mark kibort

good news, the 5 liter part euro Ljet racer is alive, but not after a fight. it seems to only want to idle with the AFM connected, but not in the air stream . its running real fat!! as soon as you plug the AFM into the "U" it floods out.

second issue is a major water leak at the top of the engine, but we didnt change the "O" ring, so i guess we have to do that over again too.

Any ideas what could be the issue? I remember the themo switch is critical, as it can be disconnected for a second, start it a few cranks til it catches, then plug it back in and it will start right up (i guess it adds a bunch of fuel) . Im thinking if that isnt working properly, as it could make it run real rich too, right? Ive pulled that connection while the car is running and it would just die on Scots car before when testing ways to start the car without the cold start circuit. I took the connector off as it seemed weak, and plugged the individual wires in separately and this didnt change anything. it only runs with the AFM, off the "U".

I dont think the temp sensor has anything to do with anything, isnt that just for the red light at overheat? the temp gauge works, and we got the engine to temp. all seems ok with the block, so thats good news!

im now thinking Ljet computer, and possibly a bad AFM?? what in the heck could have changed from the time we ran the engine a the races to scots house , some runs around town and then took the thing apart. all the same parts, no real changes. It does run fairly well at about 2000rpm, where the fuel that is being produced, matches a part throttle setting, where normally with the AFM pulled out, it would be way to lean to run!! ( as a note, i can run a properly running Ljet engine with a screwdriver in the flap vain and the AFM out of the "U".)

HELP!!

MK

ZEUS+

It does sound like an AFM problem. Could it have been stored in an area with high moisture ? Try removing the plastic cover from the AFM and cleaning the contact areas with a fresh pencil eraser. This has worked me many times. Putting a screwdriver in basically overcomes the vacuum leak from taking it out of the picture.

mark kibort

actually, the screwdriver sets the afm at a flap postion that mimics the position that it would be at at idle air speeds. remember, the AFM is on the atomospheric side of the throttle plate. we did this, when we had false air, so that we could actually get the car running as the air moving over the flap vain wasnt producing the signal for enough fuel. (due to false air leaks)

I have a hard time believing its the AFM. nothing was really changed since it was all taken apart. i have a better time believing i got a connection wrong somewhere or a ground wire is not grounding.

It certainly is a possiblity that the AFM is stuck or sending a higher position signal making way too much fuel to be sent. However, i know that cold start switch also does something funky with the mixture that could be the issue too.

thanks. anyone have any other ideas. I was racking my brain for 3 hours on this one and im just mad now !!

Mk

Normy

I'm not well acquainted with L-jetronic, but if an LH car suddenly started to run real rich ["fat"?], I'd suspect that the T2 sensor on top of the water bridge had lost its' connection with the computer. Infinite ohms = rich.

Does L have a T2?

N

ZEUS+

Sorry for my mistake, "unmetered air"that you have created. I guess you dont see driveability problems on a daily basis. The AFM sweep contacts can become poor over time. Just a suggestion from your story.

mark kibort

Thanks for the suggestion. Its just hard to believe that the AFM would suddenly just have an "offset " issue, as when it is running, if i deflect the flap even a small amount , i can flood it out as is.

I just went over the manuals and it sure sounds like it is the temp II or as it lists for the 83 cars, "temp sensor". if it is disconnected, the car goes full rich. maybe i dont have a connnection there or im using the wrong one.
on the electrical drawings, the red/white wire in a connector goes to the cold start, while the "temp sensor" has the yellow and brown wire. now, i just have to confirm that its making a connection there, or have a break somewhere down the line.

thanks

mk

mark kibort

thanks Normy!

Im with you on this one. I was mixing up the thermoswitch one with the temp sensor. as i mentinoed, the manuals call the 83's Temp II plug, just "temp sensor" (temp I is under the air filter on my S4)

i was messing with the horizontal connector, (thermo time switch) vs what i should have been looking at, the "temp sensor" which is vertical.

sure sounds like that could be the issue. it has a blue'ish connector, and there is a black connector that i think goes toward the rear to the cold start, but that has been removed. i just have to confirm that i havent got those mixed up.

thanks

mk

cdbtx

Mark,

You said it has the 5.0L block - didn't this engine have a 4.7L Euro top end? You're right about the thermo switch - which is how I start my car - with a momentary switch to flood the engine with fuel.

What vacum lines are you using on your throttle body?

Chances are it's really going to be something simple.... had similar issues when I reassembled mine - frustrated I changed the brain, etc.... but in the end I kept finding vacum leaks - Gasket on the throttle body, gaskets on the intake runners.

Chuck


83 Kiln Red 928S

ZEUS+

From your first post I thought you said with a properly running system. Is it with this vehicle you are doing the screwdriver thing ?

mark kibort

The first post said that the AFM has to be removed in order for the car to run, as it is so rich that any deflection of the afm due to air flow through it richens it even more so that it wont even come close to running.

the screwdriver thing, allows the afm to have the flap with the same position (thus the same injector fuel duration) as you would have it it was connected. this handy when you have false air and it wont start. this way, you can richen the mixture up by the screwdriver as to match the false air and throttle body throttle plate setting and get the car to run and idle.

with scots car, im not using the screwdriver, as the mixture is unusually rich. the vane cant be moved even a little, it has to be closed and not part of the air stream. this is why i remove the AFM and just run the car without it . in fact, the mixture is too lean for it to idle as well, i neeed to run about 2000rpm to have it run right as far as mixture level. this means, right now, i have the fuel being produce to support 2000rpm idle, with the flap all the way closed in the AFM. sure sounds like the tempII issue, doesnt it? but it is connected so im wondering where else there could be an issue.

thanks
Mk


Mk

mark kibort

any other ideas?
stopped by to see the car tonight. the connection seems to be correct on top of the thermostat housing. (temp sensor). it may have a bad connection, so we will do some meter work tomorrow on it to see how it ohms out.

any other ways we could be at full rich at idle speeds? again, we have enough fuel to run at 2000rpm, and the flap vain is full shut, becasue it is not even plugged in to the 'U" , but it is plugged into the circuit. maybe there is a wire that is not connected or corroded on the AFM connection.???

Mk

IcemanG17

Is it me or is Scott just cursed.......

mark kibort

im beginning to wonder. BUT, i was responsible for not putting on a new water bridge O ring, and the car is running and feels pretty strong. however, what is going on with the "rich" situation?????? if it isnt that temp II circuit, i give up!!

MK

IcemanG17

MK
I sure don't know much about the older engine mangement......everything I think of that could be wrong is all LH+ .....but temp sender is one of them?

mark kibort

temp II or the connection to pin13 on the computer could be the issue

MK