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-   -   Odd Gremlin with Fuel Light ON (https://www.ft86club.com/forums/showthread.php?t=45613)

sw20kosh 08-30-2013 03:32 PM
Odd Gremlin with Fuel Light ON
 
This is a weird question that maybe someone here who has modified their ecu + fuel system has a simple answer to.

Twice now I have lost throttle control while cruising on the freeway when the fuel low level light was on. Both times were several minutes after the light came on.

A. It will drop me out of Cruise Control and I will not be able to accelerate.
B. Car will coast for a few secs (engine still on) and then abruptly I'll have throttle control back again.
C. A few secs later I will lose throttle control again.
D. This cylce repeats.

Both times I pulled over to a gas station and filled her up with gas. Issue disappears after that.

I am thinking it must be a fueling issue but can't figure out what it may be? I haven't touched the fuel system since the Innovate Supercharger and Deatschwerks Fuel Pump install 3-4 months ago.

The car runs perfectly otherwise. AFR's are spot on. Fuel trims look good. No hesitations or loss of fuel to the engine when the tank is filled. No codes.

xjohnx 08-30-2013 03:45 PM
Quote:
Originally Posted by sw20kosh (Post 1179023)
This is a weird question that maybe someone here who has modified their ecu + fuel system has a simple answer to.

Twice now I have lost throttle control while cruising on the freeway when the check engine light was on. Both times were several minutes after the light came on.

A. It will drop me out of Cruise Control and I will not be able to accelerate.
B. Car will coast for a few secs (engine still on) and then abruptly I'll have throttle control back again.
C. A few secs later I will lose throttle control again.
D. This cylce repeats.

Both times I pulled over to a gas station and filled her up with gas. Issue disappears after that.

I am thinking it must be a fueling issue but can't figure out what it may be? I haven't touched the fuel system since the Innovate Supercharger and Deatschwerks Fuel Pump install 3-4 months ago.

The car runs perfectly otherwise. AFR's are spot on. Fuel trims look good. No hesitations or loss of fuel to the engine when the tank is filled. No codes.
how's the rail fuel pressure look?

s2d4 08-30-2013 03:50 PM
probably due to the shape of the fuel tank.

Sportsguy83 08-30-2013 03:55 PM
Quote:
Originally Posted by s2d4 (Post 1179087)
probably due to the shape of the fuel tank.
It doesn't make sense that it happens at cruising. If it were going sideways on the track ok, but cruising it should have nothing to do with tank shape.

Dezoris 08-30-2013 03:57 PM
Log when it happens is timing getting axed?

King Tut 08-30-2013 07:15 PM
What is the Check Engine Light you are getting when this process starts?

sw20kosh 08-30-2013 07:32 PM
Quote:
Originally Posted by King Tut (Post 1179583)
What is the Check Engine Light you are getting when this process starts?
Sorry typo. Meant to say Fuel Low light.

mike the snake 08-30-2013 08:10 PM
Sounds to me like your fuel level meter maybe didn't go back in correctly and even though it shows you having a little fuel left, you're actually running out of fuel.

That would explain why it works fine while the gas light isn't on.

Grymm86 08-30-2013 09:39 PM
Do you usually fill the take completely after this happens? If your fitting over 12.5 gallons your fuel light might be coming on a little late. Mine comes on after about 10.5 gallons.

sw20kosh 08-31-2013 12:08 AM
When I filled up the last two times when this happened, it only filled up to 10.2 - 10.5

I will data log it but have to wait till fuel is low.

Dezoris 08-31-2013 12:46 AM
Quote:
Originally Posted by sw20kosh (Post 1180086)
When I filled up the last two times when this happened, it only filled up to 10.2 - 10.5

I will data log it but have to wait till fuel is low.

If it it is ecu, fuel or timing related you will see it. Could be mechanical/pump related too. But log and check first before taking anything apart.

evo4g63 08-31-2013 02:23 AM
Quote:
Originally Posted by Dezoris (Post 1180144)
If it it is ecu, fuel or timing related you will see it. Could be mechanical/pump related too. But log and check first before taking anything apart.
+1

ft_sjo 08-31-2013 02:51 AM
Are you running RaceROM?

sw20kosh 08-31-2013 03:42 AM
Quote:
Originally Posted by ft_sjo (Post 1180318)
Are you running RaceROM?
Yes I am. You have a suspicion about something?

ft_sjo 08-31-2013 03:50 AM
Quote:
Originally Posted by sw20kosh (Post 1180362)
Yes I am. You have a suspicion about something?
Well, you said the only symptom is you 'loose throttle control'. You didn't say the engine cuts out, splutters, hesitates, or anything. Therefore it looks like an electronic issue, and as you know the electronics are often controlled by software... and I know RaceROM in the past has had issues with fuel gauges and stuff.

mike the snake 08-31-2013 07:29 AM
Losing throttle control=cutting out IMO. Otherwise what else would it be? If it stayed where it was that would be a "stuck throttle".

mad_sb 08-31-2013 08:52 AM
Sounds like the pump is getting starved to me. The pump is probably pushing more fuel than the siphon can pull. Should probably fill up before the light comes on if you want to keep your motor happy.

It's possible the pump has shifted in the housing if this a relatively new symptom. Also possible the pump is meeting a pre mature end.

Quote:
Originally Posted by sw20kosh (Post 1179023)
This is a weird question that maybe someone here who has modified their ecu + fuel system has a simple answer to.

Twice now I have lost throttle control while cruising on the freeway when the fuel low level light was on. Both times were several minutes after the light came on.

A. It will drop me out of Cruise Control and I will not be able to accelerate.
B. Car will coast for a few secs (engine still on) and then abruptly I'll have throttle control back again.
C. A few secs later I will lose throttle control again.
D. This cylce repeats.

Both times I pulled over to a gas station and filled her up with gas. Issue disappears after that.

I am thinking it must be a fueling issue but can't figure out what it may be? I haven't touched the fuel system since the Innovate Supercharger and Deatschwerks Fuel Pump install 3-4 months ago.

The car runs perfectly otherwise. AFR's are spot on. Fuel trims look good. No hesitations or loss of fuel to the engine when the tank is filled. No codes.

chadstyle 09-02-2013 11:10 AM
My guess is that it has something to do with the fuel pump install and the sending unit. There should be no fueling starvation or issues at "cruising" speeds. I agree with the above comments regarding logging the event. I didn't see any mention of an aftermarket throttle control module being used so I have to believe its something mechanical.

Best of luck diagnosing the gremlin..interested to see what it is.

448hpsti 09-02-2013 02:20 PM
Whose tune, just curious
Otherwise stock?

xjohnx 09-02-2013 10:34 PM
i had a similar issue when i was having fuel pump install issues. My tuner was able to see that from my datalogs (specifically the fuel rail pressure).


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