I have a 1988 Iroc, automatic, with a stock 305 TPI. After taking it out of storage, I noticed the rpms in idle and in gear are way too high. Cold start, the rpms are at 4000. After it warms up, the rpms drop to 2000.....in park. In gear, it's sitting at 1600. When driving it, it's practically redlining every time it's changing gears. I'm thinking/hoping this is a vacuum leak. Any information or possible solutions would be greatly appreciated. Thank you.

 

Definitely check for vacuum leaks. A squirt bottle of water works well for this. May need to check/adjust TPS and IAC.

GD

 

Water bottle? Nice trick. Thank you.

 

Yes - take a basic bottled water bottle and drill a small hole in the cap. Water is pretty "viscous" and it makes a nice suctioning/slurping noise and bogs the engine when it gets sucked into the leak. Here's an example:


GD

 

I will try this out and let you know how it went. Thank you.

 

Sounds like the "tach"* is inaccurate, like everybody else's, and has failed the same way everybody else's has also already failed, which is, it reads STOOOOPID high. You can easily verify by measuring the RPMs with real test equipment.

I wouldn't bother with all the "vacuum" crap. I'd suggest fixing the "tach".


* This thing is not an "instrument" or "test equipment" or anything else of the kind... it is a TRIM PACKAGE only.

 

i was hoping to see a 12,000 rpm third gen...

 

Let the "tach" go long enough in one, and you might...

 

Like Sofa said and I agree with him here , I highly doubt your engine is actually turning 4000 RPM at a cold idle , good grief if it actually WAS turning that kind of RPMs you'd leave 20 foot burnouts every time you put it into gear !

Your tach is bad , like they ALL fail in the same way eventually , and a quick search here will produce a thread or two about the problem and how to get the tach reading correctly again .

 

Ok. Thank you. I'll get it checked out. I appreciate the input.

 

Corrected.

Not to be argumentative, but that "round thing filling the extra hole" in the IP of my '86 is within 100 across the board. The only problem is that is doesn't register above 5,200 RPM, but on a 305 TPI I don't think that has anything to do with the tach itself.