Bogged down part II, any suggestions?

[msvx95]

I recently took my car to a subaru dealership for more bs and that's what I received. I told them about my bogging down issues and gave them a list of items I replaced with OEM parts list as well. After having the car for a week and 3 techs driving it, they told me there was no problem or anything out of the ordinary.
The moment I picked up the car after a week, I drove it like normal and the bogging issue began again which leads me to believe they never wanted to mess with my car.

Anyways I'm experiencing an intermittent issue of this:
1) Starting from a stop sign or traffic light in gear "3"...the car will accelerate normal, but once it hits the 1st shift point at around 2000 rpm, the car will lose power for a few seconds, then like a flick of a switch, "wake up" and begin the next shift with power. This happens intermittently and not all of the time but quite frequently now.

2) Sometimes the car will start out from a stop with no power until it again "wakes up" and something kicks in...this lasts a few seconds..

3) Finally when driving in "D" and applying throttle around 2000 rpm the car seems to feel jerky and unresponsive..I then apply more throttle and the rpms kick up and the car comes alive again....why?


I've replaced a good number of items: AACV, IACV, PCV, PCV solenoid, MAF, Coolant Temp sensor, Knock sensors (ebay item), IRIS Valve (used), IRIS check valve, TPS Sensor (and correctly adjusted), Oil Pressure sensor, and Internal tranny filter.

The dealership tested fuel pump and vacuum, both good.

I am at a loss of what's wrong, I was going to pour more money into factory OEM Knock Sensors and a new factory Iris valve.

Can anyone help?

[kwren]

Originally Posted by msvx95

The moment I picked up the car after a week, I drove it like normal and the bogging issue began again which leads me to believe they never wanted to mess with my car.

A more likely scenario would be that , like the overwhelming percentage of dealer "mechanics", they simply are not capable of diagnosing and repairing the SVX. They only are able to do routine things.

Keith

[msvx95]

Yes I completely agree with you...I think I know more about tinkering with my car than they do. I mention the word OBDI and they don't know what to do next.

[Subix]

I've noticed a slight lag or bogging from time to time in mine but it's never been bad enough or last long enough to bother really troubleshooting though I would suspect it could be a combination of the old fuel injectors and 200k mile coil packs. I don't know how well or not your car runs but I'm almost 100% positive I have a small hiccup in my head gasket somewhere that I'm going to get fixed later this year that could potentially cause the initial loss of power/bogging down like experience too. It runs pretty rough but I do have an exhaust leak/issue as well that could contribute to that.

I would have considered the MAF as well if the problem kept up. How long as it been happening?

[bwb3]

This is a long shot but, I had your symptoms to a 'T'. No codes, sensors checked out, fuel was flowing fine. After a month, my idle started being uneven. Turned out to be a coil pack with a hair line crack (naturally the hardest one to get to). Above 2000 RPM it ran like a champ. Diagnosed by listening to each injector and coil pack with a hose, hearing little clicking sounds (shorting) at #6 coil.

Gene

[msvx95]

Originally Posted by Subix

I've noticed a slight lag or bogging from time to time in mine but it's never been bad enough or last long enough to bother really troubleshooting though I would suspect it could be a combination of the old fuel injectors and 200k mile coil packs. I don't know how well or not your car runs but I'm almost 100% positive I have a small hiccup in my head gasket somewhere that I'm going to get fixed later this year that could potentially cause the initial loss of power/bogging down like experience too. It runs pretty rough but I do have an exhaust leak/issue as well that could contribute to that.

I would have considered the MAF as well if the problem kept up. How long as it been happening?

This started happening after I removed the intake manifold and replaced my old IRIS valve and knock sensors...hoses too.
I installed another used IRIS valve and bolted the car up the way I took it apart. I probably did this work about 1 month and a half ago, but the car has been at the dealership for 1 week and a glass shop for another week. So not much driving with it.

[msvx95]

Originally Posted by bwb3

This is a long shot but, I had your symptoms to a 'T'. No codes, sensors checked out, fuel was flowing fine. After a month, my idle started being uneven. Turned out to be a coil pack with a hair line crack (naturally the hardest one to get to). Above 2000 RPM it ran like a champ. Diagnosed by listening to each injector and coil pack with a hose, hearing little clicking sounds (shorting) at #6 coil.

Gene

I guess for the heck of it I should order the #6 coil pack and a set of spark plugs and attempt replacing myself. I know my timing belt was replaced at 125K (car is at 160K) so I don't suspect a worn belt. To my knowledge I can't think if the plugs or coil packs have been replaced since I've owned the car.
Just like you no codes. The injectors looked clean too.

PS. what does a bad coil pack sound like? Clicking, no clicking...intermittent clicking?..?

[radarwhiz]

Just to inject something new into this discussion:
I have had the exact same symptoms as Matt with my '92, it seems that the hesitation happens only at a certain throttle angle which led me immediately to suspect the TPS. Under acceleration, if I do so more gently or harder than normal it behaves fine as if there's a dead spot on the TPS and any position on either side of it works fine just not at that particular spot.

I have not replaced the TPS yet to be sure.

[msvx95]

I have had the same outcome with old TPS adjusted correctly vs. a brand new TPS recently installed a few weeks ago and adjusted correctly.

Could it be something in the throttle body itself that is hanging up? I've had the throttle body unbolted numerous times during my carb cleaning of it, the replacement of the IACV, and the intake manifold removal. Perhaps one too many removals? Just a shot in the dark

[radarwhiz]

Originally Posted by msvx95

I have had the same outcome with old TPS adjusted correctly vs. a brand new TPS recently installed a few weeks ago and adjusted correctly.

Could it be something in the throttle body itself that is hanging up? I've had the throttle body unbolted numerous times during my carb cleaning of it, the replacement of the IACV, and the intake manifold removal. Perhaps one too many removals? Just a shot in the dark

I'm no expert, but it doesn't feel mechanical at all. Anything like that, I'd imagine you'd feel in your right foot.

[msvx95]

For about 5 minutes the car ran great this morning...then the next 20 minute ride it bogged every time from a start and intermittently after the first shift at 2000 rpm...i didn't feel anything different in the pedal and also notice when it bogged I pressed the pedal harder and the "power" light came on and no response...then after a few seconds, finally I started feeling some acceleration.

Damn car...I need to make a decision what I will work on next. Any votes? Coils, plugs? ECU?

[msvx95]

Originally Posted by bwb3

This is a long shot but, I had your symptoms to a 'T'. No codes, sensors checked out, fuel was flowing fine. After a month, my idle started being uneven. Turned out to be a coil pack with a hair line crack (naturally the hardest one to get to). Above 2000 RPM it ran like a champ. Diagnosed by listening to each injector and coil pack with a hose, hearing little clicking sounds (shorting) at #6 coil.

Gene

Gene, I think I solved the problem...I replaced all spark plugs and have new coils installed...car runs good so far and responsive. I will drive it the rest of the week to see if the problem is gone for good. I just don't know which coil was the culprit..didn't see any visible cracks.

[bwb3]

Congrats. Thanks for providing a follow up.
Gene