Just had my engine dyno'd and air fuel ratio checked

I don't know Mike. I just know they have a shop (equivilant to 8 to 10 bays?) filled with muscle cars with experience back into the 60s.

Here's the site:

It appears there's no one in Southern California who can do reliable work or I just have a knack for finding the bad ones?

Bill

Ok, just called them up and asked about the numbers.

He told me at idle the number was .35 and at full open throttle (as much as they pushed it) it was 4.40.

He said these numbers were on the lean side.

Bill

Hopefully they meant 0.44 and not 4.40 otherwise your engine would go through approximately 70 gallons of fuel in an hour while making 120HP. If your numbers are that low, then watch the plugs after driving it for a while. Some engines will "like" a BSFC number in the mid .40s, but most passenger car engines usually run best at about .50 or so. My assumption here is that the numbers they are giving you are BSFC. One thing that would have been nice for them to do would have been to put exhaust temp probes on each header tube coming out of the ports. This would have given you an idea of the balance of fuel mixture between cylinders which would be a good way to test the injectors under running conditions.

Chris

Hey Chris,

He said the readings were on the (CO) meter if that makes a difference.

I'm going to test tonight the fuel pressure to make sure it's getting proper pressure to the rail. The R&R guys altered the fuel line slightly as it was 'pinched' from them either taking the engine out or putting it back in. They, of course, said I did it and I didn't, unfortunately, take a reference picture of the engine compartment before I gave it to them so I didn't argue on that point.

Bill

OK, they are basically giving you emissions numbers then. Has nothing to do with BSFC, but you'll have to look at your emission regulations to see if the numbers they gave you are going to cause a problem with emissions testing.

Chris

Holy crap man!

They can do 'anything' and are especially good at mix settings no matter the system!

We will put it on our Dyno and get the air fuel 'just' right!

With no machines in the freaking garage that can actually 'measure' the mix besides an emissions machine....

Man oh man....

Suffice it to say you didn't really get anything useful out of that because they couldn't even properly dyno it.....

Now if you still had the Carter BBD on her, then these guys would likely have been spot on for mix.

The problem with a tail pipe test on injection is the O2 can be seeing a nasty rich every 6th hit so it tells the injection to run full lean.

So you have 5 cylinders running full lean with one still spitting black s*it at the O2 and the O2 will hold her lean.

What comes out the tail pipe can still be just fine if the above balances....

I would just be keeping an eye on my plugs.

Mike

William Oliveri wrote:

Mike What would consist of a 'proper' dyno including the type of equipment attached to the dyno. Educate me here.

They have a Chassie dyno, is there other equipment that can be attach to a chassie dyno which measures air/fuel ratio?

Tell me for what to look for in a dyno reading. What should I make sure they do?

Thanks,

Bill

Also, if I want to make sure my injectors are performing correctly, what methodologies are used to test injectors? If I want to test injectors what kind of place should I contact to make sure they are working?

You are giving me theories to the gas wash and it's helpful but you also know my state of understanding, please extend the information by letting me know what methodologies would provide a satisfactory result.

Thanks,

Bill

There are others here likely more qualified to answer that Bill, but a couple things come to mind.

First off is you don't need the silly dyno to make an engine run right. Nobody had dynos before emissions testing, gee I wonder how we made then run back then.

That is something like a Dentist coming after you with a camera to show off the before and after as he takes your first born for the teeth work... (the local newspaper did an article and said when you see the dentist coming with a camera, run fast unless you just won the lottery)

Each cylinder needs to be monitored as well as the O2 sensor.

Injector Pulse timing, fuel pressure and maybe flow rate, spark quality (strength), exhaust temp at the manifold are some things.

Those are just guesses, others likely know.

The rough emissions testing is just fine for a carb, which is that shop's specialty, but even that can be done just fine static by rpm instead of with the tires turning.

I have had emissions done static, followed immediately by the dyno test and the engine read almost exactly the same.

Mike

William Oliveri wrote:

I would be wanting to read the pulses on a scope. The pulse timing shows if everything electrical is working. Like below, if 5 are short and the last one is long or no pulse or pulsing at the wrong time, etc.

At the same time I would be wanting to see the spark strength.

I would then be watching the leak down very closely when shut off to eliminate dirt holding an injector open.

Didn't you have carb issues before putting the injection on with flooding?

Your damage could have happened then.

Mike

William Oliveri wrote: