Actron Scantool

[20050627|3|008327|000043|65.183.99.20]

New Member. Bought my truck last week (see Sig)

I've also got an Actron Scantool that I used on my 94 Gas truck. I've been driving around getting some readings and have some questions.

1. Boost? What is the tool trying to tell me when boost goes from 101 to 130

2. Wastgate % I'm getting black somke and my wastegate % normally is about 77% and drop to ~65% when accelerating up a hill. I know I need to look at the wastegate and the vacuum to it, but what is the tool telling me?

3.RPM? There is about a 300 rpm difference between the tool and my tach. The tool consistently reads 300 rpm lower.

4. This tool does not seem to want to reset the codes. I had a loose connection in the relays behind the fuel filter that set a couple codes. I've fixed the relays but when I set the tool to reset the codes, it hags up and does nothing. After 10 minutes I get frustrated and unplug the tool. I pulled the ECM fuse to reset the codes.

I have lots of questions but am trying to tackle one issue at a time and right now want ot figure out the tool.

[JohnC]

Originally posted by Tacklewasher:
1. Boost? What is the tool trying to tell me when boost goes from 101 to 130

This is absolute manifold pressure in kpa. You need to subtract ambient pressure to get boost, then convert to psi. Roughly, 100 kpa = 15 psi = ambient. 130 is about 0.3x15 or 4.5 psi boost

2. Wastgate % I'm getting black somke and my wastegate % normally is about 77% and drop to ~65% when accelerating up a hill. I know I need to look at the wastegate and the vacuum to it, but what is the tool telling me?

This is the commanded duty cycle of the wastegate solenoid. The ECM reduces the duty cycle to reduce the vacuum to the wastegate actuator to reduce the boost. If you're getting black smoke chances are the vacuum is leaking off or the pump is NG, assuming you are not getting DTC 78.

3.RPM? There is about a 300 rpm difference between the tool and my tach. The tool consistently reads 300 rpm lower.

Most likely the alternator has been replaced and has the pulley for a gas engine. RPM for the tach comes from alternator frequency output.

4. This tool does not seem to want to reset the codes.

Talk nicely to it. Or, look at www.kennedydiesel.com (http://www.kennedydiesel.com) tech tips. I think he describes another way to read and clear codes.

[autocrosser]

If you have a properly operating wastegate it's possible, if everything else is operating properly, that your catlytic converter is clogged. Open the connection between the exhaust doen pipe and the cat and see if your black smoke goes away.

[20050627|3|008327|000043|65.183.99.20]

Re: the cat being clogged.

I'd have to have a cat first. It's been removed at some point.

I need to check the vacuum but I'm thinking of ditching the egr and getting a turbo master and ditching the vacuum pump altogether. Not sure how my ecm will react though.

[20050627|3|008327|000043|65.183.99.20]

Originally posted by JohnC:

Talk nicely to it. Or, look at www.kennedydiesel.com (http://www.kennedydiesel.com) tech tips. I think he describes another way to read and clear codes.
Swearing at it isn't the answer?

I've printed his code page but it does not cover clearing codes.

Thanks for the rest. Interesting on the alternator. Where would the scan tool pick it's RPM up from and is this an issue to performance? I don't mind the tach reading high as it will stop me from overrevving.

[Turbine Doc]

IIRC in OBD 1 computers codes can be cleared by disconnecting batts for 30 min,(that sound right anyone) if that doesn't do it, any auto mecanic/shop with Snap on scanner should be able to do it, also I also think if problem is fixed after 40 starts it is supposed to clear itself

[JohnC]

No, I don't think swearing at it will help.

The scan tool gets it's RPM from one of the engine sensors (ECM can't see alternator frequency) Crank sensor, I think.

To clear the codes, put the paper clip in the diagnostic port as described. turn the key on. Before the codes start reading, push both the brake and accelerator all the way down. Hold them there until the code reads out 1-2, Release pedals, remove pin and turn off key in that order. If the PCM is already spewing codes it will not reset. It seems that the pcm keeps spewing codes even if you stop reading them. Best thing is to let it sit for a while then try again.

At least you don't have to reset the radio presets... (Also if you leave the PCM unpowered for a while it "forgets" a lot of engine optimization parameters and has to relearn them.)