falcor

What kind of dump valve are you using? I've experienced similar problems due to a faulty (recirculating) dump valve.

dkcaims

Such as ?

Once is runs for a minute and the AFR's get down to 10.5 area, you can see the exhaust is black and it burns nose.
Also, just cleaned up the ground strap at the tranny, tests good.

dkcaims

I'll have to google "dump valve"... what is that? What does it do and where is it?
You sure this car has a dump valve? Same as blow off valve?

darth

"Once is runs for a minute and the AFR's get down to 10.5 area, you can see the exhaust is black and it burns nose." I couldn't determine from what was mentioned so far, whether or not you were trying to diagnose the numbers or if in fact the engine was running rich. Black exhaust is a good indicator of a rich running engine. But I'm not sure what you mean by "burns nose"? Was any work done prior to the change occurring? Sorry if I'm back stepping a bit... just trying to catch up.

dkcaims

No worries... maybe I have a sensitive nose, but when I inhale the exhaust it burns inside of my nose.
Essentially, one day it's running wonderfully, the next morning it starts running extremely rich.

darth

"burns nose" The heat outside must be frying my brain (i.e. I'm trying to work outside in the heat) ... I realized after asking that you must be talking about the odour, another good indicator! At the risk of repeating myself, was anything worked on or changed prior to the engine running rich?

dkcaims

Nothing worked on, nothing changed.

Makmov

I had this probably on a AM Turbocharged car. I am trying to remember what it was though.

It was always rich, I don't remember, though, now what I did to fix it. I did have a number of issues, however.

darth

"Found the mulitmeter... engine was run for 30 seconds an hour ago and I just now measured the resistance.
It measured .839 ohms.
I'll check it again in a few hours, but I think it should be much higher, correct?

ANYONE... ??? "

Not sure if this is resolved...Not only does it look low but 0.839 ohms is out of range based on the info given above
(i.e -
15-30c 1.4 - 3.6 Kohms
40c 1 - 1.3 Kohms
80c 250 - 390 ohms
)
The sensor has a typical resistance range of 390 ohms @ operating temperature to 3.6 Kohms @ ambient temperature.

Even if you meant 0.839 Kohms or 839 ohms. That still seems low. I would think the engine would be at ambient temperature if it ran for 30 seconds then measured an hour later.

Although the second reading of .342k ohms or 342 ohms is in the range of an 80C head temperature. I'm not sure the head gets up to 80C or 176F in 2 minutes? I would think it takes longer to get to that temperature?

dkcaims

New CHT installed this morning... Did not help.

Indycam

Did you ever use a decade box or pot to see if you could change the a/f ratio manually ?

I am thinking the computer is not seeing the chts .

Putting the decade box / pot in place of the chts would tell something .
If you could dial up and down the a/f ratio , then I would say the computer is seeing the chts .
If you could not dial it up and down I would have you do the same test right at the computer .

Have you ever hooked it up to a code reader ?

dkcaims

Not yet indycam...
The PSC1 has a built in map sensor and rewiring a couple wires I could bypass the AFM entirely and send the DME signals (.25 volts to 4.5 volts) based upon the manifold pressure. Would be ideal if I could get rid of the AFM entirely, I would think.
I'd have to install a intake temp sensor, but that should by pretty simple.
However... I did take some volt readings directly from the AFM (removed the black plastic cover, wiper arm looks OK too) and then again directly at the DME plug. Same values.

As far as the CHT goes, installed new one this morning. Did not make any difference. I did take resistance readings directly at the sensor plug and DME plug. Negligible difference.
I'll just go ahead and buy a decade box, seems like it would be handy to have anyway, but might be next week before it's "in hand".
I can connect and disconnect the sensor and other than a momentary spike in rpm's, it runs the same. It does not get any richer or leaner.

This afternoon, I removed the new 30lb injectors and reinstalled the stock ones (again). Set the PSC1 so it makes no changes to the values from the AFM. Verified that they are the same.
AFR's got down to 12.3
Better, but probably just due to the smaller size injector.

This evening or tomorrow and going to cap off the fuel line fitting that goes to the 7th injector, just to make sure that it is not the cause of the additional fuel.

My tech has is booked for another week and a half...
If it's not solved by then, I'll limp it down there and see if he can figure it out.

falcor

Dump valve or blow off valve yes, the valve that releases the compressed air when you back off on the throttle....If the diaphram (spelling?) in the valve is leaking it can cause all sorts of running issues.....

dkcaims

I'll look into that... Thanks

Indycam

I had a afm that drove me crazy for awhile , the wiper had cut a groove in the resistor . It looked fine to the naked eye but under magnification it was bad . The motor would start up fine and run fine and then it would have no power and or stop running . I bent the arm to no longer run in the groove and presto chango ...

This is what leads me to think there is something going on there . The computer should change the mixture based on what the chts is telling it . Disconnecting the chts on some cars kills the motor .

Can you start the motor from cold cold with the chts disconnected ?
If you can what does the mixture read on start up and as the motor gets warmed up ?

Have you tried to disconnect one injector at a time while its running rich ?
If one injector gets warm and sticks open ...
Can you kill the spark to each cylinder one at a time and see what happens to the running and a/f ratio ?

Did you buy gas just before this started happening ?