Cough and splutter, need help.

[Wolf_Tm250]

Hello,

at last I switched it on and it started ! Incredible... after one year
and a half of mods....

Let's go directly to the problem:

problem is that I'm not able to take the rpms to a fixed number, for
example at 2500 rmp, keeping the accelerator slightly opened and
steady... not simple for me to explain....
I can keep an rpm level ONLY if I accelerate and then shut and then
accelerate and so on... moving continuosly the pedal I can keep the
rpms 2200 to 2700, but if I would keep the accelerator slightly open
at a fixed position to reach 2500 rpm, then the engine fall down and die.

I even heard some "COFF-COFF CIUFF-CIUFF" sounds( in Italian... ),
like it was coughing...

I checked the intake for no leaks.

A map or a cam tuning ( too much overlap ) problem ?

1.5 years old fuel ??

Please give me some advices, so I can fix it more quickly

Thank you.

[l1ttle_d3vil]

so what sort of engine is this...?

[Wolf_Tm250]

so what sort of engine is this...?

Sorry !

3SGTE 3rd gen

but it was in my signature....

[Jebus]

sif your signature makes any sense.

[AE85coupe]

if the fuel is 1.5 years old then it will be stuffed, try better fuel

[fivebob]

Could be the fuel as it will have lost some of the more volatile components, but I suspect it's more likely to be your fuel map not being tuned correctly.

Have you changed things that would effect volumentric efficiency since the engine was last tuned?

Changes to cams, turbo, exhaust system, or intake manifold will alter VE and on a MAP calibrated engine will need the fuel map adjusting.

[Wolf_Tm250]

Have you changed things that would effect volumentric efficiency since the engine was last tuned?

Changes to cams, turbo, exhaust system, or intake manifold will alter VE and on a MAP calibrated engine will need the fuel map adjusting.

My M4 has inside a base map based on HKS 264, but I removed them and put in the JUN 264.

And I saw that Juns have a very different, steeper, ramp, so I think VE is very different now....

I degreed them to factory specs, 110 deg for the intake and 115 for the exhaust one.

I can keep the engine alive only if I tap tap tap on the gas pedal...
let me understand, what happen when I tap on the gas ?

I suspected I had to much overlap, making the MAP sensor to measure higher pressure than the real, and so enrichening too much the mixture...


Thank you !

[Wolf_Tm250]

if the fuel is 1.5 years old then it will be stuffed, try better fuel

For sure I'll put in new fuel !

[fivebob]

I can keep the engine alive only if I tap tap tap on the gas pedal...
let me understand, what happen when I tap on the gas ?

That activates the acceleration enrichment, which indicates that the engine is too lean. However, until you change the fuel it's not possible to say if this is really the case.

I suspected I had to much overlap, making the MAP sensor to measure higher pressure than the real, and so enrichening too much the mixture...

More likely the other way around, ie the engine is too lean, you would have to have a very rich engine to make it stall. To reduce the fluctuations in the MAP reading you could put a restrictor in the line, or even add a small accumlator to even out the pulses.

[Akane]

Make sure your resistor packs are plugged in.

[fivebob]

Make sure your resistor packs are plugged in.

Err, this is a Motec M4 equipped car, no need for resistor packs, not that lack of them would cause this problem, even on a std ECU

[Wolf_Tm250]

I can keep the engine alive only if I tap tap tap on the gas pedal...
let me understand, what happen when I tap on the gas ?

That activates the acceleration enrichment, which indicates that the engine is too lean. However, until you change the fuel it's not possible to say if this is really the case.

Ok, so do you think I could go in this way ?

First, change the fuel... and second play with the fuel trims to add fuel and see if it change ?

On my AF WB ratio meter, when I tap on the gas pedal, I'm getting number from 22:1 to 14:1, and the EGT are around 420 deg C....

[fivebob]

Ok, so do you think I could go in this way ?

First, change the fuel... and second play with the fuel trims to add fuel and see if it change ?

On my AF WB ratio meter, when I tap on the gas pedal, I'm getting number from 22:1 to 14:1, and the EGT are around 420 deg C....

I wouldn't tune using overall trim, but it would be ok to adjust it to see if that solves the problem at this particular point. Seems to me that the whole map will need tuning, either on the street if you have WB that you can log, or on a dyno.

Both those figures are too lean

Do you have a log of the WB that can be matched to RPM, throttle position and manifold pressure? I have some ideas of what might be happening but without a log it's pretty much just guess work.

[Wolf_Tm250]

Ok, so do you think I could go in this way ?

First, change the fuel... and second play with the fuel trims to add fuel and see if it change ?

On my AF WB ratio meter, when I tap on the gas pedal, I'm getting number from 22:1 to 14:1, and the EGT are around 420 deg C....

I wouldn't tune using overall trim, but it would be ok to adjust it to see if that solves the problem at this particular point. Seems to me that the whole map will need tuning, either on the street if you have WB that you can log, or on a dyno.

Yes, I'd like to adjust the trims ONLY to see if it's the right way....

FYI, maybe it's important...

- base map was made by Fensport, based on a similar engine ( CR 8.3:1 ) with same cams HKS 264

1) I changed the cams from HKS to JUN ( steeper ramps )
2) CR is way higher ( 9.5:1 ), so I retarded the ignition trim of 5 degrees
3) at the moment I only have the down pipe installed - btw I don't think it could cause so much difference, cause the rest of the exhaust i'm finishing to make, is free flow 3 inch.

- base map was made only to let me make a safe running in - after 1600 kms Adrian of Fensport would come here in Italy to fine tune it.

Problem is I have to be able to make the running-in !

Both those figures are too lean

I thought that they were quite normal with no load.
420 deg Celsius too lean ? What should I expect ?

Do you have a log of the WB that can be matched to RPM, throttle position and manifold pressure? I have some ideas of what might be happening but without a log it's pretty much just guess work.

If you will help me, maybe I can succeed in doing it !



Let me explain... if you remember, I have a Tech Edge WB Lambda unit, and thanks to Mr. Mc Coy of Motec, I put the values he gave me in the Lambda - Sensor Setup page, so to use my Lambda unit in my M4.
And I have the Advanced Log in it.

PS: lambda sensor at the end of the DP could read some oxygen, I think...
I'm going to finish the exhaust next Tuesday, according to my job.

Please explain me how to activate Lambda / rpm / tps / map logging, and what I have to do to let you help me !

Thank you !

[Wolf_Tm250]

Today I changed the fuel, put in Shell 99 RON, but had no difference.

I trimmed the fuel +12% and that made some difference, the 2500 rpm was more steady, btw i still had to tap some time to let it live... with no tap on gas pedal it'd died.

[fivebob]

Today I changed the fuel, put in Shell 99 RON, but had no difference.

I trimmed the fuel +12% and that made some difference, the 2500 rpm was more steady, btw i still had to tap some time to let it live... with no tap on gas pedal it'd died.

Is the engine properly warmed up?

[Wolf_Tm250]

Today I changed the fuel, put in Shell 99 RON, but had no difference.

I trimmed the fuel +12% and that made some difference, the 2500 rpm was more steady, btw i still had to tap some time to let it live... with no tap on gas pedal it'd died.

Is the engine properly warmed up?

It arrived till Engine Temp 76 deg C., but no difference from cold to hot.
Today it had much backfire, but this could be due to HC and oxygen in the DP, still without the complete exhaust...

[Wolf_Tm250]

Now my car is fine:
this message is for publicly thank fivebob...
he analized many logs I sent him, and then he sent me back new maps till it was good...

Thank you.