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Old 04-20-2009, 08:28 PM   #1
TurboRoo
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Default Severe hesitation issues

<-- That car, stock 2.2

The iacv threw a cell about two months ago. I finally replaced it, and the gasket, with a new one this past weekend. I thought that was the issue but I guess it wasnít the entire issue. Most of the hesitation is gone but it still has some. Normally when itís cold and rainy itís really severe. Like it was today. It feels like it has a miss fire and the rpms go up really slowly but once it hits 2500 it stops and takes off like it should. It hasnít given a cel yet for the hesitation or the miss fire feeling. Once the car is warmed up its fine though. Also it has stalled a few times before I replaced the iac. Once when I was sitting at a light and the other time when I down shifted but I was going very slowly, like 20 mph. It has yet to stall since I replaced it.

Iím thinking itís one of the o2 sensors. While I was replacing the iac I took ohm readings of both o2 sensors. Once they settled down I got readings of: pre cat one is 4.1 and the post cat one is 4.3. I believe I took the readings correctly. Itís the readings from the two white wires. I tried getting readings with other wire combinations but couldnít get a reading. Unless itís the plugs and or spark plug wires I canít think of much else. Unless itís the distributor or is it called a coil in this car? Is one of the o2 sensors going or should I look at something else that might be the cause?
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Old 04-21-2009, 06:19 PM   #2
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i have heard of coolant temp sensors causing driveability issues when the engine was not at normal operating temp. Have you tried a serach, yet? try one with "coolant" or "temp" as one of the keywords.
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Old 04-21-2009, 09:54 PM   #3
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Iíve been searching for the past week or two on and off. I ran across a few things yesterday that said something about the coolant temp sensor that might cause similar problems but havenít searched on that specifically yet. Iíll get some time later this week to do more searching around. Anybody have any other thoughts?
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Old 04-21-2009, 10:05 PM   #4
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Based on your description I would look at the ignition system if you haven't allready. Sounds like bad wires so far. The spark plus seals might be leaking oil into the galley. The coil pack is right on top of my car's motor, 4 wires to the plugs is all. spray it down with water or just visually inspect.
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Old 04-22-2009, 07:45 PM   #5
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wires are rarely the cause of misfires. plugs are more often the cause. And what do you mean by spark plug seals? are you referring to the seals around the spark plug tubes that keep the valve cover oil out? in any case, they do not connect to any oil galley.

OP, what was the original DTC? (CEL #) Have you reset the ECU and confirmed that no other DTC's are being thrown?
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Old 04-22-2009, 09:44 PM   #6
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Quote:
Originally Posted by RaceFaceXC View Post
wires are rarely the cause of misfires. plugs are more often the cause. And what do you mean by spark plug seals? are you referring to the seals around the spark plug tubes that keep the valve cover oil out? in any case, they do not connect to any oil galley.

OP, what was the original DTC? (CEL #) Have you reset the ECU and confirmed that no other DTC's are being thrown?

Yeah, the spark plug gallies fill with oil. Tell me, do you work on cars?
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Old 04-23-2009, 08:23 PM   #7
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Quote:
Originally Posted by treemandan View Post
Yeah, the spark plug gallies fill with oil. Tell me, do you work on cars?
There are no such things as "spark plug gallies" on subaru EJ engines. oil gallies are passages in the case (block) and heads that carry pressurized oil throughout the engine to things like crank bearings, cams, etc. The spark plugs do not require oil for any reason. I think you are thinking of the spark plug tubes that the spark plugs reside in, since they commonly get oil pooling in them when the valve cover seals fail.

I work on cars, but not professionally. I work on aircraft professionally.
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Old 04-23-2009, 08:34 PM   #8
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I'm pretty sure he means the spark plug tubes. Either way, the OP needs to check wires and plugs.
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Old 04-24-2009, 09:41 AM   #9
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Iím planning to replace the plugs in like a month anyway since they are due. Replacing the wires as well wouldnít be a problem.

I have the original code saved at home. It was a code for the iacv. It didnít throw any other codes just the same one. At first I cleared it but then it kept throwing it at various times and then went away. So I ignored it since I knew what it was. After replacing it I did check for a stored code to clear it but didnít find one. Iíll be able to double check it tomorrow for any codes.

I replaced it Sunday. Monday and Tuesday were cold and rainy days. I had hesitation issues with it when first starting it cold both those days. After it warmed up it was fine. The rest of the week we havenít had rain and itís been somewhat warm but cold in the mornings, around 30 degrees. Except for a barely noticeable hesitation at times in the mornings, all below 2.5K, itís been fine so far this week.

One other thing. It takes longer than usual to start now at times. Like an extra second or two of cranking. Even if I pause and let the fuel pump build a little pressure before starting. When it does do that itís a bit rough for a split second when it first starts then it starts normally and idles normally. This doesnít happen every time. Itís only been going on since I replaced the iacv.

I donít have any oil pooling.
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Old 04-26-2009, 08:38 AM   #10
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The original code I got was a P1507.

I was out early yesterday morning and it did the hesitation thing again and gave the miss fire sounding/feeling again. It wasnít rainy but it was cool and a lot of dew condensation. It did it again and couple times but it eventually, and finally, gave me a cell to work off of this time. It was a P0303 and P0304 and when it gave the cel it also flashed for a few seconds then went to solid. And like I said before it only happens below 2.5K when it does happen. After that it was fine the rest of the day it was fine too. I know they are misfire codes but at least now I have something better to go off of.
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Old 04-27-2009, 05:45 AM   #11
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I am subscribing to this. I have a very similar issue with my hybrid turbo'ed EJ25 Outback. Until the engine warms up there is a wicked partial throttle hesitation. The car will hesitate and buck unless the throttle pedal is pushed down beyond partial throttle engagement, I suppose at that point a more aggressive ignitior or timing or fueling map is applied and the problem is bypassed? IDK but I replaced my plugs not too long ago. I think the next logical step would be IAC cleaning and new wires. The O2 will be replaced soon with a wideband unit. I think the coolant temp sensor problems mentioned earlier are very interesting, I'll have to search for any relevant info on that.
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Old 04-27-2009, 06:38 PM   #12
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O2 = fine operation when cold and under heavy throttle. Basically when the engine runs in open loop mode (using pre-defined parameters defined in the ECU), the engine runs great. Then once the engine warms and steps out of warm up mode and during light driving, the engine will run in closed loop (using sensors to measure parameters and adjusting as needed). When in closed loop, you'll find you have problems when sensors start failing. You will notice poor operation, hesitation, loss of power, etc. when the O2 goes bad. As the readings get worse, the engine will operate worse and worse, and driveability will suffer, sometimes enough so where you can really only effectively use the engine in open loop, forcing you to drive in a manner that forces open loop operation.

So, is it the O2?

Does the car work normally when cold?

Does the car work normally when heavy on the throttle?

Does the car operate irratically only after the engine warms and only durning light medium throttle/load?

If yes to these, it is most likely the O2. The key is the open loop/closed loop switching. This is kind of a dead give away to the O2 failure. There can of course be other issues. For example, if the MAP/MAF sensor was going bad you'd have hesitation problems too, but they don't really care about the open/closed loop operation. There can also be issues with plugs and wires too, but you can check those simply by pulling the plugs and looking for wear and and if any are fouled. You can check spark as well via physical inspection.

Note the front O2 is the one that controls air/fuel. The rear one is simply a check device for the cats and doesn't do anything other then throw a CEL when a cat goes bad. It has no control over the operation of the engine. The front O2 has a lot of control over the operation of the engine and can cause serious driveability issues.
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Old 04-28-2009, 10:33 PM   #13
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The more I read the more I’m thinking that it’s an ignition issue. The past two days have been nice warm days. Cool in the mornings but no condensation in the mornings. I had zero issues with it. Tomorrow it’s supposed to be cold and rainy. I’m expecting issues again with it. I’m thinking water is getting where it shouldn’t and causing a short somewhere till the engine gets warm and the water evaporates. At least it’s predictable.

I plan to change the plugs and wires next weekend. I got new plugs today but still looking for new wires. Who knew they would be hard to find.


Does the car work normally when cold? Yes but only when I put it in gear and go to move the car that it may have problems. Again after 2.5k it stops if it does have issues.

Does the car work normally when heavy on the throttle? Yes.

Does the car operate irratically only after the engine warms and only durning light medium throttle/load? No.
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Old 05-10-2009, 09:45 AM   #14
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Replaced the plugs and wires yesterday. From now on when I get a used car replacing the plugs is going to be one of the things I do to it when I get it. 3 and 4 were really bad. The center electrode was worn down to a tiny nub and the gap was nearly 3 times more than the largest recommended gap. 1 and 2 were about twice the largest gap size but not as bad. I think that might have had something to do with it.

The inside of the spark plug wire on 4 did have what looked like a little rust on the connector. The rest looked fine but since I already got new wires I still replaced them. The spark plug wells were very clean.

Now the car has new pep! The hesitation below 2.5k rpms is gone. Now the big thing is will I have issues when it rains and is damp out. Looks like it will be a week or so till I find out if Iíll still have problems when it rains. Iíll have to report back later on that. If it was the gap that was the cause of the issues Iím not sure how the rain made it worse.
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Old 05-15-2009, 08:03 AM   #15
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Update. Seems to be fixed now. Iíve had zero issues when it rains out and when condensation is all over everything in the mornings.
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Old 05-14-2011, 12:25 AM   #16
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My 98 impreza 2.2 is also having issues. When driving, the CEL will illuminate and at times the car will run rough or die when I slow down or come to a stop. The code told me it was my IACV; however, I changed the valve and gasket and still have the same problem.

Any ideas??
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Old 05-14-2011, 10:58 AM   #17
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Quote:
Originally Posted by 98impreza2.2 View Post
My 98 impreza 2.2 is also having issues. When driving, the CEL will illuminate and at times the car will run rough or die when I slow down or come to a stop. The code told me it was my IACV; however, I changed the valve and gasket and still have the same problem.

Any ideas??
The combo of the iac and plugs and wires resolved it for me. When was the last time your plugs were changed and or the wires? If you donít know then itís probably time.

If it only happens when slowing down or at a stop. Is your car an auto? Mine is a manual. If itís an auto and only happens when slowing down or at a stop it can be a sign of a torque converter on the way out. One of my previous cars was an auto and had that issue. The torque converter was on the way out. Replaced it and it fixed the issue.
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