Fuel cutt problem?

CRX2 · Post by **CRX2** » Sun May 13, 2007 4:00 pm

I streettuned a few cars now and they all have the same problem... AFR drops in fuel cutt -mode. Example: Driving , 5000 RPM, slowing down to about 2500RPM. TPS=0. AFR is above 22, but time after time the AFR drops till 12, without touching the trottle pedal. I had this problem with two D15Z6 mini-ME's, a B18C4 n/a CRX, and a B16a 6psi del sol. Both D15Z6's also complain about the fuel consumption. Both car do 11km on a litre off fuell... With the Cr*m* prgramm is was about 15km/litre... And for those who know what fuel costs in the Netherlands.....::shock:

Is it a bug, or am I just doing something wrong?

Post by **calvin** » Sun May 13, 2007 4:19 pm

during fuelcut it drop to 12 afr? I never saw that... What i did see... Just before you go into fuelcut the afr drops to 12 afr.... Then hit a total fuelcut(22 afr)... The first column determents how low it dips before hiting the fuel cut... You can adjust the delay with FuelCut delay in mSec(fuelcut settings) Yes i can image what happens.... If you have a fuel cut active it determents when fuel is restored @ which rpm based on TPS(decel fuelcut restore). I can guess your first column is to rich and try playing with fuelcut load(mbar) so... Normal fuel delivery -> Fuel cut detected(mbar/tps)-> Fuel cut delay(e.g. 600mSec/ fuel read for column 1)->Injector cut off(afr22)

CRX2 · Post by **CRX2** » Sun May 13, 2007 5:26 pm

So the problem should be gone when I adjust the 1st column? I didn't do much to the first collumns, AFR already was very close to 14.7.

Post by **Bugermass** » Sun May 13, 2007 6:44 pm

you say the fuel was close to 14.7 in the first columb? Then your idleing in the first columb? if thats the case then your map sensor is probably a bit off and thats why your having the FC issues, I had the same problem with a boost car I did where it would idle in the first columbs and it would go way rich off throttle when it was supposed to be in fuel cut.. Make sure with the key on engine off that your map reading and your baro pressure readings are very close.. If not you need to adjust your map sensor values to get it as close as possible.. when this is set correctly it'll idle in coulmbs 2 and 3 then your decel and FC should respond normally.. This may or may not be your problem but it sounds very simular to what I was experiencing..

Post by **Gaskleppie** » Mon May 14, 2007 1:20 am

Wait a minute! Now I know what you mean. I hade the same after changing my exhaust manifold. If your engine does'nt pull enough vacuum at 0% throttle, it can fall out of fuel cut. Just search for the right fuelcut mBar setting in the fuel cut parameter menu. After setting this right, my problem was solved.

Post by **calvin** » Mon May 14, 2007 8:40 am

if you see during a fuelcut the cell tracer(map tracer) jumps to the last column(which cause rich condition) you can try to lower the mBar of the first column. If the mbar in the first column is to high and the map sensor reads below that you can get an overflow.. then it jumps and read from the last column

hackish · Post by **hackish** » Mon May 14, 2007 9:54 am

In my opinion the fuel routine should interpolate to 0 if it goes below the bottom row and it should interpolate to static if it goes above the top. In your case I'm sure the cause is as others have posted but I also wanted to say that going rich just before fuel cut isn't always that bad. It can cause a nice smooth transition into fuel cut. The side effect is that it can cause small backfires as soon as the fuel cut occurs because now you have oxygen going into the exhaust manifold and the unburned fuel is still there. Like many things there is more than one right answer. -Michael

Post by **calvin** » Fri May 18, 2007 10:18 am

Yeah i need to fix that.. Put a check if map value < map value column 0 use map value column 1

SETI20 · Post by **SETI20** » Wed Jun 06, 2007 7:04 pm

Has this problem been solved yet? On my B18C4 problems have gotten out of hand. It started to idle really rough, and stutter and stumble between 550 and 1000Rpm's in an erratic fashion to the point where the car would actually stall. While driving in the low RPM range, the car would also stutter on occasion. Especially bad when I would let off the throttle, when the car would rumble and backfire. I noticed that previously, my car would pull about -10/-11 Psi at idle. With the current problems, it would only pull -7. But with the idle so erattic, it's hard to say if it's a cause, or an effect. Fuel consumption has gone down the drain. I couldn't even finish 280km's on 32 liters of fuel. I have left it to idle for about 10 minutes, and I noticed fuel and moisture dripping out of my exhaust. (It was highly flammable, so definitely a good amount of fuel in there) It seems problems have gotten worse and worse as the weather has improved. It's definitely gotten worse over time, because last winter/spring I was not having any issues at all. Weather related is a guess. Last week I have switched back to my old chip tuned with cr*me, and the problems have completely dissapeared. Including the strange MAP readings.

Post by **calvin** » Wed Jun 06, 2007 8:10 pm

SETI20 wrote:Has this problem been solved yet? On my B18C4 problems have gotten out of hand. It started to idle really rough, and stutter and stumble between 550 and 1000Rpm's in an erratic fashion to the point where the car would actually stall. While driving in the low RPM range, the car would also stutter on occasion. Especially bad when I would let off the throttle, when the car would rumble and backfire. I noticed that previously, my car would pull about -10/-11 Psi at idle. With the current problems, it would only pull -7. But with the idle so erattic, it's hard to say if it's a cause, or an effect. Fuel consumption has gone down the drain. I couldn't even finish 280km's on 32 liters of fuel. I have left it to idle for about 10 minutes, and I noticed fuel and moisture dripping out of my exhaust. (It was highly flammable, so definitely a good amount of fuel in there) It seems problems have gotten worse and worse as the weather has improved. It's definitely gotten worse over time, because last winter/spring I was not having any issues at all. Weather related is a guess. Last week I have switched back to my old chip tuned with cr*me, and the problems have completely dissapeared. Including the strange MAP readings.

this is BS. You know if fuel is dripping from your exhaust that it's not software related more like an injector staying open or bad wiring. I had the same. Something in my ecu fried. And injector 3 was staying open.. Fuel out of exhaust. Strange map reading.. DO you know what you are talking about. Have datalog with ectune when expiriencing these problems? Let rene send your software over.. Which software version do you have? I have to see it. Maybe old with a bug? Or map scalar maybe not good? I want logs, the current bin(including logs with a wideband) otherwise i see this as an single problem.

SETI20 · Post by **SETI20** » Thu Jun 07, 2007 4:23 am

Well Gee calvin. I feel so much better when you take things serious. I'm not an idiot, and I'm fairly proficient in analyzing problems. If I say this is what happens, this is what happens. I'm obviously not the only one with these strange problems. The B16A turbosol is having similar issues. I'll have Rene hook up my zeix to his datalogger again. All my previous statements were based on the logs my VAFC2 gave me. I also made a log with my zeix software. But I'll have to look that up if it's of any use to you. My ECu is fine. My wiring is fine. My injectors are fine. All problems went away when I put my old chip back in.

Post by **calvin** » Thu Jun 07, 2007 7:39 am

Well read above. I don't have shit with Zei datalog or apexi shit. I need: Rom version Rom+calibration Log with wideband attached when this is happening. If CRX2 tunes alone have it, there is not much to say i guess.

SETI20 · Post by **SETI20** » Fri Jun 08, 2007 5:39 am

I've been talking to synoptic for a while, and the strange MAP readings seem to be more of an effect from the erattic idle than an cause. Rene should be able to provide a log shortly.

CRX2 · Post by **CRX2** » Sat Jun 09, 2007 1:30 pm

SETI20 wrote:Well Gee calvin. I feel so much better when you take things serious. I'm not an idiot, and I'm fairly proficient in analyzing problems. If I say this is what happens, this is what happens. I'm obviously not the only one with these strange problems. The B16A turbosol is having similar issues.

- The smoke problem the del sol has, has most likely nothing to do with eCtune. - The fuelcutt problem both cars have can easily be solved, you know that....

All my previous statements were based on the logs my VAFC2 gave me

I don't trust Apexi's

I only trust my datalog software (ectune in this case) The strange MAP-values you have can not be caused by to much fuel. MAP measures air pressure. If your MAP is bouncing, then your RPM is bouncing too I guess? Same problem your Crome-chip had.... Maybe a hardware problem? OBD2 IACV?

If CRX2 tunes alone have it, there is not much to say i guess.

I don't think it is a ectune problem or bug. Tommorow I meet Frank/Gaskleppie and we are going to look into the problems I have. I hope it's something stupid and easy to solve...

I emailed all my logs/bins/cal files to Frank/Gaskleppie. He is going to look into it. I hope he finds something soo this problem can be solved.

Post by **Gaskleppie** » Sun Jun 10, 2007 4:55 pm

I've been talking to synoptic for a while, and the strange MAP readings seem to be more of an effect from the erattic idle than an cause. Rene should be able to provide a log shortly.

Talking about strange MAP readings..... Today I looked at 2 problem cars. The problem was about high fuel consumption and bad throttle response. Both were mini-me's and had simular problems. After a few kilometers driving and logging it was all quite clear to me. These cars were suffering from very low vacuum readings! Idle was at 360mbar, steady highway driving was at 750mbar and at 27% or more TPS I saw no vacuum at all! Pure hardware related problems!