 secondary air inlet code; idle seemed smoother, then the P0171 came back. Tried spraying more brake cleaner about and seemed to get a repeatable rev increase when spraying down the back of the inlet manifold somewhere near the bulkhead - ? gasket leak. Bloody awkward place to get to! Confirmed that the live datastream showed stft went from 25 to -0.8 transiently at the same time, so looks like a leak down there. Will it be something I can fix without taking the engine out again? Time will tell.
Thanks for the assistance so far!

I don't see how it could leak there if a new gasket was used and all of the bolts were tightened properly in sequence. A few people have managed to pull the lower intake manifold (LIM) off by unbolting everything and pushing the engine to the other side, but Mazda recommends pulling the engine because it's such a tight area to work in without exposing the situation to risks like dirt, parts damage, etc.

Do the two vacuum port nipples have rubber caps installed on them? There's also a air intake hose connection at the bottom center of the LIM for the idle jet air bleed. You need to check those as possible leak sources.



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Yes, those caps are in place. I used a new gasket and followed the correct sequence for tightening, but now I'm having doubts! More news after i get underneath and see what I can see/reach/do.

Well, I've torqued up the inlet manifold bolts/nuts to the maximum (you can reach all 7 with varying degrees of contortion and swearing). I can no longer produce the rev rise/STFT dip with spraying volatiles around the gasket area. However, I still have a pending P0171 and also a P0410. Could the two be related? Am I right that the secondary air system can just be blanked off/disconnected?
I guess I should have posted a new set of freezeframe data! I'll get that tomorrow.

Been doing some more searching.
Since its a new engine, do i need to reset my NAVRAM?
Do I need to reset my KAM to clear the fuel trims?

So I reset the KAM and NVRAM.

Still getting the same codes. I'm working my way through the Engine Diagnostics & Control tables.
Fuel system sits in closed loop and goes into 'open loop - drive' when revved, and then tends to stall as the revs drop back to idle. Still getting SHRTFT1 25%

O2S11 PID follows the correct current pattern on revving.

On my "Since DTCs cleared" screen:
Catalyst Mon INC (does that mean test incomplete? Why?)
Sec air system - INC
Oxygen sens Mon INC
Oxygen sens Htr OK

And pics from the onboard monitor test function: Do these suggest the front O2 sensor is OK? What is the Secondary Air Mon that is failing?
Any suggestions gratefully received!:wavey:

Secondary air is the P0140 code because you blanked it off.

Sucking air into the exhaust system will also make the sensors think the engine is running lean, but the usual suspects would be bad O2 main/front sensor, bad MAF sensor, bad fuel injectors, bad fuel pressure/pump, bad compression/engine

https://cimg6.ibsrv.net/gimg/www.rx8...dc1f441737.jpg

It takes a few drive cycles for all of those to get out of INComplete mode. The car hasn't been running long enough or restarted cold enough times for the computer to conclude that the sensor and catalytic converter are functioning correctly.

Thanks for the comments guys.
I haven't blanked off the Secondary Air circuit- just wondering if that might help!
I noticed (and need to confirm) that the STFT reading is 0 until the secondary air pump switches off after a minute or so, then jumps to 25%. Does this imply a leak through the SA circuit, masked when the air is being pumped through there? I am beginning to wonder about Front sensor.

MAF seems OK and has been cleaned, new injectors, compression should be fine on a new engine. Haven't checked fuel pressure yet.

More work on it this evening!

No, it runs in open loop when the air pump is on, that's why STFT is 0. You will see STFT change only in closed loop. What is your Lambda/AFR on a cold start with the air pump on?

FWIW, when I had the same combination of codes, the vacuum line for the plenum chamber that feeds secondary air solenoid was disconnected from the UIM, but you say you already checked that...

My reader doesn't label anything AFR or Lambda. I do have EQ_RAT11 & EQ_RAT
The first reads 0.940 cold and 1.2 hot. The second reads 0.966 cold and 1.024 hot.
My O2B1S2 reads 0.04 - 0.8volts under different conditions.

On the freeze frame data for P0171, EQ_RAT is 1.004
:Wconfused

EQ_RAT sounds like equivalence ratio, same as lambda. 1.00 is 14.7ish AFR, lower than 1 is richer, higher is leaner. I don't have a good way to convert equivalence ratio to AFR precisely, but perhaps google does?

AFR = Equiv Ratio x 14.7

Thanks Loki.
So I have:-

AFR Cold 14.200, hot 15.053 - " Commanded AFR"

AFR II Cold 13.818, hot 17.64 - "AFR (wide range O2S)(B1S1)" presumably front sensor

And on the freeze frame is 14.759

Which means diddly-squit to me!:crazy: but from what you say it looks like when cold I am getting richer than commanded, and when hot leaner than commanded.
Is this good/bad, and does it say anything about my P0171, or is the base data from which the ECU decides to throw the code?

Your ECU is maxing out the amount of short term fuel trim it can put in, and it still can't get your AFR anywhere close to the commanded AFR. Which is why it's throwing P0171. Seems to me like you have a massive vacuum leak somewhere.

What is your MAF reading when hot?

Also next time you do a cold start (car has to be properly cold, with ambient temperature below 20 C preferably), watch your AFR (B1S1). If your secondary air system were working correctly, you would see an AFR of around 20 while the air pump is running, and after about 30 seconds it will shut off and the AFR should drop to 13-14 range.

MAF reading when hot is 4.5g/s @850 rpm, ECT 83 deg

AFR on cold start (18 deg AT & ECT) = 14.12 > 16.90 after AIR shuts off

I'm confused (no shit sherlock) about O2SII current. Engine manual p304 says:

Engine condition Current (mA)
Accelerated Positive value
Decelerated Negative value

While Engine Diagnostics p125 says:
Less than 1 mA when accelerator pedal is suddenly depressed (rich condition).
More than 1 mA just after release of accelerator pedal (lean condition)

Mine complies with the second lot, but isn't that the opposite of the first lot?

A scanner alone is not going to solve this. At some point you have to do real testing like fuel pump/pressure etc. i still think that there has to be a vacuum leak somewhere though. If not then I’d be looking at either the fuel pump or primary injectors.

Just curious as i'd say 9 out of 10 times this is the problem when someone is running lean.... but do you still have your Vfad in tact and is the hose connected to the UIM just under and behind the throttlebody? I know you said it is all stock but just trying to eliminate the obvious.

Well, you've got 2 things going on: your air pump is not sending air to your exhaust and you're running lean. If these faults are connected, it could be due to a vacuum leak between the vacuum chamber and the upper intake manifold. (See diagram below) No vacuum in the vacuum chamber means no vacuum to actuate the secondary air control valve. (Your SSV and VDI valves won't work either). I suggest you double check the connection of both vacuum lines at the back of the UIM. If that is not the problem, then also check for exhaust leaks. (Pipe from air control valve to exhaust manifold is apparently a frequent culprit, could be loose at either end.) It is also possible the 2 codes are unrelated, in which case Team already listed other possible causes for P0171.

https://cimg0.ibsrv.net/gimg/www.rx8...20ab7f61eb.jpg

Thanks for the suggestion, but isn't VFAD a 132 thing not present on 192?

probably, we don't deal with those much over here. The thing to do though is to pull and cap every connection on the intake to eliminate a cracked hose, bad check valve, etc.

OK, update.
Fuel pressure is low at 40 psi, but no 5-minute drop Looks like I need a new pump!

Inlet manifold vacuum 15 inHg @ idle but no vacuum detected at air control valve tubing. I need to check this again when engine has sat long enough to get properly cool - it might have been too warm this time as it was not the first thing I checked.

Think I might have cracked it. Literally.

Occam's razor for 0171 & 0410 points to the vacuum solenoid on the vacuum chamber under the UIM. So I took off the UIM, and the solenoid for the AIR system was slightly out of place and the body broken where it goes into the bung on the vacuum chamber, as in photo. I can't guarantee that I didn't do that when I took the assembly off just now, but it fits the symptoms. Fingers crossed that a replacement will sort it.

Yes, that would be a significant vacuum leak

Replacing the broken vacuum solenoid has sorted the AIR fault - the cold start AFR is now 20 and I don't get a code for it anymore. Happy days.
I wish.
Still getting lean code. Replaced fuel pump - no change.
Went round spraying brake cleaner again and sometimes get sign of vacuum leak (rev change, AFR reduction) and sometimes don't! Which is maddening! This time it was around the front of the inlet manifold.
Need to do more vacuum leak hunting, otherwise only O2 sensor or PCM left to try, but I think its a leak still, but where?! :(

You need to start at the maf and physically check every connection, hose, port, check valve, etc.

You're right, I'll do it again! Might invest in a smoke type leak detector; I'd hoped to avoid it.

Right. Update.
I have got to the bottom of it and I'm not a happy bunny!
I made a smoke generator and pressure tested the inlet side. This demonstrated a leak in the top front end of the inlet manifold gasket.
Further investigation and research and it looks like I was supplied with a gasket for a 6-port, and the engine is a 4-port. Being a noob to rotaries, I didn't spot this, just fitted it and assembled the ancillaries.
I also have an oil leak from the back of the sump gasket which was revealed when the front of the car was jacked up. That is one of the professionally built parts!

Grrrr! FFS! :wallbash: :mad:

Man, what a bummer. I feel for you bro. At least it is a 4-port though. So not having those APV barrels to deal with should make getting the intake on/off a much easier job. On a 6-port it's a real booger to do without pulling the engine out entirely. :uhh: Still not a fun job regardless.

if you're referring to the oil pan leaking at the gasket (sump gasket leaking?) you might want to consider the reusable Viton gasket that Pineapple Racing sells on their website. It makes taking the oil pan on/off a lot easier job rather than using silicone sealer, which is another pita job to cleanup after, especially if it ever leaks.

kind of surprised you haven't weighed in on my 4-port turbo engine concept thread yet ...


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Ouch. tough break.

Ooooh, you've got me intrigued - you can pull the lower manifold without taking the engine out? Really?. RotaryResurrection hasn't done a step by step has he, by any chance?
Unfortunately we've got this habit of misplacing the steering wheel, so I've got the brake servo on the manifold side which might make it worse.

Well sorry. If I understood what is being implied and your RX8 is RHD then that may complicate the situation some.

Yes it is RHD.

Might have to undo/move the steering shaft out of the way, but that’s just a guess because I only have experience with LHD RX8s. A RHD RX8 service manual should provide those details if you either have or can get one.

On a 6-port engine the APV barrels stick out about 150mm or so into the port cavity of the iron side plates. So Mazda says the engine has to come out because there isn’t enough space between the engine and the inner fender/frame rails to pull it out that far. Some people here on the forum say that if you lift the engine enough to take off the engine mounts and mount brackets, then push the engine far as you can to the LH side they just barely had enough room to take the 6-port LIM out and off the engine.

6-port LIM

https://cimg6.ibsrv.net/gimg/www.rx8...7f34bcab76.jpg


4-port LIM

https://cimg0.ibsrv.net/gimg/www.rx8...328702648b.jpg


So the 4-port engine LIM doesn’t have the APV/barrels. You should be able to unbolt it and lift it out without too much trouble as compared to the 6-port LIM I’d think. So now I’m thinking that you might not have to move the steering shaft out of the way.


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Well, I'll give it a go and report back!

You will need to pull it out an inch or two (3 - 6cm) for the Jet air nozzle extensions to clear. You can see the small tubes sticking out from the center ports on the manifold pic above.

A 192 4-port lower inlet gasket manifold gasket can be replaced without taking the engine out on a RHD car. Remove UIM & secondary air pump, disconnect fuel hoses and 2 injector plugs from LIM, Hang engine from crane. Remove LHS engine mount & bracket, remove RHS engine mount. Engine can be levered to LHS by about 4 cm, I used a wooden wedge between the mount bracket and the chassis to keep it there. Remove secondary air pipe (nuts usually blobs of rust which need heat). Undo LIM bolts and nuts, slide manifold across to clear studs x2 and jet air nozzles. Remove old gaske backwards and down between bellhousing and tunnel. Pass new manifold back in the same way - its a bit of a fiddle getting the jet nozzles and the studs through the holes in the gasket; care is needed not to bend/damage it. No need to touch the steering column or the brake servo.

Now sorted! Fingers crossed it stays that way. Correct gasket fitted and all reassembled. Brief warm up in the garage showed no codes and an STFT% of -3.5 / -4. Is this affected by premixing?

No, fuel trims will have almost nothing to do with premixing.

Ignore STFT until the coolant temperature reaches about 175°F (80°C).

Now running sweetly, all parameters within spec and no CEL.
Thanks for the help guys!

congrats, it's always a good feeling once you get something like this fixed and it solves everything.