Injector Question

[supra_kid101]

Ok I just bought an '89 N/A after being supra-less for almost 4 years. It's supposed to use the High Impendance green injectors however the moronic kid put low impedance yellows in it. Needless to say it ran like crap till I got it home. I had a set of 2JZGE injectors laying around which are supposed to be 330cc and high impedance so I put them in. It runs a million times better now but at start up it's super rich. I figured the computer would compensate for the extra fuel (330cc vs 315cc). Am I correct in assuming this? After it warms up it's runs better. Should I unplug the cold start and see if that helps?

 

[Dirgle]

At start-up the engine is in a open-loop operating mode and not incorporating any feedback from the O2 sensor for fuel trim. It won't start making adjustments until it reaches operating temps and switches into closed-loop mode.

 

[hvyman]

What's super rich? Blowing black smoke?

 

[supra_kid101]

hvyman


What's super rich? Blowing black smoke?

Yes it's blows black smoke. If your near the exhaust your eyes burn too. I unplugged the cold start and that helped quite a bit on start up. It's rich bur not smoking like yesterday. Am i mistaken in thinking the computer could handle an extra 15cc of fuel? I was told to unplug the battery and let the computer relearn it's maps. Could that help?

 

[Dirgle]

I suppose it's possible over time. Reg Riemer does confirm that the TCCS indeed use stored data from closed loop operation to modify open loop maps.

Taken from:http://suprasonic.org/pub/SONIC/MA70/TNSTCCS2.txt

The 1987 to 1995 TCCS ECUs use learned value mode to trim the long and short
fuel trims, which is shown by the Vf output voltage. The TCCS watches and
learns what is happening in closed loop mode and this data is recorded and used
to form the open loop mode fuel calculations. I have learned this information
from very reliable inside documentation on the function and control of the TCCS
ECU. Some {quote unquote} ECU tuners say that the open loop mode is nothing
more than a fixed map picture in the memory of the TCCS ECU.

I know this is an incorrect statement. I have written proof that the TCCS learns
where to put the open loop map. It is true that there is a base map that is in
memory but the TCCS can trim this based on engine conditions, air leaks, fuel
pressure problems, old age or any of the other possible contributors. In open
loop mode, the O2 sensor meter will display the shift from the usual pulsating
closed loop swinging LED's to just locking in on one LED suggesting the mixture
coming down the exhaust system.

But I'm not sure how long it would take the TCCS to compensate for the extra 90cc's in closed loop, and then apply those adjustment to open loop.

 

[supra_kid101]

Worth a try. Worst case scenario is i put greens back in once i find them.

 

[Nick M]

Open loop is not rewritten by closed loop. Long term fuel trim is adjusted by TCCS by looking at short term, and that may be what the author is thinking about. Fuel trim is followed in closed loop. When you go past the set amount (20%), you get your rich code and revert to open loop.

The Ford EEC-IV did what he is talking about, and I don't remember if GM did. Ford's program was called adaptive strategy.

 

[supra_kid101]

Going to hook up an SAFC II and AEM UEGO tomorrow and see what I can do.

 

[Dirgle]

Open loop is not rewritten by closed loop. Long term fuel trim is adjusted by TCCS by looking at short term, and that may be what the author is thinking about. Fuel trim is followed in closed loop. When you go past the set amount (20%), you get your rich code and revert to open loop.

The Ford EEC-IV did what he is talking about, and I don't remember if GM did. Ford's program was called adaptive strategy.

Your way makes sense. But I've never known Reg Riemer to dissimate factually incorrect info. I recall JJ mentioning some thing about this at one time. It would be nice if he could pop in here and confirm or deny.

 

[Nick M]

Toyota has many publications and says short term fuel trim is used to modify long term, up to 20%. That is what they claim. When you go past 20%, you revert to open loop.

http://www.autoshop101.com/forms/h25.pdf

Page 15 of 24, but the whole pdf should be read by most here.

 

[Dirgle]

Nice, I haven't seen this posted on here since before the last forum crash. A good read indeed.

 

[Nick M]

By the way, I have written things then gone back later, looked at what I wrote, and thought what the hell? So those things happen.