Intermitant misfire

[toger13]

Hi Guys just after picking your brains

A bit of background info
I have a Citroen Saxo 1.6 16v running a GEMS EM36
its running basic sensors

MAP
Crank
Inlet Air Temp
Throttle position
Knock (altough its not used)
Lambda

Thats about it I think Im not well up on the ins and outs of the gems so dont shoot me down lol

Im having an intermitant miss fire

Is all ok then all of a sudden it starts to run really lean and missfire probably due to the lack of fuel also cuts out at idle again suspect from lack of fuel

I have been round all the wiring twice and cant find any issues connections are all good

On the laptop every thing seams to be inspec its not temp related does it hot and cold

The fuel pressure is good i have checked this with the gauge on my fuel pressure reg

Then it goes back to normal and every thing it ok disapears as quick as it statrted

I thought it was down to the injectors initialy as i got them second hand and had them cleaned so i have put a brand new set in but the problem has returned

I have come to the conclution that it could be an intermitant crank sensor fault what do you think?

Im not sure how the gems reacts to faulty sensors?

Si

[RickS]

Hello,

Yes it could be an intermittent crank shaft sensor fault, to find out we can do some logging in the ECU. It sounds like you already have the software? Is it GWv3 you have or GWv4? if you have GWv3 i would reccommend upgrading to GWv4 (if you haven't already tried the software) as it's free for all GWv3 customers.

Whilst connected to the ECU go to the Logging menu > ECU Internal Logging > Erase Log > Import and select the file attached to this post. The logging file is setup to be around 18 mins long, you don't have to use all of this if the fault occurs and then goes away within 18 mins, but can be set for longer if needed. The logging conditions are set to always log so the ECU will start logging as soon as you put this setup in.

Send me the log and the calibration when your done and i can have a look.

Thanks
Ed

[toger13]

Thanks for your help im running GWv4 i will try get out in it tomorrow evening and download the log

Thanks
Si

[toger13]

Sprung a coolant leak last night before the fault occured so just waiting to a new thermostat housing and i should be able to get the log to you hopefully

Thanks
Si

[toger13]

Hi guys i think i have done the log files correctly

i repaired the coolant leak the other day and did a full log while driving with no faults i have attached this as a comparison

i started it this morning and it took a while to start then it was running poor so this evening i put the lap top on and cleared the log and started it again took alot of starting when it did start the reves were erratic then at about 30 degrees ish it seemed to clear and the revs incressed to about 1200 rpm till about 60 degrees where the revs normally drop to about 800rpm it just went lean and cut out i then restarted it but after a few seconds cut out again

hopefully i have done it properly lol

Thanks
Si

[toger13]

Any one had chance to have a quick look i cant see any thing obvious but its not somthing i have done before lol

Thanks
Si

[toger13]

right guys i have been playing with it today

again took abit of starting then its ok for a few mins while warming up then it cut out im running pico iwp006 injectors so about 225cc to get it to run i had to increase the fuel map grid i highlighted the 800 and 1000 rpm rows to the bottom and did a percentage change i incresed it by 20%

that was ok but after about 20mins mayby a touch more idling looking at the values it the went lean again and started to stutter so i had to increase it another 20% to get it to run lambda 1

before when it was intermitant it seemed to come and go it was like some one flicking a switch so it sugests an electrical fault rather than mechanical but now its doing it all the time

Any ideas?

Thanks
Si

[PQatPIT]

May we see your calibration? Not so easy to find a problem without it.

[toger13]

Ye sorry didnt read that bit

Si

[RickS]

Hello,

Please try several things.

1) upload EM36 00V89 which you can download from the downloads section of the website here: http://www.gems.co.uk/?content=pages&id=firmware then upload the attached calibration. Once you have downloaded the firmware go to ECU > upload firmware in GWv4 and select EM36 00V89.

2) Then adjust the option TPS Min so that the parameter Throttle reads 1 % (You will have to lower it to archieve this value)

3) during warm up adjust the start fuel coolant table to correct the lambda.

Sorry it took so long to get back to you i didn't get an email telling me you had responded as i usually do.

Thanks
Ed

[RickS]

Please Use attached cal instead.

Cold Idle was 800 + 1300rpm and idle exit speed was 3000 rpm so idle spark scatter table would have been going crazy.

Thanks
Ed

[toger13]

Cheers for that I will get on to it tomorrow evening

Si

[PQatPIT]

"would have been going crazy."

Injector assignments are a bit strange, too. Also, User Out 2 and WG out are assigned both to PWM8, and other things. Somewhat untuned fuel map, ehh? Wideband lambda sensor is used for fuelling feedback all the time, I'd use it at N/A area only and below eg. 4000rpm.

Boosted engine? What kind of ignition system? Dwell times seem kinda heavy.

[toger13]

Hi guys sorry to be a pain i cant download the firmware it just opens to a screen full of random letters rather than a down load screen i can open some of the others to save but over half of them do the same

Is there any chance some one could email it to me at si300zx24v@aol.com please

since it was mapped i have changed from 4x 668cc injectors to 4x 225cc primarys and 4x668cc secondarys so i have been playing with the fuel map but mainly below 3500rpm as im running it in after a rebuild i havent messed with much else.

it was running the standard saxo vts coil system but i have changed to MSD Blaster coil for a ford ztec

i take it the settings arnt looking too good?

Thanks for your time
Si

[RickS]

email sent

No,

The calibration doesn't look too healthy as a whole, These spikes and dips in the map it was applying lots of retard below 3000 rpm to try and keep the thing in idle. It was also applying coolant based retard etc.

GWv4 has the ability to convert fuel maps from one injector size to the next. If you have the original calibration then i can roughly calculate a new one which should get you within 0.05 target lambda. I will also adjust the rest of the settings for you.

Hope this helps
Ed