ETM Issue - Need Experts to Chime In

[troyhyde]

Hi folks, just got a Vida/Dice clone and first thing I did was do an ETM test. Car has had a few hiccups in the last year (failure to start on 4-5 occasions - eventually will start after a few attempts / weird flat spots while moving through RPM range, etc...). Well, the sweep test NUMBERS looked good with variation within 1.16 degrees - maybe even awesome numbers, I don't know. Looking at the graph, it looks like instead of one upward / downward continuous slope I have a half a slope up, a dip down, then back up. Same thing on the way down. Instead of a straight line I have very flat Z patterns up and down if you can picture it.

Additionally, in the Vida lookover I found that my pedal sensor was throwing a code. Thought that might be causing my Z. Not so, changed it with a good unit, code is no longer active, still have a funky graph and the car still doesn't feel quite right.

Any thoughts? Could the numbers look good despite the fact that the ETM is really not functioning correctly? It is an '04 replacement so it is probably due for failure.

Car is a '99 but I didn't want to put it in the earlier group, that forum is a tomb and nobody goes there!

[howardc64]

Post a pic of your sweep test probably makes it easier.

I did sweeptest on several 01 ETMs (I think same as yours in 99?). Here is a pic of good (page 3) and bad (page 4)

https://app.box.com/files/0/f/14495484/1/f_149940560

On the good, black line represent difference between 2 TPS. Scale is 0-0.8 degrees and difference was always lower.
On the bad, green and blue lines represent the 2 TPS angle values and black line scale is 70+ degrees. Big differences are shown.

If you have very weird graphs with low difference, its seem hard to believe both TPS is failing in the exact same place with matching errors. Anyway, take a screen shot and post a pic :)

[troyhyde]

Thanks for the reply, I have checked out your pics and anything else google would offer up. I believe I may be screwing something up in my interpretation. My curve (looks like one solid line) appears to be fine after analysis, the black squiggle below it has the jagged pattern I spoke of. I found a youtube video with some UK guy showing a "perfect" chart and mine looks virtually identical. Perfect being his words (certainly not mine). I'm at the absolute leading edge of the learning curve with VIDA.

Car has a new O2 but it doesn't really behave like I'd like it to, nice little sine curve is what I'm looking for (hence my search for a flaw/issue). I am beginning to lean toward a possible fuel pump or delivery problem or funky MAP sensor - no codes of course. Car has 155k and is on the original pump. I'm going to try and do some driving with live values on an OBD reader and see if I am leaning out severely at high RPM. LTFT is +9% which is much higher than I'd like to see in general.

I'll look into posting a pic, I am a bit computer illiterate so it may be beyond me.

[howardc64]

the black squiggle below it has the jagged pattern I spoke of.

Black lines won't show nice curvy shape since they represent the difference (in degrees). VIDA also auto selects the Y scale based on the max value it sees so your differences will bounce up and down the full Y scale. Anyhow, black lines will be naturally bounce all of the place like mine good ETM did. It was just bouncing between some minute differences.

Good to know your ETM is good, eliminate one variable while chasing performance issues.

[troyhyde]

Hey Howard, thanks for the comments, I am pretty sure my "interpretation" was the problem here... I didn't know how to read the chart.

Put my evap smoke machine on the car today and found a good sized vac/boost leak at the intake hose / ETM joint, the hard plastic hose had split in two spots where it slides onto the snout of the ETM.

Replaced the hose and the fuel trims are heading downward. Will be a few days before I can claim victory (does this ever really happen with these cars?). Ha!

Don't want to throw in too many variables at this stage so will give it a bit. Car has a 16T and aftermarket tune so is sure to be a little fiddly until all is hammered out..... Best regards and thanks for chiming in...