1998 GEO Metro - 1,0L Code PO505

Specific repair issues for all GM cars + FWD vans
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Tim Martin
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1998 GEO Metro - 1,0L Code PO505

Post by Tim Martin »

We got this 1998 Geo Metro with a 1L power plant and a 5 speed manual transmission. The issue is that it starts right up, no miss, idles perfect. The issue is that very randomly it will fall flat and shut off when you try to accelerate from a stop. The check engine comes on and then it really loses power. Scan tool shows a PO505 code which is Idle Air Control. I can erase the code, start the engine and go for a drive. It will drive for awhile fine. Then all of a sudden repeat the stumble and losing power. Fuel pressure is within specs at 38 psi with the engine running. When I diagnose the PO505 code, it leads to TPS adjustment. Scan tool reading for the TS shows an 11% opening when the engine is idling. So, i replaced the TPS, thinking it may be faulty. New TPS reads the same as the old one. Now what?
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Re: 98 Geo Metro Code PO505

Post by steven kiser »

Not sure on this one but there was an issue with the egr valves. Unplug it and give it a run. If it solves the problem the issue isn't the valve. It is most likely the computer or a bad input sensor. Possibly the egr vac amplifier may be sticking but something in my memory keep telling me pcm. Not sure but i think these pcm's were clean and all programs were on the replaceable chips. The kicker is getting one now and down loading all the up dates it holds and maybe having to make changes on the vehicle.
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Re: 98 Geo Metro Code PO505

Post by Tim Martin »

So what, is the PO505 code one of those umbrella codes that is used for more than one thing?
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steven kiser
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Re: 98 Geo Metro Code PO505

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Basically, yes it can be. Sometimes it leads right into the pcm. Like i said the pcm's of that era were blank and the program was in the mem and prom cal chips. On rare occasions I would run into updated chips that called for different sensors. I had one where i needed to replace sensors in the transmission because the chip had been updated so many times it encompassed multiple changes when all i wanted to do was solve a no start warm issue.
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Tim Martin
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Re: 98 Geo Metro Code PO505

Post by Tim Martin »

So. We got us a wing wang operation here. I see how this works.

Well, let me do some further diagnosis on this impy 4 wheeler.
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Re: 98 Geo Metro Code PO505

Post by Jeff @ Able Auto »

An 15 year old Metro. WOW! :shock:
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Re: 1998 GEO Metro - 1,0L Code PO505

Post by Tim Martin »

Well, I realized in going over a few older posts of mine that I must tell you fellows a story about this beastie.

The owners son wants to be an auto tech. So, he was studying online an came across this "fix" for when the engine just cant be fixed. He took an IV bottle, filled it with Sea Foam an drop by drop the 16 oz went into the intake manifold via a vacuum line. Took about 2 hours. He is so proud of himself that he can do things the expensive shops do not do. Says the car runs just perfect. The owner told me his son is trying to get a shop going himself an do fixes when the shops cant. I am waiting to see this happen. An, trust me, I am gonna go to his open house he says he is gonna have. If it ever happens I will post.
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Re: 1998 GEO Metro - 1,0L Code PO505

Post by steven kiser »

"the other shops can't" or the other shops won't? :lol: :lol: :lol: One of my tenants was like that. He would spend hours upon hours chasing a short. I would trace it to a specific harness, look at the wiring diagram, unplug everything it feeds if possible, power up the wire that's shorted and check all pins to see if it melted and is ghost powering anything. If yes I would chase it and if not I would just run another wire with the same ohm specs. After a few years of seeing my shop pushing work out and expanding he re thought his policy. He would come up stairs to me and ask me to copy a piece of exhaust pipe on my bender so he could patch a system. I would always ask him how much money he would make and I would point out that I would cut off the system from the cat back if it looked at all rusty and since I charged 100% mark up plus labor I made a **** load more money than he did in 1/2 the time. He finally started working on customers cars un like they were his. On Ford Super Duty's with rear harness issues sometimes it's just cheaper to replace it especially if it's a plow or sander truck. Don't get me wrong, I really like to see things through and chase problems. It keeps my mind sharp, I also do a few crossword puzzle books a year. But being a specialty shop where you spend 10 hours chasing something isn't really going to make you any money. Sure I would love to be remembered as the person that would fix a circuit board as opposed to replacing it but I can't treat every vehicle like it's mine and make money. I want to build a garage on a piece of property I own before I retire and set it up like my shop. At that time making money to support my family won't be so important and I'll enjoy spending hours repairing as opposed to by passing or replacing. It will be a personal victory. I don't want to give people the impression I'm a parts replacer, I don't throw parts at vehicles in the hope of repairing them, we diagnose and repair or replace if necessary but won't chase to the ends of the earth. If I have an old dried up crunchy engine harness that's been screwed with and the insulation on the wires is all dried up and cracking I'll replace the harness and be done with it but there are shops that will spend days rewiring and never be able to get paid for the time. Sure it's a personal victory (in my opinion) but in that time I probably made 3 or 4 hundred dollars profit on that job never mind all the other work that that tech put out. That shop couldn't charge 3 grand for the job, or maybe they could but won't be in business that long when people find out that things could have been replaced for a third of the money and never have to worry about other rotted wires in the harness. Well enough for me and I'm sure for all of you. :lol: :lol: :lol:
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