Chip Tuning and Engine Operating Envelope
 

As I mentioned in another thread, I'm toying with the idea of chip tuning my 98 E300D. I would probably have Rocketchip do it (I can easily drive my car to them) and do a Stage 2 with EGR delete. Researching this has led to some observations and questions.

1. Without question, an engine is capable of greater/better performance than is allowed by the stock ECU.

2. Mercedes engineers configure the ECU to enable the engine to balance performance and reliability in a manner that takes account of a wide range of drivers and driving conditions. From the SpeedTuningUSA site: "Why doesn't the producer perform the engine tuning by themselves? The manufacturers design cars and engines for the worldwide market. In different countries many factors, including extreme heights, hot and/or dry climates, poor fuel quality etc command a general ECU software setting. The conditions in Europe and North America are not that extreme, so there is enough tolerance for chip tuning. The HP can also be a political decision, like the 1.9l TDi 90HP engine represents a certain car tax level in some European countries." This argument make intuitive sense to me. But I don't have any reason to doubt the decisions of the MB engineers given the wide range of drivers and markets.

3. Is every car tuned exactly the same way from the factory? From a production efficiency standpoint, this would make sense. But perhaps the ECU of a car sold in the American market is different from its counterpart in another country (due to emission standards or whatever).

4. If a tuning did adversely affect reliability, in what particular ways would this be the case? What exactly would fail earlier and why?

I could see the turbo life shortening since you'll be running higher boost pressure and the injection pump will be worked harder. As long as you're starting with a healthy car and continue to take good care of it I doubt you'll notice the car deteriorating. I also think speed tunings claims are generous. You will hit a wall with you stock delivery valves and stock turbo pretty fast so they can't go too wild with the tuning. Which is a good thing for reliability.

Any turbocharged car falls victim to easy power gains. Clapped out cars with turbos due for maintenance get bought by people who spend the money they should be spending on timing belts and oil filters on a high boost retune. See the vast majority of 1.8t vws lol.

The thing I go back to is big diesel trucks. As a workhorse torque sells trucks. Whenever Chevy puts out a new torque spec fords next year comes back with 5-10 note ft/lbs. If an edge tuner adds 200 ft/lbs why doesn't ford just sell a 950ft/lb truck? I think its a question of durability. Modded trucks don't seem to last as long. A chip won't destroy a truck but to say it will make zero change in component lifespan is hard to believe.

You've got a strong low miled car and it sounds like you take good care of your cars. I say go for it.

I still don't understand how they extract as much power as they claim without swapping in larger delivery valves.

I can post and answer most of your questions. I'm just at work right now and don't have time.

News at 11.

Great...no rush.

Chip tuning these engines is OK to a degree. The ECU only effects fuel and boost (also EGR, etc...), it can't alter timing. If you're only looking for about 40HP, it's OK but the ECU is simply being re-calibrated to move the rack further to deliver more fuel as well as provide more fuel quicker - sort of like adjusting the ALDA on a mechanical engine.

One of the main problems with moving the rack further to get more fuel is that is lengthens the injection event. Rather than a "spurt" of fuel, it becomes a "sploooosh" and the total injection event extends too far into the piston cycle which lowers efficiency and raises EGT's. The proper way to increase power is to swap in larger pump elements. This keeps the injection event short and sweet.

The only drawback to this is that elements are expensive and have to be installed by someone with the right equipment.

Very helpful stuff, KarTek. Personally, I would be willing to trade SOME life for appreciable gains in power and fuel economy. My guess is I'll drive the car about 10-12k miles a year (I have two daily drivers). It currently has 77k. So can this car get to 300-350k miles? Of course. But, doing the math, that will be 25 years from now. I suspect rust will have long since devoured the body by then....and my W124 will still be going strong.

Shertex posed this question to me in an e-mail exchange this morning. For the benefit of the others on this board, here is my response to the question:

Personally and just my opinion, chip tuning is not for me.
Every engine has an operating envelope. At one end you have higher reliability and the other you have high performance. The ECU limits are there to keep the operating parameters in the "reliability" end of the envelope. As an engineer myself, I would not pretend to know all the design decisions that went into the development of the engine, and the rationale behind the limits placed upon the engine by the stock ECU. The third party guys who develop these chips don't likely have access to that information either. I would like to keep my car for a long time and I am quite happy with the stock performance (especially having started out on my MB experience with a 240D).

I don't overclock my computer either for the same reason.

My opinion, put that $435 into preventative maintenance. To include changing the air filter, fuel filters and the 6 fuel hoses. Also change the o-ring behind the shutoff valve. Also change the transmission fluid if it hasn't been done in the last 50k or so. And pull your injectors and send them off to Greazzer.

Oddly enough, all this is not completely unrelated to choices one might make that may shorten one's lifespan....quality of life vs. length of life considerations.

Except exercise and strength building generally increase the body's longevity unless you go to far and wear it out!

One other note on the chip tuning, odds are it won't increase economy because it can't alter timing. On my car, I opted for larger elements which gave it a "crapload" of power and the increased combustion efficiency has raised my highway mileage to 34 with a peak of 37.

Rocketchip claims that, on my particular car, their experience has been a 3-4 mpg increase with a Stage 2 tuning....they've evidently done quite a few of them.

On longevity, I'm thinking more smoking cigars, drinking Scotch, that sort of thing...:D

On that note...

AOL.com Article - World's oldest person turns 116 this week, shares her 'secrets'

Here is an informative and useful FAQ from Evolution Chips in the UK:

Evolution Chips? Common TDI Tuning, Remapping and Performance Chips Questions and Answers

That's WVO and ether :D.

I've had RocketChip on my 99.5 Jetta since 140,000 miles... about to cross 300,000 now :) In that car the chip affects fuel, boost, and timing. The only worry I'd have when getting a reliable chip tune is wearing out the automatic trans faster.

-J