Thank God, I've Found My Lost Horsepower!!!

[HadE55NowM5]

It's been a stressful time for me lately. A few weeks ago, I ran into another board member here in San Diego while driving on the freeway. He decided to to give chase, and in so doing kept up very easily with me to 120++ mph. A couple of days later, an E36 M3 practically kept up with me from a stoplight-to-70 mph run. These two episodes only confirmed for me what I've lately been feeling seat-of-the-pants. My car, despite having a 3.45 Dinan Differential, Dinan Cold Air Intake with Stage 2 software, a Kelleners exhaust, etc. has felt sluggish (i.e. it lost its "snappy, lively" feeling, as if it wouldn't pull as hard as a box-stock, plain-Jane E39 M5). I felt as if I had taken a big step backward with all of my modifications and "tricking-out."

At that point, I decided to travel to The Dyno Shop in Santee (San Diego), the same shop that dyno'd my car (about a year earlier) in Septmeber 2000 when I only had the Kelleners exhaust and Dinan Stage 1 software. At that time, my car made the expected 333 BHP and 325 lbs./ft. of torque in 5th gear. The test in late-October 2001 merely confirmed what my "butt-dyno" was telling me. The results were 291 BHP and 292 lbs./ft. in 5th gear. This BHP loss of over 40 BHP was both sobering and disappointing.

At first, I blamed the Dinan 3.45 Differential, since (along with the Dinan Cold Air Intake), this is what fundamentally was different about my car since the time of year-earlier dyno run. I talked to a lot of people. Some said that the drop in BHP was due to the "inertial loss" inherent to a short ring and pinion (i.e. the theory being that since the shorter gearing causes the engine to wind-out quicker in any given gear, more BHP is required to achieve this, resulting in a rear-wheel BHP loss). This line of reasoning did not seem very logical to me. Others opined that in this day and age of massive electronic managment and sensors, factory gearing is crucial (i.e. altering the gearing somehow confuses the OEM mapping parameters, causing the engine to operate in an inefficient and underpowered manner). Again, this seems like a specious argument.

That's why I contacted Andy Menard in my earlier "mysterious" post. I didn't want to go into too much detail (i.e. erroneous finger-pointing) until I did more research and investigation. Since Andy's car has virtually the same mods as mine, I'd been looking forward to see if his earlier pre-3.45 Differential dyno test results would change once he re-dyno'd his car now that he has a 3.45 Differential (which he says he is going to do soon).

After taking the car to one San Diego-area dealer (where I was told that my car was perfectly normal), I was ready to have the car shipped up to Dinan and have them look at my car (and hopefully put it on their Dyna Pack dyno -- I've always only had access to the peripatetic Dynojet 248C). I was convinced that the 3.45 Differential was causing my rear wheel BHP to be robbed. Luckily, Eric Forster in the Dinan Tech. Support Dept. advised me to phone Pat Arnold at Classic BMW in the Dallas area (Richardson).

Pat told me that he had seen a range of M5 engine problems, including several that had lost power for one reason or another. One had premature cylinder wall wear. Another had a broken valve spring. Of course, we've all heard about plugged-up catalytic converters. He also mentioned that he seen cases where the oil from the K & N-style Air Filters had somehow affected the performance of the nearby Mass Air Flow Sensors (sometimes referred to as the Air Mass Meters). He told me that when these Mass Air Flow Sensors were replaced, normal power returned.

When I took my car to that first San Diego-area BMW dealer, they downloaded all the information that they could and concluded that there was nothing outside the normal range of values for my car. In fact, the technician drove my car and reported that it felt perfect. The service manager also told me that BMW supposedly has a policy wherein BHP should be within 10% of the officially-quoted BHP. By coincidence, my 42 BHP loss represented a little more than 10% of a loss. I found it hard to swallow that this could possibly be an official BMW edict, especially for a M (Motorsports) engine. We all know the level of pride that the Motorsports guys in Munich have.

After talking to Pat Arnold in Dallas, I took my car to another San Diego-area BMW dealer. I told them to remove, inspect and replace my spark plugs, perform compression and leak-down tests (in order to discern if there is a general engine problem), and remove my K & N-style air filters and clean them. My cold compression was 170 - 175 psi and the cold leak-downs were 4-5% (with one showing 8%). These results aren't bad for a 23,000-mile engine. I also wanted them to replace my Mass Air Flow Sensors under warranty (they cost $300+ per bank). They said that they would only be able to replace them under warranty if something was extremely out of wack. Instead, my sevice guy agreed to remove the Mass Air Flow Sensors from someone else's 2001 M5 that was in for service and install them in my car in order to run a back-to-back driving test in order to detect a difference in performance. Luckily for me, my technician left these other Mass Air Flow Sensors in my car!

When I got the car back, I immediately felt the difference. The "snap" was back! A few days later, I took the car back to the same dyno shop in order see if I was imagining things. In 4th gear (which typically gives lower rear wheel BHP than 5th gear), I gleefully say 333 BHP and 310 ft./lbs. In 5th gear, I saw an amazing 348 BHP and 344 ft./lbs. I know that many people are dubious and skeptical about the consistency and efficacy of chassis dynos. However, even if one regards them as being approximate and not exact, I think that it reinforces and validates my point.

Apparently, when my car was diagnosed at the second San Diego-area BMW dealership, all of the numbers were straight down the middle, except the Adaptations (Learning) for Fuel Mixture. The Additive values, which measure the Fuel Mixture tolerances at idle, are supposed to be + or - 0.25 milliseconds. On Bank 1 it was -0.418 milliseconds and on Bank 2 it was +0.34 milliseconds. The Multiplicative values which measure the Fuel Mixture tolerances at part load are supposed to be + or - 15%. For me, it was +21.6% on Bank 1 and +21.7% on Bank 2.

It's possible that these Adaptations got messed up when I had to get my car re-mapped after getting the fix for the VANOS Rattle Noise After Engine Start Problem (Bulletin 11 04 01). As part of this fix, an electonic solenoid is installed so that maximum oil pressure is fed into the VANOS from the exact moment of start-up onward. The original design has a mechanical system governing oil flow to the VANOS. The update requires re-flashing the engine map so as to enable the dormant electronic circuit in order to control this retrofitted electronic solenoid. Those of us with Dinan Stage 1 (and Stage 2) have to get our cars re-mapped by a Dinan dealer so as to replace what was lost/erased. Most versions of this revised (VANOS electronic solenoid) factory mapping are compatible with Dinan engine programs. Maybe my Adaptations (Learning) values didn't take correctly when I had this recent (post-VANOS fix) Dinan re-flashing done.

The bottom line is that Dinan referred me to someone (Pat Arnold at Classic BMW) who was able to shed light on the possible causes of power loss. I highly doubt that any of my local dealers would have thought about replacing my Mass Air Flow Sensors as a cure, since my diagnostic numbers were down the middle (except for my Adaptation numbers being out of tolerance). The reason that I am writing this long and boring post is so that others can possibly benefit from my hard toil, trial and error, and general frustration. I simply wouldn't accept the party line (i.e. 10% BHP loss is acceptable, etc.).

I just have a nagging suspicion that the Mass Air Flow Sensor problem might be A LOT MORE PREVALENT THAN ANYONE THINKS!!!! Maybe this is something that needs to be brought to BMW's attention, especially by those guys on the East Coast who recently posted the (low BHP) results of their group dyno run. Maybe there is something defective about the OEM design of the Mass Air Flow Sensors. Maybe it isn't a matter of oil migrating from the K & N-style Air Filters to the Mass Air Flow Sensors and causing damage. Maybe normal dirt build-up is corrupting them (like in late-model Mustangs GTs, etc.). In today's day and age (i.e. economies of scale) maybe manufactures such as BMW don't specify such tight tolerances from their vendors. Tighter tolerances exponentially raise component costs.

Maybe I'm on to something. Maybe BMW needs to do a recall! Maybe this would explain the wide range of observed rear-wheel BHP numbers. I know this won't be an easy sell to BMW as they don't regard chassis dynos as particularly reliable and consistent (i.e. too many variables such as how tight the straps are, the amount of air fed to the motor by the external fan in the shop, how warmed-up the dyno is, etc.).

As a general reminder, please don't forget to turn off the A/C when doing the dyno run, and to remove Fuses 17 & 30. Also, it's best to shut the car off for at least 15 minutes between dyno runs so as to allow the catalytic converters time to cool off.

Sorry for the rambling post.

[greg]

Wahoo! Congratulations on your sleuthing and insistance - it clearly paid off for you.


Clarification - since you have K&N's on your car, are you suggesting this problem would be likely for people who use them only, giving credence to the argument that the oil screws up the MAFS, or are you suggesting the MAFS might just fail for another reason that we all might experience?

Also - I'm not sure I understand some of the measurements done - but maybe you can clarify there too - can the faulty MAFS's be detected simply by looking at the right data from the computer, or do they really need to be swapped out to find out?

Thanks for the great info!

/Greg

[PaulMarin]

Elliot, I was wondering where you've been, now I know.
I need to digest your whole post a little more. Dont worry about long posts. A lot of us are on the lookout for smart info on the sometimes mysterious ways of the E39 M5 engine. Mine is in right now for what seems to be a bad cat issue. I'll post my story, (its long but I think of interest), after its finally sorted out. Way to go, we must stand up and fight Government (BMW) Arrogance! Tell us more tales, any news on Stoptech?
Paul

[Aussie2U]

Wow, what a great post! I just wanted to add one "general" point on Mass airflow sensors.

In the past few years, I have learned that you NEVER want to spray your engine compartment down with silicone spray. I used to do this all the time as it really enhanced the appearance, making hoses & plastics look new again. Plenty of car dealerships do this too on their used cars. I learned that the Silicone "vapors", present long after you have stopped spraying, can coat the mass airflow sensor and cause bad readings.

Therefore, it makes sense that if silicone vapors have been shown to throw off readings, then maybe the red spray oil in the K&N filter could be getting sucked over the sensor during WOT and setting you up for some power loss as was mentioned above.

[EBMCS03]

Wow Elliot... very nice informative post! Glad to hear that u found the problem! Any new exotic cars at the shop lately?

[AndyMenard]

Elliot:

Glad to hear that your BEAST has found its lost power?!! I had my bank2 cam sensor replaced this past Monday but I haven't time to go do a dyno run... I still plan to do this however as soon as I can find the time.

I am now very curious though on the issue of the MAFS causing bad readings? I wonder if my Dinan CAI will eventually cause this same problem in my car too??

Have you or anyone else talked to Dinan about this??

[PhilSeastrand]

I wouldn't call that a rambling post -- rather it was a very detailed, informative post. Thanks for taking the effort!

[KirklandM5]

I would not worry too much about a "rash" of bad HFM (aka AFM, MAS) Heated Flow Meters.

The ones on our cars are basically the same as found on the M50 2.5L...we just have 2 to make up for more displacement. Bosch basically makes four models

1 for 4 cyl
1 for 6 cyl 2.5L-3.0L
1 for 6cyl M3s and V8s (4.4L)
1 for Porsche Turbos (the big one)

You either got a bad one, or those K&Ns don't do the job vs paper.

Since hp gains are minimial with K&Ns and CAI, I don't think it's worth the expense...I'd rather get a lower diff.

JL

[HadE55NowM5]

Originally posted by greg
Wahoo! Congratulations on your sleuthing and insistance - it clearly paid off for you.


Clarification - since you have K&N's on your car, are you suggesting this problem would be likely for people who use them only, giving credence to the argument that the oil screws up the MAFS, or are you suggesting the MAFS might just fail for another reason that we all might experience?

Also - I'm not sure I understand some of the measurements done - but maybe you can clarify there too - can the faulty MAFS's be detected simply by looking at the right data from the computer, or do they really need to be swapped out to find out?

Thanks for the great info!

/Greg

Simply put, I don't know. I'm not sure if the loss of efficiency of the MAFS has anything to do with the oil in the K & N-style filters. Maybe we can take a pole of those with low-ish BHP results and see how many of them have these types of filters (either as part of a Dinan CAI system or in conjunction with OEM induction.

I'm not sure what data would lead a BMW tech to conclude that there's a problem with the MAFS. In my case, all of my data was down the middle except for the Adaptions. Even with these Adaption numbers being outside the "acceptable range," my tech wasn't going to change my MAFS until I insisted on it. This "hint" resulted wholly from my conversation with Pat Arnold at Classic BMW. Even if my tech didn't do this "swap-out" favor for me, I was ready to spend $600+ of my own money to see if this could/would cure my BHP loss. Luckily, I didn't have to "roll the dice."

I wonder if the owner of the "donor" M5 (which now has my old MAFS) will soon be complaining to the dealer about a loss of power......Maybe the disease will spread.

[HadE55NowM5]

Originally posted by KirklandM5


You either got a bad one, or those K&Ns don't do the job vs paper.

Since hp gains are minimial with K&Ns and CAI, I don't think it's worth the expense...I'd rather get a lower diff.

JL

Kirkland M5,

You've got a point. However, I like the improved throttle response afforded by the CAI. The nicer induction sound/whirl is also a nice by-product. However, I wish there was a way to run "paper" air filters with the CAI, so that way I wouldn't have to worry that the oil might again "corrupt" the MAFS (if that's indeed the cause of my MAFS problem).

Believe me, after all the recent hassles I've gone through I'd be happy to re-install the OEM induction system if that meant that I would never again have to endure a MAFS-related BHP loss.

[m5monster]

Glad to hear your lost horses are back The info in the beginning of the thread is a great asset in my opinion. At least for me.

My own experience with lost HP, it's gonna be long , but it's like venting out my regret after all this time. Bear with me:

I had a 540i Automatic. It had Dinan CAI and automatic transmission software. I did the modification step by step, i.e. Dinan software stage 1, then, a month later CAI plus stage 2 software. What I felt after Stage 1 download was really noticeable in terms of throttle response and my butt-o-meter dyno also felt this. So I was sold to upgrade to CAI.

Turned out this decision was not approved by my butt-o-meter dyno. The car lost its snappiness. But I got a nice intake sound instead, so I told myself:

what a great feeling this must be, the car is faster, hear her out, my butt-o-meter must have been biased, this upgrade cost a lot of money, the graph shows much more increase in hp and torque.

Anyway, as much as I tried to convince myself, whenever I accelerate away, deep inside my heart I still could't feel the improvement.

To make long story short, I sold my E39 540i to buy the beast . A month later, I heard from the buyer that the 540i wouldn't go beyond 70 mph Then fortunately he was able to fix it. Turn out that the both of the oxygen sensor needed be replaced.

CONCLUSION
After reading this post, and my own experience, I believed more that K&N style filter is not good. And CAI's improvement cannot be felt by butt-o-meter, but sounds good to the ears. Taking into account the cost, I would pass CAI and K&N airfilter. Now I'm using Powerchip. It's been one month. Very noticeable feeling, and it gets better over time, as the car ECU needs time to "learn"