Was told after having the converter replaced that I had to get a check done on the car. They said the exhaust is running hot, buring more gas than it's supposed to. Well till the other day I didn't worry about it much cause it didn't overheat. I turned the AC off yesterday and let it idle. It's overheating with the AC off. I just replaced both tensioners, waterpump, thermo, etc., I have a thermo that if goes bad it stays open. No code either. Any ideals? Thanks!

O2 sensor, and bad injectors is all I can think of and I have no codes for them. I have noticed that sometimes after turning it off and restarting it right afterwards it chokes somewhat.

what about your radiator fans? are they cycling on and off like they're supposed to?

i just checked them out, doesn't seem to turn on till about 220 to 230. I've seen the gauge go up to the half way mark but never checked anything cause I shut the engine off. Now this is just the bigger one on low speed, never went to high speed. The temp did come down somewhat, 210 then back to 220/230. I also checked the fans with the ac on and both of them came on, at high speed, and stayed on. Turned the ac off and back to the same. After about 5 to 10 minutes of running the car at idle, the lower part of the engine just gets way to hot. Even the plug wires are hot, at the spark plug, not at the coils. Seems for sure the fan would come on but it doesn't, not till the upper part of the engine gets as hot as the lower part.

It sounds like your fans are working as designed! The fans should come on (high speed) when the AC is on, or the defroster is on. (This mode bypasses the coolant sensor). With AC or defroster off, the low speed fan should come on at about 220 degrees, and shut off at about 200 degrees. You might want to consider installing a 180 deg thermostat to allow the coolant to circulate out of the engine sooner (or cooler); however, this would not change how the fans turn on. Also, be sure to bleed the air out of the system a few times using the bleeder on the water neck.


You have a couple of choices on how to keep the fans running, if you want. First, leave the AC control "on" and let the auto temp control the cabin temperature. Second, you could wire a switch to ground the fan relay, by using a toggle switch under the dash. Personally, I leave the AC control on year around. Remember, the compressor only engages when it needs cabin cooling.


Another option, and what I did on my Z28, is to modify the fan temp parameters (lower) in the prom, to control on/of cycles. (This modification should not be needed need on a daily driver.)

Running rich, would more than likely make the manifolds glow red :angryfire,rather than running lean. Check your fuel pressure.:iceslolan

Wow thats hot.. thinking here.

Mine runs about 160 indicated in 80 degree ambient.
Clogged radiator?

Your start sequence you mentioned a little ...
This engine uses MAF sensor and ECT sensor during start and waits for the 02 sensor to go into closed loop.
Clean your MAF sensor? ... carefully. OR disconnect it.. for a check. It will throw a code if you do.

GOOD LUCK

The MAF is clean, no codes, still runs on the hot side. Nothing really gets hot on the engine in the first couple minutes except the bypass solenoid which gets extremely hot with in minute or so.

HotZ said check fuel pressure. It's at 32 psi, I rev it up alittle and it goes to 38 then right back down to 32 psi. Holding it at 2000 rpm is at 32 as well. I went to shut if off and didn't take it off right away, about 2 minutes passed and I noticed the gauge was going up, slowly, it topped off at about 40 psi and about 15 minutes later it has about 3 psi. When I first turn the key the pressure is at 38, then goes to 32 after starting it. Is this all normal?

From the book..
Fuel pressure with ignition "on" and fuel pump running..
41-47psi.
With engine in idle a slightly lower pressure depending on barometric pressure.

You say it chokes!... could you have a leaky injector?

Good luck

I had to take my fuel rail off when replaceing the SC. I noticed 2 that looked like they had been leaking and replaced them, the others looked ok. Don't really know how to check fully.

Now on the fuel psi, I get a 32 psi reading even when at 2000 rpm. If I push the throttle fast from an idle it goes to 38 then back to 32. If I do it slowly it stays at 32. The fuel filter is brand new. Does this help?

Your fuel pressure is a bit low. What temp thermostat is in the car?

To check for leaky injectors that leak into the cylinders you evaluate the spark plugs for rich condition after a good long idle.
I saw a shop checking them with a strobe light, checking spray pattern, piss or spray.

Here is what i think is one of the better of the web sites for Plug evaluation.

http://www.4secondsflat.com/Spark_plug_reading.html


I understand pressure hasnt much to do with the fuel filter at the pump... mostly the flow to the rail.
A bad filter restricts the flow reducing the pressure at the rail.

Checking during a rev and run is a bit arbitrary due to barometric conditions cleanliness of filter, damaged fuel lines.


Good Luck.

PS; this is a guess... someone else hopefully may post..
but I wonder if run your car at an idle for a bit 5 min.. and cut it off..wait 15 minutes and pull the plugs and can look smell for fuel.

What if I have exhaust smoke after a few minutes of last running it? And more at cold start up. Doesn't last long, a couple seconds thats it. Its blueish-grayish-blackish looking. Could that be the injectors causing that? I was thinking valves.

What if I have exhaust smoke after a few minutes of last running it? And more at cold start up. Doesn't last long, a couple seconds thats it. Its blueish-grayish-blackish looking. Could that be the injectors causing that? I was thinking valves. Your exhaust smoke, does indeed sound like leaking valve seals. Drive the car down the street in low gear and do a WOT burst for a few seconds, and then let off the throttle. Look behind the car in your rear view mirror, to see if smoke is coming from the rear of the car. This "quick check" procedure has been used for many years to check for worn valve guides of leaking seals. :grinyes:

The thermo is 196, and is new, it's one of those new stays open when goes bad types.

Was trying the WOT at idle, just pushing the throttle real quick and letting go. Was checking for smoke in the exhaust. I noticed some. And I also noticed that when letting off the throttle as it was coming down to idle, it was rough sounding, like it was missing pretty bad. Not smooth at all. Reving it sounded normal except for the little hest. it has when I first push the petal fast. Does this help any?

Very white smoke can be coolant burning in the engine. It smells funny, sweet some call it.

I think if it blue smokes when you let off the throttle is suspicion of exhaust seals.
When you power up and get into the throttle and it smokes its intake valve seals leaking.

Pretty much all the time smoke could be rings.
These engines have not had alot of ring problems, but still possible when mistreated like running without a intake air filter.

Blackish smoke is a better sign it may not be so costly. Black is unburnt fuel and could be repaired more easily.

The smoke doesnt address the overheating issue very well..

Timing and poor coolant system are my thoughts.

I'm lost...don't see anymore smoke. The smoke was more blackish. I don't have an overheating problem so the gauge says. It just seems like the exhaust is to hot, like it's running to rich or to lean. It still seems hot. Can I have something causing this that is not code related? Like I noticed my supercharge bypass solenode gets extremely hot within a minute or 2 after starting the car. Is that normal?