I just drove home and I have a few concerns. My friend who put in the kit (Drag III) said to keep the EGT under 1250 or so. However, even when I'm cruising at 65mph in 5th gear and 10% throttle, I'm at 1300F. I'm in vacuum, and it still runs hot. I have to let off the gas to get it down again.

When I do boost, the temp goes up mighty quick. From a start, I get up to 70mph and I'm already at 1300F. How am I going to run down the track that way?

My car also backfires, which means it's running rich. But in order to lower the temp, I have to add more fuel with the AFC. This sucks...hehe.

What can the problem be? I'm only boosting at 5psi right now, with no check valves.....

Sorry for the long post, and thanks in advance.

 

That means your running lean. do you have a vafc to richen it up. you don't want to be running lean too long. you'll detonate and blow up that engine.

What rpm is it backfiring at?

 

Hey man the guy u talk to does not what he talking about u don't have to keep your egt's below 1250f just make sure the when you are at wot don't let the egt''s go over 1500f.trust me on this. and when you are cruising don't even sweat what your egt's go up to mine go as high as 1600f cruising so chill.

 

Ya think so? What do you other guys have to say? I thought that I was running lean, so I added more fuel. (Yes, I have a S-AFC). No change, however.

It backfires when I rev up, and then let off the gas.

Weird stuff.....

Thanks for the replies....any more?

 

OK if you rev it up and let off the gas that is ok for it to backfire, what happens is there is a abundance of fuel left in the chamber and it doesn't get returned to tank right away so hence it backfires. That is understandable and normal.


As far as the egt goin up in temp just richen it in that rpm range. Have you dynoed your car yet? Looks like you gotta dial in your af ratio. better to be rich than lean.

 

Well, you want to keep it below 1500-1550 F or so. Valves and such can begin to melt at 1650+ F.

1250-1300F is typical for a 70mph cruise.

These numbers assume that your EGT probe is BEFORE the turbo. EGT is affected by static ignition advance. If your ignition timing is too far retared, it may still be burning somewhat on the way out of the combustion chamber and will result in higher EGTs.

You do not run lean in vacuum situations, hence the O2 sensor. EGT as a tuning aid is only useful at wide open throttle.

Dustin

 

Thanks for the replies.....so what do you guys run your EGT's until?

Dustin, I do have it on the manifold, before the turbo.

Please note that I have an internally stock motor (except cams). It's not built up in any way. And I also have 115K miles on it. Would that affect anything?

How come the temps are higher cruising in 5th gear, than in 4th gear (even boosting a little)? This is so confusing! Sorry if I sound dumb...hehe.


[Modified by shamoo, 9:37 PM 11/5/2001]

 

Shamoo, as long as your friend installed the fuel pump and FMU correctly in your car then you shouldnt even need the AFC. I'm assuming your running stock injectors, 12:1 FMU and Airtex fuel pump.

 

There is more load on the motor in 5th gear. EGT is a function of load and RPM.

Dustin

 

Yup, I have the supplied Vortech FMU, I assume it's 12:1 and the Airtex fuel pump. I'm just worried cuz the temps rise so quickly and I'm only at 5psi.

I just took it for another drive, and noticed that the brake is soft. After I hit it, it hardens up again. Is it because I have things running off the vacuum lines? Do the brakes work with vacuum as well?

 

i beleieve the brakes work as a hydrolic function.... (pushing liquid through a small hard piping "brake lines" and has nowhere to go so they press on the pads and stops the car....

but i dont know if a vacuum runs soemhere to supply the fuild or soemhtin....

 

It would seem to me that in fith gear you are using less throttle, then less fuel = more lean. A lean engine runs hotter. In fourth boosting a little the FMU is dumping more fuel, cooler temps because there is still not a whole lot of load on the motor.

 

Throttle controls the air allowed into the engine. Throttle position has nothing to do with how lean or rich a motor is.

Dustin

 

how does the engine know how much fuel to add then as the throttle opens up and lets more air in? Is that what the MAP sensor does?

 

Yep

 

Brakes do work with vacuum, but the turbo shouldn't make a difference. You never brake when boosting so the power brakes always will work.

You probably just need to bleed those brakes. A couple fast runs and hard stops will boil old fluid in a hurry. i speak from experience.

Randy


[Modified by RGAZ, 8:02 AM 11/6/2001]

 

hehe, same deal with me drove it home last night.
it scared me to see 11F on the gauge but its cool.

 

if you cruise the same speed in a lower gear i guarantee that temp will come down.

 

You guys all so clueless, Amateurs............

 

Wanna offer some help then?

Doesn't the AFC use throttle position to supply the amount of fuel? That's what I was attempting to do to fix the heating up issue.

I guess the basic question I have is, if I'm either in vacuum or boosting at about 1-2psi, and I rise to about 1400F or so, do I need to be worried?

My friend says to use the EGT as a guide to know when to let off. As of now, I can cruise at 75mph, but not 60mph.....and going uphill, forget about that. Hmph.


[Modified by shamoo, 11:00 AM 11/8/2001]

 

FROM WHAT I'VE READ:

IF you are overly rich, you may be experiencing afterburn... where all the
fuel is not burned up in the cylinders, and is actually being burned in the exhaust
manifold... You may want to try leaning it A LITTLE, and seeing if the temp goes down.. and if it does, continue leaning it until the temp decline comes to a stop, and begins rising again... stop at this point

 

dont have my egt gauge back yet, ben anything??

 

Before you start playing with the AFC (which you shouldn't have to at all with your set-up) take your car to a dyno to find out what its doing. The egt's being slightly high could be from any # of things.

The 5th vs 4th gear thing...5th gear is an overdrive gear, forces are exponentially greater on the motor while in 5th gear under boost, hence why the EGT's climb so quick in 5th.

If i were you (i used to have a turbo LS, so i speak from experience) make sure the airtex is indeed hooked up properly. (you should hear the pump purr when you turn the key to the 'on' position.) if its hooked up right, then re-check all of your connections, make sure the FMU vac lines are hooked up correctly and aren't leaking. Also, turn off the AFC until you get onto a dyno, tuning with your butt for boost is a no-no. With the 12:1 (blue, right?) fmu, and airtex pump hooked up correctly your car should be getting all the fuel it needs (slightly more than it needs, but at this point its fine).

Do you have an a/f gauge?
You mentioned you have no check valves, how are you working around that?

have fun.
edit: i just saw you were from NJ, maybe i could help you out some...

Tom


[Modified by Tomakit, 2:23 PM 11/8/2001]