3400 Engine questions

[99ALERO]

:huh?: My car starting to run rough at idle and after it shifts and is running at low rpms. Also when your in the final gear you have to step pretty far on the gas pedal to get the car to go faster. I can feel alot of vibration sometimes when i do a hard aceleration.

Also sometimes when the car is cold it doesnt shift outta 3rd gear until the car gets hot. Anyone else have this??

Any help is greatly appreciated!

[misslindseysue]

I had a similar problem, and I had an exhaust solenoid stuck open. I was still under warranty though. Are you? Did you set a light that you can get scanned at Auto Zone? Sounds like a problem though, I'd get it checked out somewhere.

[overdrive75]

The solenoid she is referring to is the EGR solenoid. If that is stuck open, the car will run like crap.

[misslindseysue]

I specifically asked if it was the EGR solenoid, and he told me it wasn't. He may have lied to me 'cause he didn't think I knew what I was talking about, but that's what he said.
Whatever was wrong with mine, it would take a few cranks to start. When it started the idle would dive, and if you gave it a lot of gas it would usually not die. It was the worst right after I got gas. Once I was on the highway it wasn't very noticeable, just used more gas.

[3.4Alero]

Possibly a clogged or bad injector?

[zyklor]

I have the same problems.... its bad injectors. Using injector cleaner helps for a little bit. I recommend Techron made by Chevron. It is harder to find than some of the other cleaners, but it is the best.

[2000NavyAleroGLS]

Are you sure that it is actually third gear. Cause it does run in a lower gear when cold just to warm up quicker. But I think if you put it in third the rpm would go up just a little. It may juswt be like a cold idle type of gear.

[DarkAngel]

This is a common problem with both the alero's and ga's. The problem is in your injectors, if it was an egr solenoid it would trip the computer and set off a code (unless it is stuck only partially open but that rarely happens)
The thing with the injectors is that they will have to do a couple hit or miss diagnosis on them before they start replacing.
First they'll probably try a purge, if that doesn't fix the problem, they will put the car on the scanner that measures pulse width on the injectors. The balance test will determine the pressure drop between the injectors. GM notices that a drop greater then 3 or 4 psi, i forget which, between the leanest and richest injectors is substantial evidence of a bad injector, they will replace the one or some times two injectors that stand out against the 6.
In rare cases, you have an electrical problem between the connectors on your injectors that they call fretting where movement and vibration between the electrical connections creates some sort of debris between the male and female ports that acts as an insulator, but that nifty engine light won't set off untill there is a complete loss of electrical continuity, so diagnosis is difficult.
I've never seen this fretting problem myself or have seen any of the other techs do one but we were told by gm that if that was suspected, just to use dielectric grease i believe between the terminals.

So
0.8 for diagnosis of lean and rich injectors, usually
whatever your local garage charges for a purge
1.2 for an injector replacement + 0.3 for each additional injector
If you want the fretting checked, your looking at straight time labour

Purging isn't covered under warranty
diagnosis is only covered under 3 year 60,000km
injectors are covered under manufacturer and extended warranties

Hope this helps or makes you cry

Just keep dumping STP crap in it and use really good gas for a while. May work

[AleroGLS]

maybey a hole in a vac. hose. For the rough idle. just a thought ?????