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.
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.



.

 

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!

 

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

 

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

 

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! 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 **** 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.