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Discussion Starter #1
2004 Suz Forenza with 112k miles
Accidently let it stall from running out of gas (idling on a slight grade).
I was able to start back up and drive to a station, but ever since, it's had a gradually worse rough idle and stalling problem that is minimal when cold and worst in the hot afternoon.
I figure there is still a wide range of possibilities since this could be coincidental.
I know it has good spark, and the ignition module is fairly new.
I plan to test fuel line pressure and escape rate and listen to the injectors.
What should the fuel pressure be?
Next step would be compression testing. Any better direction would be appreciated.
 

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hi. well it could probably be a few different things but one easy one to check is the IAC valve. it controls the idle. heres a link to a thread about how you can clean it.
http://www.suzuki-forums.com/suzuki-forenza-reno-forum/53971-question.html
also, one of the problems with running out of gas is that you end up sucking whatever gunk is at the bottom of your gas tank through the system. you may just have to run it out. let us know what you find out.
 

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Discussion Starter #3
When you say " you might just have to run it out" how do you recommend speeding that process?
Thanks for the information about the valve controlling the idle.
 

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hi. just driving the car till the crap is out of the system. probably not going to help anything but it might.
 

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I think I can replace the injectors relatively cheap and easy. I found a website based autoparts company that I've bought quite a few parts for this car from and so far they've been good quality and name brands for much lower cost than retail or dealer. PartsGeek.
 

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I really wouldn't buy parts just to buy parts. You need to figure out what the problem actually is. I would start by checking the IAC valve and maybe cleaning it like how it says in the link above. It really doesn't cost anything to do and if it works it saves you a bunch of money.
 

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FYI stock fuel pressure is around ~45psi
 

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Discussion Starter #8
Thanks! I needed to know that. I suspect a weak fuel pump.

I did realize that replacing the injector (gates) won't do any good, if there was a blockage. And I honestly don't know for sure where the nozzles are located on the engine. Is there any other likely places particles would hang up?
Know of a good service manual? I'd love to find something on this car comparable to what a Suzuki certified ASE would reference.
Maybe you know of a good method for me to learn more about the full scale maintenance of this car.
On a side note, I once knew a guy who modified/made a hook tube air nozzle that he could feed into the spark plug hole and carefully position it to blow through the injector nozzle to clean it out. I'm suspecting there to be an easier way.

Does this car premix before the cylinder chamber?
I don't know when I'm going to find time to work on it. It keeps raining in the evening. Wife and family keep taking my weekends. I still have to buy a pressure gauge to test the fuel pump/lines. But glad I don't have to look up the pressure now. (This car doesn't have a typical gas filter. Just a screen on the pick-up tube, so it seems very likely to me that dirt did get into the system).
I bet the IAC is filthy and has been for years. Good info, I was unaware of this maintenance item. Definitely seems like a contributing factor.
Thanks to both of you for your time and experience/knowledge.
 

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I think the link is still posted here somewhere in the forum for the Forenza service manual... I do have it somewhere myself as well. If you can't find the link let me know maybe I can host it for you or something. 7-even maybe u remember the link?

I'm not sure what you mean by injector gates.... I haven't heard that term before.

Are you talking about a pre-mix chamber? Like some diesels have? No, this motor has MPFI (multi port fuel injection) which injects fuel right at the intake port of each cylinder.

As for fuel filter, yes its only the pre-filter attached to the pump in the tank. I also inquired to the dealer about replacing this item at one point, and they do not sell it separately. They would only sell the entire fuel pump assembly for $700+. Basically that item is supposed "to last the lifetime of the car". BS if you ask me.
 

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Discussion Starter #11 (Edited)
Agreed. If they intend to have a permanent screen filter in the gas tank, then I believe they should have also included a drain cock to wash the sediment out every once in a while.

The fuel pressure was oscillating between 58 and 59 PSI. When I stopped the engine it fell to 53 and didn't move. About an hour later it was at 40 PSI Seems like I need to back wash the fuel lines. Think I could run the pump in reverse?

I cleaned the Intake Temp Sensor (a black plastic thing with 4 waffle passages through it) located on the flexible tube from the air filter to the (pre-throttle) air intake housing.

I also removed a sensor on the top of the throttle body mounted on a small chamber. The sensor was on the side near the firewall. It had a brassy metal cone on a plastic protrusion about 7/16" diameter. That was coated in black which took some scrubbing with a soft cloth.

There's another sensor between the engine and the throttle, about 6 inches down from the opening. I figure on pulling it and cleaning it tomorrow morning when it's light out again (and no mosquitos). My wife is expecting me to take her to the gym at 9am and then wants to be chauffeured to sell off some used baby clothes.

I'm going to remove the Air Filter Housing to fix a slipped nut preventing the cover from opening fully. Then I'm going to inspect the entire plastic intake assembly for leaks.

Why isn't there a filter of some sort on the positive crank case ventilation tube? Seems like there should be a sponge of some sort...
(A place to catch all those hydrocarbons instead of the intake manifold)

Any suggestions for cleaning the throttle body? I suppose I should learn to test all associated sensors... At least if I don't find the answer to my trouble yet, I can tighten up the wire on the throttle valve to make it idle higher (as if holding the gas down slightly). Maybe then it won't stall in idle.

Hopefully I find a second vehicle soon so I can take this one off the road.
 

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Discussion Starter #12
Daewoo Manual

I have the link to the manual. It's a sticky on the main page. Here's the link
Daewoo Service Manual
Hopefully it can help you find the problem
I can't seem to read the manual. When I click to expand the options it won't expand anything beyond 'service manuals'
Can you please try to view it so I'll know if it's a site problem or my browser?
 
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