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Falls on its face... Dealer stumped


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51 replies to this topic

#26 calebz

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Posted 04 June 2005 - 09:46 AM

Tried to hotwire it eh?

If you sorted something out in the process, its possible you smoked the alternator. These things run like crap and do all sorts of funny things when the alts go bad.

Are any of the idiot lights on the dash on?

#27 Boo

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Posted 04 June 2005 - 10:53 AM

Yea Calebz...

All the idiot lights work and is has recharged the Battery... when it cuts out... it will do it at a very precice rpm, like 2.3k now or 1.5k at first... runs good and smooth and pulls [like up hill or ramps] to that point, go over that an it almost dies. A couple times be in developing it would run normaly which makes me think not belt cause they never get better... but i'm running out of machanical things to check. I pray it not in the computer-controller modules- whats the ignighter i read that could be damaged by grounding the coil leads.
Boo

#28 calebz

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Posted 04 June 2005 - 12:49 PM

no no no

Not asking if the idiot lights work.

Was asking if they are on (even dimly) during normal operation.

#29 [HTi]Johnson

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Posted 04 June 2005 - 12:59 PM

What about your injector plug wires. I had one loose, and it was doing the same thing as your's. How are the plug wires? What about plugs, my friend had two plugs pretty much explode in the cylinder. Cap and rotor? GOod?

#30 NorthWet

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Posted 04 June 2005 - 03:04 PM

...How are the plug wires? What about plugs, my friend had two plugs pretty much explode in the cylinder. Cap and rotor? GOod?

This was (and always should be) my first thought: Ignition parts, especially secondary circuit. I took a quick rescan throught his thread and didn't see any mention of this. Good ignition parts are really important in the stressed-out world of the turbo. Also, is the rpm cut only under load, or does it happen if you are sitting still and rev the motor? And, did you check that the turbo plenum is securely hose-clamped down as mentioned previously? They really do love to pop up at the most inconvenient of times.

#31 critical_max

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Posted 04 June 2005 - 03:19 PM

Agreed with other posters, this sounds like plugged exhaust if you can't rev to 3000!!

The turbo usually kicks in between 2000-3000 so that would explain why you're only seeing it once in a while... a bad turbo would NOT keep you from being able to rev up to my knowledge...

The catalytic converters can get plugged up over time and need to be replaced when that happens. You have two, one on the downpipe and one down under the car.

#32 Boo

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Posted 04 June 2005 - 03:30 PM

no no no

Not asking if the idiot lights work.

Was asking if they are on (even dimly) during normal operation.



Got Ya
they are not on just when i turn it on, like normal
Boo

#33 BoostedBalls

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Posted 04 June 2005 - 06:33 PM

OK, sounds like a fuel startvation problem to me- I don't think it's a clogged cat, if it had a clogged cat, it probably wouldn't turn the turbo light on because there would probably be too much back pressure to let it spool up. (turbo light "on" means you are over 2psi intake pressure.)

Does this happen right off the bat or does it take a while to start messing up? The next time it happens- leave the engine running and open the fuel filler cap. If your vent isn't working it will make a huge sucking sound. Then drive with the fuel cap off and see if the problem continues.

If your fuel tank is not venting it will put the tank under vaccuum until it get's to the point of fuel starvation. This will create a lean HOT condition and toast your engine if you continue driving it that way. Your turbo should only glow red durring and right after a good hill-climb or 1 minute full throttle blast, or towing. If you weren't doing any of those things- you have a fuel issue.

Luckily- the fuel pump is not inside the tank and way easy to replace (provided that the fuel tank venting has been ruled out)

Good luck, let us know how it goes!
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#34 Boo

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Posted 05 June 2005 - 02:38 PM

Hello Oregon... and thanks rebuilders thanks everyone for a lot of common sence advice and your right old timer [I'm 59 but i never grew up in my mind] it doesn't cost anymore to be nice and if it takes any extra effort thats how we build the world we live in. OK there were some questions and I'l try to address them... when i changed [and double - triple checked] the belts... I changed the water pump, rotor, cap, wires. plugs... the plentum isn't leaking, it quits at a certin rpm [just over 2k since i changed the fuel filter 1.5 before] hot or cold almost like it had a govoner on it. It worked at first, i thiught it was fine... started up [the problem] intermitenly and then all the time. I just checked the down pipe CAT [ by droping it and running the engine] ... did not help... replaced the fuel pump and made sure the lines were clean and free flowing... still the same;.
Today is a nice day in Craig Co. [its been wet, rainy, muddy. cold all week]
and I'm puttin all the things i checked yesterday back togather... to make it ahhh drivable again then I'll check some more things out.
Boo
Oh Yea I tryed running it without the gas cap too

#35 Cougar

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Posted 11 June 2005 - 10:49 AM

After looking over the progress on this, has anything been done to check the throttle position sensor for a problem, like Roundeye suggested in post #17? I think the problem may be with the contacts in that. Monitoring the wiper contact with a voltmeter will show how it is doing.

#36 presslab

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Posted 11 June 2005 - 12:38 PM

Hello Suby Lovers...
I'm trying to love mine, a 88 MPFI turbo GL wagon. Fell in love with the car right away, started fixin it up... drove to Col. [from AZ] and broke a belt...[idler pully froze] fixed it, [thanks to your forum]... it ran good for a couple days, except once it lost power over 1500 rpm's but returned to normal after a 5 min stop and inspection. Left for home the next day and 15 miles out of town it lost power over 1500 rpm's again... stopped and rested at the next town, and a few hours later it started and accelerated smoothly to 65mph only to crap out after afew highway miles, to only 1200 to 1500 rpm and i limped back 40 some miles that way. The dealer here says he cant tell whats wrong... no erroe codes fuel pressures ok [says he couldnt check volume]... he said he'd go on lookingat $70/hour but I'm away from home... broke and staying with friends... sooo.. I'm gona fix it. I changed a slow fuel filter and got 2000 rpms [before crap out] disconnected the catalytic converter-tail pipe-muffler [thought it might be pluged] and got 2500 rpms before it falls on its face and stops pulling. I'm sure the cam timing belts are right and that wouldn't be an intermitten problem any way. Anyone ever heard of a problem like this... any educated guesses? I'm at a loss.
Boo
Stuck in Colorado


Make sure your O2 sensor is toggling, i.e. check the voltage on the signal wire (not the heating element) and make sure it is bouncing around from about 0.3 to 0.8 V, this would be after letting the engine idle for a minute.

My idea: Maybe open loop when the O2 sensor is cold it worked fine and as soon as it went into closed loop it crapped out, and the red exhaust is from a super lean condition caused by a faulty O2 sensor or something like that.

Anyway this can tell you a lot, if the computer can't close the loop (toggling O2 sensor voltage) then something is wrong, maybe bad O2 or wiring, maybe vacuum leak or MAF sensor.

Ryan

#37 royboy159

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Posted 11 June 2005 - 02:13 PM

Did the dealer verify MAF and TPS working?

Hey Boo---This has my vote. Various sensors can send the ECU crappy info that older model ECUs "see" as reliable and thus send crappy control signals to the engine.
I doubt the O2 sensor since it will send crappy info at all RPMs. The procedure for checking it can be found here:http://www.ultimates...rticle.php?a=75
Hot wiring as you did could, but not necessarily, cause damage. The damage would most likely prevent the engine from even starting.:banghead:

#38 Boo

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Posted 11 June 2005 - 05:11 PM

Thanks round eye, royboy, cougar, press lab and the rest...
Still stuck in Colorado and baffled... like whats MAF-TPS... I've checked out most all the mechanical problems... and they are not at fault. This engine should run like a top but on the road i cant get more that 2k rpm in all gears. I'm startin to think its electrical too... some controller. I'm tryin to check the throtle sensor but I'm having trouble getting the connector off... dont want to force it and have more problems but I'll keep tryin.
I'm thinkin by running a hot wire from the battery to the + coil lead to make sure it had voltage to the coil and spark may have done something... but would it run to 2k then? [by the way i checked the coil... put a new one in... its OK]
I'll also check the O2 sensor for voltage.

Could be a long slow trip back to AZ....


OK... got it off, the squar one, throtle sensor connector... theres 5v reference signal fron the harness, the throtle sensor knows idle from go [on off voltage], now i will check the sensor with a voltage checker by , with the ingition off. applying voltage to one pin and seeing if one of the other 3 goes up and down like a dimer switch would when i work the throtle.

#39 Cougar

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Posted 11 June 2005 - 05:23 PM

The MAF is the mass air flow sensor and its job is to precisely measure how much air is going into the engine so the ECU can mix the proper amount of fuel with it. It does this by sending a voltage change to the ECU as the air flow changes through it.

The TPS or throttle position sensor lets the ECU know how open the throttle body is by a voltage change on the sensor. It usually has a range between 0 to 5 volts. You should be able to measure a smooth voltage change as you press the throttle from idle to fully open. I suspect your problem is with this sensor.

#40 Boo

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Posted 11 June 2005 - 06:51 PM

OK... I got it and that makes sence... the book says says to 'back probe the connector [on the TPS] to ground to read the voltage... guess I'll use a pin into the wire to read it... hooked up, connected... and ignition on... to see what kind of curve and voltage its puttin out.
Boo
Just did it... it puts out a smoth voltage curve from 1v+- to 5v when the throtle opens up... it works. I get no voltage out of the O2 sensor just sittin there cold... storms comin in so I'll try it hot tomorrow... but.. theres only 1 wire, from the O2 sensor, how can there be a loop if it only puts voltage out?

#41 NorthWet

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Posted 11 June 2005 - 09:59 PM

OK... I got it and that makes sence... the book says says to 'back probe the connector [on the TPS] to ground to read the voltage... guess I'll use a pin into the wire to read it... hooked up, connected... and ignition on... to see what kind of curve and voltage its puttin out.
Boo
Just did it... it puts out a smoth voltage curve from 1v+- to 5v when the throtle opens up... it works. I get no voltage out of the O2 sensor just sittin there cold... storms comin in so I'll try it hot tomorrow... but.. theres only 1 wire, from the O2 sensor, how can there be a loop if it only puts voltage out?

The EGO (O2 sensor) does not put out a signal until it gets hot. There is no "loop" to it, unless you are talking signal and ground (the ground is thorugh its threads to the exhaust system, which is ASSUMED to be grounded :rolleyes: ). The EGO senses the exhaust's O2 concentration, converts it into a voltage, and the ECU adjusts the mixture to suit, and the EGO senses the resultant O2 concentration (this is the closed-loop).

Disconnect the EGO and the system goes "open-loop", using pre-programmed values to adjust mixture. This would eliminate the EGO as a problem source.

#42 Cougar

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Posted 11 June 2005 - 10:45 PM

"Open or closed loop" refers to the ECU operation, not a sensor wiring design.

Did you try measuring the TPS voltage while the engine is running to see if the engine runs smooth also? If the TPS voltage is ok then you should look at the MAF output voltage and see how it is while the engine is being rev'ed up. It may be hard to tell if there is a problem with it since the airflow will change if the engine has a problem.

#43 royboy159

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Posted 12 June 2005 - 09:55 PM

I get no voltage out of the O2 sensor just sittin there cold... storms comin in so I'll try it hot tomorrow... but.. theres only 1 wire, from the O2 sensor, how can there be a loop if it only puts voltage out?

Hey Boo---The short of this:http://www.ultimates...rticle.php?a=75 is that the O2 sensor only produces voltage fluctuations once it reaches it's proper temperature. It grounds back to the engine through the exhaust pipe. The simple test is to just disconnect it, which will throw a code, but the vehicle will run half decent in open loop at all RPMs. If it doesn't, the problem isn't the O2 sensor.:brow:
Ah! Just what Northwet said.

#44 Boo

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Posted 12 June 2005 - 11:16 PM

Hey Boo---The short of this:http://www.ultimates...rticle.php?a=75 is that the O2 sensor only produces voltage fluctuations once it reaches it's proper temperature. It grounds back to the engine through the exhaust pipe. The simple test is to just disconnect it, which will throw a code, but the vehicle will run half decent in open loop at all RPMs. If it doesn't, the problem isn't the O2 sensor.:brow:
Ah! Just what Northwet said.


Thanks for that tip... is that true of the other sensors... disconnect them and go to default values... but it will run ... any others? like MAF [ahh airflow]
Boo

#45 royboy159

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Posted 13 June 2005 - 09:43 PM

Thanks for that tip... is that true of the other sensors... disconnect them and go to default values... but it will run ... any others? like MAF [ahh airflow]
Boo

Hey Boo---Yes. The ECU will operate by defaults for disconnected sensors. But the responses vary from poor gas mileage to no run. I believe a disconnected MAF causes very crappy performance at all RPMs. And if this gets you over 2K then it would appear the MAF is the culprit.:)

#46 Boo

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Posted 17 June 2005 - 05:54 AM

Welcome From Arizona !...

got home yesterday... I was running out of things to check to find the problem with my Suby and when i got 2.5k rpm's out of the engine [about 50 mph] before it would crap out and start jerkin, missin and back firing... i decided to make a run [maybe a trot]for home. [having more time than money].
I cant say what caused the improvement, the only changes i made was to replace a bad distributor cap... which i put on just before the problem. I think they gave me the wrong one cause when i checked it the center contact was broke and the spring and contact were missing.[found it, not in the distributor], and the distributor was full of white plastic dust or shavings ground off the contacts inside by the rotor tip.
The new cap produced no immediate results. I put my original fuel pump back on cause the new one did not help [got a refund]... I also broke off the wire to the O2 sensor in the process of checking it out, so that was out.
I think the the fine shavings in the distributor may have 'blinded' the optical reader 'eye' in the distributor.
Well... anyway. I put in a can of fuel injector cleaner. filled up... left the gas cap a little loose... and the O2 wire off, and left for Arizona... at 2,5 K rpms... after about an hour, it started improving... and smothing out to 3k rpm... highway speed... and i kept a rollin... by the time i hit Az... it was running relitively great up to 4krpm plus... and the turbo was kickin in like it used to. hell, I was passin people.
In my mind i was thinking this was like a weird dream it broke down for no apparent reason... nothing i did seemed to help, and it fixed itself on the same strech of road it broke down on... and here i was home and the car was runnin OK... Thats the truth...I couldnt make this ************ up.
Thank you every body... i learned an aweful lot about my Suby... and whats not wrong with it... and about the good spirit of people all over... bless you all... and thank you again.
Boo...
Home in Arizona.

#47 Zoobaru

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Posted 17 June 2005 - 06:10 AM

The main reason I know of that causes exhaust overheating before a cat, is retarded ignition timing.

#48 RickOregon

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Posted 17 June 2005 - 08:09 AM

Welcome to the USMB. So, it sounds like a crudded up fuel injection system. Glad you found it. The symptoms appeared much like a plugged muffler to me - pieces of broken catalyst material stuck somewhere in the tailpipe/muffler. But that doesn't appear to be the case. You learned a lot in the process, so all that work you did was worthwhile. Good deal. Rick

#49 MorganM

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Posted 17 June 2005 - 08:52 AM

In my mind i was thinking this was like a weird dream it broke down for no apparent reason... nothing i did seemed to help, and it fixed itself on the same strech of road it broke down on... and here i was home and the car was runnin OK... Thats the truth...I couldnt make this ************ up.


I've lost count how many times my Subaru has done that :drunk: Some wierd problem that just goes away before I can figure out what it was.

Glad you made it home safe.

#50 subyrally

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Posted 17 June 2005 - 11:30 AM

happy to hear you made it home safe, and i know its a bit late, but welcome to the comminity. just keep an eye on your ignitiion system, check the connections and keep it running good.




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