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Old 11-13-2008, 02:37 AM   #1
winston856
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Default See if you all can help me on this

Alright so I've had this problem pretty much since I've had the car, it's not a HUGE deal but I really want to get it solved and I think these things are related.

The Symptoms:

When idling especially cold (which would be fast idle), if I touch the gas lightly it's like the RPM's pause then jump. Almost like the car coughs. It doesn't backfire but it's similar to a pop. It's going perrrrrrrr pop perrrrrrr, that pop is when I touch the gas. It's not a POP but a little tiny stutter kind of pop.


The Symptoms, Continued:

The next bit is when I'm warm more so than cold. If I rev out first or second gear. Lets say first, if I'm in first and going 10-15MPH the RPM's are over 2k, like 2500 ish.

Holding the throttle steady the car lurches or jerks a bit. Think of it like when you turn on your garden hose if it hasn't been used in a long time the water comes out in a stream but there are breaks where it sputters for a second.

It's noticeable when I hold the throttle steady like I was saying, the car will lurch or jerk not real hard but you can feel it.

It seems that these two things are related or so I think.

Things I've changed on the car:

New Plugs (NGK copper)
New Wires (NGK Blue)
New Coil pack (MSD Blaster)
New Knock Sensor (OEM)
New PCV Valve
New Air Filters
New Front and Rear O2 sensors (OEM)
New Fuel Filter (OEM)

What could this be, I was thinking Throttle position sensor since it's sort of throttle related but I don't know what could cause this. Anybody experience this or something similar? Have any thoughts?
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Last edited by winston856; 11-13-2008 at 12:49 PM.
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Old 11-13-2008, 09:29 AM   #2
obs2008
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i see it says you did an auto to manual swap, are you using a manual or auto ecu?
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Old 11-13-2008, 10:50 AM   #3
ibanez24_7
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Sounds fuel related. Could have a clogged fuel filter or the fuel pump could be dieing. If its an older car wouldnt hurt to replace those since you already replaced the coil pack and ignition parts.
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Old 11-13-2008, 11:03 AM   #4
watchunglava
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Default take it for what its worth

my opinion is its your timing belt. sounds like its stretched that slightest bit and needs replacing and you need a timing job
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Old 11-13-2008, 12:49 PM   #5
winston856
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Sorry guys forgot to add fuel filter to the list, I did change it about 5k miles ago.
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Old 11-13-2008, 12:52 PM   #6
winston856
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Quote:
Originally Posted by obs2008 View Post
i see it says you did an auto to manual swap, are you using a manual or auto ecu?
Still using the auto ECU but this problem existed when it was an auto as well. Ground pin #80 or 81, whichever it is to make it think it's a manual ecu.

It could be fuel related but if I step on it the car will go, and it revs ok.

If my revs are at idle and my engine's warm, if I tap the gas sometimes it will do that little cough thing and rev up, it's like a split second stutter. If my revs are at 1000rpm+ it doesn't do this. When it's cold if they're under 1500rpm's and I tap the gas it will do that little cough thing.

Last edited by winston856; 11-13-2008 at 01:03 PM.
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Old 11-13-2008, 01:09 PM   #7
watchunglava
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i would say timing belt how many miles are on your belt? or did you check your throttle cable? maybe it needs to be adjusted. could be alot of things. its a 96? did that have obdII? possibly cloged exauhst somewhere. you have to trouble shoot it
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Old 11-13-2008, 06:04 PM   #8
winston856
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Quote:
Originally Posted by watchunglava View Post
i would say timing belt how many miles are on your belt? or did you check your throttle cable? maybe it needs to be adjusted. could be alot of things. its a 96? did that have obdII? possibly cloged exauhst somewhere. you have to trouble shoot it
The timing belt I believe was changed at 193k(when I bought the car (I've got the paper work at home)) and I've got 212k on the car as of today.

I did take the slack out of my throttle cable. It is a '96, yes it has OBDII.

I have a full headerback custom 2.25" catless exhaust.
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Old 11-14-2008, 01:39 AM   #9
watchunglava
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Quote:
Originally Posted by winston856 View Post
The timing belt I believe was changed at 193k(when I bought the car (I've got the paper work at home)) and I've got 212k on the car as of today.

I did take the slack out of my throttle cable. It is a '96, yes it has OBDII.

I have a full headerback custom 2.25" catless exhaust.
is it street legal without that cat? where the hell do you live like india or something?

i dont know what to tell you man . your description is kinda vauge. like could it be your clutch?
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Old 11-14-2008, 01:41 AM   #10
watchunglava
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i have to tell you im just joking before someone thinks im being serious. not your clutch!!!
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Old 11-14-2008, 01:44 AM   #11
JonofScio
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sounds like timing or fuel.

check o2 sensor(s) and for laughs check your timing belt. if it's happened since you got it and the belt was replaced before you got it, how do you know it was done at all? Just because it was taken to a shop and there is a receipt doesn't mean something shady didn't happen.
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Old 11-14-2008, 03:23 AM   #12
winston856
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Quote:
Originally Posted by JonofScio View Post
sounds like timing or fuel.

check o2 sensor(s) and for laughs check your timing belt. if it's happened since you got it and the belt was replaced before you got it, how do you know it was done at all? Just because it was taken to a shop and there is a receipt doesn't mean something shady didn't happen.
Very true, I don't know if it was done for sure, I'll have to double check on that.

I'm going to change out my ECU tomorrow so we'll see what that does.

Also I have to mention, the condition gets worse when it's warm out. It was cold out tonight (39F) and the car was loving it, pulled harder etc...

If the car is hot it'll do that jerking if I hold the throttle steady in 1st above 2000 RPM. If I'm just driving normally I don't notice it very much at all, but if I exaggerate my shifts, letting the engine rev out longer I can feel it.

This is only with light throttle, less then 1/2. If I give it more gas or just floor it I take off.
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Old 11-14-2008, 07:11 AM   #13
indytruckboy
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Check your throttle body. Usually this can be fixed by a good cleaning. Open the throttle blade and look on the backside. An old tooth brush and some throttle body cleaner. After the cleaner burns through you should be alright.

And you do realize you have 212k on it......... motor could be getting tired.
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Old 11-15-2008, 02:49 AM   #14
winston856
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I've been meaning to check the TB but I haven't take it off because I have this idea that if I do that I can't reuse the gasket. Right?

I've swapped ECU's and other than a nice power boost the problem still exists, though not as prevalent, it's still there.
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Old 11-15-2008, 07:31 PM   #15
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Well I switched ECU's and that didn't make it go away, I switched MAF's today with a spare I had here, so we'll see how that goes tonight.
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Old 11-16-2008, 12:36 PM   #16
yarrgh
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what about the kind of fuel you put in? do you get the same octane at the same place every time? try switching that up. get some higher octane for a tank or 2, see if that helps.

if you can do some datalogging, see if the computer is pulling timing.
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Old 11-16-2008, 07:38 PM   #17
winston856
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Changed the MAF and it didn't do much, the problem is still there.

I measured my TPS today, I thought it was it at the start and it looks like it might be my problem.

The book states the voltage with the throttle closed must be between 0.5-1.0v, and it measured 0.2v and was jumping around.

The volts must also be between 4.5-5.0v with the throttle fully open (WOT), they measured about 3.5v and were jumping around a lot, bouncing from 1-3v.

So suffice it to say, I think my TPS is on it's way out. I've got a new one ordered and will put it on tomorrow.

I also have been running premium fuel in this car since I bought it.
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Old 11-17-2008, 08:15 PM   #18
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Well I changed it and if I had to say something right now perhaps the problem has gotten a little better, but nothing earth shattering.

I'm going to be driving tonight at work so I'll have a chance to see if anything further happens.

I changed the TPS out for the new one today and aligned it properly, works fine no CELs. I then reset the ECU and took her out for a spin.

After driving for a while to get it warmed up (read: 10 miles), I proceeded to stop and do a few light throttle applications. Like backing out of a parking spot, slowly inching forward in a drive through etc.

The stumble is still there so my next objective is to get a video of this thing so you all can hopefully see what I'm dealing with here.

I still do need to check that carbon can but I ran out of time for today and won't be back under the hood until probably friday, maybe wednesday.

I probed the TPS before and after I checked it. I have the 3 pin TPS, pin 1 is Ground, pin 2 is REF and pin 3 is SIGNAL. The book tells me to backprobe pins 1 and 3 and read the voltage.

I did this with the old and new TPS sensor and still was getting jumping readings with both, I don't know what this means. Maybe I was probing it wrong. I used little paperclips to stick in the back since they were so small, then touched the probes to them to get the readings making sure I touched the negative probe to the ground and the positive probe to the SIGNAL.

So, I don't know, I'm frusterated and a little disappointed.
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Old 11-17-2008, 09:31 PM   #19
soulhassorrow
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i had a similar problem and it was the throttle postioning sensor like you said!!!so hopefully that's it man.gl with the fix!!!!
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Old 11-18-2008, 03:49 PM   #20
winston856
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Thanks. Well since the TPS didn't change a whole lot I think I'm going to be looking at the Idle Air Control Valve next. That's known to be a problem on certain Subaru's but I have the style that's located on the passenger side of the throttle body, not on top like the newer phase II engine's have.

I'm trying to check things that are related to the throttle and or idle since that's where the problem is.
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