Hi folks,

I'm new here so forgive me for having two questions in one post. I just bought a 1989 RS/ 305 TBI/ 700R4 and I have a couple of problems I need to fix.

First, when I cold start the engine the idle speed is around 1400 rpm until it warms up- WAY TOO FAST- it acts like a carburetor with a fast idle cam out of adjustment. It idles fine after warming up. Is there an idle speed solenoid that I can adjust or is there a sensor I need to check/ replace? I have a Chiltons repair manual but it doesn't cover this particular problem. I have a very basic understanding of EFI but not enough to diagnose too many problems. Any suggestions or ideas on how to diagnose the problem will be appreciated.

The second problem I'm having is with the 700 R4 transmission. If I need to post to a transmission forum let me know. The lockup function doesn't seem to be working. On every other GM vehicle I have owned with this trans I could feel the converter when it locked up and could feel it unlock when I touched the brake. On this car I can't feel either function. I looked under the dash for loose wires on the brake pedal switches but found none. Any ideas on how to get it to lock up, or how to determine if it is an internal problem with the tranny?

Thanks for your help,

Mike Hannah

 

Welcome aboard.

I'll move this over to the TBI forum, as you're more likely to get a useable response over there.

The torque converter lockup may or may not be a transmission issue, fault location-wise.

 

Welcome aboard. Your high idle at start-up is normal. our tachs are notoriously off so you may not be as high as you think. A little boost in rpm's when cold will allow the engine to heat up faster as well as build oil pressure quicker.

 

Like said above, the idle sounds right on the money for the engine being cold.

As for the lack of lockup, there are lots of causes for that. Could eb a stuck valve, electrical fault, a faulty switch, bad clutch in the torque converter, etc. About the only thing to really look at is to make sure that the connector on the drivers side of the transmission is hooked up properly and there isnt any problems with the CTS. Other then that youll have to take it to a shop to have it diagnosed and fixed if you want lockup in overdrive.

 

Thanks for the opinions guys. I know that I should have a higher idle speed when the engine is cold but I think this is way too high. I have to really hold the brakes to keep from taking off when I put it in gear (which also causes me concern due to the shock the driveline gets). After looking at the tach again I realize that it actually idles cold at about 1600-1700 rpm and hot idle is about 700-800 rpm. That cold idle speed just seems too fast to me- I sure wish that I could adjust it down some.

My gas mileage is also a problem. It runs great other than the idle speed but I only get about 18-19 mpg with this car. Obviously with the lockup converter not working that would hurt gas mileage but I'm not sure it would make that much of a difference (maybe 5%). I have read on some of the posts on this site that some guys get mid-twenties mpg from 305 tbi third gens. I'm about 25% off from that level of fuel economy.

I plan to check the connector on the trans and maybe check for trouble codes in the computer when I have a day off from work. Any more suggestions will be appreciated.

Thanks, and oh yeah...nice board here...I think I'm gonna like it!

Mike