engine question

[pamike]

when i start out from a stop and hit the gas the car takes off good. when i am accelerating hard the rpm's go to about 4000 in first then it goes into second but right after it hits second it acts like i let off the gas for a few seconds the rpm will drop like 500 then pick back up again and accelerate fine after that. it doesn't do it under light acceleration.

[Huffer]

Sounds like hesitation. it'll be worse if it's an auto

Could be the following:

bad spark
bad knock sensor - might need relocating
bad fuel filter
clogged injector
ecu needs reset

If the engine mounts are worn, this will contribute to an over-active knock sensor as a lot of vibration can cause the sensor to retard timing.

Others will chime in shortly I suspect.

[Wiscon_Mark]

What oil & oil filter do you use? Is this when the engine is cold?

[pamike]

it does i regardless of temp. i think the filter is a puralater and oil is valvaline durablend.
other than that it runs great and has good power. if i'm allready moving down the road and stomp on the gas it takes right off.

[GrassyKnoll]

does it happen more when you are making a hard right turn? If so, I have the same damn problem :evil:

[pamike]

i never really noticed a difference on turns. but i'm pretty sure it's engine related.

[GrassyKnoll]

yes. Does it matter how much gas you have in the tank? Mine only happens when I have half a tank or less.

[pamike]

doesn't matter what the tank has in it

[GrassyKnoll]

k. ill shut up now :|

[Huffer]

could well be a faulty grounding issue.

For example, the speedo on my car will fail to "work" on occasion, until I hit 40mph, then the needle will ressurrect itself and ping straight to 40mph.

I think that I have a loose connection somewhere in that circuit, or a bad ground, and that at 40mph I have generated enough current to make the connection arc (?) and hold. I'm certainly no electrician though.

[scottzg]

check if your knock sensor is cracked.

[SammyDaFish]

judging simply by the way that you described the problem, the chances you'll fix this yourself are slim to none. Driveability problems can be hard to diagnose when you have the car in front of you, let alone over the Internet. bring your car to a reputable shop and have them diagnose the problem. The only other way you'll fix it is by replacing random parts that people on this forum mention that most likely will have nothing to do with this problem until you get lucky. Save yourself the headache.

[pamike]

what it's doing is not hurting anything and the car runs great i mainly just wanted to know if anyone ever heard of a car doing this. as long as it still runs good and has good power i'm not really planning on replacing alot of parts.
i also have drove another 90 and a 96 both not mine, and my 90 seems to have alot more power than the other ones and it has the most miles on it. when i had a timing belt and water pump put on back in feburary the guy at the garage said it seemed like it had more power than the subie's he's driven. :twisted:

[Wiscon_Mark]

when I asked about oil, I meant the weight of the oil...

[pamike]

i think it was 10w30

[Wiscon_Mark]

I too had hesitation issues with 10w 30 (subaru reccomends 5w 30) but only when it's cold.

[Manarius]

Could be fuel pump ground. Could be knock sensor. Could be Coolant Temp. I was having this issue recently and it turned out to be the MAF.

[pamike]

is their a way to check the maf. and it's not the coolant temp sensor thats new allready

[Wiscon_Mark]

is their a way to check the maf. and it's not the coolant temp sensor thats new allready

replace or clean it. Although a faulty MAF would probably chuck a CEL up there.