3 replies to this topic

[orac69]

Hello guys,

 

A little more help if you'd be so kind.  IAC / Stepper / Log file related.

 

'95 spi, all sensors are new, all pins to ECU have been checked, vacuum lines replaced, inlet manifold cleaned, new gaskets, new coolant sensor, new throttle cable, brand new TPS.  New O2.  New 88 thermostat.  Stepper motor checked resistance etc and the plunger lubricated / moving.  There is NO sensor on the pedal end on this car.  Plugs, leads are new.

 

- I can connect to the ECU with Webmemsfcr (by andrew jackson) just fine.  

 

- Using the same cable, same laptop (windows 10) I cant connect using Leopolds mems-rosco3.  It just gives an error something about the port being invalid (which it isnt). Im gonna try another laptop.

 

- Webmemsfcr seems to connect / work fine - but when you turn the ignition off, you lose connection and I have to restart the browser and connect again which is a real pain.   I cant find the old non web version (github version has gone) - if anyone has a working link Id be grateful!

 

Ive done the ignition on, move the cam fully, ignition off to get the stepper indexed.   The initial IAC value (which shows in a green box on screen by the way) always seems to show in the 90's....  

 

First issue;  No matter how long I run the engine for I dont seem to be able to get it past 85 degrees temp. Sat at idle for 20 mins, rev to 2.5k for a few minutes, go for a decent drive - still max 85.  The CTS is brand new, just replaced one I thought was bad (but isnt), manifold isnt blocked.  No air leaks, cable fine. 

 

Second issue; IAC value.  I have been trying to set the stepper value to 30-35, but no matter how hard I try I just cannot get the value to go lower than approx 45 with the engine up to temp at my max of 85.  Also when I turn the IAC screw (ive had it all the way in, all the way out by the way), webmems doesn't immediately show the value changing at all (as I believe it should).  The changes in values only seem to be reported when I drive it, or engine off and restart (pain).  

 

Third issue; Car drives sort of ok, revs quite nicely BUT has a real hesitation / flat spot around 2-3k and when you lift off the throttle to coast - it seems (and sounds) like its "lumpy" / misfiring at these low revs.

 

The idle seems slightly high @ 1300 or so.

Lost motion gap is bang in the middle.

 

I wonder if anyone would be good enough to cast their eye over my last log file (attached), see if they can see anything obvious - and any suggestions on what I should do next.

 

Im wondering if webmemsfcr isnt reporting quite right....  Which is why I was trying to run mems-rosco3.

 

Thanks everyone for your time.  Appreciated.

Attached Files

•  2026-10-06-112732-99000203.txt   155.37K   2 downloads

Edited by orac69, 06 October 2026 - 12:16 PM.

[orac69]

A bit of an update on the logfile / query.

 

I found a thread on here where someone provided a logfile, and @genpop commented that the throttle angle was off - anyway, I have compared my log with this log and have found significant differences in some of the values - some of mine appear to be "static".    So either webmemfcr is reading wrong, or I have something badly amiss...

 

For example, in the log file generated from a 5 minute drive from stopped, with the engine already warm;

 

ambient temp on mine shows constant 200   vs  28  (plus or minus)  in the other persons

fuel temp - constant 200    vs   30

throttle pot - (approx) 2.x    vs  0.7x 

throttle angle - (approx) 53.x +    vs  19 approx

lambda sensor frequency - constant 255 vs 20's

lambda sensor duty cycle - constant 255 vs 50-80

short term fuel trim -  minus 18 or so on mine vs +90's

Im still trying to get mems-rosco running to get a log from that, and I will reset the ECU too and start again, but does anyone have any idea why I would have such crazy values?

 

Thanks!

[orac69]

Another update.  Up to temperature, running Memsfcr  (Webmemsfcr and Rosco wont run for me)

 

I simply cannot get the IAC value lower than 80 or so, with revs staying around 1100/1200.   Even with the screw wound all the way in - so it isnt even touching the plunger...!   See pic.

 

Ive reset the ECU, run it again, same values.

 

Any ideas?   Stepper motor bad even though its functioning and the windings test out...??

 

 

 

 

Attached Files

•  IMG_20261008_122854.jpg   36.89K   2 downloads
•  IMG_20261008_122928.jpg   44.72K   2 downloads

[orac69]

I think (hopefully) ive found the problem....

 

 dodgy-stepper.jpg   42.25K   2 downloads