What is considered a normal idle on a 5S-HE? My '90 Celica has a transplanted motor from a '96 Camry and it seems to idle high, about 1100-1200. Car's a manual and I was having issues with surging when the AC was turned off. I corrected that by replacing the vacuum switch that increases the idle when the AC is engaged but it still seems high to me. I haven't had a chance to drive it enough to see if fuel economy is effected but it also seems to run high at highway speeds, at 75mph the motor is turning around 3300 rpms in 5th gear. Is any of this normal?
What is considered a normal idle on a 5S-HE? My '90 Celica has a transplanted motor from a '96 Camry and it seems to idle high, about 1100-1200. Car's a manual and I was having issues with surging when the AC was turned off. I corrected that by replacing the vacuum switch that increases the idle when the AC is engaged but it still seems high to me. I haven't had a chance to drive it enough to see if fuel economy is effected but it also seems to run high at highway speeds, at 75mph the motor is turning around 3300 rpms in 5th gear. Is any of this normal?
Idle for a manual trans should be 800-850 RPM.
3300rpm's @ 75mph is OK. Kinda low actually.
I'd check timing and then adjust idle.
Are timing and idle speed computer controlled on these motors? If I was wrenching on my old Vortec 4300 or GM 3800 I'd guess the throttle position sensor or idle air control valve, maybe gunk in the throttle body? Is there a similar sensor on the Toyota engine?
Both of those sensors are on the 5SFE as well. If you remove the intake hose from the trottle body, just inside before the butterfly, on the bottom you'll see a small hole, thats for the idle air control valve. The throttle position sensor is on the back side of the throttle body facing the firewall.
The 5S before 92 had an idle speed screw, 92 and after was solely electronically controlled. If your timing checks out, then I'd suggest trying to clean the idle air control valve as they seem to be a common source of idle issues on these engines.
That's where it's going to get complicated, the car's a '90 with a '96 motor. Am I going to run into any conflicts between the two? I'm not sure how much of the original plumbing came from the old motor and how much is from the new. I've hardly had any time to get under hood except for the replacement of the AC switch. Where is the idle screw located?
hopefully they used the manifold and throttle body from the original engine.
The picture below is of my engine which is a '92. On the throttle body you can see a small round light silver cap right behind where the intake hose connects. If yours has an idle speed screw, it would be where this cap is located
Rob,
Big negative there, the intake is different. Looks like it's all from the transplanted motor. I drove the car around town today, with and without the AC. Without AC the car idles consistently around 1200-1300rpms, engaging the AC drops the idle to just over 1K, the problem is that every so often' with the AC running, the rpm's will drop down to 850-900 and the car will act like it wants to stall. It quickly jumps back up to 1200+ and stabilizes. I cleaned out the butterfly this afternoon and checked all vacuum connections, everything is 10-8. Idle air valve? I don't want to do like other cars I've owned and just shotgun parts in hopes of fixing a problem. WTF?
I'm going into a work week, so I won't have a chance to pull the valve & give it a good cleaning till next weekend. I'll pull it ASAP and le you guys know what happens next. Thanks for bearing with my lack of knowledge.
Update on this;
I pulled off the throttle today and cleaned out every trace of gunk. Also pulled the IAC valve, the passage on the right (if the electrical connector is facing towards you) was filled with bizarre black stuff that almost looked like black insulation or foam rubber; black, crumbly and full of little bubbles. I cleaned put every trace of that stuff, reassembled and the idle is still high and surges when the AC is disconnected. With the AC running it idles around 1250 steadily. Turning off the AC causes the idle to surge to 1200, quickly drop down to around 900 and then jump back up. I know there's and idle up switch that regulates the idle when the AC is on, could this be the issue? The idle is noticeably smoother and the car seems to have more power at idle but the surging is bugging me. Before pulling the throttle the idle was smooth regardless of whether or not the AC was running, it only appeared when I cleaned the crud out.
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