Engine/Transmission (1994 - 1998) High idle

[RShafer]

Just had my TPS switch replaced on my 97 12valver stock dually. problem was hard starting and when I hit the gas it would die. Diagnostic at the shop said the TPS switch was only showing . 9 volts. After replacing the truck starts great but the mechanic said that he bumped up the idle because I was running around 500 RPM and now I am around 850. Sounds a little high at idle to me. What is the normal idle or is that a dumb question.

Thanks

 

[champspa]

I think it's 675 rpm with it in gear and air cond. on

 

[Matthug]

I set mine to 800 in neutral with A/C off. My A/C knocks it down 50 and I'm not sure since I have a manual trans what putting it in gear takes it down too. 850 sounds right for an automatic in park though, unless thats 850 in gear than yeah it's way too high!

 

[Joe G.]

Did you keep the old TPS? It sounds to me like you didn't need a new TPS in the first place. Idle should be at least 750 RPM in gear with the AC on. 800 is better. The way to make a quick test if your truck is hard starting because of low idle is to give it a little pedal and see if that cures the hard start problem. You can rig a low voltage TPS to make better voltage with a cheap variable resistor in the ground wire to the TPS connector.

 

[RShafer]

I would hope that was not the case as my mechanic is also a good friend... hey but what are friends for eh? Seriously the truck would start with a half throttle but I must say that with the new TPS I can stand outside the truck and it will start within a second. The RPM in neutral is around 1k. In gear with AC on is around 850 (auto trans). Seems high but I am putting my trust in my friend... however the last time I did that he is now married to my EX :

 

[Joe G.]

It starts quickly now because of the idle adjustment. The TPS has squat to do with starting. It tells the CPM where the throttle is for transmission control. Your '97 has an all mechanical fuel system. Nothing that the CPM does affects starting or running for P7100 equiped engines. So the TPS has no way to affect starting. Check your service manual wiring diagrams.

 

[RShafer]

Well that SUX. This is what you get when you trust a mechanic. Hell for all I know he didnt even replace it. He did show me a small rubber coated sensor but it could have been a relay for a stereo for all I know. Water over the bridge and no return customer. Thanks for the info JOE. I wonder if he wants my wife to boot Oo.

 

[RShafer]

Trans issue

Hey Joe,

Seems like you know much about the dodge diesel. I pull a 11k 5th wheel and she seems a little boggy. Do you think that a torque converter replacement and pump service would do the trick or go with a goerend bros or DTT transmission. Dont want to waste a bunch of cash when I can the same effect with a titanium TC

 

[Joe G.]

With that kind of weight I think you will have to go with a DTT or some other major vendor transmission. Especially if you increase your power. More power is cheap and easy on a 12 valve. However, if you do that you have to get at least an EGT gauge. Better to have boost, fuel pressure, and trans temp gauges too.



Where do you live?



The big problem with having a 12 valve is that it may be the last purely mechanical engine in a popular vehicle. All the mechanics (excuse me, technicians) now expect electronics to be involved. I found out that is true even at the local Dodge dealer. They had a '97 in the shop with a bad AFC and could not figure it out. It belonged to the parts department manager who is a friend of mine. He asked me what I thought was wrong with his truck. I told him it sounded like a bad AFC and that's what it was.

 

[RShafer]

Of course I live in an area that would required pulling power. I live in Blue River Oregon which is about 45 miles up the McKenzie River from Eugene. I think you are right with the DTT as I dont want to dump money and still have to replace it later, especially with a 5k pricetag already on a specialty trans. Overall she has been a great truck since I have had her and dont want to let it go to waste. Present mileage is only 111k and I believe I still have many miles to go. Plus the tag for a newer model would be much more. This one is paid for.

 

[JPittinger]

... as I dont want to dump money and still have to replace it later, ...

I hope you don't think you'll have to 'replace' the Goerend transmission in the near future! There are a lot of guys here that will say a lot of good things about Dave Goerend's shop, including me. BTW- It won't cost you $5k either.

 

[Joe G.]

I was up that way last weekend. Fishing the Umpqua River above Idleyld.

 

[RShafer]

So I was told it was around 5k. Can you give me a better ballpark figure. I shoud probably call them, take a couple of days vacation and just get it done.

Bob

 

[Joe G.]

I really don't know. I bought my VB and TC several years ago. They are working fine, but I don't tow near what you do.