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ProudGecko · Joined: 26 Nov 2002 Posts: 129 Location: Indiana

Ok so here's the deal. My car starts up rough when cold, sometimes it'll start and then die unless I give it some gas at which point it will idle just fine. It also has a severe hesitation when the engine is cold at low rpm's, it will nearly die sometimes in first or second gear. I have also noticed a slight hesitation that sometimes occurs when accelerating, and this is all the time at any engine temperature. My fuel efficiency seems to have also decreased considerably, and also the car wouldn't start if the temperature dropped below about 25 deg F. I'm pretty sure it's fuel related, I'm going to try to check the engine temp sensor tomorrow and see what that tells me but I don't think it's the problem. Any clues as to what could be the problem?

Thanks
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1988 Porsche 924S
1986 Kawasaki Concurs ZG1000
1984 Mercedes 190D
1973 Honda CB500

Sleykin · Posted: Sat May 22, 2004 5:33 am Post subject:

My first guess would be a bad or mis-adjusted TPS
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Glenn Neff
Medford, OR
87' 924S

ProudGecko · Joined: 26 Nov 2002 Posts: 129 Location: Indiana

I can hear it clicking when I move the throttle so I know that mechanically it is working, but i don't think i've actually tested it yet
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1988 Porsche 924S
1986 Kawasaki Concurs ZG1000
1984 Mercedes 190D
1973 Honda CB500

Sleykin · Posted: Sun May 23, 2004 1:57 am Post subject:

The clicking is not real useful. It just means the parts are still there. Use an ohmmeter and verify less than 1 ohm resistance. You might try running some injector cleaner through your tank too. There is a great writup on Clark's garage in the shop manual for troubleshooting this area.
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Glenn Neff
Medford, OR
87' 924S

ProudGecko · Joined: 26 Nov 2002 Posts: 129 Location: Indiana

ok finally got around to testing the TPS and it works just fine, i tested it both at the DME plug and the actual sensor plug. I've also tested the engine temperature sensor and it appears to be working just fine as well. Anyone have any ideas as to what else the problem may be? Oh and I've been running injector cleaner through it for awhile with little to no improvement and I did replace the fuel filter as well with again no improvement.
_________________
1988 Porsche 924S
1986 Kawasaki Concurs ZG1000
1984 Mercedes 190D
1973 Honda CB500

Sleykin · Posted: Mon Jul 12, 2004 2:32 am Post subject:

Ok ... so much for the easy stuff

What do your plugs look like? Do you have the fuel economy guage? It can give you some clues. I would lean more to ignition related things at this point. Mine has developed a slight hesitation when cold at about 1500 RPM accelerating in first and second gear. I think I need to clean my speed and reference sensors ... when I get around to it. So far it only does the hesitation thing first go out. After driving a block or so it is fine.
_________________
Glenn Neff
Medford, OR
87' 924S

ProudGecko · Joined: 26 Nov 2002 Posts: 129 Location: Indiana

my plugs are fine, and the speed and reference sensors are clean. I cleaned them when I replaced the clutch a couple of months ago. Mine does the same thing, after a minute or two of driving it drives pretty much normal. And no i don't have the fuel economy guage
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1988 Porsche 924S
1986 Kawasaki Concurs ZG1000
1984 Mercedes 190D
1973 Honda CB500

Lizard · Posted: Mon Jul 12, 2004 3:59 am Post subject:

check your fuel pressure regulator or ust replace it
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3 928s,

Sleykin · Posted: Mon Jul 12, 2004 5:44 am Post subject:

I meant to read the plugs for a general idea of how your mixture is set. If you are happy with everything in the ignition then yes the next check would be fuel pressure and volume and a careful check for vacuum leaks.
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Glenn Neff
Medford, OR
87' 924S

ProudGecko · Joined: 26 Nov 2002 Posts: 129 Location: Indiana

ok so after some issues with trying to order a fuel pressure regulator, i finally got a new one and installed it. It certainly didn't fix my problem although i think it has smoothed out the engine a bit and it seems to have helped my fuel economy. So what should i be checking next?
_________________
1988 Porsche 924S
1986 Kawasaki Concurs ZG1000
1984 Mercedes 190D
1973 Honda CB500

Paul · Posted: Tue Aug 10, 2004 8:27 am Post subject:

I'd test the AFM next.

Sleykin · Posted: Tue Aug 10, 2004 9:30 am Post subject:

What did you see when you pulled the spark plugs?
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Glenn Neff
Medford, OR
87' 924S

Manning · Joined: 29 Feb 2004 Posts: 151 Location: Akron O-Hi-O

Oh so many things it could be.

Have you checked all of the vacuum lines to make sure they are attached and not split? Is the intake boot firmly attached to the throttle body and AFM? Have you had the manifold off and checked the ISV? How about the larger hoses, like the ones to the ISV or the oil mist seperator, are they still pliable and make seal to the associated nipples?

I had a rough idle and cold start/idle hunting issue and replacing all those bits, which were realitively cheap except for the ISV, mostly cured the rough idle and got rid of the cold idle hunting issue. Getting rid of the MSDS cone filter cured it completely.
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Michael Manning
1988 924S Undergoing weight loss program