ITB bug

[Pehlen]

Hard to be happier.

Phase 1 of the ITB project is complete. I'll post some pics and a video link.

The tach issue was a rookie mistake: the AEM Infinity must have it's Tach output setup and it needs to match the 1988 tachometer's need - which I found on Pelican, but for anyone reading this in the future, the AEM needs an output set for Tacho and that output is 3 pulses per revolution.

I fixed the sluggish throttle release with a heavier spring helping to pull the new bell housing back to closed throttle. Pictures to come, but I got the idea from Clay.0's thread.

I have a good bit more to do on getting the throttle bodies balanced from side to side, and phase 2 of this project will take me into the first phase of tuning.

All and all, it's hard to happier. The second drive around the block was uneventful, with a couple of backfires at ~3000 RPM and off throttle, but she drove quite well.

I clearly need to get a tune on it to make a judgement on the seat-of-pants difference, so that is coming.

[Pehlen]

I've been busy street tuning - learning a lot and getting things basically dialed in using David Borden's Excel workbook (which has been a huge help, by the way). Today I'm starting to trees the acceleration and deceleration trims (as you can see from the latest log screen shot).

I've been using MAP as the X axis and am thinking I need to either switch to TPS, or a blended/multi map approach. I'm not quite sure how that will work yet, with the AEM Infinity, but it appears to support it. Any thoughts on that would be useful.

As a side note, the sound is awesome and this setup was a hit at our local Cars and Coffee.

The red line on the graph is RPM. The lower graph is Lambda target (yellow) and Lambda1 (green). Clearly more to do, but trust me, it's come a long way in a week!




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[Pehlen]

More progress...



I've switched over to TPS instead of MAP for engine load on the VE table and that has made a noticeable difference in how the motor runs. Also, it helps to install the brake booster vacuum check valve in the correct orientation (oops).



I am now down to targeting a couple of awkward TPS / RPM regions on the VE map and beginning to tune for cold start. After that, I'll start working on wall wetting fuel trims based on rate of throttle change.



I'm going to need to validate my AFR targets - from all I have read, the should be on the rich side for our air filled engines.



And... once that is all complete, I'll visit a dunk (DYNO - not a dunk; auto correct) to start truing to find more power - in particular through ignition advancing.



Here are some pictures. I'll post a youtube link for sound shortly.

[Omegaman]

Great work! When I was tuning my ITB / ECU setup I found the off idle part the most tricky. Basically you want to turn off the acceleration enrichment and try and get the fuel cells as near to the AFR you want. Then turn on acceleration enrichment to sort out the off idle lean spike. I use a DTA ECU, I guess it may be called something else on the AEM system.

[Pehlen]

More progress this weekend.

Embarrassingly enough, the best improvement was finding that I had a loose coupling in the throttle linkage. It was just loose enough to create some play that made the throttle feel more sluggish than I had anticipated. Once tightened up, the throttle feels amazingly quick to react and acceleration is fantastic, especially in mid to high RPMs.

Here's a video...

https://youtu.be/BFN-skXFVho

[al lkosmal]

nice job Phil.................all of you that are on the fence about upgrading your 911 to an EFI/ITB system, look at how Phil has so quickly installed and tuned his new system. He took the time to research, read, and learn and that dedication, combined with good DIY skills/patience made this a successful project. Phil contacted me a time or two with good questions regarding tuning, but it was 99.9% him.

I know that there is still tweaking to do, but congrats.

regards,
al

Al Kosmal
the x-faktory
koz@x-faktory.com
RGruppe #669
X-Faktory - Home

[Tippy]

From what I can tell, it drives really nice. With the jumpy MAP, increasing the vacuum log vacuum might dampen the pulses. I was impressed even with the jumpy map, how smooth your AFR's remained. Is there a lot of smoothing used on your MAP settings?

Great job on having it turned around in only 1.5 months running that good!

[Pehlen]

The Pelican boards and some timely, key input from Al paved the way.

As for the MAP sensor, Tippy, I decided to go with TPS as the Y axis (load) on the VE table, while maintaining MAP for ignition and fuel. This has an effect of blending TPS with MAP (as it was explained to me by a guy from AEM). I'm probably only at ~40% saturated in my understanding of what the AEM Infinity can do for me, but the out-of-the box settings for most things, after configuration, has been quite good.



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[Omegaman]

Could you not drill between the bores of the adapter plate and then tap a vacuum line fitting into the middle bore....that way you would only need one vacuum line from each bank.

[Pehlen]

It's been awhile since I last posted. The car is driving great, and I continue to tinker with the tune. Eventually I will get to a dyno tomtune the ignition timing. My only issue currently is sluggish summer time cold starts.

I have nearly popped the top off one of the filter socks, so while that is on order I did some research and fabricated some velocity stack screens. Brief video link attached (https://youtu.be/8UKGT4UhEU4).

[Pehlen]

It's been about 1 year since I ordered the parts and about 9 months since I started tuning.



I finally found a place to get the car on a dyno and get some help from the pros. Let me make a big shout out to Cody and his team at Black Forest Racing in Denver, NC (just outside of Charlotte). I was like a kid in a candy shop.



The car made peak HP at the rear wheel of 199.47 @ 5370RPM and more impressively, 210.9 lbft of torque at 4157 RPM. They did a great job of fixing my VE table and flattening out the AFR curve as well as dialing in an aggressive, but safe, ignition map.











And a short video for extra fun: https://youtu.be/D7E1lq3jvcE

[al lkosmal]

nice work phil.

regards,
al

[darud35]

Looking good!