fiveoformula

I've had an EBL for little while tuning my cam/heads 305TBI. Hasn't ever run that well (yet) but it was driveable. I recently got around to installing an 18PSI fuel regulator spring and cop car injectors. I began to tune for those upgrades and got it to run basically how it was before with the other injectors. I went to do one more tune adding a few degrees of timing across the board and now the car runs terrible at cruise speed. Idles fine and accel is ok. But cruise speed nearly pegs my wideband lean. I tried going back to a couple of my previous bins and I still have the same symptom... makes me think it might be a mechanical problem. Anyone have any insight or suggestions?

RBob

iTrader: (1)

If the ECM isn't going into lean cruise highway mode, I'd say that the fuel pressure is dropping off.

RBob.

fiveoformula

I should say it happens anytime I try to hold a constant speed. wether that's 45mph or even like 15mph. I'm suspecting fuel delivery.. or maybe a dead spot in the TPS. I wouldn't think it would go into lean cruise mode at such slow speeds correct?

RBob

iTrader: (1)

It could if the MPH threshold for lean cruise was lowered.

Are the BLMs dropping? ECM still in closed loop? Dead spot in TPS should be easily seen on the WUD.

RBob.

fiveoformula

Sorry I took so long but I have a little update, haven't found the problem yet, I'm a bit confused. I checked fuel pressure, running its rock solid at 18psi, even when driving the car in this lean situation. However, when I prime the fuel pump (key on, engine off). The pressure goes right up to 18, then imediately bleeds off to zero. I then pinched off the rubber part of the return line and primed the pump, and pressure goes way up and stays there without bleeding off. Does all this sound normal?

EagleMark

Yes that's normal.

When you installed new injectors and raised fuel pressure did you re-calculate BPW?

fiveoformula

No I didn't.. the car didn't run this way right after I installed the injectors. If that means anything. How much should I adjust it?

morgsie

iTrader: (1)

EBL Utility

fiveoformula

What?

morgsie

iTrader: (1)

Use the EBL Utility (it comes with EBL) to calculate your BPC.

fiveoformula

I found the calculator, I then adjusted the BPC from 134 to 95. still Have the same symptom. noticed that even with the car in neutral (not moving) when rev'd it will lean out if I try to hold anything over 2k RPM. Any thoughts?

RBob

iTrader: (1)

Is the INT & BLM dropping and causing it to go lean? If so then it is an O2 sensor issue.

RBob.

fiveoformula

Well this happens in open or closed loop. I think changing the BPC actaully made it drive worse.

RBob

iTrader: (1)

I would expect that as that will produce a smaller injector PW.

Have a data log of it leaning out?

I would also double check the fuel pressure. Connect a gauge, start the engine, and whack the throttle wide open. If the pressure drops even a single psi then the pump isn't keeping up.

RBob.

fiveoformula

Well I just triple checked the fuel pressure, slamming open the throttle it stays solid @ 18psi. I have not done a datalog with it runing like this yet. But I can, I've also never sent a datalog. What kind of file should I send it as?

RBob

iTrader: (1)

You can attach it as a zip file.

I thought of something early this morning. There is a good possibility that the injector PW is getting small and the compensations are not correct. This has the affect of leaning out as the injectors barely open.

Think of it this way, the PW is now smaller as the injectors have a higher flow rate. And, the additional fuel pressure makes the injectors open slower. Add to this table:

INJ - Injector Correction Offset

Note that in general this will make the engine run a bit richer. So be sure to follow up with VE Learns and expect the lower load areas to have higher corrections then the higher load areas.

RBob.

fiveoformula

Interesting, should I start out by adding a lot to see what it does?

RBob

iTrader: (1)

Try adding 200 usec to all table entries. If that doesn't take care of it add another 150 usec. This is easy to do in TP using the offset function.

Note that the 0 volt entry should be the same as the 12.8V entry. So change that too is required.

RBob.

fiveoformula

Well I got out to the car today first added 200usec and didn't notice much but added the additional 150 and that made the car somewhat driveable. Still gets really lean but now does not buck and fall on its face. Idle smoothed nicely, although very rich @ 12.4:1 on my W/B. I did try to add 20% more fuel in the VE table on every cell after 1100rpm and noticed no change, still very lean in that area.

RBob

iTrader: (1)

Have a data log to post? Otherwise we are just guessing.

The going richer is normal, the PW at this time is small so by increasing the injector offset compensation it is adding a large percent of the original PW in.

RBob.

fiveoformula

Trying to but having trouble, the file size is to big at 3.15MB and is there a way to put into a zip file?

RBob

iTrader: (1)

Use WinZip or better yet, WinRAR? Then post it.

RBob.

fiveoformula

Maybe it might be easier if I emailed it to you? Sorry to be a pain but even when I compressed it, the file is still a little to big to post.

RBob

iTrader: (1)

That works.

RBob.

fiveoformula

Alright I just sent it, thanks alot for helping me.

RBob

iTrader: (1)

Replied to email.

RBob.

fiveoformula

Well turns out both those open loop AFR tables were modified, I'm guessing I changed them a long time ago in attempt to fix some other drivability problem.. changed them back and the car is much much better driving. There is a little lean spike still there, only noticed when I accelerate from a stop very little thottle. But made a lot of progress this far!