First startup with MSII questions

[fe3xclone]

Today I tried firing my 455 for the first time with my MS setup. I am running an MS-II in a MS-1 ver. 2.2 board. I left a standard vacuum advance HEI distributor in the engine for now so that I can focus solely on getting it running on fuel only.
The engine was run on a test stand prior to this with a 750cfm carb and the same distributor mentioned above to verify everything worked properly in that configuration. I set the initial timing at that point as well and haven't touched it since.

I went through the step by step process in the mega manual for setting up the initial parameters for the engine.

My REQ_FUEL was 14.6 but on the initial start, I used the default cranking pulse width parameters of 12.0/4.0 with a 6.0 priming pulse that were in megatune. It actually fired on this try and stayed running for a few seconds until I accidentally hit the accelerator pedal and then it sputtered and quit. After that, I couldn't get it to fire again.
The idle was pretty rough and even though I have a large camshaft, it still just didn't "feel" right.

After that I set the cranking pulse width to 12.9 (88%) and 3.4 (23%) based on my REQ_FUEL number above. Tried starting again and all it would muster is one short blurp and then nothing.

So I dropped the numbers down to 12.1 and 3.2 then tried again. Still nothing.

Dropped them another .8 and had the same result. Read that the priming pulse should be 4.0 or less so I set it to 4.0 and tried again. Nothing.

After all that I decided to pull one of the spark plugs to see if it indeed was flooded and confirmed it was. Spark plugs were very wet so I'm going to clean them up and try again tomorrow.

Just thought maybe someone could take a look at what I'm doing and tell me if I'm going in the right direction? How lean is too lean when adjusting the crank pulse width? Is there a certain number you don't want to go below?

I also had a question regarding the REQ_FUEL calculator in Megatune. It asks for your engine size, fuel injector size and air fuel ratio. The first two are simple enough but what should I be entering for the AF? I've been using 14.7:1 but don't know if that's what its asking for or not.

Details of my engine:

455 +.030" Olds (actually 468cid)
242/254 duration @ .050, .595"/.595" lift, 114LS hydraulic roller cam
Single plane Offenhauser Super-Sonic intake modified for port fuel injection
42lb/hr injectors (8)
1600cfm Edelbrock Dominator throttle body with progressive linkage (secondaries open at half throttle). Has Delphi style TPS and IAC
AEM single Wideband O2 sensor

MS-II in MS-I ver. 2.2 board with engine wiring to relay board.

Is there anything else I should be looking at or modifying in Megatune to get it up and running or do I keep messing with the cranking pulse widths first?

Thanks guys!

[fe3xclone]

So I cleaned the plugs today and double checked a few connections and tried to start the engine again. I could get a few sputters like it wanted to catch then nothing. It just cranks over.

I noticed on my realtime display in MT that my IAT sensor wasn't reading correctly. The coolant sensor says its 63*F but the IAT sensor was pegged at 215*F.

A month or so ago when I was just setting things up, both the coolant sensor and IAT sensor would read the exhaust same (air temp) on a cold engine.

So is my IAT sensor bad? What would cause it to have gone bad since the last time I worked with it?

Thanks for the help,

[fe3xclone]

Okay, so I managed to get it idling after remembering I had never set the idle speed on the throttle body. After opening up the throttle blades a bit I can now at least get it to idle consistantly.

But the IAT still has me baffled. I checked the resistance between PIN 20 and PIN 7 on my connector out to the relay board it came up with 0 Ohms on a 2000K ohms scale.
I double checked my connections at the relay board and they look to be correct. Not sure where to go next beside buying another sensor and trying it.

[41Willys]

Hi Andrew,

Check to be sure your wiring to the IAT isn't pinched and shorted somewhere. I know it can happen, I did it. Then pull the connector on the IAT and try and measure resistance there. You should get around 3.2K to 3.5K, whether it be the open style or you're using the closed slug style sensor that looks like the water temp sensor. If not, then the sensor is bad.

Your engine, cam and injectors are not all that different than mine, with the exception of the blower, which is underblown and I never really see boost anyway while driving. Here's my msq file. I'm pretty close on everything, I think. If it's of value, great. Use it. If not, send it to the refuse bucket.

Your question on AFR in the REQ_FUEL is usually 14.7, I think. That's what I used. By the way, you'll find that the engine will probably be happier idling at around 13 to 13.5, though. That's what I found. Although, you're port injecting, so you may not have any rolling idle issues like I did.

Dan

[fe3xclone]

Thanks Dan!

I'll double check the wiring tomorrow. I did measure the resistance on the IAT sensor itself and it was around 3.2 or so. I double checked it with the coolant sensor which reads the same. And yes, my IAT is the same as the coolant sensor.

I also checked my MS ecu with the stimulator and the IAT functions normally with it so I ruled out the ecu.

Thanks for the file. I'll give it a try and see what happens!

[41Willys]

Careful with just throwing that file into your ECU! It may not be match up well enough for you to run off of without additional tweaks. For instance, I'm not port injecting, I'm throttle body injecting. There are probably more things that are different. I do have a blower on mine, and that certainly makes things interesting. I also had a lot of XTau in there because of the huge internal mass of the blower and plenum. Go through the file to be sure you know what you have before you fire it up. It's still a work-in-progress. On the other hand, aren't they all?

Dan

[fe3xclone]

Yep, did just that. Basically I used your VE and AFR tables and then changed the other parts to match my engine (port injection, etc.)
It seemed to help quite a bit with the off idle stumble but I obviously have a lot of tuning left to do. I can get it idling okay but it still seems to have an erratic idle with the rpm not staying very steady. Its also been pretty rich on warmup. Enough so that you can see the cloud of fumes and your eyes burn.
I've been reducing the cranking pulse widths lower and lower and it seems to keep getting better by doing that. I'm just really far away from the "rule of thumb" in the megamanual.

I also still need to figure out why the IAT isn't reading correctly. Today it was reading -1300*F ??? for some reason. I checked the resistance through the wires from the sensor and got a 3.04. My coolant sensor reads 3.00 to 3.01. Unplugged the relay cable from my ECU and checked PINs 20 and 7 and get 0 ohms resistance there. Checked the MS ECU with my stimulator and the IAT functions normally there.

So I've postponed anymore "tuning" until I fix the IAT because I'm sure I'm just shooting myself in the foot.

Something odd today I ran into was when I tried to Open a new tune file I had saved and when selecting yes to burn it to the ECU, the ECU connection to my laptop would go bad and I would get a no connection error. However, if I open the file, click no on "Burn to ECU" and then burn the different parameters individually, it works.

It also seems like my idle is changing from one start to another. I've found that a lot of times I need to press the accelerator to the floor to get it to fire. Once, it does fire it tends to stay running okay, albeit really rough. I messed with my idle speed stop on the throttle body but I don't know how far I should have it open to adjust the rpms compared to the TPS value.

Any thoughts?

Thanks,

[41Willys]

The only thing I can think of left is that somehow you tried to calibrate the IAT in MegaTune and the calibration got messed up. Try going back to the default for that. Maybe something is messed up there.

You have a host of problems. 1. Get the IAT fixed. 2. Maybe something is corrupted in Megatune. Try uninstalling it and reinstalling it. I haven't run into that. Maybe you need to run a fresh thread and ask that question exclusively. Matt Cramer may be able to shed some light. 3. Having to press the throttle to the floor means that you've flooded the engine, and it's taking all that air to purge out the fuel from the engine and eventually firing on what's left when the mixture finally gets right. Setting the idle and the mixture is outlined in the manual - lowest RPM along with minimum MAP level (highest vacuum). Sounds like you may not have gotten it near there yet.

Keep trying and learning. I think that's what most people that have become experts here have done. Don't give up. Try something, and if it doesn't work, go back to the previous msq file and try something else. You can't really hurt anything, as the engine isn't under enough load to begin to cook anything. Keep reporting back results.

Dan

[fe3xclone]

Well Dan, looks like you were right to begin with. That zero ohm reading is where the problem was at. I double and triple checked my IAT sensor and confirmed it was reading properly.

So, as a last resort I decided to pull the DB37 connector sheilds off both ends of wires. Turns out that one of the wires was pinched pretty badly and was grounding to the connector itself since they are metal.

When I removed the connector, I no longer had a zero ohm reading between PINS 20 and PIN 7. However, when I double checked my CLT sensor wire through this, I found that it had a .41 or so ohm reading between PIN 21 and PIN 19. I don't get any reading from the IAT PIN 20 and PIN 19 so my next test is to see if I even have continutity through the IAT wire itself. Looks like I'll probably have to cut, splice and solder a new wire in.

Thanks,

[41Willys]

Hi Andrew,

Well, you found it! That's a good thing. Once you get the wiring issues taken care of, you can venture back into the tuning process. But, you need all your sensors 100% first. Glad you found it. I thought that when you had zero ohms at pin 20 and 7, that you were checking the wire continuity at 20 and the wire continuity at 7, not zero ohms between the pins themselves! Sorry about that. I would have harped on that first.
When you get to tuning again, report back, or maybe start a fresh thread for whatever problem you decide to tackle first.
Good luck,
Dan