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Engine hesitation, power loss, sluggish acceleration: Potential fix
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)
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):
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 (thereís 2óa 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 converterÖ
I pretty much ruled out the fuel pump, fuel filters, and fuel pressure regulator as my car didnít 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.
Anytime you have gas burned in your engine chambers, not all of it burns up and youíll 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 Iíve read other numerous posts, Iíve summarized a posterís 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 ďatomizedĒ but if an injector is clogged, it can form large droplets that donít 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 engineís power and economy. As the combustion chamber accumulates sharp-edged deposits, these sites can act as nucleation sites for pre-ignition (aka ďengine knock,Ē throwing off the carís timing (and again, loss of power)óthis can be evident in older cars that seemingly ďneedĒ 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, Iím 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 1970ís (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 reformulatedódoes 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). Iím 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 Concentrateóitís just a watered down version of it from what Iíve read.
The use of the PEA fuel system cleaners is listed as every 3,000 miles. Personally, from what Iíve read, I would use the cleaner about 2 weeks before I got an oil change, as the cleaned up deposits will wash into your oilónot 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, Iíd use the cleaner ideally when you can make longer drives in your car to allow the cleaner to do itís job at full operating temperature.
To use the PEA fuel system cleaners, get your gas down to about ľ 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 didnít 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 carís power again. Iíll report back if I something else develops.
Summarily, if your car has similar symptoms (hesitation, sluggish acceleration, rough idle, and power loss) as Iíve reported above, itís 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.
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.
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Hope this helps others. Of course, your mileage may vary with these PEA-containing treatments depending on what the root cause of the problem is...
Lastly, the above directly recommended products have PEA as the active cleaning agent, other fuel system cleaners and/or fuel injector cleaners most likely do NOT have PEA, so they are not recommended (as seems to be the general consensus from what I've read elsewhere on the web). Of course, if you have other products that worked for you chime in--this forum is for information sharing.
Last edited by SeattleGS400; 09-15-08 at 01:26 AM..
The Redline and Amsoil I can have used when I was in Mexico (along with bottles of Techron). Amsoil, in my opinion of what I felt, seemed to work the quickest of the bunch. Gumout is the only one that I don't have experience with.
I tried a bottle Redline in a full tank when my 01RX reached 78K miles in August, and then I put BG 44K for a full tank at 79K. I did feel an improvement on acceleration with less hesitation. I have a few more cans of BG 44K and plan to use one every 7,000 -10,000 miles.
At the same time, I also tried Chevron Techron 12oz for my 06Civic at 37K miles. It worked well for mileage improvement as I checked with two tanks.
I just recently recovered maybe half the missing from my parent's neglected 1990 LS400 with a $5 bottle of Redline SI-1. This car had been demoted to spare car status. Filled for the past few years only on Costco gas, and driven extremely infrequently for things like getting bags of garden soil from OSH when they didn't want to get the LS430 dirty.
Had tried before to fix the issues with this car with a half bottle for a full tank but no effect. So went further and dumped the full bottle in for a full tank of gas.
Definitely go for the "shock" treatments as in my opinion the maintenance doses have little effect.
Additionally I think Redline has an octane enhancer or other random goodies in there that do make a performance difference, especially if the gas in your area is E10 such as in CA.
I just used a full bottle with my well maintained GS300, and do feel a performance increase. But I think this is from the additives as it seems to go away on the next refill.
Thanks A lot for this post. I have recently had this lag problem to the point where I am afraid of merging into traffic worrying i wont have enough power to make it. Sometimes at highway speeds I will feel a little hesitation from the engine like it shifted down or it's cutting off, that is very annoying.
Will try first the fuel system cleaner and follow with the cleaning of the MAF and throttle body later.
Again thanks for the elaborate post
I used to own a Firebird with an LS1 in it. It developed bad idle properties and a slight hesitation even though once it spooled up it was fine. I was turned on to Techron by a club member and was told to run down to 1/4 tank and dump an entire large bottle of Techron in it. I was leary but I did it.
WOW... it was like having a new car again. Techron... FTW!
I do the same with Lucas. Obviously Chevron, Redline, etc do not recommend such high concentration because of possibly lawsuits, but if you're careful, the results can be pleasing.
Lucas says their 1 quart bottle will treat 100 gallon (or 3oz for ever 10 gallons). I dumped half the bottle (16oz?) in my tank and pumped 5 gallons only. After driving around for a while, my shaky idle was disappearing and pickup speed was better. There will be smoke on start up, and that can cause an attraction
Even if you maintain your car well, you eventually build up deposits. Some argue that it's not necessary because gasoline already have additive packages in them (chevron w/techron). You'd be a fool to believe they dump that much in to make a real difference on your car. If anything, it just helps maintain an already clean engine.