Constant Adjustment of A/F Levels

[IJ.]

SG: It's time to unplug ALL of the piggy backs and get back to basics.

Verify that it runs correctly on just the ECU as there are too many variables in play at the moment.

 

[supraguy31]

Ok, Were I disconnected the VPC/SAFC and put the Stock AFM back on. Started the car up and the Initial VF Signal was .05 but after letting it Idle for it bit, It moved to 1.1v

Turn it off and restarted it, VF Signal went to 2.1 and the A/F guage at Idle didnt go rich at all. I noticed something else though. Looks like someone Tapped the top of the FPR to try and increase the fuel Pressure. I will draw up a Diagram on what Im talking about. I heard that you could to it but I never seen it done. I think its RRFPR time.

Robert

 

[IJ.]

Rob: Sorry I'd assumed your fuel system was functioning correctly and this was just a management issue. (doh)

 

[flubyux2]

figures... Tunes dont change or deteriorate. it had to be a hardware issue.

also... why are we setting the Hi-throttle point at 75%? i can get full boost at 25% throttle. i would like to t hink that i need fuel enrichment SOONER than 75%. i have my throttle points at 15% and 25% since my turbo can be spooled with as little as 25% and as early as 2100rpm in 5th gear.

normally, youd lean out the low throttle map to compensate for larger injectors or increased fuel pressure. VPC people probably wouldnt have to deal with it since they can get chips to recalibrate the base settings for the larger injectors...

however, im running 52psi static fuel pressure on stock 440's and a Lex meter with a GSS341 in the tank, not rewired. i leaned out the 1000rpm area on the low throttle so the ECU wouldnt go nuts trying to trim the fuel to get the O2 feed back readings in range. the ecu only has a certain amount of control over the fuel trims. if i tried to idle on larger injectors, the ecu wouldnt be able to trim it back down.

 

[Poodles]

the stock FPR is quite durable, but any cletus trying to get more pressure out of it by crushing it would probably damage it instead of making it have higher pressure...

 

[Buddafucco]

I have a Walbro pump, bypassed j-tube, constant 12v, & aem fpr. My car does it regardless of fpr or pressure, so I doubt if thats the problem.
Did you let the car fully warm up when you restarted it without the AFC hooked up?
There is a mention on the sonic website about heat soak making the car run rich on restart but it only gives a grocery list of possible problems to start checking.

 

[supraguy31]

Well Dam Dude and I thought that I was getting somewhere.

Yes I let the car fully warm up and infact when it does completely warm up, the VF Signals jumps from the .09 to the 2.10 settings and doesnt miss a Beat after that. If Im correct the MKIV TT pump pushes more FP than the Walboro pump does, When I changed out that Bad FPR that was on there last night and Put another one on, the Idle of the car Dropped down to 16.0 and it doesnt matter how many times I start it now, it Still Idles at 15.7 to 16.0 so Now Im working on the Mid Throttle Tuning and once that is complete I will see where I am at that Point. Im still replacing that Stock FPR with a Aftermarket one that I can read FP with. Just need to find one on here or somewhere else.

Robert

 

[Buddafucco]

You lost me a little bit. You said your working on tuning mid throttle, does that mean you hooked your vpc & afc back up? And your a/f's aren't changing to rich any more?

 

[supraguy31]

Im on the Stock AFM at the moment. I havent hooked anything back up yet but when I do Im sure it will jump around again.

Im tempted to Pull it all off and put it up for sale. I have the 440 and 550 chip for the VPC so maybe someone else will have better luck with it. Looks like MAFT Pro or AEM coming up if I sell it.

 

[JesseH]

Has anyone found the solution to this? I am also having this same problem so i figured I would add it on to this post rather than make a new one.

Im having the exact same problem as the thread starter, My A/F ratio is right where it should be for factory settings at idle, cruise, and wot until i turn the car off. When i shut it off then back on when the motor is still warm i get around a 12.5 afr at cruise and 13.0 afr at idle. Once the motor cools down it is perfectly normal again.

I have changed just about everything i can think of that would have a effect with this situation. I even took the maft basic off and went back to the stock AFM till I get the problem resolved. I have changed my narrowband oxygen sensor, And my wideband sensor is fairly new (about 6 months) and it is about 30 inches away from the turbo.

Can anyone point me in the right direction? or any tips would even be a big help.

thanks,
Jesse

 

[supraguy31]

I ended up replacing the wiring harenss. Seems that I had some bad wiring somewhere in the harness. I unstalled the new one and as soon as I started it up, Everything started working as it should. A/F Levels never changed from then on.

You might want to look at that since you have done everything else like I did. I replaced all the Sensors (Wideband and Narrow band) and nothing changed until I replaced the harness

 

[JesseH]

I ended up replacing the wiring harenss. Seems that I had some bad wiring somewhere in the harness. I unstalled the new one and as soon as I started it up, Everything started working as it should. A/F Levels never changed from then on.

You might want to look at that since you have done everything else like I did. I replaced all the Sensors (Wideband and Narrow band) and nothing changed until I replaced the harness

ahh thanks....that saves me so much, i was about to pull my hair out with this thing lol Did you change out the ECU too? Before I saw your post the next thing on my list was the ECU then the harness just beacuse Im sure I could borrow one and it takes about 10 minutes to change.

 

[supraguy31]

Did that too and it didnt make any Difference.