Tuning Headache

IGOTASTi

System Operator
Staff member
Bzktmoto, sorry we have been slammed at the shop with all this snow. Let me see if we could get you in and tell you what's wrong with the car. What is your schedule like for this week?
 

Bzktmoto

New member
Thanks CRZ, but today Clark told me I fixed the leak. Don't ask me how haha I must of did something while messing around in the engine bay. I then asked him about my high idle and he said he raised it on purpose so that helped ease my mind. So hopefully once I get my revised map back from him i should be good!
 

IGOTASTi

System Operator
Staff member
Okie dokie glad you got it fixed! Hope everything works out. Let me know if you need anything.
 

Bluedemon_II

New member
Are you sure your not getting the "Don't bother me any more response"? Take a log and post it here to see it if you can. It's nice to have multiple opinions.
 

Bzktmoto

New member

Bluedemon_II

New member
Second and third logs show Massive Fuel trim corrections on the lean side. The Ecu is adding almost max fuel at low rpm partial load. Ither your intake is badly tuned or you have a leak between the maf and the turbo inlet.
 

Bzktmoto

New member
Hmm, how do you know its between the MAF and the turbo inlet? I've pressure tested the inlet without the maf pipe on more times than I can count. CRZ maybe I should bring it down to your shop.
 

HolyCrapItsFast

Drinks beer!
Hmm, how do you know its between the MAF and the turbo inlet? I've pressure tested the inlet without the maf pipe on more times than I can count. CRZ maybe I should bring it down to your shop.

I expained it in my first reply. Still if you are absolutely sure you are leak free then it points to three possibilities IMO. Bad MAF scaling. A bad MAF sensor or a bad o2 sensor. Your idle trims are beautiful so I would start with investigating the MAF first.

As for the waste gate it is on the exhaust side so if you pressurize the intake system it should have no effect on the EWG, It sounds to me like pressure from the intake is leaking past the diaphragm of the EWG into the exhaust side but I'm no expert when it comes to EWG's. I would pressure test the Vac/Press line leading to the waste gate itself to rule out a leak in the diaphragm.

As for the log can you post one so we can have a look? I would not be so concerned with MAF voltage. 1.30 sounds about right to me for an idle. I would however be concerned about the AFR and both fuel trims. If you could make a log with the condition you are seeing that would help allot.

If you have a leak after the MAF sensor but before the turbo it will show in your logs with exaggerated high fuel trims and lean AFR's. If your leak is after the turbo you will see the same condition when at idle but go rich under boost.

George
 

Bluedemon_II

New member
Fuel trims is what your ecu uses to control differences in fuel quality and air density changes when the values in the environmental tables aren't accurate. It references the Front oxygen sensor for closed loop operations, it measures the oxygen content in the exhaust and compares the value obtained with the value given by the maf table. If this value is different, the ecu will add or take fuel accordingly to achieved stoichiometric parameters.

The Long term Fuel trim adjusts fuel for larger periods of time While short term changes on the fly. If the Short therm trims can't keep the fueling in check, Long term trims start adding up values to even things out. The STOCK max or min fuel that the ecu can take out is 14.5 + o -. You have 14.5 in some driving areas and that means that your ecu is attempting to add 14.5 percent more fuel because the value in the maf table is wrong. Of course the value of the table could be spot on and you could have a faulty sensor. Maf sensors rarely die, oxygen sensors on the other hand are sensitive.

A general tuning guideline is that the Long term fuel trims should be as close to 0 as possible, with a 5 + or - error of acceptance.

Hope that this helps.
 

HolyCrapItsFast

Drinks beer!
What are fuel trims and what are they normally?

If you have a look at the last two columns in your logs, they show you fuel trims. Fuel Trims are an indication of how much fuel the ecu is adding or taking away to compensate for changes in the environment. The values are a direct % of mass of fuel that is being applied to achieve the proper amount. Fuel Trim Short is an immediate change in fuel and is like a fine adjustment. Fuel Trim Long is learned over time and is applied based on conditions that have been seen often. It is like a course adjustment. To see the whole picture you need to look at them both together. So look at the sum of FTST and FTLT together.

Check out this thread. It may help explain some things for you.:thumbsup:
 

HolyCrapItsFast

Drinks beer!
Sorry Blue... You beat me to the punch. But it's the same jist :lol:
 

HolyCrapItsFast

Drinks beer!
I'm not particularly happy about any of them...

In the driving log I see high fuel trims and poor tip-in. The good news is the long term trims are right around 0-1 but with the high short term fuel trims I can't see them staying there for long. There is also some low level knock but that is not cause for concern right now.

In the WOT log I see your IDC are above 108%. I think your injectors are too small and coupled with the high fuel trims you run the risk of leaning out. You are currently running at the top of your injectors.

In the idling log your long term fuel trims could be much better than that.

Over all I would say that, A. You need bigger injectors, B. MAF scaling needs to be tweaked quite a bit.

Again all this assumes there are no mechanical issue.

I would be interested to know what the vacuum pressure is at an idle.
 

Bzktmoto

New member
I had PE850's but Clark told me they were a waste and I didn't particularly need them at this point so I sold them. I'll have to ask about the fuel trims and my vacuum according to my Defi gauge is inbetween 20-22 mmHG IIRC.
 

HolyCrapItsFast

Drinks beer!
I had PE850's but Clark told me they were a waste and I didn't particularly need them at this point so I sold them. I'll have to ask about the fuel trims and my vacuum according to my Defi gauge is inbetween 20-22 mmHG IIRC.

Vacuum is good which indicates a healthy bottom end and no leaks after the throttle body. You already tested the rest of the system for leaks so I would say it is all tuning and injectors at this point.
 
Top