Ok, I'm getting kinda worried about my new RS that I recently bought. I won it on Ebay for $3500. It only has 68K original miles on it and it is pretty good condition. LO3 w/5-speed manual. Anyway, I finally got to look at it this weekend (I've been out of town) and the car is in pretty good shape, the interior and engine need cleaning, but will clean up well. The car needs new exhaust (the cat is broken and you almost pass out from the fumes when the car is running. My first deal is with the engine and the tach. The engine seems to be taching way too high. At start up it will stay around 2500RPM when it maybe sounds as if the engine is at 1500RPM. When I drive the car the tach will never drop below 2000RPM. When the car idles after being warmed up, it idles at 1500RPM and often surges and idles erratically. I also noticed that the heater hoses have been cut and bypassed...probably meaning the heater core is bad. I bought a MSD blaster coil, Cap & Rotor, but the tach is still doing the same stuff. What is the first thing you think I should do, I'm starting to regret getting the car...

 

You check the timing? I have a funny feeling he may have done something to the timing to get the car running.

 

I have been having the same problem with my LO3 and now my throttle seems to be getting stuck so looks like my car isn't going anywhere until i figure this out

 

Formula4Speed
Are you running a open air element on your car?

 

I'm still running the stock air cleaner so I don't think its a vacuum leak. I think its my throttle plates that are sticking so when I get a chance I'm gonna try to take a look (any advice on what to look for would be greatly appreciated). I know it could also be the throttle linkage but I'm not sure what to look for, I'm new to the whole DIY scene I usually pay someone to fix my car...

 

not to sure about a sticky throttle but i heard somewhere that it could be because the bushings are worn out, as far as i know thats something that you need to have a professional look at.

i'd take off the TBI and hose it down with a cleaner. if you feel like taking it apart you could use some "ez off over cleaner" and strip the gunk off. just dont get the cleaner on plastic things or the little screens on the injectors, it will clog them up. At least when i took my tb off the underside was covered in burnt oil and clogged up some of the vaccum ports.

 

Alright, so what should I do? It is obvious that my engine is not really idling at 1500-2000RPM, and when I drive the car, the engine sounds normal but the tach is hovering around 3000 and pegs up from there when I drive it...also the "shift" light is all messed up coming on wrong I guess from the messed up tach. What should I do? I don't have $ to be taking this car to the shop!

 

You haven't said anything if you checked the timing.

 

My friend had a similar problem a while ago in his 95 Trans Am. The tach kept jumping around but the car seemed to run ok. It ends up that one of his plug wires got too close to the exhaust manifold and melted a lil. Every time it would hit the manifold it would ground out causing the tach to go nuts. I'm not sure that this is your problem but it's another option to check out.

 

1st off, ignore the tach.

they are terribly inaccurate..... and they get worse with age.



now you said you noticed hoses cut.... id start off by looking very carefully at every Vac hose under there...

do you have a Service engine light? even if you dont, try to pull some codes off the computer... you need a paperclip, or a hair pin, or a piece of wire... even some alum foil rolled up tight can work...
theres a how to on checking it here: https://www.thirdgen.org/newdesign/faq/thirdgen.shtml

its near the bottom, 2nd to last.


now get a timing light, and following the directions on this site, disconnect the timing connector, and check the base timing.

then post up anything you find, the codes you have, and your current timing...

once you do that, while you're waiting for a reply, id do a search on the IAC and how to clean and adjust that.... that should fix a high idle.....


edit: btw, i should rephrase.. it wont fix a high idle unless its sticking and thats your problem... but its just a good idea to clean it out anyway... if you have a vac leak, that will still cause a high idle.

 

if it is sticking, try tossing a carb throttle return spring on it.

the car SHOULD idle high when cold. around 1500rpm, once warmed up that should drop to about 600-650rpm.

like everyone else says, ignore the tach. i shift mine at about 9300rpm that is how bad the factory tachs are.

 

a good way to check and see if your tach is off for sure, (i'd think you could hear that its off but incase you cant) is go to the equations section on the thirdgen.org homepage. I have an automatic w/ stock 2.73 gears, not sure if its the same for the manual but you could find that out somewhere on here or on yahoo. Any way go to the equation page and set your cruise at different speeds in different gears and record the info it gives you and plug them into the equations to see if it all adds up right.

BTW, mine's an 89' and its right on, must'ave gotten lucky
-chuck