My L98 idles hot in gear 750 rpm and 950 in neutral. is this normal?

And how can I lower the idle?

 

That seems a bit high but not so bad. My '88 warm idles at 700/600rpm.

What year Vette??

 

Auto's should idle at 600 fully warmed and 700 in park. Manuals are programmed to 700. high idle means lean condition. could be vacuum leak, or bad IAC, or somebody has screw up the throttleblade screw. Do a search for setting minimum idle air.

 

This comes up so often that I bookmarked the link:

http://forums.corvetteforum.com/1570563689-post1.html

 

How do you know it is high? My tach read 300 over actual. Actual was verified by a scanner and a tap of the plug wire with an snap on timing light with tach. Both of them said the tach was 300 off.

 

how many posts do you have to make to get that many stars and yet don't know the answer to that question...Is this a test????

 

You never know. Don't overlook the basics that someone thinks it is high because the inaccurate tach says so.

It is strange though. I had a 91 Firebird where the tach was always on. I haven't heard too much of dysfunctional tachs but in Vettes, it seems more prevalent.

 

I have a C3 for many years and it has carb with a 5 speed manual so it is easy to work on.
I am just trying to get some educated info from people here that have lots of experience with EFI and 700R4 transmissions.

This L98 and 700R4 is in a 56 Chevrolet step side pickup. I bought the L98 and trans on line 5 years ago and the company I bought it from is no longer in business so I now have to rely of folks that have experience from this section. Unfortunately I have received lots of confusing info and so many folks thinking that everyone wants to build a hot motor and trans. Not to worry I get that from folks on the C3 forum all the time.

I am just trying to get a stock motor and trans to work as it should.

Over here almost all old American cars have Toyota motors and transmissions in them but I really don't want to do that. My C3 has a small block chevy motor with a 5 speed manual and it runs and drives good.

Please keep in mind that over here there is no parts available and no help either, so here I am trying to learn what I can.



Also understand I am a Corvette owner and want to keep a Chevrolet motor and trans in my 56 Chevrolet pickup that I have been working on for 4 years now.

BTW, my tachometer is spot on it is a new Dakota digital, tested with a hand held scanner.Now after reading many suggestions I now think the hot idle problem is a vacuum leak.Many thanks fellow Corvette owners.

 

holy crap...nice engine.....I didn't mean to sound mean...I guess it would help to know what year is the engine or what ecm you have...if it's runing off the normal ecm, there are lots of threads on setting the minimum idle...from the pics, it doesn't look like a lot of 'stock' is left...

 

If the idle is really high, what does the ECM command idle?

 

As you noticed it has allot of changes made including LPG injection with a separate computer, also a controller for the Dakota digital gauges and shifted indicator.I mostly use the gasoline system that is a mixed unit. the ECU see attached picture.

I don't know how to find that info?

 

I use my scanner and inside desired rpm is your answer.

 

OK thanks.. I will see if my friends scanner has that option.