93 Lumina 3.1L - Hesitation. Injecters? Solution?

[nickapalooza]

So I bought a single-owned, garage kept 93 Lumina with 100k miles that is in excellent condition. However, I have a small problem with it hesitating when I press the gas, resulting in a jerk on take-off. Additionally, it can sometimes take longer to shift between gears, also resulting in a jerk. A friend said the problem was the injectors. I went on that and have went through probably 7 or so bottles of fuel system cleaner, injecter and carb cleaner, etc. The problem definately dissipated some, but is not completely gone. My guess is that the car was left sitting for too long of periods of time. The jerking is very annoying and I was wondering what would be the best way to resolve this issue besides paying to have an un-touched motor torn apart.

[Blue Bowtie]

I'd suggest cleaning the throttle body, especially behind the throttle plate and in the IAC air passages.

Test fuel pressure to verify that the pump and regulator maintain at least 36 PSIG with the engine idling. If the fuel pressure drops at throttle tip-in instead of increasing as it should, you might want to consider changing the fuel filter.

As a caution, the Multec injectors used in the early '90s are not very tolerant of astringent cleaners and harsh solvents, so curtail usage of those add-in fuel injector cleaners if at all possible. Running clean fuel through them and, if necessary, Techron cleaner in the proper concentration ONLY, is usually safe and can help if they are not completely clogged.

Inspect the vacuum lines and hoses, and test idle vacuum. Especially pay attention to the vacuum line to the transmission modulator (on the front of the trans). Getting a reading of idle vacuum might also help to identify problems.

Since the vehicle has 100,000 miles, it should be on its third transmission oil and filter change. However, since you cannot be certain how the vehicle was maintained, another change could be a good idea.

[nickapalooza]

Thanks alot BlueBowtie, but I wouldn't even know where to begin with all that. I think I'll just take it to a shop and have them check those things out. Recently I gave the motor a little hell and it helped the problem ALOT, it's almost shifting beautifuly.
However I have a new problem that's popping up. When I start the vehicle it's idling really high, and sometimes the Service Engine Soon indicator activates. However after less than a mile it runs normal and the light will go off. A friend said the choke is probably sticking. I haven't had the time to pull the hose off and check myself though. If it's not the choke, what else could it be?
One more thing-as far as maintaining goes, what other than trans oil and fuel filter can I do to maintain the motor and entire vehicle? I would surmise that this vehicle was well-maintained, but ya never know. I want to KNOW that EVERYTHING that can possibly helped is in great shape.

[dbstainbrook]

i would check into a iac motor for the idle problem

[1993LUMINATOR]

well a high idle push its annoying but nothering to worrie about.
generly either ur throttle cable is sticking or ur IAC is got bit too much carbon on it.

also to your car does NOT have a choke

[ISmellRubber]

The 3100 series had two flaws that I have had to do tear downs for. The first is easy fixin', check the mounts to the base plates on the coil packs ....thta is where they gound for the most part( same is true for the 3800 series) next I would also check the crank sensor if this is bad OR loose this will have those characteristics. Next, and the most painful is the lower intake manifold gaskets ( GM has a TSB registered for this ) the factory original gaskets were sub-par and would rupture over time.....check you oil for cloud, or if your antifreeze keeps running low you have a problem there.
This isn't a defined answer just some ideas....no one mechanic can solve your car problems without seeing or driving the car.

"What is it about sex that makes me want to take a good dump"
-King Pin-

[richtazz]

The intake gasket issue only applies to Vin-M 3100's, and is most prevalent on 96-newer models. The Vin-T, W and early Vin-M's didn't suffer from that issue. My best guess is that your car needs a tune-up. When you drove it hard, you blew some carbon out of it. If your spark plug wires still have the cylinder numbers on them, they are original and way over due for replacement. Also, that engine didn't come with platinum/iridium plugs, so they need changing about every 50k miles or so. Don't forget the air filter, fuel filter and PCV valve while you're in there.

[spdfrk1990]

My car just started doing the same thing today and I just filled up on gas. I know the fuel filter prob needs changed and I also might of got a bad tank of gas.