CORV3TT3

Hi!

I've registered here after being gone for several years. I have been reading through the posts- so, not completely lost- but still looking for advice. Rbob has a similar email awaiting him in his inbox that I just sent to him- thought about posting here after I already hit send. Oops- oh well. My brain is fried for the night.

I've finally got my motor together with the cam I wanted. It's an Erson .465"in / .488"ex cam. I am running with the CFI system- but using a 80# injectors and fuel pressure set to 15psi. No- I haven't parallel plumbed them at this point, but will eventually. Same goes wiring in a IAT- haven't gotten to that one yet either.

All of this sits in an 82 Vette with EBL and a Renegade intake.

I've got a "chugging" thing going on. I also think my lean cruise is a problem- the cAFR says 16.5 during lean cruise at times. But it also runs really rich too (108 BLM).

Here's may data log. Since the engine hasn't broken itself in yet, there's not a lot to see. Any ideas around the tuning for this would be great.

Otherwise, the car seems to accelerate fairly off idle and from a stop (I haven't beat on it since the motor hasn't even been broken in.

RBob

iTrader: (1)

The cam is why it is so rich at lower RPMs. Disable highway mode by setting the MPH high:

HiWy - Min MPH

Change both values in this table to zero, this prevents async injection mode:

INJ - ASync Transition PW - TBI Only

Need to reduce all values in the following three tables by the ratio of stock injector flow to the new injector flow:

AE - MAP PW
AE - TPS PW
PRP - Gain vs O2 Error

Which is:

66 / 85.9 = 0.77 (multiply the table entries by .77).

Then do VE Learns, lots of them. Three is more info in our Intro to Tuning Part 2 on our web site:

http://www.dynamicefi.com/Tune_Intro2.php

The chugging at lower engine speeds may not be avoidable. The cam isn't going to start working until 2200 - 2400 RPM. Just need to see how it is after some tuning.

RBob.

CORV3TT3

Thanks rBob!

I had the sense that I needed to update more than the VE, SA, BPC, and a few others than I already had updated. I was thinking there must have been some things that remained that needed to be looked at. Thank you for pointing out which ones!

I've already completed on VE learn and that helped me adjust the VE tables- and it is improving. Will post more later!

CORV3TT3

Bob- the HiWy - Min MPH, INJ - ASync Transition PW - TBI Only, AE - MAP PW, AE - TPS PW, and PRP - Gain vs O2 Error settings made a HUGE difference. The chugging is almost nonexistent now.

Four VE learns later... still making some tweaks and walking it in. FWIW- I think I was perhaps off between 10-20 in almost each cell for most of the VE tables.

Idle is pretty good in neutral. Could be a bit better in drive with the brake held and coming off/on complete stops.

CORV3TT3

I've gotten through about 8 VE learn sessions so far.

Attached is a screen shot with the low speed table.


Idle in park is good... idle in drive seems to want to stall out and die. It will hover around 700rpm when the brake is held and then start to drop and stall out unless I give it a little more gas to hold the idle.

Any thoughts about idle and that cam?

CORV3TT3

I finally got around to knocking the anti-tamper plug out and set the idle to 800rpm in neutral. I can't get it to hold minimum idle air in drive without stalling.

VE learns are not taking anymore fuel out- so, that appears good for now.

In park- the IAC sits at 0 steps now.

However, I'm not getting anymore than 35 steps from the IAC before it stalls and dies in gear after about 10 seconds or so. Also- it holds between 55-70 KPAs at idle. I'm wondering if I need to look at the MAP settings with this cam.

CORV3TT3

Here is the most recent datalog...

Basically, at about 5 minutes... it starts to die in gear as I am backing it in the drive way and into the garage.

Any thoughts here about what to do with the idle?

BIN and datalog included...

RBob

iTrader: (1)

I suspect a vacuum leak. The engine idles at 0 IAC steps in P/N, then jumps to 47 steps in drive. This is also why it takes so long to idle down when the transmission is shifted from drive to P/N.

The engine died as the ECM thought that the MAP reading was incorrect. And the default MAP value isn't calibrated correctly for that engine.

Set this value to 80 KPa:

MALF33 - MAP Hi BARO Limit (1bar)

RBob.

CORV3TT3

Thank you!

A vacuum leak is completely reasonable given the age of the car and some of the hoses. Other than a few of the vacuum lines, the gaskets were all replaced as part of engine work. Will recheck all of that though to be sure.

I have disabled the EGR with a cap on the TB until I can get a new vacuum relay. Should I adjust a value or table somewhere for this?

I was wondering about the IACs too. Seemed like when I unplugged the passenger side IAC it made more of a difference as I was getting ready to set minimum idle air initially (I also had a lot of IAC counts prior to raising the idle- I wonder if the "difference" I sensed was related to a bad IAC). Unplugging the drivers side IAC... not so much. Perhaps one is going out- or would that come across as looking like something other than a vacuum leak?

How about throttle body balance? I have yet to build a $10 water manometer, but I did pay very close attention to the turns- I moved the TBs in 1/4 turns. Seems like the balance is decent since it holds an idle in neutral well. Would that be some thing that could contribute to what you suspect as a vacuum leak? Also, in judging by the way the car would run with one idle screw adjusted while I was about to adjust the other one, I can completely see how important balance is as a whole.

Bob- I can't thank you enough! I really appreciate all your help with this!

dfarr67

iTrader: (2)

What is the full spec on the cam- just ordered one- roller hydraulic, TPI 383.

CORV3TT3

Mine is an Erson.

Specs- .465"/.488" Lift 224* / 234* @.05 Duration 112 L/C

CORV3TT3

I looked over all of the lines. The vacuum cap on the balance port for the front TB had a hole in it and was likely drawing in air. All other lines were good.

I've made that adjustment to the BIN... will load it up soon and see how it goes from there.

dfarr67

iTrader: (2)

Did you specify EFI cam- that duration is over the top with a map based system.

CORV3TT3

Agreed- usually is for most EFI systems.

It is a slightly ratty cam but I'm confident with the flexibility of the EBL it'll be a challenge but not insurmountable. It runs great outside of the idle in drive with virtually no other issues. And no SES light.

I think there are some guys like Dominic, Ronny, and others who have tuned other large cams and set ups with EBL.

dfarr67

iTrader: (2)

fast355 looks like he knows his stuff.

CORV3TT3

Yup. Lots of great info here. Which is why I am here!

dfarr67

iTrader: (2)

I'm just winding up a 383 build, like wise with an Erson 4/7 swap- good guys to deal with. Have the EBL now but am saving up parts for a GM 411 conversion.

CORV3TT3

My vacuum leak was more like two bad, sticking IACs. I tested the voltage on both connectors just to be sure. Yep- good voltage- the wires weren't the issue. They were stuck slightly open- and one was worse than the other. How annoying. I've never had an IAC go out on me.

I was able to find one in stock the other day in a store- and found another at another store and have to drive out to pick it up.

Well, at least I have my water manometer... spent a total of $4, printed a ruler off from a PDF, and taped it to a piece of scrap wood.

CORV3TT3

SUCCESS!!!

• Idles at 750-775 in park
• Idles at 700 in drive
• Throttle bodies are balanced
• IACs work (new parts)
• Runs at 14.7 AFR in closed loop with an average of 128/128

I am debating on setting the idle down a bit in drive on the ECM (currently set for 750). The cam gives it a bit of a roll- as it blips a bit above and below but within 60rpms or so.

I'm at about 45 steps- but she holds that idle well even with the .465/.488 cam.

RBob

iTrader: (1)

Great, those pesky IACs will do it. Running open loop idle may help smooth it out, can try it and see. Option flag:

Option Word 1 - Bit 2 - OpIdl

RBob.

CORV3TT3

Here's the tune so far...

Lots and lots of VE learns later, this is what it looks like- so far.

I still have a ways to go I think. FYI- I have not brought it past 2.4k yet as the engine hasn't been 500 miles. So, the high speed tables are largely unlearned.

Really... all of my tuning thus far has been low speed tables focused on the idle, throttle body balance, SA & avoiding knock counts, and getting the IAC transition from drive to park right.


It is running very, very well from idle to 2,400rpm.

CORV3TT3

VE learns continue...

I adjusted "PRP- Gain vs O2 error" and that had helped a lot.

Now, I had been reading in some other threads that reducing "PRP- Gain Multiplier vs Airflow" to compensate for larger fuel injectors and higher pressures would help with low load RPM backfires.

So, I reduced "PRP- Gain Multiplier vs Airflow" down to 77% of the original values to the correct percentage.


It seems to have taken any residual chugging at low rpms out as well as the occasional pop coming back through the intake when the rpm is between 1k and 1.5k and there isn't enough % throttle to engage the passing gear.

Bob- any thoughts on this BIN?

I have had no significant VE learn changes to the tables between idle and 2.8k rpm for about two sessions now.

I have also set the idle speed down a bit. Minimum idle speed is at about 600-650, 750 in park, and 700 in drive. It rolls between 710 and 740 according to the WUD.

The tables from 2.8k up to 5.2k are unlearned as the engine isn't fully broken in yet and I have yet to run it that high. But... idle to 3k seems really solid now!

CORV3TT3

I guess a better question is... is it time to consider a wideband and what would the benefit be over the narrow besides accuracy?

dfarr67

iTrader: (2)

You should have had one to start with. Check out 14point7.com (spartan)

CORV3TT3

Thanks for the link. Those are some serious products!

At this point, I want to focus on utilizing the EBL system and the VE learn function within it. Wideband I think will be helpful, and would compliment what I have done with the narrow band to date.

So, instead of buying an add on really expensive stand alone wideband that would require a lot of extra work potentially to integrate, I am going to use the TT-1 wideband from Dynamic EFI as it seems like it will meet my needs and work just fine.

With the low speed VE dialed in, I am thinking the next things I want to look at would be AE and getting that dialed in. And that is on top of working on VE for the high speed tables.

dfarr67

iTrader: (2)

I put the spartan unit on mine to replace a cooked LC1, very compact as the controller in integrated with the plug, sensor and harness are very reasonable.