95 6.5 idle problems

[Gunar]

Hello friends,

Happy new year still on the other end of the world!

New year, new problem...

I also have now high rpm in idle. Now 850/900... 650 rpm before. Engine has operating temperature.

My Volt is 14,8 V at the alternator. I'll change tomorrow.

Can lead this to the high rpm ?

Where is the fast idle solenoid installed?

Thank you...
Gunar

 

[ak diesel driver]

If your talking your 95 tahoe it doesn't have a fast idle selenoid, it is controlled by the PCM

 

[Gunar]

Hello,

I have not seen the 93, only the- "6.5 idling too high" ;-)

It's about a 1995 6.5 Tahoe.

This morning it is started bad. The engine sounded terrible.

I changed the PMD... Very good start, rpm was normal at 650 (operating temperature).

Then i did a test drive: engine shut off with the Key- again bad start and the rpm was back at 850-900.

I still not changed the alternator.

 

[Will L.]

@Gunar

Direct to your question, on the 1995: cleaning all the grounds, replacing the 2 wire temp sensor, do you have any codes? Maybe ohm put the throttle pedal. Completely disregard what I said about cruise conrol before and such- it has no bearing on a ds4 pump system.

@craig marshall Is yours working ok now, or giving you problems still?

 

[THEFERMANATOR]

And what's the point?

Would you have an answer to my question, then you guys can answer here too...

I'm polite...it fits to the theme/thread-o.k. not to the year also.

You mean I get a right answer, when I'm opening a new thread?

As Will said, it would be like asking about problems with your 1999 corvette's ls engine in a thread about a 1969 corvette. Technically they are both 5.7l engines, but theres where the similarities end. Ones carbed, the other is not only fuel injected, but drive by wire with no throttle cable. One has a distributor while the other has a crank sensor, cam sensor, and individual coils for each plug. It's really difficult to have a discussion about one engine going, then to completely change directions on a completely different truck. If the added discussion is for the same truck, then by all means go ahead and ask. But to ask an idle question in a thread about a db2 mechanically injected engine about a ds4 all eletronically controlled engine is confusing to say the least. If I get on my laptop later, i can split it off, but I'm not very good at doing that stuff from my phone, and don't want to chance deleting everything.

 

[WarWagon]

Hello,

I have not seen the 93, only the- "6.5 idling too high" ;-)

It's about a 1995 6.5 Tahoe.

This morning it is started bad. The engine sounded terrible.

I changed the PMD... Very good start, rpm was normal at 650 (operating temperature).

Then i did a test drive: engine shut off with the Key- again bad start and the rpm was back at 850-900.

I still not changed the alternator.

I feel like you should change the alternator rather than agonizing over it. Just Do It and get the "throw parts at it with no results" completely out of your system. Think about upgrading it to a larger and more reliable CS144 so it's not a total waste. Maybe you get lucky and fix it. With the lack of reliability of the small overheated one in there it's not bad general advice, but, not relevant to your specific problem. So before you go through the trouble disconnect the 2 wire alternator plug and see if the engine runs different on just the batteries. Even that isn't a good test as I found a bad TBI injector that was voltage sensitive to unplugging the alternator, linky.

It's a good read and a case in point example of troubleshooting before replacing parts. I read the 14.8v at the alternator as irrelevant. So does the alternator because it's not sensing the voltage at the output terminal. It's sensing the output voltage from the main positive junction and making up for any voltage loss across the charge wire from it to the main power junction.

Read codes is easy.
Disconnect the batteries and load test them.
Clean the grounds.
Then get the GMTD SCAN TOOL SOFTWARE (link) and ask the ECM what temps it's seeing etc. If and only if it's not seeing a failure and displaying "table data" vs. real data, but, that's for the real tough ones to fix.

The above advice echoed here for good batteries and grounds as well as positive cables in good shape comes from the fact that "brown outs" cause the ECM to do weird things. At some given voltage and current the ECM quits functioning as designed, sadly, this voltage is above the voltage it just flat quits working. Bad or low batteries taking a high rate of charge can expose weak connections that wouldn't show up otherwise.

Don't be shy: I will also encourage you to start new threads so we can save you some money fixing your 6.5.