MAF flow help please

[SS]

Hi.

I'm not sure if this is the correct forum to advise me but here goes -

I purchased PCMScan to assist me with an engine problem that is plaguing me. My C200K 2003 (M271 motor) drives really well with its Kleeman boost kit, except under the load of a long hill, or at WOT from low revs. Then it misses and gives a 302 error code (# 2 cyl missing).
Although I am sure as anything that it is because the engine is being over-fueled, I have swapped plugs, swapped ignitor coils and swapped injectors out of cyl#2 to be sure. I've also bled the fuel rail.

On using the PCMScan on a laptop driving around, I was surprised how low the MAF readings are.
Idle is around 3 g/s but even on full load with the Load guage showing 80%, the highest the MAF goes to is 180 g/s for 163 kPa in the manifold.
I am not familiar with grams per second readings, but it seems low to me.

However, if it is low, then I would have thought the fuel would be lean rather than rich - is this correct?

I am convinced its running rich as the engine starts from cold overchocked and smells rich, it error codes a lot easier under choke (open loop) than it does once warmed and into closed loop, the exhaust pipe is black, the fuel consumption is high.
The idle is extremely smooth and there's no hesitation off the mark as a lean motor would give. It pulls very strong up and down the range, but any time I encounter a long hill, the engine will miss and show 302.
The engine has a shaky missing idle. Turn the engine off, then restart and its as good as new again until the next time we strike a hill.

I'd love any suggestions and advice please.

[hornerm]

Use web search MAF READING.  Mostly, it invoment with MAP.

I had this  problem before because of dirty pin map. Work need to remove the main header and map itself with pin senor.  All this had to do with air intake system. Cleaning is the best solution. It made be floud with carbon.

For cyl #2, it this the nearest to intake? If so, the ECM take the nearest reading next to intake for cyl reading.

Hope this help.
Ray

p.s. If you have PCMSCAN software and take about problem on hardware, software or car, you have come to the right place.

[SS]

Thanks for the reply.

The MAF is ahead of the Kompressor, so it doesn't favour any particular cylinder.
From the research I have done till now, it seems that the engine management system can detect missfires, but is not so good at picking exactly which cylinder it is and so usually picks the same code for any one of the cylinders. (I think maybe it chooses Cyl#2 on my engine because perhaps the ping detector (pre-ignition sensor) might be closest to Cyl#2 - but I don't actually know if my engine has this sensor or not).

What I was hoping was that someone might be able to indicate to me what range MAF readings I should expect to see. My engine is the Mercedes M271 which is a 1.8 litre Supercharged motor. With boost at 63kPa over atmospheric (total of 163kPa), does a reading of 180g/s seem correct?

I'm sure the engine is overfuelled, but I don't know yet if its a fuel delivery problem or an air inlet problem.

The engine has only done 22,000klms, but its good advice to check the mechanical condition (clean the pin) of the MAF and I will do so.

I'd appreciate anyone's input as to the readings I should expect to see, and/or if they have suggestions to try.

[hornerm]

SS

If you can access the EGR and MAP pin easly, try cleaning both. Use Cab cleaner.

My EGR waring code alway light up. Had replace EGR ($120) but show again in two week. I remove MAP pin sensor and clean them up. and reset the OBDII. Had no problem for over two years. MAP sensor connect to air intake after EGR.

Hope your MAF relate to MAP system.

Good luck

[mikayo]

Hi SS.

The MAF readings are mainly  involved with the engine displacement , RPM , MAP´s , Air density and the one of the most important terms called VE or VOLUMETRIC EFFICIENCY , this parameter indicates the ability of the engine to BREATH AIR.

At more air you can put more gas and then more POWER.

You added a booster that increase the pressure 63 Kpa at atmospheric pressure only if you are at sea level 101.3 Kpa.

The VE is a lookup table used by the ECU to calculate the BPW (Base Pulse Width) of the injectors , at more air more gas .

When you enter in WOT , something happens in the ECU , one is the engine goes to OPEN LOOP and the fuel ratio 14.7 goes down from 12 to 11 this condition is called POWER ENRICHMENT , you can see this using PID 03.

The pre-ignition sensor or the KNOCK SENSOR detecs when the engine enters to a KNOCKING CONDITION , end then reduce the spark to protect the engine. (SPARK RETARD).

Misfire is detected by the engine angular velocity over a one entire revolution , using the CAM and CRANK sensors.

If you are more interesting in the MAF readings ples visit the following links.

http://www.installuniversity.com/install_university/installu_articles/volumetric_efficiency/ve_computation_9.012000.htm
http://www.hstuners.com/forums/showthread.php?t=24518

I hope this help you.

Regards.

Mikayo.

 

 

[hornerm]

Good information MIKAYO

All these information from mikayo, I think it is best if you take your car to 'speed shop' and have them re-adjustment the OBDII ECU to new specification. Yes, ECU need to re-adjustment to match new "Kleeman boost kit".

I don't know where you can get good specification but I think the speed shop can do this.

You may have to put the money down on them for their job. Sorry.

Good luck.

[SS]

Hi.

I need to expand on my request for help as I didn't provide all the information. (sometimes on forums if a problem looks too hard, no one replies.

The M271 engine is already fitted with a Kompressor from factory - its the std engine in the C180K, C200K and C230K. Its a 1.8litre.
At the factory they change Kompressor sizes and compression ratios etc to achieve the three different power levels. (ie: since 2003, the C200 is not a 2 litre, nor the C230 a 2.3 litre.)

Kleeman provide a power-up kit in supplying a larger diameter front drive pulley.
They also provide a rising rate fuel regulator which progressively takes the fuel pressure to 5 bar once the manifold pressure goes positive. Standard fuel pressure is fixed at 3 bar all the time.

Then they provide a piggyback box which breaks into the MAF and MAP sensors.

The system works in Europe and the USA (supposedly) without problems.
However, mine gives the problem I have described.

Kleeman have been quite helpful initially, and sent me a second K-Box that had been updated since they sold me mine.
However, the problem is persistent and now they have abandoned me.
Kleeman are in Denmark and I am in Australia, so Its not a matter of confronting them with the car and saying "fix it or give me my money back".

I'd like to solve the problem because at all times other than this missfire occuring, the engine is sweet and a big power lift over standard which is very obvious when driving. Std = 120kW / Kleeman = 147kW.

I have played with the rising rate fuel regulator in backing it off, but then the engine doesn't start well from cold and isn't smooth through the rev range.
I've had a look into the K-Box but its sealed in epoxy.
I have checked and rechecked and rechecked the connections etc and they are all correct.
Kleemann went through just about everything they could think of as well. They were as helpful as they could be by long distance, but now they don't reply to me.

Thats why I purchase PCMScan - so that I can try and figure out what is going on.
I already had a scanner and I've checked the freeze frame data each time the problem occured but couldn't see anything obvious. It only froze 5 PIDs each time.
I was hoping the PCMScan would give me a wider view as to what was happening whe the problem occured.

[SS]

When you enter in WOT , something happens in the ECU , one is the engine goes to OPEN LOOP and the fuel ratio 14.7 goes down from 12 to 11 this condition is called POWER ENRICHMENT , you can see this using PID 03.
 

My scanner shows me changing between closed to open loop, but I cannot find an guage or PID indication in PCMScan to show on the dashboard when this occurs.
The PIDs are not numbered so I cannot find "PID 03", or anything in the drop down list that is "Power Enrichment".
I'd like to observe this change point if I can, so can you assist me further as to where/how to find it please.

I have version 1.4.3.

[BrianP]

The beta version of PCMSCAN supports these PIDs. If you download the beta, look for Fuel System Status.

[SS]

The beta version of PCMSCAN supports these PIDs. If you download the beta, look for Fuel System Status.

Brian - have you also thought to include an indicator on the dashboard and graph display of when an error code is generated - ie: a marker?
It could be just a red "light", or a pop-up box or a small readout that displays the actual code.
It would be very helpful for identifying exactly when a problem occured.
If you already have this feature - I apologise, but I cannot find any way to co-incide a fault gerneration with the readouts.

[SS]

For the helpful diagnostics that are following this post, I have set up PCMScan MAF and MAP scales such that MAF is 0 -100 and MAP is 0 -200.

I would expect that the two graphs would run roughly parrallel - with my set up the MAF is slightly below the MAP lines.
On drives where I experience no problems, they do run mostly parrallel although the do come close occasionally.

However, on drives when I experience my PO302 missfire, the MAF graph actually crosses the MAP line, and although I cannot tell exactly, I think this is about the time the engine does missfire and the LIM light comes on.
As stated, the error code is always 302 (#2 cyl missfire).

Am I on to something here, or are there any circumstances where the MAF might exceed the Manifold pressure (in particular on a supercharged engine)?

[BrianP]

Brian - have you also thought to include an indicator on the dashboard and graph display of when an error code is generated - ie: a marker?
It could be just a red "light", or a pop-up box or a small readout that displays the actual code.
It would be very helpful for identifying exactly when a problem occured.
If you already have this feature - I apologise, but I cannot find any way to co-incide a fault gerneration with the readouts.

I'm not sure what you mean when you talk about an error code. Do you mean have the software check the trouble codes, and when a DTC comes on, show an error? Or do you mean add some functionality so the end-user can set up some kind of alert (i.e. when RPM goes above 6500), that draws a red background or something like that?

[SS]

Brian - have you also thought to include an indicator on the dashboard and graph display of when an error code is generated - ie: a marker?
It could be just a red "light", or a pop-up box or a small readout that displays the actual code.
It would be very helpful for identifying exactly when a problem occured.
If you already have this feature - I apologise, but I cannot find any way to co-incide a fault gerneration with the readouts.

I'm not sure what you mean when you talk about an error code. Do you mean have the software check the trouble codes, and when a DTC comes on, show an error? Or do you mean add some functionality so the end-user can set up some kind of alert (i.e. when RPM goes above 6500), that draws a red background or something like that?

Sorry Brian - I'm a bit more computer orientated than technician oriented.
I'm am referring to when a Trouble Code is generated.
I'd like to see on Dashboard B (the graphs) exactly when a trouble code occurs so that on playing back logs, a tech (me) can see the exact parameters that occured at the time of the trouble code appearing. It would be nice to have an indicator on Dashboard A as well for realtime driving test sessions.
For me, freeze frame data doesn't reveal enough.

(Your red background "alert" sounds like a great idea also if a tech was looking for certain events).

[rat]

Don't know if you figgured the original question out yet, but that sounds about right for maf readings.  I have logged a bone stock chevy 4.3L, and it maxed around 163g/s.  That motor has about 190hp@4400rpm, and 250ft-lbs of torque at 2800rpm.  I assume that this is similar to your power levels.  At idle it pulls around 6-7g/sec, but this is a much larger motor, so that can be expected to be a little more.

The actual number isn't really that important, and doesn't necissarialy correspond directly to an air flow reading.  If you have access to some tuning software and have a wideband o2 sensor you could see exactly how lean or rich the motor is, and modify the maf tables so that your air fuel ratio's are in line.  It could also be a combination of the maf and map if your vehicle has both not corresponding correctly causing erratic air fuel ratio's.  Annother option for altering the maf signal is a maf translator.  I don't know if your maf is frequency baised, or voltage baised.  The frequency baised ones have many options for this.


The map and maf readings are compleatly different.  When the map is high(high load) the maf will report high air flow.  The map is reading pressure.  The maf is reading airflow.  The two measurements are related to some small extent, but they can and should differ from one annother.  The maf readings are highly rpm dependant.  For example you can have 100kpa map(if you were n/a for example) for the entire rpm range.  However you would see that the maf readings change with rpms, at low rpm's you would have lower reaings, and at high rpm you would have higher readings.

[SS]

Don't know if you figgured the original question out yet, but that sounds about right for maf readings.  I have logged a bone stock chevy 4.3L, and it maxed around 163g/s.  That motor has about 190hp@4400rpm, and 250ft-lbs of torque at 2800rpm.  I assume that this is similar to your power levels.  At idle it pulls around 6-7g/sec, but this is a much larger motor, so that can be expected to be a little more.

The actual number isn't really that important, and doesn't necissarialy correspond directly to an air flow reading.  If you have access to some tuning software and have a wideband o2 sensor you could see exactly how lean or rich the motor is, and modify the maf tables so that your air fuel ratio's are in line.  It could also be a combination of the maf and map if your vehicle has both not corresponding correctly causing erratic air fuel ratio's.  Annother option for altering the maf signal is a maf translator.  I don't know if your maf is frequency baised, or voltage baised.  The frequency baised ones have many options for this.


The map and maf readings are compleatly different.  When the map is high(high load) the maf will report high air flow.  The map is reading pressure.  The maf is reading airflow.  The two measurements are related to some small extent, but they can and should differ from one annother.  The maf readings are highly rpm dependant.  For example you can have 100kpa map(if you were n/a for example) for the entire rpm range.  However you would see that the maf readings change with rpms, at low rpm's you would have lower reaings, and at high rpm you would have higher readings.

Thanks for your info - I appreciated it.
The horsepowers between engines (taking into account the Supercharger) probably do have similar MAF readings (air "consumption" I suppose we could say).

This PCMScan software does monitor the O2 sensor and this maintained a voltage between 550 to 750 for most of the time with wider variations on trailing throttle. The Lambda reading orbits very close to "1" all the time.

I went back over the logs for both a "good" run and a "problem" run and in both cases the MAF doesn't track the rpm very well at all - it spikes and valleys mostly independent of the rpm.
I'm guessing that this is due to the supercharger being engine driven and having electronically controlled by-pass (pop-off) and other such controls.
ie: I can see that in a normally aspirated motor, the MAF would probably track the rpm.

However, my MAF does track the MAP extremely closely, except where the engine is under load up a long hill and the MAF spikes, immediately followed by the trouble code appearing and the engine missing.

I would have expected the MAF to track the MAP as more air is compressed in the inlet manifold giving a correspondently higher MAP, and visa versa.

Now I just need to work out why the MAF spikes under certain conditions and triggers a misfire and trouble code.