1.8 Ljet overfuels |
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1.8 Ljet overfuels |
davesprinkle |
Dec 30 2007, 09:09 PM
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#1
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Senior Member Group: Members Posts: 720 Joined: 13-October 04 From: Berkeley, CA Member No.: 2,943 Region Association: None |
My 1.8 Ljet left me stranded yesterday. I did the usual debug stuff. Turns out the ECU is overfueling the engine. Injector pulsewidths are 10ms to 15ms under cranking conditions. This is roughly 10x what I would expect at startup. Anybody have any suggestions for what might be causing this problem? The airflow sensor maybe?
Thanks for any suggestions you can offer. -dave sprinkle |
Twystd1 |
Dec 30 2007, 09:17 PM
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#2
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You don't want to know... really..... Group: Members Posts: 2,514 Joined: 12-September 04 From: Newport Beach, California Member No.: 2,743 |
Check your grounds FIRST....!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
BROWN wires. LOOK in your manual for ALL the injector connection points. Then just for shits and grins. Pinch off your cold start injector fuel line with a flat faced locking pliers (Vice Grip). Or pull the fuel line and plug it. Just to keep that possibility out of the over fueling equation. Clayton |
Katmanken |
Dec 31 2007, 09:11 AM
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#3
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You haven't seen me if anybody asks... Group: Members Posts: 4,738 Joined: 14-June 03 From: USA Member No.: 819 Region Association: Upper MidWest |
If your fuel pressure regulator is sticking, then you will get a higher fuel pressure and squirt too much fuel during a normal injection time.
Check the pressure. And the CHT. Ken |
davesprinkle |
Dec 31 2007, 09:39 AM
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#4
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Senior Member Group: Members Posts: 720 Joined: 13-October 04 From: Berkeley, CA Member No.: 2,943 Region Association: None |
Thanks for your responses, guys. Ground are OK. Fuel pressure is 40psi.
Here's the fundamental problem -- the injector pulsewidths are 10ms when cranking. This is roughly 10 times larger than what would be valid for a starting condition. It ain't the pressure, and it ain't the cold-start valve. The ECU is commanding too much fuel. |
Cap'n Krusty |
Dec 31 2007, 09:58 AM
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#5
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Cap'n Krusty Group: Members Posts: 10,794 Joined: 24-June 04 From: Santa Maria, CA Member No.: 2,246 Region Association: Central California |
FIRST thing to check on a 1.8 is the air flow meter. The Cap'n
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davesprinkle |
Dec 31 2007, 03:37 PM
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#6
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Senior Member Group: Members Posts: 720 Joined: 13-October 04 From: Berkeley, CA Member No.: 2,943 Region Association: None |
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davesprinkle |
Mar 29 2008, 12:59 PM
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#7
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Senior Member Group: Members Posts: 720 Joined: 13-October 04 From: Berkeley, CA Member No.: 2,943 Region Association: None |
I've finally found the cause of my ljet fueling problem. A puncture in the pressure reg diaphragm was passing fuel through the vent line and was dumping it into the intake plenum. Note that the pressure reg was STILL MAINTAINING PRESSURE even while filling up the engine with raw fuel.
Why am I surprised? I should have inferred from the deterioration of my targa seal that rubber parts don't last 30 years... Thanks to everyone who offered advice and spare parts. |
Cap'n Krusty |
Mar 29 2008, 04:05 PM
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#8
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Cap'n Krusty Group: Members Posts: 10,794 Joined: 24-June 04 From: Santa Maria, CA Member No.: 2,246 Region Association: Central California |
That's not all that uncommon on Vanagons, BMWs, and Volvos, but it's the first 914 I've heard of with that failure. Glad to hear you found it! The Cap'n
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davesprinkle |
Mar 29 2008, 06:56 PM
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#9
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Senior Member Group: Members Posts: 720 Joined: 13-October 04 From: Berkeley, CA Member No.: 2,943 Region Association: None |
Yeah, thanks for the support, Cap'n. Wanna sell me a new reg? Cause I don't think I'm gonna trust the spare one I've got in my old parts bin.
That's not all that uncommon on Vanagons, BMWs, and Volvos, but it's the first 914 I've heard of with that failure. Glad to hear you found it! The Cap'n |
type47 |
Mar 29 2008, 07:02 PM
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#10
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Viermeister Group: Members Posts: 4,254 Joined: 7-August 03 From: Vienna, VA Member No.: 994 Region Association: MidAtlantic Region |
A puncture in the pressure reg diaphragm now how in the world did you find that? or think that was a possibility? you're GOOD! (IMG:style_emoticons/default/pray.gif) |
davesprinkle |
Mar 29 2008, 07:41 PM
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#11
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Senior Member Group: Members Posts: 720 Joined: 13-October 04 From: Berkeley, CA Member No.: 2,943 Region Association: None |
Thanks for the kind words, but I can't claim any brilliance on this one. It was a triumph of perseverance over lack of insight. I tried a new ECU, a new loom, a new sensor, but still had the same problem of too much fuel. Finally, today, with the injectors all removed from the engine, I STILL HAD FUEL GETTING INTO THE ENGINE. What the EFF? Is this engine MANUFACTURING gasoline??? The last remaining connection between the fuel system and the plenum was the reg vent line. I pulled it off, turned on the fuel pump, and sure enough, it pissed fuel into my face. Don't worry about me, I'll recover my eyesight soon.
So, no, I'm not good. I'm slow. It took me, what, 3 months to figure this out? Jeez... A puncture in the pressure reg diaphragm now how in the world did you find that? or think that was a possibility? you're GOOD! (IMG:style_emoticons/default/pray.gif) |
jesiv |
Mar 29 2008, 10:38 PM
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#12
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Senior Member Group: Members Posts: 552 Joined: 5-August 07 From: Pensacola/Milton, Florida Member No.: 7,975 Region Association: Northern California |
I don't quite understand. However, this sounds totally awesome. Do you have pics of what you are describing. I have a 75 1.8 and I am trying to understand what is casuing it to run so rich.
Regards, James |
davesprinkle |
Mar 30 2008, 12:10 AM
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#13
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Senior Member Group: Members Posts: 720 Joined: 13-October 04 From: Berkeley, CA Member No.: 2,943 Region Association: None |
Sorry, James, don't have any pics of the damaged pressure regulator diaphragm. The pressure reg is a crimped can, so I haven't seen the puncture. I'm just inferring it from the fact that I've got fuel coming out of the vent line -- the only way this could happen is if the diaphragm is damaged.
If your 1.8 is running rich, I would suggest checking out the airflow meter. It could have been damaged by a backfire, which is a common failure mode. It might also be a cold-start valve that isn't shutting off. You might also want to verify that your fuel pressure is OK. Good luck. -dave I don't quite understand. However, this sounds totally awesome. Do you have pics of what you are describing. I have a 75 1.8 and I am trying to understand what is casuing it to run so rich. Regards, James |
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