AJM: Sudden Power Loss, Lots of Oil Consumption

Hello,

ich setze hier mal ein Problem für einen Kollegen rein, der sich leider aus ominösen Gründen sich hier nicht einloggen kann. Er wrote:

'Since I couldn't find a solution to my problem in the forum, I wanted to post about it myself, but unfortunately, that didn't work out.'

I drive a Passat Variant TDI PD (with 115 hp, engine code AJM), manufactured in May 1999, with 53,000 km on the odometer.

Last September, I had a chip installed by INMotion Tuning, a company based in Austria (W. Grundner).

The increase in performance in the lower RPM range was quite impressive. At higher RPMs, I didn't really feel much difference (and the top speed probably didn't change much either - maybe 3-4 km/h at most!). I've never had a car on a dynamometer.



It seems like the consumption has increased somewhat. I would estimate the average to be around 0.5 liters (less with economical driving, and correspondingly more with full load, that's my impression).



If anything, I got the impression that the car produced slightly more soot than it did before the tuning. It was hardly ever visible in the rearview mirror.



BUT things have been different for a few weeks now.



I have the feeling that the acceleration (from low speeds) has become weaker. When I compare myself to other Passats with 110 horsepower, I can barely keep up (despite having a 115 horsepower PD engine and a chip).

The maximum speed is still just below 200 (and only achievable with a very strong initial acceleration). Reaching speeds of 180 to 190 km/h is relatively quick.



'Furthermore, the car now smokes when I accelerate hard from low RPMs (1400 to 1900 RPM). A cloud of smoke follows me, making it difficult for drivers behind me to see me. Above 1900 RPM, the smoke dissipates (or spreads out more evenly).'



I had previously disabled the automatic brightness adjustment (ABA), but I re-enabled it a few weeks ago to see if I could detect any difference in power consumption.



I have removed the LMM (Bosch 028 906 461) – it's right here in front of me. The metal rods on the sensor appear to be clean (shiny) on the right side. I'm not sure if I should use brake cleaner on it? Could I damage anything with it? The LMM hasn't been checked by the workshop yet.



After reading so much in the forum, I'm starting to doubt that the problem is related to the mass airflow sensor. I'm not experiencing any jerking, and the maximum speed seems relatively consistent (although I haven't been able to go faster than 190 km/h recently, probably because the road was too crowded). The idle is smooth.



About 8 weeks ago, I experienced a mysterious defect. Shortly after starting the car, it would jerk strangely, and it would stall at traffic lights. It felt like it was only running on 2 or 3 cylinders. The power was completely lacking. However, it seemed to improve somewhat at higher RPMs. When I turned it off for 10 minutes and then tried to start it again, everything seemed to be fine...!?

The workshop immediately read the error memory, but couldn't find any errors. Afterwards, it sounded like it might have been the mass airflow sensor (MAF), right? It's strange that it started working again afterwards. I can't say for sure whether I've experienced increased soot in the lower area and slightly reduced acceleration since then.



Someone online wrote to me suggesting that the turbocharger boost hose might also be faulty. Do you think that's possible, or do you have any other ideas?



'How can I only submit my problem to diesel mechanics? I've already registered twice, but I can't log in. Maybe they're just having a problem today.'

Hello,
I'm the colleague that DocSnydor posted about earlier. Fortunately, it worked out, and I can now write here. Thank you, DocSnydor!

I have already cleaned my mass airflow sensor (MAF) with brake cleaner and a soft paper towel or cotton swab. The AGR valve is original. Unfortunately, I read the instructions too late and realized that you shouldn't touch the sensor. Now, I might have damaged it.

During the test drive just now, I almost lost faith. The car (TDI/PD/115 hp/285 Nm - AJM) pulled worse than a 54 hp diesel. It barely had any power.

I then drove approximately 30 km. After the first few kilometers, it gradually improved, but it was far from being as powerful as it was before my cleaning. I then revved it up to 4600 RPM (170 km/h) in 4th gear, which was quite a struggle. In 5th gear, there was almost nothing left.

Otherwise, I haven't changed anything. I just cleaned the air filter properly.

What I just noticed, however, is that the black smoke at lower RPMs (when accelerating) is now gone. But, of course, the engine power has decreased as a result.

I only noticed a dark cloud in the distance for a brief moment while the aircraft was stationary.

'Something else I noticed is that I didn't feel any boost when accelerating above 1950 RPM. Even when driving slowly, between 1300 and 2200 RPM, I can barely hear the turbo whistling. Hmm, this probably has nothing to do with my cleaning of the mass airflow sensor, right? I haven't done anything to the turbocharger.'

...never touch a running system, oh yes!

I hope you have some more tips for me.

Thank you and best regards,
Jörg.

Oh man, I really wish I hadn't touched the LMM!!

First, go to Mercedes and buy a Mass Air Flow sensor (MAF sensor) from an older E320CDI for about 70€, and then install it.

Hopefully, your problem will be gone after that!

Regards,

Manuel.

It sounds like you might not have plugged the connector back in after cleaning the mass airflow sensor .

He destroyed it while cleaning!

Regards,

Manuel.

I plugged the connector back in. I didn't really try it multiple times, I'm just hoping it fits correctly the first time.

Then, next to that, there was another part attached to the air filter housing. I had also disconnected the connector from that part so I could open the housing.

But I've reattached that part as well.

He destroyed it while cleaning!

Regards,

Manuel.

I read that too, but I thought the symptoms might also be related to a disconnected cable. It's happened to me a few times before.
It seems the mass airflow sensor probably failed.
My sincere condolences.

Hello everyone,

Yesterday, I received my new mass airflow meter (MAF sensor) from Pierburg, which I ordered from Turbofan (by the way, it's a great product!). I installed it right away!

After a test drive, I can say that I had completely cleaned the old mass airflow sensor using the cleaning process (brake cleaner, compressed air, and a cotton swab)!
After that, I estimated that I had roughly 30 to 40 kW of power remaining.

The engine power seems to be back to what it was before the cleaning process (though it's just a feeling). I didn't have the mass airflow sensor measured before or after the process.

Unfortunately, the carbon buildup in the lower RPM range (from 1400 RPM) is still present when using full throttle.

Some of you have suggested a faulty boost pressure hose, a defective throttle position sensor, or a stuck EGR valve. Due to my lack of knowledge, I am unable to check these things myself (except for the EGR valve).

I hope that the diagnostic tool (VAG) will now be able to find the defect in the error memory.

Thank you all again for the tips.

Best regards and a lovely weekend to everyone.

Jörg.

Oops, I saw this thread too late. I replied to the other one because the question was posted twice here (/viewtopic.php?t=3298).
It's probably not the LMM (mass airflow sensor), but rather the intake manifold. You can usually identify the leak by visual inspection. The leaking area is usually oily. The weakest link is likely the LLK (low-pressure coolant system), so take a look at that.

Best regards,
Uwe.

Hello,

I also have a tuned AJM engine, and I installed a Pierburg mass airflow sensor.
The car was really speeding: squealing tires in second gear, without using the clutch!
Approximately 1000 km later, I had a hole in the piston due to combustion pressure spikes!

I work in engine development at Audi, and I recently had a chance to examine a piston. The diagnosis: clearly, there's too much pressure!

I would appreciate it if someone could give me some advice on how to deal with excessive smoke coming from my 2015 Audi A3 with approximately 70,000 km (43,500 miles).

It produces a lot of black smoke when running at full load around 1600 RPM, but it's fine at 2000 RPM. At higher RPMs, the black smoke becomes more noticeable again.

Thank you!

CU, Flo.