After installing a schrick/ultrik cam (same specs), I noticed a large drop in mpg (consistently over 30 to low 20's). Most of my driving is around 2500 RPM, and the cam timing is in favor of anything over 4k.
I have had a pre cat rich code, followed a few weeks later by pre cat o2 sensor rich, "open circuit". Would running rich over the period of a few thousand miles pollute the oxygen sensor enough for it to become disfunctional? I replaced the o2 thinking it was just worn, but I am still rich.
There is no black smoke pouring out of the exhaust (as far as I can tell), however the back of my car has a layer of black crap on top of all the winter sand and road dirt.
I am using a 19% with GIAC and works injectors.
I am going to use my stock cam, probably tomorrow and see if I get back to my normal MPG figures, and if the rich condition ends.
I figure since the two cams have different timing and duration, that at the low end the computer is adding a normal amount of fuel based on the map sensor's inputs and the temperature. However it is not adjusting to the oxygen sensor reading a rich condition.
I should finally add that I have misfires (which feel like rich misfires) only between 1k and 2800k rpm, in any gear, usually limited to 90%-100% throttle.
Thoughts/experiences?

 

Please report the actual codes you are getting along with the freeze frame data for the codes; I am concerned about the misfire codes.

Misfire will cause a lean condition at the o2 (due to the unburned oxygen in the exhaust stream) remember that the o2 cannot detect hydrocarbon, it can only detect oxygen, misfire is the absence of combustion therefore an excess of oxygen is detected and the ECU will command even more fuel to the combustion chamber making a bad situation worst.

If the fuel trims are positive, this means the misfires created a false lean condition and the ECU tires to deliver even more fuel, this will load up the CAT with HC leading to excessive temperature and melting of the structure inside the CAT.

 

Have you tried changing your plugs and plug wires.

Jeremy

 

Any chance the cam was installed 'out of time'? We've never had any issues with our cam unless it was installed a tooth or two out of sync...

Yes, the car will still run although the power will be slightly down...

edit: or maybe a boost leak?

Ken

 

No boost leaks, and the cam was installed properly (gear only goes on the cam one way, and the gear never left the chain. If I remember, the code was P0176. I havn't put in the stock cam yet. I will report when I do (and will also make a DIY article, for anyone interested).
I have recently changed the plugs, about two weeks ago. It is not an electrical misfire, it is mixture related. I do not have a wideband to report a/f ratios, or I would post them as well. My only guess is that the GIAC software (not tuned for a cam) is setting its leanest fuel trim it will allow, and it won't correct the rich condition because the software is saying "i'm too lean already!"
If my problems are fixed with the stock cam, I might consider an adjustable cam gear, and adjust the timing when I go to track events. I think if I set the cam timing towards the low end (retarding), I will be flowing enough air for the fuel tables to compensate themselves. Again, thats a complete guessing game, unless I can figure out how to datalog with the GT1 to be certain.
I should also add that I have noted low rail pressure (43 psi, spec is 50 psi). I had a fuel problem in June, and had to change the fuel filter about a thousand miles from home. Whether or not the rail pressure is related, I suppose it will directly affect my a/f if the pressure differential is less. It's not as much as a problem other than that I am a fuel economy nut. It could be the winter fuel, with a different mixture of ethanol or additives, and it could be the cold dense air charge (car ran without misfires today at 50F, or approximately 65F after the intercooler), but I think those are too small even combined to do anything.

 

If it's a misfire code....it should tell you which cylinder. Trade leads to see if the misfire follows the potential duff lead. I can see lower fuel pressure hurting you too. Good luck!

Jeremy

 

Unfortunately, there are no misfire codes present or stored in memory. Theres only the codes that show up under the SES light.

 

Oh sorry from your first post you stated you had misfires. I would rather swap around plug leads/look at coil terminals and spark plugs before swapping out a cam. Again best of luck!

Jeremy

 

Low fuel pressure will cause a large positive fuel trim at idle; fuel delivery concerns can be identified by monitoring the B1S1 parameter on the scan tool while engaging WOT; the B1S1 should go high and remain there for the duration of WOT. If B1S1 does not react as expected this is an indication of fuel starvation.

 

Have you checked your bypass valve? We've seen some that fail to close all the way over time...

k

 

I have checked the bpv in the past when I first bought the car. What effect can that have towards my condition?

 

Faulty bypass valve will cause a drop in mpg and loss of power...

k

 

Just to be sure you're testing correctly, on a cool to warm engine with the key on-

it will be a few psi higher on a hot engine.

With the engine running at idle -

 

I don't see the bpv being relative, but thanks nevertheless for your inquiry

 

If I remember correctly, the Bentley manual spec read 50 Psi at idle +- 2. At idle, and with the key on, the readings I got were about excatly the same as depicted in your photos. What I am wondering, however, is if the 380 injectors cause a pressure drop because of the larger diameter nozzles, and if I can change the rail pressure regulator to be within the 50 psi spec.
However I don't think stock to 380 would make that much of a drop, especially at idle, where the duty cycle is lower %.

 

My pressure reading in the bottom photo has been varified as correct for idle by more than one MINI tech. If there was no change from the key on to engine at idle reading, that would mean the fuel rail pressure pulse regulator was malfunctoning (or disconnected).

 

If you are running over sized injectors with a higher flow rate the ECM will still try to maintain a 14.7/1 air fuel ratio once in closed loop; therefore the ECM will apply a shorter duty cycle to the injector to compensate for the increased flow rate and bring the mixture back into control.

If this is occurring I would expect the Long term Fuel Trim value to be very negative (less on time). If it goes far enough (sum of LTFT and STFT = 25 ) the SES light will illuminate.

Also if the fuel pressure regulator is open to atmosphere (no vacuum or hose disconnected) the injectors will have too much pressure at idle; again the o2 will report a rich condition and the fuel trims will go negative to compensate and bring the A/F ratio back to stoichiometric.


Can you measure the LTFT at idle?

 

--->Frenchie: The ECU LTFT can adjust over 25% pulsewidth; this is more than adequate in transitioning from 330cc/min to 380cc/min the OP is running. Your second point about checking the FPR vacuum line is good advice!

Generally speaking, the cam will increase VE, making the car run lean on first startup. The LTFT will then add fuel over time to the entire map based on closed loop trimming. In the end, a few hundred miles later, the car will have slightly less fuel economy, but it should be really minimal, one MPG at most. The big delta you're seeing is most likely from something else related to the CEL's, not the cam.

 

Also larger CAMs can have more overlap (when both intake and exhaust valves are open at the same time)

The net effect of this is lower vacuum at idle; because the MINI uses speed density (MAP and not MAF) this lower vacuum would be interpreted as more load and command the ECM to over fuel resulting in negative fuel trims.

Likewise lower vacuum will also affect the FPR as mentioned before.

If this person is running a custom tune with non OEM fuel tables then it may be OK.

I am still curious about the vital signs. A rich code was reported; I still don’t know the value of the LTFT or STFT or Freeze Frame (the conditions under which the ECU tested and failed causing the light) would be interesting to see if it was under load or idle. Would also be interesting to see if the o2 reading B1S1 goes high and remains there for a WOT run.

 

On a boosted engine it's unhelpful to run a cam with much more overlap than stock, as you end up blowing the boost out the exhaust. IIRC the Schrick cam ends up running a whiff more overlap, so idle vacuum is about 1 inHg less than stock.

A narrowband O2 better switch high during WOT or you have a dangerously lean situation. If the upstream O2 was switching or low during WOT it would indicate a major problem far beyond the fuel trims, assuming the trims are stable.

From this side of the screen, we can't give a good diagnostic with the minimal data presented. A list of the codes and their freeze frames along with some basic datalogging would help tremendously.

 

I concur!

 

I replaced the oxygen sensor, and my rich condition went away. My open circuit code has not come back, and I do not have any other related codes, besides a P0442 in the fuel tank. I still have the misfire, but only under high loads at low RPM (going WOT in 6th at 30 mph, etc).
I have no issues above that RPM range in any gears. Spark plugs are new as previously stated, coil was changed under warranty a while ago (30k miles) for a corroded terminal, along with a wire that was damaged as a result. I know throwing new wires will not make it better. What tools are being used to datalog Mini? We have a GT3 but it is not the newest version, and it won't let us data log (comes up with a software fault).
Thanks in advance for continuing feedback/advice

 

You mean WOT in 6th at 60mph not 30mph correct?

I'd swap the leads and coil. It's fairly cheap. I checked the resistance of my 40K mile + stock leads to replacements and there was a huge difference! It was even hard to get continuity on a couple of them while testing the stock leads!

Jeremy

 

[FONT=Calibri]I would expect the engine to go into labor (6th gear / 30mph).

The only code is a P0442 (evap small leak).

Misfire is the absence of combustion. The ECM looks at the rotation of the crank through the eyes of the crank position sensor.

Each time a cylinder contributes to the rotation the crank will speed up. The lack of a slight increase in crank rpm is detected; when this occurs too many times within 200 revolutions the SES light will flash as long as the condition is present. Is the SES light flashing?

If the misfire exceeds a certain value within 1000 revolutions the SES light will be on steady and a relevant P03XX code will be present.

Most scanners with the ability to read data stream (Mode$01) will also have a recording capability.

I use the AutoEnginuity PC based scanner to datalog. If you are looking to log just generic OBD-II data you can purchase the base model without the BMW enhanced functions.[/FONT]

 

Will the Autoenginuity measure Intake air temp, boost, Rpm, Maf grams per second, Oxygen sensor lambda for the R53 and R56?
I know the R53 uses a MAP, but those are what I need, equivelant to that of a GT1.