hesitation at low rpms

[1-3-2-4]

I've been noticing something here my car cranking is taking a lot longer then normal it sounds almost like a flooded engine but the idle is fine... but say I'm rolling in 2nd gear at like 25-30 mph and give it more throttle the car hesitates but once it clears the 2-3K range it's fine.. sometimes the car starts fine when off for awhile and sometimes it's the same longer start time..

 

 

NOW before you say replace the ECTS I replaced that about 2-3 months ago but that was not the issue (glad I kept the old one) What else could it be? I have no CEL or anything.

[Fairtax4me]

Vacuum leak? Worth checking all the hoses at least. How does the knock sensor look?

[wally]

could be many things. i'd look at something easy first, like spark leakage from the plug wires. spray them with a mist of water in the dark. if you see sparkies, that's part of your problem.

[Suba9792]

I'd look at the plug wires and coil, if thats not it maybe you have a bad fuel pump

[1-3-2-4]

I will check both but I figure bad fuel pump would cause issues at idle too right?

[Fairtax4me]

Not necessarily. If the pump is working but doesn't make the proper pressure it can be fine at idle but the low pressure will lead to problems at higher rpms or when under load. Generally the fuel pump is not the cause of low rpm issues, without there being other symptoms.

[jzacher85]

I have this same problem and I am getting only like 23 mpg a tank! Could this all be related to fuel pump? I have an extra fuel pump from my vanagon/subaru 2.2 conversion could I use that?

[1-3-2-4]

I think it's my injectors at this point.. I was set to do some work on the car until a friend told me he needed help cleaning out his fire damaged house.. so nothing done today..

 

When you start the car like right after you stop it like a 3 min break (getting something to eat) its normal but when I was helping move stuff and sitting like 1 hr it sounds almost like a flooded engine when I head back out to get gas (MPG taking a hit) I will be sure to grab a sound clip after it's been sitting for 2 hours.

 

I guess it's not enough to cause a CEL because well the ECU still sees that the injector is connected.

 

and how many miles you got jzacher? I rolled over 232 not too long ago.. but really.. How much longer can I expect for injectors to keep shooting fuel?

Edited November 20, 2010 by 1-3-2-4

[Fuzpile]

Something else which occurrs is the evaporative canister or the jiz near filler and tank. The Sube is particular about the level of gas and in the owner's manual, Cautions you to not overfill. I overfilled beyond a few clicks (because I needed to siphon a few pints). It's miserable trying to siphon from a Subaru. Anyway at full point I ascended a steep drive replete with bumps. The next drive encountered terrible running and CEL and this was removed by detaching the battery for a short time. A good warm up period may make this okay but it is like being nonattended. Once saturatrated I would need look at this system more closely.

[Fuzpile]

The evaporative systems are like those in many vehicles. They work so well we don't pay any attention to them. When two or one big one mucks up it can cause lots of problems.

[1-3-2-4]

You know I was thinking about this when getting gas this morning when I would leave for work like 5-6 months ago the on-ramp near my house I will be in 3rd gear and I'd keep steady on the throttle and you could feel a very slight hesitation back then.. but now in the past few days it's gotten much bigger. when I was last testing fuel pressure like a month ago it seemed to read fine but the pressure went to zero pretty quick after the car was shut off.. i have a youtube video showing that.

 

back when I did that fuel test I wanted to also test the coil pack but I had a hard time getting the clip off.. I think you test between the terminal and one of the pins on the clip?

 

I also got a sound clip of what the car sounds like starting up after sitting for like 40 min.

Edited November 21, 2010 by 1-3-2-4

[1-3-2-4]

Here is a youtube video I just uploaded from my phone

 

[Gloyale]

replace the Coolant Temp Sensor.

 

it's giving false data.....to enough to throw a code.

 

 

Confirm by unhooking the CTS and testing resitance both cold and then hot. (it should start quickly with the CTS disconnected.)

 

It should have 2-3k ohms cold, dropping to around 500-ish when warmed up.

[1-3-2-4]

replace the Coolant Temp Sensor.

 

it's giving false data.....to enough to throw a code.

 

 

Confirm by unhooking the CTS and testing resitance both cold and then hot. (it should start quickly with the CTS disconnected.)

 

It should have 2-3k ohms cold, dropping to around 500-ish when warmed up.

 

Im going to go hook my live data scanner up and see if Im getting a false reading from it.. I replaced the CTS no more then 4 months ago.. I still have the old CTS in the box the new one came in and I tested it and it's fine.

[1-3-2-4]

Hmm check this out..

 

 

lazy front oxygen sensor?

 

Oh and pulling the plug for the CTS was not the issue.

Edited November 22, 2010 by 1-3-2-4

[Fairtax4me]

It's not staying on 0.

What are some other other readings? Map? Maf? IAT? ST/LT FT? Try to get these while it's acting up.

[1-3-2-4]

its hard to get the readings because it only happens under load so I would have to be driving..

 

I can check the ST and LT fuel trim..

 

I don't remember if the FSM has it but which wire on the oxygen sensor is the signal wire so I can back-probe with my oscilloscope

 

I would not be one bit surprised if the o2 sensor is slow to react to changes but I don't know if the sensor has so much in say to cause hesitation.

 

oh yea no pending codes yet

Edited November 23, 2010 by 1-3-2-4

[Fairtax4me]

O2 sensors can cause problems with idle and driveability but only when the engine is warm. If you have the same problems when cold the O2 sensor is probably not the cause.

[1-3-2-4]

Oh I went out for a drive the STFM seems to be within it's correct range Im going to check the coil pack in the morning my birthday is on saturday so not much work is going to be happening then.

[1-3-2-4]

Im going to start with the cheapest which is replacing these cheap plug wires the last owner got with some NGK wires. At the same time finally get to those intake manifold gaskets that need to be changed.

 

After that I will move on from that point on. Most likely I will be working on the birthday

[1-3-2-4]

Hmm do I work on the car today or not (my birthday) Oh why the hell not!

 

Haha sweet my order that got split up with rockauto is all going to come at the same time today new plug wires, Intake manafold gasket and right front strut.

 

If I'd a spring compressor I would of did the struts today.. trust me.. stock struts at 232,000 are downright scary!

 

Anyways I will do the gasket and wires today and report back any findings

[1-3-2-4]

replaced the wires...

 

 

Here is what plug #4 looked like once I was able to pull it out of the boot.

 

 

[1-3-2-4]

Wow dunno if it was the gasket or wires or both but my whole power band is so much smoother!

[wally]

if the hesitation is gone, it was the wires, not the gasket.

[1-3-2-4]

if the hesitation is gone, it was the wires, not the gasket.

 

I had a hissing noise at the gasket.. Engine sees all that extra air coming in after the air was metered from the MAF.. Idle is no longer lumpy at idle..

 

Too much to explain if you were not driving the car.