Hey guys, its been a while. I've been 4x4ing my 88' pickup alot this summer and i am begining to notice an abundance (or respectable amount) of power when she is cold or at that first start of the day and then a LACK of power when it reaches operating temp. Its not drastic, but does usually make a 1 gear difference on certain hills where i live or when out in the bush. Haha yes, i will admit im runnin 35s with stock gears <img src="/forums/images/graemlins/drunk.gif" alt="" />. I have heard of this problem before and im 95% sure its not a overheating issue. Can anyone shed some light on this? Thanks.

Might want to pull any stored codes in the ECU (if any).

Also, check out the EGR system. It can affect engine operation if that valve is open at the wrong time. Might be the EGR valve is stuck open.

I've noticed the same problem with my 4Runner lately <img src="/forums/images/graemlins/confused.gif" alt="" /> No stored trouble codes and disabling the EGR valve makes no difference. It feels as if there is no ignition advance. Advancing the base timing makes it run better when its acting up but is no real solution. My TPS is properly adjusted and sweeping nicely. I've tried a different knock sensor just in case the ECM was recieving an erronious report of pinging. I even tried my spare ECM. Of course I also confirmed minimal voltage drop on the main power and ground circuits as well as many of the sensor signal circuits. Under what other actual or percieved conditions will the ECM inhibit ignition advance? <img src="/forums/images/graemlins/confused.gif" alt="" />

Thanks guys, i will take a gander at my EGR system and check for codes. Also, i forgot to mention that during all this my brakes seem to be affected as well, kinda feels like the MC is crappin out and the pedal will almost go to the floor quite easily once the engine reaches operating temp...wierd! Thanks again.

Well, it must be something attached to global warming. Everything you guys are describing sounds exactly like my truck for the last 2 months. I checked the EGR, all the sensors I could find, VSVs, removed and cleaned the throttle body and reset the TPS, and it still runs like there is no vacuum advance. <img src="/forums/images/graemlins/angry.gif" alt="" />Since my brakes are also acting up, I am now beginning to suspect the vacuum brake booster is leaking and there is a "path" causing vacuum leak symptoms.

Here is some good information regarding the operation of the ignition advance systems. TCCS VAST ignition system