Low trim lean (136%) after turbo and fmic install

[tom04841]

Let me start out by saying that my trims were almost perfect before the swap. Now low trim is at 136%, mid is 101%. Haven't done much driving since the install, so don't know what the hi is.

I did a boost leak test. Leaking at bov gasket and tb elbow gasket. I suppose with no load, it could be drawing in unmetered air??

Also, the car sometimes sputters between 10inhg and 0 psi. Lower vaccum, it runs fine, and in boost is fine as well.

Sometimes stalls when i come to a stop. ISC is new.

Im stumped.

 

[KeltonDSMer]

Any boost leak under vacuum will allow air to enter the motor that is not metered. This would definately cause the engine to run lean under vacuum and rich under boost.

 

[oldman]

Im stumped.

This is a hard one.......wait I got an idea!!!! Maybe you should fix the leaks and finish the leak test.

 

[tom04841]

Maybe you should fix the leaks and finish the leak test.

I know this....i have every intention of fixing them. Those where the only 2 spots that had a leak, and they were very small. This was done at 20psi I might add.

Would the leaks cause the sputtering in that specific vacuum range and also for it to stall sometimes when when stopping?

 

[oldman]

What is your vacuum reading at idle? Fuel pressure reading? Was the 20psi (boost leak test) on the boost gauge or on the compressor regulator gauge?

 

[tom04841]

Vaccuum at idle is 18-20. Fuel pressure at idle is 37. 20 psi was on the compressor regulator guage

 

[oldman]

Fuel pressure at idle is 37.

Fuel pressure of 37 at idle with the vacuum hose attached? Did you change your base pressure on the Eprom?

20 psi was on the compressor regulator guage

Re-test and see what you get on the boost gauge.

 

[tom04841]

Sorry, base is 37 with hose off

 

[oldman]

Sorry, base is 37 with hose off

Are you just guessing? Do you even have a fuel pressure gauge? Are you saying after I asked you about the fuel pressure, you went out, started the car and pulled the vacuum hose off to get the reading? If so, what is the fuel pressure at idle with the hose on?

 

[tom04841]

No, i am not guessing. I am a mechanic...yes i have a fuel pressure guage. When i checked it, the hose was off. I rechecked it this morning at work, with line on, and it is 30 at idle with engine at operating temp.

 

[oldman]

No, i am not guessing. I am a mechanic...yes i have a fuel pressure guage. When i checked it, the hose was off. I rechecked it this morning at work, with line on, and it is 30 at idle with engine at operating temp.

You have a miner case of FPR overrun with the 190, something to keep in mind when you deal with fuel trim. Now how about that boost/vacuum leak test? Setting the compressor regulator to 20psi doesn't mean you're holding 20psi in the intake tract in most cases, I have helped poeple who's regulator is set to 20psi but the boost gauge doesn't even move at all.

 

[tom04841]

I will keep that in mind. As for the boost leak test, i wont have a chance to fix the leaks and retest till tomorrow night or sat morning.

 

[oldman]

I will keep that in mind.

Just to make it clear mainly for people who always say 190 will not overrun the stock fpr (not every day you run into a 190 user with a gauge ), with -18-20 inHG of vacuum, your fuel pressure at idle with hose attached should be 37 - 9 or 10 = 28 or 27 psi.

 

[tom04841]

Fixed leaks and boost gauge held for about 20 seconds before going to 0. In the process, i did find a leaking injector seal, which i couldn't fix yet because the parts store doesn't have them in stock.....they're on order.

It does appear that the sputtering has stopped....although i haven't driven mush necause its snowing and traffic is CRAWLING

 

[oldman]

What other leaks did you fix? Did the boost gauge ever got up to 20psi. Any leaks after the throttle plate, like the injector insulators, is a vacuum leak and will lean out your low trim.

 

[tom04841]

What other leaks did you fix?

The BOV gasket, and the tb elbow to tb gasket. i also replaced the tb to manifold gasket since it was unbolted as a preventative measure.

Did the boost gauge ever got up to 20psi.

Yes, once up to 20 psi, it took about 20 seconds to leak down to 0

Any leaks after the throttle plate, like the injector insulators, is a vacuum leak and will lean out your low trim.

Well here is the weird part. I didn't hear the injector isulator hissing during the leak test, but sprayed them all down with soapy water anyway. That is how i found the leak. With the car idling after the boost leak test, i sprayed some carb cleaner down there, and the idle didn't change. This suprised me since this is how i have always detected vac leaks.

 

[steve]

Well here is the weird part. I didn't hear the injector isulator hissing during the leak test, but sprayed them all down with soapy water anyway. That is how i found the leak. With the car idling after the boost leak test, i sprayed some carb cleaner down there, and the idle didn't change. This suprised me since this is how i have always detected vac leaks.

When the car is idling you have -8psi pulling down on the injector and 27 psi trying to spit the injector out of the fuel rail. The two work to help the injector seal.

Under boost the situation changes.

Steve

 

[oldman]

Also to add, though not as severe as if behind the throttle plate, leaks that you fixed before the plate will also draw in unmetered air which can account for your leaner low trim.

 

[tom04841]

Well, fixed the insulator, and rechecked for leaks.....NONE!!

BUT, the sputtering is still there. From 10 vac to 0psi. I watched my logger, and the my O2 trim is at 32% and O2 voltage holds at .97(PIG RICH) when it is doing this. I also get puffs of black smoke from the exhaust. When it is below 10 vac or above 0 psi , O2 cycles normally. O2 sensor is brand new

Low trim is down to 98%.

Any ideas?

 

[Ultimatedsm]

Running pig rich means either your fuel pressure is too high (Stuck closed FPR or FPR overrunned or pinched returnline), you have a leak fuel injector or you have a problem with the ignition system. Spray some water on your wires and check your plugs and re-gap them to 0.028". Why don't you post your log so we can find out whats going on with your car.