ouch! what's happened to my injectors?

[gloucester Q]

i had a lumpy idle last year, ohm'd out my injectors and found this:

cyl ohms1 13.12 13.33 13.44 14.55 13.46 12.97 13.58 39.4

i replaced 8, thought about replacing 4 but decided not to at the time. this spring, the lumpiness is slowly creeping back--not as bad as it was last year, but i'm getting this weird hesitation (definitely not the transmission, definitely feels like a fuel delivery issue) too, so i've just ohm'd out the injectors again and much to my dismay, here are the results:

cyl ohms1 14.22 12.33 12.34 193 (!!!)5 21.26 12.27 18.58 12.4

obviously, 4 is cooked, and i thought it was on it's last legs anyway so that's not a surprise, but 5 & 7 also seem bad. so, a few questions:

oh, first some background. 93 q, 75000 miles, use exclusively premium at the mobil station, use 2-3 cans bg44k per year, measured resistance at the efi harness connectors.

is it possible a bad harness is causing any of these readings? i'm not sure i can check the harness and/or individual injectors without pulling the plenum. can i?

assuming that the injectors (4,5,7, &1) are bad, is there anything that anyone could speculate on that might be causing this? i just replaced the fuel pump and filter a month ago, so if either of them was potentially a source of problems, they aren't any longer.

any insight would be welcome and most appreciated. looks like i'll be calling joe soon, the only question is how much of what will i be buying. thanks. randy

[911/Q45]

Welcome to the club! I'm replacing the remaining 6 injectors and the harness after doing the first 2, one at a time. A bad harness will usually show 0 or infinite ohms, due to a short or a break in the circuit. Our cars are just at that age that injectors fail, especially mine with CA gas. I'm replacing the KS harness as long as I'm under there too.

[texasoil]

di dyou do any external engine cleaning--like in the valley with some kind of solvent? Injectors are not a common failure except in the AZ area with all the crap dumped there from Ca refineries that they cannot sell in Ca.

Ma went to oxygenated fuel (ethanol)for summer just recently. You might send a customer querry/complaint to the Exxon/Mobil customer service hot line and report your experience.

Personally, using Mobil gasoline, I don't think the BG 44K is warranted. Mobil advertises 'clean-up' performance, and it IS real and documented.

[Jeff Williams]

Randy, welcome!

Here is what I would do:

Buy 8 injectors, replace all 8, and keep the ones that are within spec, for spares, or sell them on eBay.

Since you will have the plenum off, Replace the harness, all old vacuum lines and fuel lines, do a rail flush, and plenum cleaning. Possibly a power balance, once the new injectors are in.

Then, I would consider the following:

Drain & clean the fuel tank, blow out the fuel lines, replace the fuel filter, and possibly replace the fuel pump, unless it has recently been replaced.

I agree with texasoil, write a letter to Exxon/Mobile.

I have been using exclusively Chevron gas, for the last 5,000 gallons, in my car.

[Q45tech]

93Q with only 75k...........12 year old injectors. At least 2 years beyond its legal life......from a liability standpoint.

In Massachusetts, Representative Demetrius Atsalis and others introduced a bill (in January 2003) similar to Connecticut's PA 00-175. It did not pass. The legislature will likely introduce a substitute bill by the end of this year that mirrors Connecticut PA 03-122. The substitute bill would phase out MTBE by or on January 1, 2005, according to Michael Karath, Representative Atsalis' chief of staff. "

You know what caused them to fail but proving it will be impossible.

Who knows what kind of juggling has been going on since you noticed the problem last year.

MASS uses 16,800 barrels per day [705,600 gallons per day ] of MTBE in both conventional and reformulated gasoline.

Don't worry Ethanol will be worse for the first year till they get it down to a science. Can't be sent thru pipelines must be splash blended at the tank farm terminal.The following states use no MTBE currently:Illinois Colorado Indiana Iowa Kansas Michigan Minnesota Nebraska Nevada Ohio South Dakota Washington North Carolina and the Southern Stateshttp://www.eia.doe.gov/emeu/st....html

[Q45denver]

Definately a problem in Colorado. I think my car with 155K is already is on its third or fourth set, and is acting up again. I use 44K about twice a year, and usually buy my gas at Costco.

[gloucester Q]

thanks guys for the input. bummer, it's the gas eh? so what's the background here? when did who start adding mbte to gas? and what did they think were (or are--presumambly there's some) the benefits of mbte? i have for a while been wondering when i'd get to the under-plenum work, now i guess i've got an idea that it'll be sooner rather than later.

[Q45tech]

Not just MTBE, but some of the other hundreds of compounds found in gasoline.

Orginally the injections were designed to last 100,000 miles minimum on conventional gasoline 100,000,000 cycles.......we now know from experience that they can last more than 3 times as long [when used with the correct fuel].

"Does ethanol use cause injector failure? A: This seemed to be a problem on certain vehicles from 1988 to 1993. The manufacturers changed the injector coil insulation. It appears that this problem does not exist on late model vehicles."

Unfortunately fuel compositions have change since they were designed in 1988..........even with this they all seem to last beyond the warranty time mileage 6 years /70,000 miles.

[gloucester Q]

what about the injector i'll buy? is it an injector manufactured as it was designed? or is it an injector that's been revised to account for the changes in the fuel? i hope it's the latter, but yeah, all day i was thinking 'well, the car was originally designed 15 years ago or so.' if it were the company i work at, there's no way that we could account for what we did 15 years ago.

[texasoil]

there have been changes in the legal gasoline composition since 1990--some of which are good for engine & injector life, and some may not be.

Total aromatics (strong solvents for polymers) are way lower now. Sulfur content is way lower now , down from 500PPM avg to about 150 PPM now, going to 30 PPM soon. (sulfur poisons emission catalysts and causes engine & exhaust system corrosion). Detergency level is way up, but legal minimum is still way too low for lifetime keep clean. Oxygen content (in some areas) is now required as high as 2%--way up from zero. The oxygen can be from MTBE, ethanol, or T-butyl alcohol. Of these MTBE is the most positive (high octane, fewest effects on fuel system components.) Some areas of the country are 'dumping grounds' for undesirabel gasoline components that cannot be used in the locations where they are manufactured. For instance, Phoenix (AZ in general) has no refineries, and Ca refiners ship gasoline by pipeline. The gasoline is of lower quality than what is sold in CA. AZ is a very 'price competetive' market, and the cheapest gas is what sells there--so that is what gets delivered there.

[Q45tech]

Texasoil, what do you think of the recent Shell/Texaco fiasco in Louisana and Florida....[Motiva Enterprises refinery in Norco, La].....no one realized if enough sulfur [?] was present to destroy the fuel gauge contacts---- what it will do to the cats.

A few thousand plus for each car?

http://tampabay.bizjournals.co....html

"The Shell outbreak would be the third this summer of sulfur-related fuel problems. The first occurred in Erie, Pa., this month, a few days before similar problems began in Louisville"

"Casey said most of the complaints her company has received have been from drivers of domestic cars. Toyota and Honda models haven't been affected, she said.

"We have a pretty good database at this point. We've had over 13,000 complaints," Casey said. "There are only a handful of foreign cars in there.... That's why (the problem) appears to be an incompatibility between our summer gas and domestic gas gauges"

"Motiva supplies gasoline to Shell and Texaco-branded stations. Texaco was once a partner in the venture. But in order to receive government approval to purchase Texaco, Chevron had to agree to sell the Texaco retail outlets.

The problem, however, is not limited to Shell and Texaco stations. Gasoline marketers frequently swap out fuel with one another, depending on their proximity to supplies, and add their detergent mixes later.

ChevronTexaco, which to this point has been barred from selling gasoline under the Texaco name as part of its agreement with the federal government, has plans to resume Texaco gasoline sales this year.

"I do not believe this will have an effect on ChevronTexaco's effort to market gasoline under the Texaco brand, when we are able to legally do that later this year," ChevronTexaco spokesman Jeff Moore said"

[texasoil]

I am hunting for 'horses mouth' information. I am very puzzled about what was/is wrong. It's not just the amount of sulfur, but the type of sulfur compound. I suspect some trace H2S (HSH) or mercaptan (RSH) (or even free sulfur) somehow escaped their Q/A testing. disulfides (RSR) are not corrosive, nor or thiophenes. One of the new sulfur removal processes can make mercaptans in the last part of the process and if they are not removed--you get them in the finished gasoline.

In ANY case, they should have caught the quality problem well before it left the refinery. Someone goofed up big time.The Federally required gasoline corrosion test (D-130 Copper Strip Corrosion) should have identified the problem immediately.

[ScottJackson]

I had a slightly rough idle and thought it would be a good time to change plugs last winter. Changed plugs and checked ohms on each coil pack as I went. All was well and I put new plugs in. Still idled rough. Checked injector harness and found some injectors with 30ohms or higher, one that was 100+. Before freakin out and buying new injectors while also knowing that what generally causes injector failure is a bad coil inside the injector, I figured I'd wiggle the little wire harness clips on the injectors. That cleared it up. It started doing it again about a month ago and about 2 minutes of reaching my fingers down and wiggling the harness connectors and all was pretty smooth again. Then after a MAF cleaning with brake parts cleaner it runs silky smooth. I know I should pull the injector harnesses one by one, clean them and coat with di-electric grease to prevent future problems, but until I get a hose kit for under plenum from Joe, I'll wiggle them when needed.

[Q45tech]

For those to which the previous was GREEK:http://www.bakerhughes.com/bak...t.htm

[Q45tech]

Yep, high resistances are always suspect in a narrow just above normal range, but the 13.8 volts and 1.0 ampere flowing [pulsing 2-11 millisecs] usual keep the contacts pretty clean.

Many places replace injectors when they need to clean the injectors and replace the harness.

[Q45denver]

What is a replacement harness and labor going for these days?