MGB V8 Tuning Help

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MGB V8 Tuning Help

Postby Johnous » Tue Dec 06, 2016 4:13 pm

Hello All! I posted in the Find a Tuner forum originally, and was kindly directed here. I have built a 3.5L rover V8 with a borg warner WC T-5, and put it into my 1978 MGB. This is my first attempt at Megasquirt, and I am more used to tuning carbs.

The car has been running fine, but there are a few problems. First, I had to set it up with 4 squirts per engine cycle because 2 made it run lean and truly shitty. Secondly, acceleration tends to make the engine go way lean (quite nerve wracking). I have attached an msq and a compressed data log with that tune.

My board is a v2.2 running MSnS. The ignition signal is through a Mallory Unilite optical shutter in my distributor, and spark is triggered through an internally mounted BIP373. I am running 19lb "yellow" ford injectors, which considering this engine will be lucky to exceed 200hp should be fine. I am using a wideband Innovate LC-2 O2 sensor about 30 inches down from the collector (was considering this distance as a potential part of my lean problem) and the controller from Innovative. I rewired the whole car, and my grounds are excellent as far as I can tell.

This was my first car, and belonged to my grandpa before that.This has been a really long and daunting process to get the MSnS working. I want pretty badly to hoon the bejeezus out of this thing, but am constantly afraid of running lean (as my TunerStudio gauge seems to indicate) and breaking s***. Any assistance you tuning gurus could provide me would be deeply appreciated
Attachments
2016-09-19_14.51.46_PostAnalysis1.msq
MSQ after doing one round of VE Analyze
(38.84 KiB) Downloaded 20 times
2016-11-24_11.33.30 - Copy.zip
The Log File. Had to compress
(276.58 KiB) Downloaded 16 times
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Re: MGB V8 Tuning Help

Postby DaveEFI » Wed Dec 07, 2016 3:22 am

Generally, if it runs slightly better on 4 squirts than 2 it means it is running lean. If you are certain you have calculated the req_fuel correctly (including any allowance for actual fuel pressure for injector flow rate) and used a generated VE table based on your engine data as a starting point, it should start out on the rich side.
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Re: MGB V8 Tuning Help

Postby whittlebeast » Wed Dec 07, 2016 9:41 am

You have two big issues.

You do not have your wideband set up correctly. You will need this to get closed loop working.

You have way too much AE going on. Are the injectors mounted down near the intake valves?

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Re: MGB V8 Tuning Help

Postby Johnous » Wed Dec 07, 2016 10:11 am

DaveEFI wrote:Generally, if it runs slightly better on 4 squirts than 2 it means it is running lean. If you are certain you have calculated the req_fuel correctly (including any allowance for actual fuel pressure for injector flow rate) and used a generated VE table based on your engine data as a starting point, it should start out on the rich side.

I used TunerStudio's req_fuel calculator based on my engine constants (215 cu in, 19lbs injectors, 8 cyl). Regarding fuel pressure, I am running a high pressure EFI pump externally from my original MGB fuel tank which I suppose could be starving the engine of fuel... there is a schrader valve on the fuel rail, which can be used to test fuel pressure. I recall getting 40PSI when I first pressurized the fuel system (engine off). Would fuel pressure at idle be enough indication? Or would fuel pressure really need to be monitored during driving conditions? I could get under the hood and rev the engine and see if the fuel pressure stays where it needs to be.

whittlebeast wrote:You have two big issues. You do not have your wideband set up correctly. You will need this to get closed loop working. You have way too much AE going on. Are the injectors mounted down near the intake valves? Andy

Andy, is the issue on the O2 sensor regarding its position in the exhaust stream, or a software configuration issue? I haven't entered any acceleration enrichment myself, but that may be something VE Analyze has added due to the lean running. The injectors are mounted down by the intake ports in the standard 14CUX configuration (http://www.britishv8.org/articles/rover-14cux-efi.htm). I have read that when installing a later EFI intake on an earlier rove block, you may need to notch the intake gasket and head to make sure they don't interfere with the injector spray pattern. There was maybe 1mm of intake gasket coming into the port that I saw before I put the injectors in... Could that be part of what you are describing?

Really appreciate the help y'all. Sounds like I might have a few hardware issues to address, and a new base tune to begin, before heading down the path any further... now, I must try not to be paranoid about that WOT pass I did :evil:
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Re: MGB V8 Tuning Help

Postby whittlebeast » Wed Dec 07, 2016 12:43 pm

I am referring to getting the wideband to report to the Squirt and get the AFR calibration correct.
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Re: MGB V8 Tuning Help

Postby Johnous » Wed Dec 07, 2016 3:43 pm

whittlebeast wrote:I am referring to getting the wideband to report to the Squirt and get the AFR calibration correct.

When i play back the datalog I am seeing AFR readings, and when I use TunerStudio the AFR gauge is working. Doesnt that mean the O2 is talking to MS? Or is there a specific setting you are referring to? Not trying to be dense or anything
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Re: MGB V8 Tuning Help

Postby v8fiero » Mon Dec 12, 2016 10:18 pm

Johnous wrote:
whittlebeast wrote:I am referring to getting the wideband to report to the Squirt and get the AFR calibration correct.

When i play back the datalog I am seeing AFR readings, and when I use TunerStudio the AFR gauge is working. Doesnt that mean the O2 is talking to MS? Or is there a specific setting you are referring to? Not trying to be dense or anything


Hey Johous

Your Innovate LC-2 has two analog outputs. From the factory, these two output are programmed differently. From the LC-2 manual

Factory Programmed Defaults:
Analog Output 1 is programmed to output between 0 V for an AFR of 7.35 (gasoline) and 5.0V for an AFR of 22.39.
Analog Output 2 is 1.1 V for an AFR of 14 and .1 V for an AFR of 15.

If you are using Output 1 to drive the included LED display and Output 2 to drive MS, you MUST reprogram Output 2 to be the same as Output 1. If you drive MS with Output 2 without reprogramming, it is basically seeing a narrow band O2 type signal.

Once you have the LC-2 set up correctly, then you have to configure TS with the correct settings.

I saw your post in the Find a Tuner forum. I am not an expert by any means, but I have gone through the exact steps you need to do. I am located in NW Austin if you need a hand getting this set up correctly.
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Re: MGB V8 Tuning Help

Postby DaveEFI » Tue Dec 13, 2016 3:29 am

What injectors are you using? The flow rate for the original low impedance ones on my RV8 3.5 is given as 16.46 lb.hr @ 36 psi fuel pressure.

Thing is if I generate a VE table using your tune and the nominal performance figures for an injection RV8 3.5, I get very odd one. Which suggests to me your req_fuel is wrong.
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Re: MGB V8 Tuning Help

Postby Johnous » Fri May 19, 2017 1:56 pm

DaveEFI wrote:What injectors are you using? The flow rate for the original low impedance ones on my RV8 3.5 is given as 16.46 lb.hr @ 36 psi fuel pressure.

Thing is if I generate a VE table using your tune and the nominal performance figures for an injection RV8 3.5, I get very odd one. Which suggests to me your req_fuel is wrong.


I am reviving a dead thread, sorry! My injectors are not the original RV8 injectors, but low-impedance yellow Ford injectors rated at 19lbs. Regardless, you are right that my req_fuel was off. I failed to account for the lower fuel pressure available since I converted the original MGB carburetor gas tank. The system is delivering 32lbs at idle, which is less than the 39lbs these injectors are rated for. Therefore, I am going to start from scratch to get the req_fuel right.

I also discovered a size-able air leak in my intake manifold that was pretty much completely hidden from view until I disassembled it all. Newbie mistakes aplenty. I am preparing to correct these issues, as well as properly configure the O2 sensor, and take another swing at getting this running right.

Really really appreciate everybody's suggestions and advice. I am determined to make this work!
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Re: MGB V8 Tuning Help

Postby Johnous » Fri May 19, 2017 1:58 pm

v8fiero wrote:Your Innovate LC-2 has two analog outputs. From the factory, these two output are programmed differently...
I saw your post in the Find a Tuner forum. I am not an expert by any means, but I have gone through the exact steps you need to do. I am located in NW Austin if you need a hand getting this set up correctly.


Thank you so much for the offer (btw, I love Fieros). I want to get this a little closer to working order before dragging a good Samaritan into it! However, if there are any more stumbling blocks I will hit you up
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Re: MGB V8 Tuning Help

Postby DaveEFI » Sat May 20, 2017 2:20 am

Did you convert your tank via a standard return line and regulator for vehicles of this age? Fuel pressure has a very big effect on fuelling. MS expects to see the normal vacuum referenced variable pressure.

Other thing is to make sure your injector dead time is correct.

Also - which inlet manifold did you use? The injector holes in the RV8 manifold changed in shape between Bosch hi and lo-Z injectors. So the seals are different. Any air leaks there could cause a problem.

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Re: MGB V8 Tuning Help

Postby Johnous » Thu Jun 01, 2017 7:49 am

DaveEFI wrote:Did you convert your tank via a standard return line and regulator for vehicles of this age? Fuel pressure has a very big effect on fuelling. MS expects to see the normal vacuum referenced variable pressure.

Dave, I used the old MGB carburetor line as a return and ran a new parallel 3/8" line fed by an external high pressure pump. Utilizing the stock Rover vacuum-activated fuel pressure regulator mounted on the fuel rail. I had some issues getting the high pressure pump low enough to feed adequately, but managed to get it to provide 32PSI at idle. I will remeasure the fuel pressure to ensure the req_fuel is dialed in correctly.

DaveEFI wrote:Also - which inlet manifold did you use? The injector holes in the RV8 manifold changed in shape between Bosch hi and lo-Z injectors. So the seals are different. Any air leaks there could cause a problem.

Running the hotwire injection system from a 3.9L Rover. I did have to tweak the fuel rail mounting to fit beneath a lowered plenum, so I will ensure that there is a sound O-ring seal between the injectors and the intake manifold.

Appreciate the feedback! Going to tackle this all this weekend and will hopefully have a new data log to post afterward.
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