PDA

View Full Version : EGT readings dont match wideband



Juggy
09-06-2008, 02:15 AM
ok i think i got a problem here.

my AEM wideband is reading about 10-11 afr at idle :yuck:
EGTS when first fired up are around 1700???? (wideband reading 10.5ish)

car warms up some and EGTs come to rest at 1400

I was told this is lean at idle, and am looking for about 1100-1200

but the wideband isnt reading with them #s according to EGT. its a brand new wideband, i powered it up b4 and had it exposed to fresh air b4 installing into the downpipe, or is there another way to calibrate them???

maybe my EGT probe is messed? its placed in the corner bend (#4) on the SS TU header.

fuel pressure is also WAY down, like 30-35psi?!?!? car puffs some black smoke when the FP is up at stock, and u rev it up and she wants to backfire. this is a 3 bar cal for 2.2 and G head. runs the car MUCH better then the stock TII SMEC.

not too sure whether to trust the wideband or the EGTs at this time??? im also thinking I could have a bad o2 sensor, as the car didnt seem to run any worse when it was fired up with it unplugged

contraption22
09-06-2008, 08:34 AM
I hav the same issue with my EGT. I installed the probe in that area and have noticed high egts. Turns out that spot will register pretty high temperatures.

I pretty much ignore my EGT anymore. I tune by the wideband and knock sensor.

Rich conditions will also raise EGT compounding the problem, as fuel is still burning in the exhaust manifold.

8valves
09-06-2008, 10:46 AM
As Mike pointed out, 1700 EGTs can be a rich or lean condition. Maybe your cal is that far off?

GLHNSLHT2
09-06-2008, 11:22 AM
I hav the same issue with my EGT. I installed the probe in that area and have noticed high egts. Turns out that spot will register pretty high temperatures.

I pretty much ignore my EGT anymore. I tune by the wideband and knock sensor.

Rich conditions will also raise EGT compounding the problem, as fuel is still burning in the exhaust manifold.

+1, watch the wideband and knock sensor, EGT's be dammed! :)

Juggy
09-06-2008, 11:43 AM
yes im leaning towards the fact that the fuel is still burning in the exhaust creating these EGT readings, guess I wont find out whats really happening here until I can get some driving time on it

hopefully getting 2 the track 2night, get some runs and dial things in!!! shes not plated so I cant bring it for a rip in town (unless i really wanted to be courageous) but Ive already had a couple complaints from the neighbours when I took it for a cruise down the street (open downpipe burring the needle on the speedo heheheheh).

Speedeuphoria
09-06-2008, 05:36 PM
EGT raises when too rich or too lean.

Agree with others, trust the wideband and hopefully the EGT will give you useful info but it very likely may not ever give you the info that you are expecting(or comparable to others). The best thing is after awhile you will get to know your EGT on your setup and could use it to spot issues or make changes.

MopàrBCN
09-07-2008, 08:03 AM
I think you should definetly look at your cam timing as well. I have been told that retarded cam timing can cause exactly this fenomen, by burning excess fuel in the manifold, and this in turn could, if correct, be a very logical explaination why my turbo housing, exhaust manifold and Swingvalve cracked under excessive heat........

I am only happy if my EGT's and A/F Readings match up!!!

moparzrule
09-07-2008, 12:42 PM
There's no way that EGT gauge is correct, something is off whether it's the gauge or the probe. Probably the gauge.

The issue is indeed in the cal. With your taft S3 cam you are idling at low vacuum. Less vacuum equals more fuel, you need the cal revised to have the correct idle amount at the correct vacuum amount that you have an idle. If you are only idling at 14'', it's putting in over twice the fuel than if you were idling at 20.

ssheen
09-10-2008, 10:23 AM
Like MopàrBCN says, I would check the cam timing some. Once it warms up it cools off a bit, could be linked to too rich. I would be leaning towards a bit too much fuel with a cam timing issue. The startup/cold fuel tables put more fuel when cold. Which with the cam timing off could explain what you are seeing.

t3rse
09-11-2008, 11:14 AM
There's no way that EGT gauge is correct, something is off whether it's the gauge or the probe. Probably the gauge.


Probably not the case...10-11 is wayyyyy too rich at idle: burning fuel in the manifold

also keep in mind that dropping fuel pressure down can cause atomization problems leading to an incomplete burn and excess fuel to be measured.

Juggy
09-13-2008, 02:53 PM
car pulled a code 54

HEP sensor, car is guessing at injector timing

will this cause a rich problem???? I swear the car is stuck in open loop


fuel pressure is now at 45 static, dropped down 10 from base pressure.

felt like it hit a cutout (not boost related) at WOT the one night at 4K RPM....but after dropping pressure and boost is now holding 16psi (had OB problems) it seems to have gone away..unless it was because i eased into the throttle instead of just mashin it??

moparzrule
09-13-2008, 07:04 PM
Check the shutter wheel in the distributor to see if it's wobbly.