Popping and poor warm start

[mustanglx_1989]

Hey guys. I figured out my original problem. It wouldn't start because I had the wrong firing order cam in the car. I was told I was receiving a modern HO Mustang firing order cam and it turns out it is the old Ford firing order. No big deal. I switched the plugs and re-soldered the injectors to the correct order.

So now it fired up finally. I set the base timing for 10* and verified it in Tuner Studio. It is still popping and banging and has a bad hesitation at any throttle. Now this is just sitting in the garage. I figured out how to record a log, so I have a couple of those. A local BS3 guru came over and helped get it going but didn't stick around too long. He was a major help in trouble shooting.

I shut it off a few times and it was hard cranking during start and had to have the throttle open. I am looking for any advice on where to go next. I did manage to pick up an Innovative MTX-L for a decent price at the NMRA race in Joliet yesterday. I still need to put it in so any advice on that would be great as well.

Thanks,
James

Mustang Base.msq

Hot Start.msl

[billr]

It's kicking back against the starter while cranking? Is the cranking advance 10 deg (as shown with a light)? I don't know the peculiarities of the TFI/PIP stuff, but try to find a way to get cranking timing reduced to 0 deg. Take that 10 deg out of the "base" and put it back into the table used when the engine is running.

Your battery voltage looks to be drooping a lot while cranking. Does a meter right at the battery terminals show the same?

[mustanglx_1989]

It's not so much kicking back as it feels like it's putting a ton of timing in it while starting. It's already a higher compression motor and that combined with extra timing makes it crank pretty slow in spots.

It's mostly popping when you stab the gas. I set the base timing at 10* with the light and verified it with TunerStudio.

It sounds like a timing problem but I don't see any settings that are way off.

I'll meter the battery today, but it probably is dropping. It's high compression with a mini starter so it's probably taking a lot to turn it.

James

[billr]

What compression readings (psi) do you get? I don't need for all cylinders, just a typical so I have an idea about what you are calling "high compression". If you disable spark and then crank, is the cranking significantly different in regard to the "kick back"? If so, that is a sure sign cranking advance is too much; easy to try...

[mustanglx_1989]

It's in the neighborhood of 12.5 to 1 according to the engine builder. I can do the math and probably find a more precise number. It has 93 octane in it and was ok on the stock computer.

I can unplug the distributor and it spins better. It acts as though it is getting advance but I don't see from where. I verified the balancer marking when I degreed the cam, so they are dead on. I have all new electronics in the distributor that were installed by a Ford mechanic.

James

[billr]

I asked about actual compression pressure because often engines with high compression ratios also have enough valve duration that "compression" isn't all that high at low speeds, especially cranking. (I'm ignoring VVT systems) What ignition timing do you see with a strobe light while cranking? my understanding is that is 10 deg BTDC, is that correct?

[mustanglx_1989]

I can get a compression tester if need be.

It is 10*BTDC at idle. I am not sure about cranking. If the computer is locked out, it shouldn't be adding any. Is that correct?

James

[billr]

The last .msq posted shows "use table" for spark timing and none of the values in the table is as low as 10 deg; so if it is idling at 10 deg actual then something is wrong with your "base timing". The unknown here for me is that TFI/PIP stuff, I can't help any figuring that out. However, if you will check the timing while cranking we can tell if spark timing is causing the hard cranking (kick-back, call it what you want...).

Edit: If by "computer locked out" you mean you were using "fixed timing" and that was 10 deg, then yes, you should see 10 deg with a strobe light; at idle and all other speeds. That still does tell me what spark timing is while cranking, since the "cranking advance" field is greyed-out in your tune; and I think that is because of the TIF/PIP mode selected. That's where I run out of knowledge and can only advise to check spark timing while cranking and with a light.

[mustanglx_1989]

Thank you Billr.

I just tried to start it cold and it just cranked and cranked. I recorded a log but it says it's too large.

Anyway, I will get someone over here to crank it while I try the timing.

It is also popping on acceleration and shooting flames out of the headers. I still haven't put the wideband on it.

I am actually hoping to get that installed so I can see what is really going on. My narrow band keeps saying lean, but it sure smells rich in the garage.

[billr]

Don't count on the WB to help you right now. That will be a great tool for tuning, but not-so-much (if at all) for a basic problem like you must have. I don't think the WB is going to give accurate readings at start-up or with it running so bad. Have you checked cranking spark timing with a light yet? I am suspicious of the firing order confusion, have you turned the engine slowly by hand, with the valve covers off, to check that the valve sequence and pointing of the dizzy rotor are in agreement about the firing order?

How long did you crank for, that the file was too big to post??? I can log a run for many, many minutes and still have a file small enough. And I have seen ignition logs posted here that are also quite long.

[mustanglx_1989]

It could have been a glitch on the site. It kept telling me 1MB limit or something to that effect.

I didn't get to time it while cranking, but I was just playing with it a little bit ago. I locked the timing at 10* and tried to re-run the Trigger Wizard. While I had the light on, the timing was bouncing like crazy between 10* and 20*. So now I am at a loss. When my buddy was helping, we had it nailed down at 10*. I am not sure what could have changed so much.

It is harder starting now as well.

[mustanglx_1989]

Could anyone suggest some filter numbers to try out?

I can't help but wonder if maybe it's something as simple as a dirty signal triggering the wrong timing.

James

[mustanglx_1989]

Well, it seems to be getting worse. It is surging and won't run without a little throttle, where as it would before.

I messed with the tune a little bit, making minor changes here and there. I feel like I am getting nowhere though.

Any input at all would be appreciated.

James

Cold Start.msl

Idle.msl

Mustang Base.msq

[billr]

I suggest you turn off the AFR/EGO control until you have the tuning more stable; especially since you have a NB right now. Have you resolved the ignition timing fluctuations? When we look at a run file we have to be able to assume that the spark advanced logged is true.

Also, it looks like the TPS is going nuts, that needs to be corrected. Do you have a TPS connected?

[mustanglx_1989]

I can't seem to find out how to log the ignition signal. I thought I ran into it once and would like to see if it has a solid tooth pattern or a bunch of random spikes. I just kept changing the timing in the MS until it would start. It is still bouncing around quite a bit.

I also have no idea what it up with the TPS sensor. It is a new Ford unit and was solid before. I am going to check all of the grounds again today.

Every time I work on one problem, 2 or 3 are appearing.

James

[mustanglx_1989]

Alright guys, I turned off the EGO and is seems to be much better.

It is running fairly smoothly, but the idle timing is still jumping between 12 and 18 degrees, which is an improvement.

I have a chance to pick up an MSD dizzy at speed shop cost tomorrow. Does anyone here think it would be worth it?

Here are the files from tonight. It still needs a lot of throttle to fire, but does ok. It died when I put it in gear at the end.

Hot Start.msl

Idle.msl

Mustang Base.msq

[billr]

If you set spark timing to "fixed", something like 15 BTDC, does the strobe light show timing jumping around? Personally, I wouldn't spend money on an aftermarket dizzy. Use those dollars to fit a 36-1 or 60-2 crank wheel and 4 waste-spark coils.

[mustanglx_1989]

It's jumping around while fixed.

I'm hoping is a dizzy problem. The new one is already in, I just have to wait until I get home.

I'm not worried about buying parts for this setup because my brother will be using everything in his car when he is home from college.

I'm upgrading to a 408W, hopefully boosted.

How can I tell what crank trigger is compatible?

I'm liking this one: http://shop.holcombmotorsports.com/AERO ... CCTSBF.htm

[billr]

Did you securely lock-out the centrifugal advance in the old dizzy? I don't see any teeth on that wheel you linked to, and didn't see anything in the description. I wouldn't consider anything except 36-1 or 60-2; those are common enough, no need to settle for anything with less accuracy.

[mustanglx_1989]

There is no mechanical advance in the stock distributor that I am aware of. The computer takes care of it. That's what make me suspect the stock one is no good.

That crank trigger has magnets in the wheel itself, not the sensor. I have been told they are a little more accurate in high rpm applications. I'm not sure to the accuracy of that statement, but I see a lot of them at the strip.

I have the distributor in and am getting ready to try it. We will see what happens.