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Old 12-19-2020, 10:30 AM   #1
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Join Date: Dec 2020
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9-5 2003 b235r Starts from second time only

Solved: it was fuel injectors. Increased fuel start map to +20% and now it starts every time fine.

Hi all, car is 9-5 2003 b235r stage1.

So i have this strange issue for two months i think. Car fails to start from the first time but starts right up from the second time with no problems. It feels like it is just about to start and dies.. This happens only when the engine is completely cold. And for the rest of the day there is no problems.. I have tech 2 and there is no problems i can think of and all parameters seems right.


So far what i did:

New mass air flow sensor - genuine new,
New o2 sensor genuine bosh,
New CPS sensor,
Checked fuel pressure with gauge all seems normal and it holds pressure.
Checked fuel pressure regulator also seems normal. EDIT: changed to new one Bosch. Didn't helped.
Tried running fuel pump with tech 2 for 20 seconds before starting still first time not started..
Cleaned injectors with brake cleaner and spray pattern was good before cleaning..
Changed injector orings didn't helped.
Engine compression was tested a few months ago and it is good.
Di cassette was bought new about an year ago OEM so i think it is good and no check engine lights flashes or constant light. Changed to another and still no luck
New NGK spark plugs.
Evap disconnecting didn't helped.
Brake booster disconnecting didn't helped.
AMUL is about +3 and there is no air leaks.
Main and Fuel relays replacement didn't helped.
Coolant temperature sensor shows good temperature.
Absolute pressure is showing equal on 3 sensors.
Car battery good, charged.
Additional negative cable connected from thermostat housing to car battery. Other two grounds cleaned.
Adjusted throttle body to +20-30 rpms, car runs smoother but didn't help the first start


Also tried to spray a little bit of starting fluid and it starts from the first time, but again it doesn't show what is wrong with the car..



What do you suggest checking further?



Adding t7suite log from today.

Last edited by Deividas; 12-27-2020 at 12:23 AM. Reason: solved the issue
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Old 12-23-2020, 09:04 PM   #2
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Join Date: Apr 2011
Location: Mountain View, CA
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I know you said you checked fuel pressure and even primed the rail manually, but that sure sounds to me like the check valve on the output line from your fuel pump has failed. When you say seems normal, how many PSI are you reading before trying to start?

The fuel pump has two ports on it, an output and a return. The hard plastic fuel lines that go to these ports are terminated with 90 degree plastic connectors. One should be white and one should be black (or maybe some other color code on your car) and are slightly different sizes. Those plastic connectors each contain a one-way check valve.

The check valve on the return line is to keep fuel or vapor pressure from backing up to the fuel rail, which is not terribly important.

The check valve on the output is to keep all the fuel in the line between the pump and the fuel rail from draining back into the tank after you shut the car off. It doesn't need to hold full pressure, but it at very least needs to not let the line go empty.

With the car totally cold first thing in the morning, hook up your pressure tester again and lay it against the windshield where you can read it from inside. Get in and turn the key to "on". By the end of the few seconds of priming by the ECU, it should be 50 psi or thereabouts. If it's nowhere close to that, that's a strong indicator it's the check valve.

It's possible to buy the connector separately from the line for just a few bucks, but it's a tease, and they're not really serviceable. I ruined my line trying to remove the old fitting with a heat gun the first time I went through this, which seemed like a very sketchy and dangerous operation anyways, and ended up replacing the whole line. I've been through this same repair on a c900, ng900, and two viggens.
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Old 12-27-2020, 12:22 AM   #3
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Quote:
Originally Posted by jerrit View Post
I know you said you checked fuel pressure and even primed the rail manually, but that sure sounds to me like the check valve on the output line from your fuel pump has failed. When you say seems normal, how many PSI are you reading before trying to start?
Thanks but i solved my problem. In was fuel injectors. I solved it by listening to one guy and increasing fuel start map to +20%. Now it starts every time
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Old 12-30-2020, 05:18 PM   #4
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Location: Mountain View, CA
Posts: 201
If the problem was the injectors themselves, wouldn't you need to increase duration across the board to keep it from being lean?

Again, this sounds like increasing duration is successfully compensating for low pressure on first start.

Unless, your stage 1 tune had accidentally set the start map durations too low before.
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