I have been seeing a lot of this mod lately and was wondering if this has created any exsessive heat or any other problems in hot or cold weather? Opinions please

 

Bypassing the TB will reduce heat to the plenum. In warm and hot weather this is desireable. The reason GM put coolant through the TB is reduce icing of the TB blades.

I have a bypassed TB and I have driven in -10*F and never had this problem. However, the lack of coolant made the plenum so cool that it disabled the EGR from functioning (enable temp is around 5*C measured in the plenum). When the EGR ceases to function, you will get a greater occurance of knock at part throttle due to the high spark advance at part throttle. Also, it caused the engine to run excessively rich and burn too much gas.

If you want to do a TB bypass and you live in a climate with cool winters, you should have the EGR Enable Temp set to a lower temp via the eprom. The plenum will always run a few degrees warmer than actual ambient air temp due to latent heat. So if the ambient air temp gets below +25*F, the plenum's temperature may drop suffieciently enough to trigger the 5*C threshold for the EGR and stop it from functioning.

One further note, if you are also running a relocated MAT, then the EGR will stop functioning when the relocated MAT detects any temperature less than 5*C. A relocated MAT just further compounds the problem.

[This message has been edited by Glenn91L98GTA (edited September 29, 2001).]

 

yah the MAT relocation thing is just somethin i never got. GM runs the cars a little rich anyway, why put the MAT out in the cold air to make the problem worse? however i just thought, when installing a big cam, you may need a little more fuel. would this be a way of doing that along with an AFPR?

------------------
86 IROC
43,000 miles
305/700R4/3.23 gears
maroon, gold stickers, black interior, T-Tops.

current mods.
shift kit
headers
cat back exhaust

mods planned for this winter
cam
3.73 gears
subframe connecters

 

On SD cars, the MAT definitely affects the fuel mixture (along with the EGR). On MAF cars, I can only find it affecting the EGR; not the actual fuel mixture - it all appears to be compensated by the MAF.

With a MAF car, a relocated MAT will cause the EGR to cease to function sooner as the MAT will not be reading the latent heat in the plenum. Other than that, it appears to do no more than be a fancy ambient air thermometer for a MAF car.

An AFPR has it's greatest effect at high load (like WOT) and least effect at low load (like idle/deceleration). Given the AFPR's non-linear aspects, it can actually cause problems with the MAF Scalar tables for fuel metering and actually require the MAF Scalar tables to be "adjusted" to properly compensate for higher fuel pressure.

With a MAF car, simple mods can be compensated for to a large extent, though it can benefit from "fine tuning" of the eprom. When you start getting into "large cams", it causes its own problems, especially "reversion" during idle. Even stock MAF cars benefit from having the eprom "tweaked" and with large cams, it can become a necessity.

For MAF cars running the 165 ECM, using the ARAP BIN is a good starting point for "tweaking" the eprom. It is much tighter.

 

Is the MAT reloation a good idea for SD cars then, or no? How about those TPS enhancers? Are those a good idea?