Engine hesitation, power loss, sluggish acceleration: Potential fix

[SeattleGS400]

SUMMARY

Symptoms: Gradually increasing car hesitation, power loss, sluggish acceleration, lowered fuel economy.

Cause (probable): Dirty fuel injectors, dirty engine valves, and combustion chamber deposits

Fix: Chevron Techron Concentrate Plus (or similar known PEA-containing (polyether amine) fuel system cleaner products like Gumout Regane, Redline SI-1, Amsoil Performance Improver, and BG Products 44K)

BACKGROUND

I looked into fuel system and fuel injection cleaners as part of my hunt to figure why my 1999 Lexus GS400 was seemingly losing power and hesitating more. It was very noticeable when I went up a slight incline and I had to push down on the gas more just to go a constant speed. When I first got my car many, many moons ago, I could set the car to a speed and it would hold the speed unless you had a steep incline, and only then would it need further accelerator input. Next, my car over the past year seemed to hesitate and have sluggish acceleration from a dead stop. FYI, as I moved and started a different job almost a year ago, my commutes are only a short 3 miles each way instead of a 10 mile one-way trip. I almost exclusively use only Shell, Chevron, or Texaco gas in my car.

My initial hunt for power loss started with a MAF and throttle body cleaning with a resetting of the ECU (see my other DIY post on this):

http://www.clublexus.com/forums/showthread.php?t=345147

The above procedure seemed to fix the hesitation and power loss, however, after about a week, I still got the symptoms back. The hesitation and power loss problem seemed to be incrementally getting a bit worse over time. Recently, I went out for fast food (rare for me) and was waiting at the drive-in with my windows down next to the restaurant wall, I noted that my car seemed to either have more valve noise and/or fuel injector noise.

After some research, a few things came to mind that I might need to look further into (in no particular order):

Fuel pump, fuel filters (there’s 2—a bag filter for the fuel pump, and a tank-type filter), fuel pressure regulator, ignition wires, fouled spark plugs, dirty fuel injectors, poor engine compression from wear and tear, clogged catalytic converter…

I pretty much ruled out the fuel pump, fuel filters, and fuel pressure regulator as my car didn’t lunge/starve for fuel on wide-open-throttle acceleration. As for the other things, I figured I should start with the easy fixes before moving on to more expensive options. The valve noise and/or fuel injector noise hinted that I should try cleaning those parts first.

SUMMARIZED RESEARCH

Anytime you have gas burned in your engine chambers, not all of it burns up and you’ll eventually get deposits forming on the valves, combustion chamber, and fuel injectors. Gasoline is supposed to have detergents in them to keep your engine parts clean (some top-tier gas have more detergents than the government specified amounts), but driving short distances without having your car fully warmed up can lead to faster accumulating deposits.

Although I’ve read other numerous posts, I’ve summarized a poster’s notes from PriusChat.com in what can lead to engine power loss and hesitation:

When fuel injectors get clogged, the fuel spray pattern is affected (fuel normally is “atomized” but if an injector is clogged, it can form large droplets that don’t vaporize easily), and the fuel may not completely burn once the spark plug fires or it may burn long after the optimal burn cycle has been initiated, causing an apparent loss of power. Next, the intake valves can become coated with deposits which can soak up injected gas and affect the burn cycle, and can block the flow of heat from the cylinder, again affecting the burn cycle, thereby decreasing the engine’s power and economy. As the combustion chamber accumulates sharp-edged deposits, these sites can act as nucleation sites for pre-ignition (aka “engine knock,” throwing off the car’s timing (and again, loss of power)—this can be evident in older cars that seemingly “need” premium fuel to reduce pinging.

THE APPARENT SOLUTION

A fuel system cleaner that contains PEA (polyether amine). Alternatively, you can pay your dealer for a fuel injection cleaning service (around $250). Nonetheless, I’m always the one to try a cheaper alternative before I buck up.

Chevron Techron Concentrate (32% PEA, based on an older published MSDS spec sheet--may be different now; $8 for 12oz. bottle) has been the leading fuel system cleaner since its development sometime in the 1970’s (it's also a touted leading detergent in gas, albeit in MUCH lower concentrations than the stand-alone concentrate formulation). The main active cleaning ingredient is PEA. Other known fuel system products containing PEA include the following:

• Gumout Regane (30-40% PEA content based on published MSDS data; about $5 for 12oz. bottle)
• Redline SI-1 (30-50% PEA based on MSDS data; about $9 for 15oz. bottle)
• Amsoil Performance Improver (28-37% PEA based on MSDS data; $10 for 12oz. bottle)
• BG Products 44K (unknown PEA content since they reformulated—does anyone have this data?).

Other than the active-cleaning PEA, each product has variable fillers/detergents (i.e. Gumout has kerosene, Redline seems to have an octane booster, Chevron and Amsoil have naptha among other ingredients). I’m sure that there are other PEA-containing fuel system cleaners, but the previously listed products (with the possible exception of BG 44K) are known, sure-fire products (so I can not recommend any other products). Also, as an FYI, the cheaper Chevron Fuel Injector cleaner is NOT the same as Chevron Techron Concentrate—it’s just a watered down version of it from what I’ve read.

The use of the PEA fuel system cleaners is listed as every 3,000 miles. Personally, from what I’ve read, I would use the cleaner about 2 weeks before I got an oil change, as the cleaned up deposits will wash into your oil—not necessarily a bad thing as the oil can probably absorb and neutralize the deposits, but there will be peace of mind from having clean oil in the engine. Also, I’d use the cleaner ideally when you can make longer drives in your car to allow the cleaner to do it’s job at full operating temperature.

To use the PEA fuel system cleaners, get your gas down to about ¼ tank. Put the whole bottle of PEA-containing fuel system cleaner in your tank, then fuel up to get it properly mixed. FYI, Chevron Techron Concentrate (12 oz treats up to 12 gallons), so I used two 12-oz. bottles as the GS400 has a 20 gallon tank. Follow the manufacturer instructions for the other products.

MY SUBJECTIVE EXPERIENCE

After putting in my PEA-containing fuel system cleaner, I drove the mile home uneventfully. The next morning, my car seemed to drive with a little more authority on the commute. Nonetheless, after driving around town later that day doing some extended errands (including some freeway jaunts), my car seemed to regain more power and I found that I didn’t have to modulate my accelerator pedal as much to go a constant speed. After a week of more driving, these subjective findings were noted: the car did not hesitate as much, the sluggish acceleration significantly improved, and the power was more apparent. The car seemed to be a different beast and idles smoother and quieter than before.

The MAF and throttle cleaning helped somewhat, but I truly feel that the PEA-containing fuel system cleaner is the fix I've been looking for (cause: dirty injectors and valves). The PEA-containing fuel system cleaners saved me a few bucks (as the next potential step was to take it to the dealer for a diagnostic workup and/or fuel injector cleaning) and lets me enjoy the car’s power again. I’ll report back if I something else develops.

Summarily, if your car has similar symptoms (hesitation, sluggish acceleration, rough idle, and power loss) as I’ve reported above, it’s worth a shot trying the PEA-containing fuel system cleaners ($16 for 2 bottles of 12 oz. Chevron Techron Concentrate in my case) before moving to more expensive diagnostic options.

Some links that may be of interest:

http://www.amsoil.com/storefront/api.aspx

http://www.chevron.com/products/ourf...tives/tcp.aspx

http://www.redlineoil.com/whitePaper/15.pdf

http://www.redlineoil.com/products_fueladditives.asp

I do have the published MSDS for each product (listed in the following posts)--the data may be outdated but the PEA concentrations are all pretty similar. Newer MSDS sheets are a bit more "cryptic" to read for each product.