l-jet problems Options

[driver_37_kart]

heres the problem, i was driving along running fine, until my negative battery terminal came loose off the wire, which then everything died on the car. i shoved the wire back in (i had no tools with me) and went for another mile or so until the wire fell off again, but this time when i hooked it back up it didn't start. (i don't know if the ground wire story has anything to do with my problem or if it is pure coincidental)

so where i am now is, it has spark and fuel in the rails. it starts off the cold start valve until it runs out of fuel and then it dies. i pulled off the terminals to the injectors and put a test light to it and it pulsates but the pulses appear to fade after it starts up. so its almost like the resistor block isn't energizing (i've never heard of one going out) so thats where i am now. everyone tells me to leave the fuel injection on but i'm sure losing me patience and money over it.

[ClayPerrine]

Check the double relay. It supplies power to the injector and the computer. If it fails, all the injection quits.

[r_towle]

First off,clean and re-install a tight battery connection.

Then, with the key in the run position, open the air cleaner...remove the paper filter...slide your hand in and activate the flapper valve which will activate the fuel pump.

Make sure the fuel pump is working...

You may have a fuel deivery problem, you could have blown a relay or fuse....check your relay, both the big ones under the battery, and the single one in the relay board...

rich

[driver_37_kart]

i replaced the dual relay and the fuel pressure is at 35psi the injectors work and i switched out the air flow meter with no different results. i just find it odd that it sends power to the injectors.

[jd74914]

Did you some how ground the brain? My car would only start on the coldstart valve until I found out that Pin 1 (IIRC) in my brain was grounded. Once i undid that the car ran perfectly

[Dave Bell]

What to you mean when you say that you, "switched out the air flow meter."

Do you mean you took it completely out of the system and still had the same results with and without it... would indicate a bad electrial connection to the air flow meter.

Or do you mean you switched in a different air flow meter and got the same results.

[driver_37_kart]

i switched out the meter and got the same results, therefore unless i happend to have gotten two bad airflow meters, my bet is that the problem isn't the air flow meter

and also, i have checked the head temp and it is good (going by the 914 george hussey book) and i've replaced the relay on the relay board. the onthing i have not checked other than jd's idea is the resistor block.

[markb]

Doesn't disconnecting the battery while tha car is running kill the alt? Or is that just djet thing?

[Brando]

Check all your fuses... Probable that in disconnecting the battery terminal could cause an increase in amperage blowing a fuse.

Last worst estimation: The ECU got a lot more amperage than it should have.

[ClayPerrine]

QUOTE (driver_37_kart @ Dec 17 2005, 06:06 PM)

i switched out the meter and got the same results, therefore unless i happend to have gotten two bad airflow meters, my bet is that the problem isn't the air flow meter and also, i have checked the head temp and it is good (going by the 914 george hussey book) and i've replaced the relay on the relay board. the onthing i have not checked other than jd's idea is the resistor block.

FYI.... You can remove ALL the relays on the relay board on an L-Jet injected 914 and it will still run fine. The L-Jet system uses NONE of those relays.


Did you check the pulse on the injector when it is cranking or running? There are different ways to engage the double relay when its cranking vs when its running.

[sean_v8_914]

sounds like yous guys have some good L-Jet experience. the above is all good stuff.

I would go over that double relay plug. it gets nasty there under the battery and causes wierd issues. consistent with what clay said, it could engage one mode but not the other.

is that connector clean?

[Tobra]

I am pretty sure everything on the L jet can be checked with a test light, do you have one? Is L-jet the same on VW and on Porsche? Can't imagine they are too different. My Bentley for the SB has a pretty detailed description of the L jet setup, sort of an add on chapter at the end, with photos of a bald German guy who appears to have eaten too much strudel pointing things out. That dual relay is pretty spendy isn't it?

[Mueller]

QUOTE (driver_37_kart @ Dec 17 2005, 04:43 PM)

i just find it odd that it sends power to the injectors.

hmmmm, I find it odd that someone buys a 30 year old car and does not track down all the information they can possibly find to help understand the car before they start to have troubles (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/wacko.gif)

L-jet troubleshooting guide

it's not written for the 914, but it gives you the basics so that you should understand the L-jet front and back....