Power Enrichment

Hey guys,
Just finished doing a VZ 6.0 turbo, runs great took a bit of tuning but got there in the end.One thing i did notice tho was that the engine is reluctant to drop out of 14.7 commanded a/f when just rolling on the boost. Played wit all the P.E figures, its great if you squeeze the throttle quickly drops straight in. But if gently rolling on the throttle and easing into boost it wont richen up and can even be made ping a bit.Anyone else experienced this. Its really noticable on the dyno where you can hold a load, not as bad on the road but still there.Any ideas??

Sounds like you need to adjust your Normal/Hot PE Enable Tables...

Make a map that can log RPM vs. TP% vs. MANVAC and log those 3 pids. Set the labels for the RPM rows based on the increments in the PE Enable tables in the tune and the TP% columns to 0~100 in increments of 5. MANVAC is your data. When looking at your log, don't take the average "x" - hit the down arrow to see the lowest MANVAC reported for each RPM/TP% cell. Ideally, I like to set PE to enable based on RPM/TP% cells that see 10kPa or less of MANVAC. Then, adjust the enable tables accordingly. On my D1SC car, I hit PE by 35% throttle or less. Stock, it was set to 60% or so down low.

Unfortunately there is no tables as such in the VZ 02598977 calibration, thats the problem.Theres only really tps enable and commanded fuel.theres no rate of change style figure to set the P.E running. the problem is with so much power on tap that lane changes etc require only small throttle changes so the engine doesnt see enough change in tps. ive set the P.E to commence at 85kpa but it can hang on till 110kpa when the throttle pickup is eased on

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Originally Posted by shane

Unfortunately there is no tables as such in the VZ 02598977 calibration, thats the problem.Theres only really tps enable and commanded fuel.theres no rate of change style figure to set the P.E running. the problem is with so much power on tap that lane changes etc require only small throttle changes so the engine doesnt see enough change in tps. ive set the P.E to commence at 85kpa but it can hang on till 110kpa when the throttle pickup is eased on

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There's no B3618 PE Enable table?

Hi Shane.

The PE tables need to be viewed a little different in the VZ. You don't say if it's an E38 or an E40 ECM and there may be no difference, but it will need to be checked as the following has only been tested against an E38.

As would be expected, you can control PE by both TPS% and MAP in the E38. For starters, ensure you are logging with ETC-TP% ( GM.ETCTP ), do not use GM.TP as it will give misleading results.

The main parameters that you will want to look at are B0157 ( MAP threshold ) and B0156 ( P.E. Mode Throttle Threshold ) and to a lesser extent B0155 ( P.E. Mode RPM threshold ). Assuming the engine is at normal operating temp, these settings should give you the control you need. There is one fairly large "gotcha" though in B0156.

The TuneTool TPS% settings in the table do not directly match up with measured ETCTP% readings. So you have 2 options...

1. Set the ETCTPS% setting very low and control PE with the MAP setting.
2. Re-plot the ETCTPS% axis on the table to match the measured values and adjust as required.

I've attached an image of the remapped ETCTPS% figures that I did on mine a while ago. It shows that if you want PE to come in at a ETCTPS Reading of 30%, you need to use a setting in the TuneTool of just 6%. I think this is your problem as easing on the throttle will build boost quickly, but keep the ETCTPS reading fairly low. The stock settings I have are 48% up to 3K RPM which actually works out to nearly 67% TP.

For a boosted application, you should probably be running a very low TP% setting and then controlling PE by MAP anyway. that way as long as there is boost, you have PE. Try the following settings and see if it helps...

B0156 = 4% across the board.
B0157 = 80kPa

Additionally, you may want to alter B0169 to a slightly larger value that stock to ramp in PE a little quicker.

Simon.

Good advice. This will solve your problem, Get PE enabled with low throttle percentage and 80kpa manifold vac. Even possibly lower vacuum, I would be commanding 13.0 by 80kpa in a turbo engine and step down to 12.0 by 100kpa.