I looked a little, couldnt find a thread on this. Don't flame me.

I want another guage to monitor my engine. I have an aem a/f and boost guage. I'm new to FI, and I dont particuly like how random the A/f reading is. At wot i'm at a steady 11.5, yes, but it flutuates so much. I take my foot off the throttle and it may jump to 16 for a sec then level off at 14.5 or so. I feel like can't rely on it.

Would it be a bad idea to take out the a/f guage and replace it with a egt and oil temp?

What i'd really like is a cylinder head temp guage to monitor "cold shock" to the top end. Any thoughts?

 

EGT will give you a HINT as to what your a/f ratio might be. **Higher then average** gas temperature could mean a Lean ratio and vice versa.

By a/f gauge tell me you mean Wideband..... because actual a/f gauges arent precise worth ****. Aem has been know to have wideband sensors AND gauge goes bad (Aem UEGO). If its possible try and swap it out for one you know works well and see if that changes anything. But a wideband is a must to monitor your A/f at all times.


** there edited...

 

http://www.avweb.com/news/maint/egt_..._198791-1.html

 

If you want to add a EGT, by all means... but I would not replace the AFR with an EGT. My AFRs will be in my cubby, so I'll only be actively monitoring them during spirited driving. I'll be adding an EGT ans swapping it into my pillar pod, so I can see quickly if it spikes.

 

This has been addressed in some other threads

Downfall to EGT gauges is there is no good benchmark for what is safe vs not safe.
Placement of the gauge means everything.....if you have the exact same setup as someone else, and have the gauge in 1inch different position in the collector vs that other setup, that could be a huge temp difference (like 300degrees)....

EGT would be ideal if you had one in each runner!!!!!!!!

Don't get me wrong, I'm not saying its a bad gauge to have, its just a hard one to judge against others.

Tom

 

i think oil pressure is the next most important, followed by fuel pressure. LIke Thom said, placement is key, so the only safeguard you'd have would be your own historical knowledge

 

It is not abnormal for your afr to fluctuate. It is normal for your gauge to go lean when you release your gas pedal. Pretty much the way you are describing how the gauge reacts is normal, whether you are boosted or not. As for the aem gauge or the sensor being bad I have had mine for 4 yrs and it is still dead on when I have the car on the dyno.

 

yes, afr is supposed to go lean when releasing the throttle.

But, I am experiencing something different. When releasing the throttle, my AFR runs to ~9.8-10, before going lean. dunno?

 

I don't see anything wrong with that. You're suddenly closing the throttle, which means there's going to be a shortage of air, and management hasn't adjusted yet. MAP/MAF's resolution isn't the speed of light.

What EMS are you using?

 

(And, I believe TPS is only used to _add_ fuel when the throttle is opened quickly)

 

f-con vpro, also have a uprev reflash

 

your AFR gauge is working exactly as it should - it reads things in real time, so the data will constantly change as your throttle inputs change

that is the most important gauge you have - I wouldn't replace it

oil temp is nice to have if you're tracking the car, or it's driven during very warm outside temps

I find EGT useless on a street car with a wideband in place - before widebands became so affordable, they were somewhat useful in that it could be used to correlate data with a datalogger. I think they have lost their practical use given the affordability of the widebands though

 

What? LOL. It fluctuates because of your foot! Welcome to the world of FI! It's a great learning experience for many of us.

Seriously, now that I have stopped chuckling (sorry), as others have said, the AFR is most important, then oil pressure. Either one out of whack (in the appropriate context) and the motor is finished.

I miss not putting in an EGT gauge, but only because I've gotten into tuning and I'd like to be able to confirm how the combustion cycle is altered when changes are made to the tune...

 

Get the oil temp and call it a day

 

I have to agree with oil press being a must have for any built/FI engine. ive gone through 2 AEM UEGO gauges, wasnt a wiring issue just bad gauges. Might have just been a bad batch cause its the most popular wideband Gauge ordered round here! and ive only seen a few including mine go bad. but then again i've had my share of badluck with other electronics.... such as the Apex'i AVCR boost controller... injector pinout fried upon startup installed following very precisely the diagram given by Apex'i for my specific application

 

This is the truth! back in my DSM days (on a budget) i used to street tune my s-afc based on my EGT temps and other variables. Considering affordable widebands are all over the market now-a-days, EGT gauges have lost thier worth. As stated earlier, having an EGT probe on each runner is ideal, but does anyone know which cyl. runs the hottest on the VQ? I remember on the 4G63, the #1 runner burned hottest and I used that as my failsafe, anyone care to offer factual insight to those who may find this thread on a search?

 

I'm runnin the stock ecu with GTM reflash and tune.