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  #16  
Old 02-07-2006, 01:51 PM
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TomsSVX TomsSVX is offline
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maybe you have a leaky injector?? Causing the engine to flood out one or more cylinders?? Just a thought

Tom
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  #17  
Old 02-07-2006, 04:27 PM
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Quote:
Originally Posted by svxcuseme
Thanks for the info Bill. My problem is a little different. I get jerks or stumbles as the car accelerates, usually under load and under 2000rpm. I also get a serious stumble/jerk when accelerating hard sometimes between 3000-4000 rpms. I did have a stalling issue until I changed the MAF. I'm totally stumped.

I've swapped the following parts to no avail.
-MAF
-Ignitor
-both Cam sensors
-New TPS a couple months ago
-Cleaned intake and TB
-New PCV valve
-New plugs (OEM)
-replaced all coils with used working
-new fuel filter
-?????

I'm going to look at my crank pulley, crank sensor, and timing setup. I haven't changed the timing belt since I bought the car. It is due. Maybe there are some clues under the timing covers. Also even though I never saw evidence of spark leak I may try and seal up the boot or find new boots and eventually new coils

Question
Anyone no where to get new boots for our coils and what the part number was (Assuming you bought a new wire set and used the boots)?
Thinking about it, to get a "stumble jerking", something would have to suddenly go on and off. It is different to the effect that the MAF or fuel starvation would cause. I feel it would be electrical, you have ruled out the coils, but some thing is turning either the spark or fuel on and off.

You say you replaced bothcam sensors. There is only one cam sensor, and two crank sensors. This is the sort of effect that I would expect if the crank signal was interrupted. It would turn the spark and injection on and off, you may also see the rev counter flick as it is driven by the crank sensor.

Having gone through all that. It could also be a bad ground to the engine. The main one is at the back of the block to the firewall, below the Igniter block. If this is having trouble, it would cause the same effect, by turning the injection on and off.

I feel it has to be along these lines somewhere.Back to you.

Harvey.
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  #18  
Old 02-08-2006, 09:02 PM
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Hopefully optimistic

Quote:
You say you replaced bothcam sensors. There is only one cam sensor, and two crank sensors. This is the sort of effect that I would expect if the crank signal was interrupted. It would turn the spark and injection on and off, you may also see the rev counter flick as it is driven by the crank sensor.
My mistake. My list should have read, replaced the Cam sensor and Crank angle sensor 2. I got them confused seeing as how the parts are identical.

I pulled a crank sensor from a 93 Legacy a couple weeks ago, hoping I could make it fit in Crank Sensor 1 hole (sensor diameter and depth is identical to the SVX sensor). Just got around to replacing it tonight. Altered it a little, bored out the 10mm mounting bolt hole, fashioned a make shift connector for the harness, and fired the old scoobie up!

I had a slight issue with the idle dropping too low and almost stalling but I'm sure it's due to not having the sensor fully seated. A washer over the top of the bored hole, to hold the sensor down correctly, should fix this. Have to hit the sack tonight so I'll finish up testing and confirm results tomorrow.

P.S. This sensor eliminated the jerking, skipping, missing at low RPM under load! More to follow ...

Last edited by svxcuseme; 02-08-2006 at 09:20 PM.
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  #19  
Old 02-19-2006, 04:40 PM
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Problem Solved - ******NOT ****** Read post above by me

The shocks while cruising uphill or under load at low RPM's were caused by Crank Angle Sensor 1. NO MORE MAJOR SHOCKS, Stumbles, mis-fires, or whatever the heck you want to call them!!!!!

Last edited by svxcuseme; 03-02-2006 at 05:29 AM.
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  #20  
Old 02-19-2006, 05:44 PM
oab_au oab_au is offline
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Ah good news.

Thanks for the feedback, felt that would be it, good to know for sure.

Harvey.
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  #21  
Old 02-19-2006, 07:06 PM
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What do the cam and crank sensors do?
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  #22  
Old 02-20-2006, 01:04 PM
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Quote:
Originally Posted by NikFu S.
What do the cam and crank sensors do?
They trigger the spark plugs/engine timing, etc.
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  #23  
Old 03-02-2006, 05:28 AM
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O.K. - I need to fess up and say the new/used Crank Angle sensor did not fix the problem. It is just much less noticeable.

During my troubleshooting / maintenance checks I replaced the timimg belt. The belt over the Drivers Side CAM was one tooth off (idiots). That was amplifying the shocks I have been experiencing. Once I fixed this problem and swapped out the Crank sensor I thought I had it licked, but did'nt.

The problem is still here. However, it is no longer amplified, and much less noticeable. I think this behavior may be more a function of the air/fuel mixture ratio at low rpm rather then a problem.

I'd be interested to here if others driving a 5 speed experience this condition when in under load, rpms below 2000.

If I shift around 3000 rpm, I seldom incounter this issue.

Thanks,
Marc

Should I continue searching or is this normal bevaior?
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  #24  
Old 03-02-2006, 08:34 AM
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My engine has a bit of hesitation when stone cold, but is smooth at any rpm after it warms up a bit.
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  #25  
Old 03-03-2006, 05:38 AM
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Thanks Mychailo. I'll keep looking for the problem.
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  #26  
Old 03-08-2006, 05:52 PM
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SVX running hot ?

This is the final chapter ... I promise

I have all but eliminated the issue.

I removed the thermostat to see what effect it had on engine temp. Car runs much cooler but only when moving at a steady clip. Once stuck in traffic, temp gauge rises to middle of gauge. I realize this may be normal but I prefer a cooler running engine for many different reasons.

So, to try and get temps down further, I kicked one fan on full time. Temp gauge falls slightly below mid point, but again rises to mid in stop-n-go traffic.

Kicked both fans on full time, with thermostat out, and temp gauge rides just above the C. Much much cooler. Car runs much smoother, and does this damn hesitation / jerking thing in low rpms almost never. In fact, I've only noticed it once in the last week and I tried to make it happen on several different occasion.

So, looks like excessive heat my be a major culprit. Now on to ECU tune stage 1 . hehehe

Temp gauge after 1 hour driving in traffic, 66 degrees F outside temp...
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  #27  
Old 03-08-2006, 09:14 PM
want-a-fast-svx want-a-fast-svx is offline
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I know you said you have your reasons but the thermostat is there for a reason and definitely aids in the engines performance. It does need heat to help the oil no turn into sludge as well as helping the combustion process. Removing a thermostat is a bandaid to a more serious problem if its a cooling system problem. Again this is just my .02c but i just wanted to make sure you know that its there and is needed.
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  #28  
Old 03-09-2006, 07:13 AM
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svxcuseme svxcuseme is offline
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Right, I've read all the technical discussions on the subject. Most talk about sludge build up, increased water turbulence, localized overheated, inability for the radiator to absorb heat (coolant moving too fast through radiator) etc.

Fully aware that the thermostat is there and needed for optimal combustion and fuel economy. I would'nt dare say I have more technical knowledge then the engineers at Fuji Heavy Industries. Practical experience? Well, that's a different story alltogether.

In my opinion, the difference between the engine running at 210F and 180F, in a Subaru engine, in the summer, is negligible. I drove my '86 gl for over 150,000 miles with no thermostat in the summer (Summer only). This was after replacing clutch fan, electric fan, thermostat sending unit, water pump, thermostat, and radiator. The car would simply get too hot in the summer in traffic. FYI, I sold it in perfect running condition after over 15 years of faithful service.

I'll give you guys a temp reading with and without the stat using an Infrared Pyrometer. You can draw your own conclusions from there.
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  #29  
Old 03-09-2006, 09:09 AM
want-a-fast-svx want-a-fast-svx is offline
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Cool like i said i was just putting it out there to make sure you knew
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  #30  
Old 03-11-2006, 12:38 AM
19svx94 19svx94 is offline
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top end cut out

hi, i have a 1994 svx, and i just started having a problem in the upper rpm's, around 5000-5500rpm the car cuts out for a split second and then comes back in, the check engine light pops up everytime it cuts out, i know this problem exists in park, nuetral, d,3,2, and 1. i have not tried anything to fix it saying how the problem just started arising today, i believe it may be my MAF due to my idiot friend who sprayed about a half can of carb cleaner straight on it while keeping it floored to try and clean out the carbon out of my intake. i will keep my solutions posted.
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