Scan tool

[9365turbo]

Who sells a inexpensive scan tool that will check the injectors on my 2002 lb7? It's smoking more then normal at idle. White gray smells like fuel. Engine oil is fine.

[Kennedy]

We have a nice basic code reader, but will not do injectors. The reality is that you will look at balance rates, they'll look fine but with the smoke that you have you'll end up replacing the injectors anyhow.

We have one in now that is same way smokes like a pig so you can't stand to be around it yet runs smooth as can be. It gets injectors tomorrow.

[9365turbo]

True. I would buy a tool that would sit in a drawer. I thought about taking it to Davis diesel here in Spokane,but I think already know whats wrong with it. So why waste the money on a tool. When the injectors are so expensive. My truck runs just fine, but your embarrassed to stop at a traffic light. Thanks for your response.

[More Power]

We have a nice basic code reader, but will not do injectors. The reality is that you will look at balance rates, they'll look fine but with the smoke that you have you'll end up replacing the injectors anyhow.

We have one in now that is same way smokes like a pig so you can't stand to be around it yet runs smooth as can be. It gets injectors tomorrow.

You would know. But, it doesn't make complete sense to me. I would think that if just one or two injectors were the cause of the white smoke, you'd see some indication of that in the balance rates. The computer adds fuel so that cylinder's contribution to engine running matches the contribution of the other cylinders.

On the other hand, if most of the injectors are more or less in the same condition, the balance rates might be closer to one another.

[greatwhite]

Complete guesstimate, but I'm thinking the reasoning is that all eight injectors have similar wear on them due to all have same miles under the wheels, so the wear can be expected to be the same.

Hence, similar balance rates but flow or pattern is out of spec.

But like I said, complete guess.....:cool:

[DmaxMaverick]

It's a lot more than just the balance rates. Without fuel pressure rates and response times, total leakage rates, and PWM (Pulse Width Modulation), the balance rates mean nothing.

For example, your balance rates could all indicate 0.0, and it could smoke bad. The PWM would tell the rest of the story. Normal PWM is around .4 (the default). If all 8 were at .1, with flat balance rates, that would indicate that all 8 injectors were overfueling equally, and the PWM is compensated with a shorter event. This is a hypothetical situation that can't really happen. If all 8 injectors were all worn equally, the engine would continue to run somewhat normal, until a point is reached when the fuel system is unable to provide sufficient fuel volume at pressure to the cylinders. If they all leaked (into the cylinder) equally, the engine would never idle, and the computer would have a fit (DTC's and likely limp mode).

However, if all 8 were overfueling equally, it wouldn't only smoke, the engine would just run away. The reason you see white smoke and not black, is the suspect injector(s) are fueling outside of the compression cycle, or very late in the combustion cycle, and raw fuel is being pushed out with the exhaust. White smoke with a knock indicates an injector that doesn't stop fueling (continuously wet cylinder that doesn't have a chance to get up to optimal combustion temp), or there are multiple different conditions occurring on multiple cylinders.

[Kennedy]

Yeah what he said :D

We've seen this over and over again where giuys take them in to have diagnostics run and the results come back inconclusive.

We also see people get overly protective and check their balance rates obsessively to the point of being hypochondriacs and almost inventing a problem where none exists.

Balance rates are highly over rated and I equate more like taking one's body temp because they don't feel right. Yep running a little off center, now what???